Dyno - 447 RWHP on CIS
08-21-2003, 04:20 PM
#46
Nordschleife Master
I would prefer the oil to be a little warmer, and the WGI day was in the 70s and fairly dry which was similar to the log I pulled from last year. On a warmer day, it runs closer to 200 degrees, but I've yet to see 210. The center mounted cooler makes a huge difference.
250 degrees is too hot.
The 3.2 Carrera head temp sensor is a stock Porsche part and was retrofitted to my 930 head by machining into the head and tapping it. The head needs to come off to do this and you need to make sure it clears the scavage pump, especially the larger aftermarket one. I had the sensor sent out and calibrated and built a table in one of the temperature inputs on the MoTec M48.
250 degrees is too hot.
The 3.2 Carrera head temp sensor is a stock Porsche part and was retrofitted to my 930 head by machining into the head and tapping it. The head needs to come off to do this and you need to make sure it clears the scavage pump, especially the larger aftermarket one. I had the sensor sent out and calibrated and built a table in one of the temperature inputs on the MoTec M48.
08-22-2003, 01:13 AM
#47
Rob,
I think I owe you a reply. I've been on vacation an just back.
I've read your recent posts and although I agree with you about EFI verses CIS, I do feel you are putting too much hope on the EFI system. If you want throttle reponse, the Carrera manifold is not a good solution in a Turbo application.
Another huge factor is the Ignition type and if large single Injectors are used, Idle and throttle transistion quality becomes very poor with non sequential fueling. These 930 engines with these huge hemi chambers require completly different approaches to EFI, than say a 4V Pentroof design. Ignition type, Injector placement, Intake manifold size, and sequential/non sequential fueling will all play aHUGE part in your throttle response. Forget the HP, you won't get there very quickly, and before you dothe other cars will be long gone. Remember, big HP is bragging only. The time it takes to get there is racing.
I can only recommend talking to Neil @ PD, (949 646 7461),who built my engine. It does not make big HP, (500), but it drives like a hot rodded NA engine. Everyone who has driven it remarks how quickly it accelerates.
Spend the $ once.
I think I owe you a reply. I've been on vacation an just back.
I've read your recent posts and although I agree with you about EFI verses CIS, I do feel you are putting too much hope on the EFI system. If you want throttle reponse, the Carrera manifold is not a good solution in a Turbo application.
Another huge factor is the Ignition type and if large single Injectors are used, Idle and throttle transistion quality becomes very poor with non sequential fueling. These 930 engines with these huge hemi chambers require completly different approaches to EFI, than say a 4V Pentroof design. Ignition type, Injector placement, Intake manifold size, and sequential/non sequential fueling will all play aHUGE part in your throttle response. Forget the HP, you won't get there very quickly, and before you dothe other cars will be long gone. Remember, big HP is bragging only. The time it takes to get there is racing.
I can only recommend talking to Neil @ PD, (949 646 7461),who built my engine. It does not make big HP, (500), but it drives like a hot rodded NA engine. Everyone who has driven it remarks how quickly it accelerates.
Spend the $ once.
08-22-2003, 02:37 AM
#48
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m42racer;
Throttle responce? 3.2 manifold? What did Porsche use on the 993TT. Its very similar to a normally aspirated manifold.... If you want throttle response, lower your turbine housing A/R and re-do your headers. Hell, scrap the single turbo and twin turbo your engine. As you said "Spend the $ once"
Throttle responce? 3.2 manifold? What did Porsche use on the 993TT. Its very similar to a normally aspirated manifold.... If you want throttle response, lower your turbine housing A/R and re-do your headers. Hell, scrap the single turbo and twin turbo your engine. As you said "Spend the $ once"
08-22-2003, 04:05 PM
#49
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Whoa, can of worms just opened...
M42Racer, thanks for your thoughts. Please respond to my PM if you get a chance -- I'd like to correspond with you.
You raise a very interesting issue that I'm not well informed about. I've been told that the 930 manifold is a poor design for airflow in general. The 90 degree bend is not conducive to good flow characteristics for a turbo motor or any other. However, it has a relatively small volume, which may be advantageous, and of course, it's there -- if you start with a stock 930 like I did. The reason I've shyed away from it is that the price of the injector blocks (for electronic injectors) that are compatible with the 930 manifold is considerable, and by the time I have custom fuel rails and other necessary details, I've spent much more than I would for a set of 3.2 manifolds complete with fuel rails, pressure regulator, damper, and so forth. It really came down to cost - and it seemed like bad logic to spend *more* to use a 930 manifold for EFI, which has a lower flow potential. (0f course, the total cost of a 930 setup might be less if you don't have to replace or modify the rest of the intake setup, such as the IC).
Please tell me why you think the 3.2 manifold is poor for a turbo application. Why does it produce poor throttle response and why would the 930 be better? And by the way, I'll likely be going with sequential EFI and a good twin plug ignition system, if that affects your advice.
As I've indicated before, I'm not in a horsepower race here at all. I want a fast track car with a license plate on it. But if I want to join a horsepower race in a year or two, it seemed like a better idea to go with the 3.2 manifold now, rather than be limited by the 930 (the Spend $ once theory). I'm told by Dennis Aase that it is nearly impossible to push more than 550 hp though the the 930 manifold. He described that threshold as "a brick wall." My goal is a maximum of 550 right now, with a usable 480 to 500 on the track, so I can run with turbo I own (thanks, Kevin) without having to replace it for the third time in 600 miles. As you can see, I have violated the "Spend $ once" axiom. I'm still trying to repent.
And Kevin, I didn't understand your response to M42. Are you disagreeing with him about his statement about the 3.2 manifolds? I realize there are always better ways to do things, and that you've been pushing the envelope with creative designs (which I truly admire), but I'm feeling rather conservative right now. This is a big enough change for me. I just want something that's tried and true but has some room for growth. If there are other designs that may be slightly better, but require considerable fab work and develpment, I'm not so interested right now. Twin turbos would be nice for some, but I'm not doing that now -- I've got to stay focused on the single turbo plan so I don't have a life of franks and beans.
M42Racer, thanks for your thoughts. Please respond to my PM if you get a chance -- I'd like to correspond with you.
You raise a very interesting issue that I'm not well informed about. I've been told that the 930 manifold is a poor design for airflow in general. The 90 degree bend is not conducive to good flow characteristics for a turbo motor or any other. However, it has a relatively small volume, which may be advantageous, and of course, it's there -- if you start with a stock 930 like I did. The reason I've shyed away from it is that the price of the injector blocks (for electronic injectors) that are compatible with the 930 manifold is considerable, and by the time I have custom fuel rails and other necessary details, I've spent much more than I would for a set of 3.2 manifolds complete with fuel rails, pressure regulator, damper, and so forth. It really came down to cost - and it seemed like bad logic to spend *more* to use a 930 manifold for EFI, which has a lower flow potential. (0f course, the total cost of a 930 setup might be less if you don't have to replace or modify the rest of the intake setup, such as the IC).
Please tell me why you think the 3.2 manifold is poor for a turbo application. Why does it produce poor throttle response and why would the 930 be better? And by the way, I'll likely be going with sequential EFI and a good twin plug ignition system, if that affects your advice.
As I've indicated before, I'm not in a horsepower race here at all. I want a fast track car with a license plate on it. But if I want to join a horsepower race in a year or two, it seemed like a better idea to go with the 3.2 manifold now, rather than be limited by the 930 (the Spend $ once theory). I'm told by Dennis Aase that it is nearly impossible to push more than 550 hp though the the 930 manifold. He described that threshold as "a brick wall." My goal is a maximum of 550 right now, with a usable 480 to 500 on the track, so I can run with turbo I own (thanks, Kevin) without having to replace it for the third time in 600 miles. As you can see, I have violated the "Spend $ once" axiom. I'm still trying to repent.
And Kevin, I didn't understand your response to M42. Are you disagreeing with him about his statement about the 3.2 manifolds? I realize there are always better ways to do things, and that you've been pushing the envelope with creative designs (which I truly admire), but I'm feeling rather conservative right now. This is a big enough change for me. I just want something that's tried and true but has some room for growth. If there are other designs that may be slightly better, but require considerable fab work and develpment, I'm not so interested right now. Twin turbos would be nice for some, but I'm not doing that now -- I've got to stay focused on the single turbo plan so I don't have a life of franks and beans.
08-22-2003, 08:36 PM
#50
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Rob,
You realize going EFI that it will test your patience and wallet? What you sell off is a drop in the bucket compared to what you will spend unless you can do most of the work yourself. THERE IS NO DOUBT THAT EFI IS WAY BETTER THAN CIS. It's cool that you have the hp bug just as long as you know what your getting into. Make sure you talk with the best in the business to get your game plan down before spending gobs of money.
Brent
You realize going EFI that it will test your patience and wallet? What you sell off is a drop in the bucket compared to what you will spend unless you can do most of the work yourself. THERE IS NO DOUBT THAT EFI IS WAY BETTER THAN CIS. It's cool that you have the hp bug just as long as you know what your getting into. Make sure you talk with the best in the business to get your game plan down before spending gobs of money.
Brent
08-22-2003, 10:30 PM
#51
Rennlist Lifetime Member
While the 3.2 intake can benefit greatly by being flowed its basic design was carried over to the 3.6NA and 993TT and the 996TT. The 3.6 design utilized a removable throttle body which made the switch to the 993TT easy (also a change in bolt pattern and injector attachment). It now has shown up in the 996TT. Both the 993TT and 996TT doesn't utilize the tuned chamber through the bottom pot in the intake. My point is while the 3.2 can benefit from a few attention to detail issues, but the over all design is fair and works fine. The design is still working for the TTs today.
08-23-2003, 03:08 AM
#52
Rob,
The 3.2 manifold will require some fabrication etc to fit. Also, the 993 and other manifolds,(variants) had the secondary butterfly and runner control. I have driven cars with the 3.2 manifold and IMO, the throttle repsonse was poor. The volume is huge compared to the 930 manifold. Yes there is a limit to the 930 manifold, and I only wanted 500HP. The only reason the 3.2 manifold is used is because its thought as the "only" one avaialble. I'm not sure about the reasons for the 3.2 because of the 993/996 use. These are street cars, with street car response. True response is way better than these engines produce. Keep the manifold as small as possible so that the volume is held at vacuum for the least amount of time. If you are intending to use large nozzles, (required for 500+HP)the transistion from off throttle to on, accel factor will become very poor with Injector control and manifold pressure changes. No air and big nozzles give very poor transistion. At least with the 930 manifold the time required to charge the manifold from vacuum to positive pressure is less. Intercooler volume and fitment all become factors also. I am not advocating the use of the 930 manifold, just that I used it and have 500 HP with way better response than the 3.2 manifold would give. Ideally, multi butterflies and Plenums are best, but the cost is high.
As stated, get all the info you can. The main parts are easy to price, its all the little pieces that add up. Expect to pay some good $ for Intercooler mounts, throttle body reversing etc. It all can be done cheap, but don't lift the bonnet to show off your masterpeice if it looks like crap. You get what you pay for.
So, manifold volume, Injector size, fabrication costs, Ignition type, EFI fueling firing etc, all will play huge parts in your final outcome.
I will email you this weekend to discuss my own choices. I do have 2 regrets. Not going to the 98.00mm bore, and my Intercooler is too small for long power runs. The Intercooler is easy to cahmge compared to the bore.
The 3.2 manifold will require some fabrication etc to fit. Also, the 993 and other manifolds,(variants) had the secondary butterfly and runner control. I have driven cars with the 3.2 manifold and IMO, the throttle repsonse was poor. The volume is huge compared to the 930 manifold. Yes there is a limit to the 930 manifold, and I only wanted 500HP. The only reason the 3.2 manifold is used is because its thought as the "only" one avaialble. I'm not sure about the reasons for the 3.2 because of the 993/996 use. These are street cars, with street car response. True response is way better than these engines produce. Keep the manifold as small as possible so that the volume is held at vacuum for the least amount of time. If you are intending to use large nozzles, (required for 500+HP)the transistion from off throttle to on, accel factor will become very poor with Injector control and manifold pressure changes. No air and big nozzles give very poor transistion. At least with the 930 manifold the time required to charge the manifold from vacuum to positive pressure is less. Intercooler volume and fitment all become factors also. I am not advocating the use of the 930 manifold, just that I used it and have 500 HP with way better response than the 3.2 manifold would give. Ideally, multi butterflies and Plenums are best, but the cost is high.
As stated, get all the info you can. The main parts are easy to price, its all the little pieces that add up. Expect to pay some good $ for Intercooler mounts, throttle body reversing etc. It all can be done cheap, but don't lift the bonnet to show off your masterpeice if it looks like crap. You get what you pay for.
So, manifold volume, Injector size, fabrication costs, Ignition type, EFI fueling firing etc, all will play huge parts in your final outcome.
I will email you this weekend to discuss my own choices. I do have 2 regrets. Not going to the 98.00mm bore, and my Intercooler is too small for long power runs. The Intercooler is easy to cahmge compared to the bore.
08-23-2003, 01:20 PM
#53
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m42racer;
You are mixing 2 different design theories... When the 930 came out, Porsche designed the turbo for small port sizes to speed the air velocity up through the heads. Why, because turbo's were small and inefficient. You'd need a turbo the size of a bowling ball to move any air with lag that would put a turtle to sleep. Today the factory uses high pressure & CFM to pack the cylinders with air. You are talking to an individual that wanted to make the pancake 930 manifold to work, hell I have the CNC'd injector blocks made for every size of ports you can think of. The problem is that after I had welded the stock manifold and matched ported it (40 hrs later with flowing) it was still restrictive and could not match the other manifolds.
I see your point with throttle response, however you have a design build of 500hp, I can grab 5 turbochargers off my shelf that will produce so much CFM that customers cannot get enough fuel and by the time they solve the issue the cars are over 650hp. The pancake manifold is barely hanging on at 500hp! Noway at 550hp.... Your throttle response is largely there because of your headers and the use of a small turbo sized for 500hp. What turbo are you using? K27-7200? Post your full boost RPM's and the RPM's when you start to make .5 bar.... I'll shed some light on that issue..
You are mixing 2 different design theories... When the 930 came out, Porsche designed the turbo for small port sizes to speed the air velocity up through the heads. Why, because turbo's were small and inefficient. You'd need a turbo the size of a bowling ball to move any air with lag that would put a turtle to sleep. Today the factory uses high pressure & CFM to pack the cylinders with air. You are talking to an individual that wanted to make the pancake 930 manifold to work, hell I have the CNC'd injector blocks made for every size of ports you can think of. The problem is that after I had welded the stock manifold and matched ported it (40 hrs later with flowing) it was still restrictive and could not match the other manifolds.
I see your point with throttle response, however you have a design build of 500hp, I can grab 5 turbochargers off my shelf that will produce so much CFM that customers cannot get enough fuel and by the time they solve the issue the cars are over 650hp. The pancake manifold is barely hanging on at 500hp! Noway at 550hp.... Your throttle response is largely there because of your headers and the use of a small turbo sized for 500hp. What turbo are you using? K27-7200? Post your full boost RPM's and the RPM's when you start to make .5 bar.... I'll shed some light on that issue..
08-23-2003, 02:57 PM
#54
Kevin,
Actually, quite the contary. I have a Garrett 350 series Turbo which is good for 550HP max. Yes I do have the basic small length exhaust , but I had this before.
The throttle response is directly related to the Intake size, and how the EFI system has to react to the amount of change between vacuum and positive MAP.
I am sure the 930 Intake is limited to aroung 500-550 HP. Its a stock Intake, but telling me that the 3.2 manifold is better for respone at the same power levels is not true either. I've driven cars with this type of manifold. I checked it all out when I was deciding on which way to go. Take a look at any race Plenum on a turbo engine. They are really small in volume. They usually lengthen the runner lengths to alter the torque curve only. I was not aftre big HP. I asked for 475Hp, but I wanted Torque and throttle response. I've seem these 600+ cars at the track. They typically cannot get out of the way thro the corners and are all power down the straights. Take a look at the lap times. They are not always the fastest. I like ther approach from a shifter kart idea. Not the most powerful, but the response lowers the lap times considerably. Maybe your development and requirements were different to mine. Again, I would rather drive a car with torque and plenty of response, than a car with 600HP.
The approach I was shown, was small Intake, lowering the time required to go from vacuum to positive MAP, due to the single butterfly, sequential fueling, controlling the fueling at very lower RPM's and MAP, because of the single larger Injectors required, CDI Ignition over Inductive, enabling the EFI to light off a leaner mixture at the lower MAP, small volume exhaust, and a ball bearing Turbo. Also because of the placement of the larger Injectors, low, is was very important to control the fuel delivery.
Perfromance Developments did alot of development on my engine system, and build both a non sequential, Inductive system nad the one I have now. The difference is huge. You cannot have clean crisp throttle response without controlling the fueling at the transition from part to WOT, and having the MAP change happen quickly. As I have said earlier here, the Ignition is extremely important also. All this being equal, the choice of Cams, Cylinder Head porting/flow and valve sizes are all part of the equation.
As for the RPM my boost comes on, the ball bearing turbo makes a big difference. I am in boost at 1800 RPM and depending on the load, gear I am in, the boost is all there around 2500-2800 RPM. This was a problem in the beginning as it made the car very hard to drive as it became sort of on or off like. Performance Developments rewrote the software for the boost control, so that the boost is now not only a function of RPM but a function of throttle angle. So if I have 220Kpa programmed at 5000 RPM but ony 50% throttle, I will get 110ka boost. These parameters are all programmable, so I acn change wahtever I want. It makes it really nice when alot of my driving is part throttle on the freeway.
I am really happy with the outcome. It did save lots of $ doing it this way. I did have the choice, a 3.2 manifold or the stock 930. given all the options and my brieg, I got what I wanted.
Actually, quite the contary. I have a Garrett 350 series Turbo which is good for 550HP max. Yes I do have the basic small length exhaust , but I had this before.
The throttle response is directly related to the Intake size, and how the EFI system has to react to the amount of change between vacuum and positive MAP.
I am sure the 930 Intake is limited to aroung 500-550 HP. Its a stock Intake, but telling me that the 3.2 manifold is better for respone at the same power levels is not true either. I've driven cars with this type of manifold. I checked it all out when I was deciding on which way to go. Take a look at any race Plenum on a turbo engine. They are really small in volume. They usually lengthen the runner lengths to alter the torque curve only. I was not aftre big HP. I asked for 475Hp, but I wanted Torque and throttle response. I've seem these 600+ cars at the track. They typically cannot get out of the way thro the corners and are all power down the straights. Take a look at the lap times. They are not always the fastest. I like ther approach from a shifter kart idea. Not the most powerful, but the response lowers the lap times considerably. Maybe your development and requirements were different to mine. Again, I would rather drive a car with torque and plenty of response, than a car with 600HP.
The approach I was shown, was small Intake, lowering the time required to go from vacuum to positive MAP, due to the single butterfly, sequential fueling, controlling the fueling at very lower RPM's and MAP, because of the single larger Injectors required, CDI Ignition over Inductive, enabling the EFI to light off a leaner mixture at the lower MAP, small volume exhaust, and a ball bearing Turbo. Also because of the placement of the larger Injectors, low, is was very important to control the fuel delivery.
Perfromance Developments did alot of development on my engine system, and build both a non sequential, Inductive system nad the one I have now. The difference is huge. You cannot have clean crisp throttle response without controlling the fueling at the transition from part to WOT, and having the MAP change happen quickly. As I have said earlier here, the Ignition is extremely important also. All this being equal, the choice of Cams, Cylinder Head porting/flow and valve sizes are all part of the equation.
As for the RPM my boost comes on, the ball bearing turbo makes a big difference. I am in boost at 1800 RPM and depending on the load, gear I am in, the boost is all there around 2500-2800 RPM. This was a problem in the beginning as it made the car very hard to drive as it became sort of on or off like. Performance Developments rewrote the software for the boost control, so that the boost is now not only a function of RPM but a function of throttle angle. So if I have 220Kpa programmed at 5000 RPM but ony 50% throttle, I will get 110ka boost. These parameters are all programmable, so I acn change wahtever I want. It makes it really nice when alot of my driving is part throttle on the freeway.
I am really happy with the outcome. It did save lots of $ doing it this way. I did have the choice, a 3.2 manifold or the stock 930. given all the options and my brieg, I got what I wanted.
08-23-2003, 10:43 PM
#55
Nordschleife Master
M42Racer,
You are really making statements that are both inaccurate and not factually based and creating confusion. As with project, it is a system of component parts that must be matched properly. You've apparently been able to do that with your EFI conversion. However, I take issue with many of your statements.
I have currently 5 turbo cars running various configurations, from individual throttle bodies, to 3.2 Carrera intake manifolds, Batch and Sequential fuel injection, and some with very large injectors. All 5 of these cars make over 550hp. In fact, I have an 800hp 3.6l with a stock 3.2 Carrera intake manifold with the only modification being extrude honed, stock throttle body, running a Haltech E6k which is a Batch EFI system, and 82lb/hr injectors at a base fuel pressure of 50-55lbs and a single T72 turbo. The exhaust on this car has 1.5" inside diameter tubing made of Inconel. This car does not have any idle quality issues, nor does it have poor throttle transition as you've stated above. This particular car is mated to a 6spd gearbox and is very, very fast with no lag issues.
I've found that the BOSCH 280150403 55lb/hr injectors running reasonable base fuel pressure (50-55lbs) can handle approximately 550hp, the 72lb/hr Siemens or Rochester Indy can handle approximately 700, and the 82lb/hr Siemens can handle about 850hp. I've not had idle quality or any fueling issues for that matter with any of these injectors as long as they are sized properly. Obviously if you put 82lb/hr injectors with a 500hp engine, you'll more than likely have problems.
One of these cars is a 3.6l with TWM individual throttle bodies running 72lb/hr injectors and while you might think that it would have far better throttle response than a plenum based manifold, it is barely noticable. Additonally, there is a major difference between 1.0bar and 1.2 bar where there appears to be significant air reversion or turblance with these particular throttle bodies. While they work well in a N/A application, given a choice, I would always choose a plenum type manifold for a turbo application.
With advance engine managment, there are two basic ways (there are others) of metering fuel. Either you can use a MAP sensor as the fuel load site or your can use throttle position for fuel load site. A TP based system (called alpha -N) will always give you better throttle response than a MAP based fuel table. This is because MAP sensors are slow to respond and therefore the fuel lags behind the engine. Individual throttle bodies require the use of a TP based fuel map since you cannot get a stable pressure reading until the car comes up on cam. With that said, again, I generally would use a MAP based system, the differences are minimal for all but a racing application.
The 3.2 Carrera manifold DOES NOT NEED to be cut and turned around. It is in my opinion a cost that is unnecessary. As I told Rob S, Have Sperco build an intercooler (about $1000), and have someone locally complete the plumbing ($500-$1000) and bolt the thing on with the stock throttle body. It DOES NOT get any EASIER than that. You use all the factory Porsche fuel rails, fuel dampener, fuel regulator, etc. It is tried and proven to 700hp. In fact, a Porsche GT2 race car (993 based) used a N/A style manifold.
An engine management system will also control ignition. If you run lots of timing and a lean mixture under vacuum condition, you will have much better throttle response. This is probably the biggest advantace over CIS. I can't tell you how many times I've seen a turbo car running 12.2-12.5AFR under vacuum conditions with 25 degrees of timing. Poor throttle response, well, yea! I run my cars at times as much as 15.2:1 and 37-38 degrees of timing and the throttle response is incredible.
As Kevin mentioned, proper turbo sizing and as I've said many times before, proper gearing will ensure a car that performs very well. The Garrett GT35 turbo you mentioned running is not a particularly stellar performing turbo. Its compressor effeciency is only 71% compared to 75-78% of some of the better Garrett wheels. It is also rather small which would explain why you are experiencing fast spool up times. That turbo flows approximately 30lbs of air at 1bar which is enough to support a 300hp engine. More than that and it is overspinning and the efficency falls off even further. It will not support 550hp as claimed. The compressor wheel options range from 71-76mm and that is huge. Additionally, the ball bearing units will not hold up to our oil cooled application and should be avoided at all costs.
Lastly, I just came back from an open track event at Watkins Glen and I can tell you that on any corner at that track, I can have full boost BEFORE the apex of the corner. You should see the distance of a GT3 Cup car shrink comming out of the toe of the boot and up the hill. There is no waiting for boost.
You are really making statements that are both inaccurate and not factually based and creating confusion. As with project, it is a system of component parts that must be matched properly. You've apparently been able to do that with your EFI conversion. However, I take issue with many of your statements.
I have currently 5 turbo cars running various configurations, from individual throttle bodies, to 3.2 Carrera intake manifolds, Batch and Sequential fuel injection, and some with very large injectors. All 5 of these cars make over 550hp. In fact, I have an 800hp 3.6l with a stock 3.2 Carrera intake manifold with the only modification being extrude honed, stock throttle body, running a Haltech E6k which is a Batch EFI system, and 82lb/hr injectors at a base fuel pressure of 50-55lbs and a single T72 turbo. The exhaust on this car has 1.5" inside diameter tubing made of Inconel. This car does not have any idle quality issues, nor does it have poor throttle transition as you've stated above. This particular car is mated to a 6spd gearbox and is very, very fast with no lag issues.
I've found that the BOSCH 280150403 55lb/hr injectors running reasonable base fuel pressure (50-55lbs) can handle approximately 550hp, the 72lb/hr Siemens or Rochester Indy can handle approximately 700, and the 82lb/hr Siemens can handle about 850hp. I've not had idle quality or any fueling issues for that matter with any of these injectors as long as they are sized properly. Obviously if you put 82lb/hr injectors with a 500hp engine, you'll more than likely have problems.
One of these cars is a 3.6l with TWM individual throttle bodies running 72lb/hr injectors and while you might think that it would have far better throttle response than a plenum based manifold, it is barely noticable. Additonally, there is a major difference between 1.0bar and 1.2 bar where there appears to be significant air reversion or turblance with these particular throttle bodies. While they work well in a N/A application, given a choice, I would always choose a plenum type manifold for a turbo application.
With advance engine managment, there are two basic ways (there are others) of metering fuel. Either you can use a MAP sensor as the fuel load site or your can use throttle position for fuel load site. A TP based system (called alpha -N) will always give you better throttle response than a MAP based fuel table. This is because MAP sensors are slow to respond and therefore the fuel lags behind the engine. Individual throttle bodies require the use of a TP based fuel map since you cannot get a stable pressure reading until the car comes up on cam. With that said, again, I generally would use a MAP based system, the differences are minimal for all but a racing application.
The 3.2 Carrera manifold DOES NOT NEED to be cut and turned around. It is in my opinion a cost that is unnecessary. As I told Rob S, Have Sperco build an intercooler (about $1000), and have someone locally complete the plumbing ($500-$1000) and bolt the thing on with the stock throttle body. It DOES NOT get any EASIER than that. You use all the factory Porsche fuel rails, fuel dampener, fuel regulator, etc. It is tried and proven to 700hp. In fact, a Porsche GT2 race car (993 based) used a N/A style manifold.
An engine management system will also control ignition. If you run lots of timing and a lean mixture under vacuum condition, you will have much better throttle response. This is probably the biggest advantace over CIS. I can't tell you how many times I've seen a turbo car running 12.2-12.5AFR under vacuum conditions with 25 degrees of timing. Poor throttle response, well, yea! I run my cars at times as much as 15.2:1 and 37-38 degrees of timing and the throttle response is incredible.
As Kevin mentioned, proper turbo sizing and as I've said many times before, proper gearing will ensure a car that performs very well. The Garrett GT35 turbo you mentioned running is not a particularly stellar performing turbo. Its compressor effeciency is only 71% compared to 75-78% of some of the better Garrett wheels. It is also rather small which would explain why you are experiencing fast spool up times. That turbo flows approximately 30lbs of air at 1bar which is enough to support a 300hp engine. More than that and it is overspinning and the efficency falls off even further. It will not support 550hp as claimed. The compressor wheel options range from 71-76mm and that is huge. Additionally, the ball bearing units will not hold up to our oil cooled application and should be avoided at all costs.
Lastly, I just came back from an open track event at Watkins Glen and I can tell you that on any corner at that track, I can have full boost BEFORE the apex of the corner. You should see the distance of a GT3 Cup car shrink comming out of the toe of the boot and up the hill. There is no waiting for boost.
08-24-2003, 06:24 AM
#56
Well Geoffery,
We differ on just about everything here. I don't know where to start. I suppose it would be better to just agree to disagree.
I don't know who you are and by the sounds of things you are not reading my posts to the full. I was not affter more than 500+Hp and neither was Rob from what I read. Unless I read his posts wrong I understood he was looking for similar perfromance as I was. . What we both appear to be after is throttle response, and that is somethiong that could be a difference of opinion of what is really good response. Lets leave that there I suppose. As for your statements, I cannot agree or disagree with any, as I do not know what you have done. What you have said is you apppear to be after more than 500+HP. Too many peolple get caught up in this high Hp number game. So what! My car has 800+HP, mine has 1000+HP. I've heard it all before many times over. Most of the time, the only times these cars make this Hp is on the dyno. I'm not into paying for something, and having something that does not make usable HP.
I am not here to find fault with what you say, but I do not agree with anything you say about the EFI applications. How you can say that for street systems the use of TPS v RPM is the way to go I just do not understand. Most sytems I know of, mine included are MAP base with a TPS correction, the TPS function used for bosst control among other things. In a Turbo application, you can have the same TPS and RPM, but way different MAP. I expect you just made a mistake in your explaination here.
What do yoy mean by "it doen't matter unless for racing" The EFI doen't know if its racing.
My note regarding the Ignition was the use of CDI over Inductive systems. The use of Inductive Ignition on these big hemi chambers is a poor choice. I am not sure what you are using. It has nothing to do with the amount of advance you are running. What I do know is the amount you state will most probably give a higher idle. The difference between batch or grouped injectors and sequential Injectors at Idle and at low levels of throttle is huge. This I know from first hand experience. Again, I suppose its comes down to what we both think good throttle response is, right. The EFI system Performance Developments used on my engine was sequential and has 6 channels of CDI ignition. In their tests they originally tried group fueling and Inductive. I am using the 403 grey nozzles I think. The ones I have needed the O ring kits fitted on top if I remember.
I wanted to use the ball bearing type. It works great. Its oil cooled and will flow enough air for 550 HP. In fact, these Turbo's are now becoming the common choice for amny tuners. Maybe you are thinking of another size. As with most Turbo's, wheel size etc is very important as you state. This is an area I do know something about. Its my daily grind. As a applications engineer for a major Turbo manufacturer here in LA., I deal in Turbo sizing all day. Yes these Turbo's are normally water cooled, but oil can be used. Its just a plumbing exercise. As for reliability, so far so good.
If the 3.2 manifold works for you great. As I said, I am very happy with my engine and its outcome. That is the main thing here. When I choose PD to do the work, the fact that they built the quickest car Road and Track tested 0- 100 -0 , did sway my thinking. In fact I recently saw their time was just beaten by Posche again. But the 0-100 time still stands as the quickest. I think only the new Enzo privately tested shows quicker times. Not bad for a 5 speed car. In all of the hype, real true track testing by Road and Track does cut thro the BS and prove who is real and who is not. My car is far from the one tested, but it does show what this company can do, and this did give me good feeling about what they could do for me.
I am glad we can discuss this who;e issue here. It gives me further ideas and show me how others do things. This is really good. PD is presently building a 944 Turbo engine for me, so I am really hopeful this turns out as good as my 930 did.
We differ on just about everything here. I don't know where to start. I suppose it would be better to just agree to disagree.
I don't know who you are and by the sounds of things you are not reading my posts to the full. I was not affter more than 500+Hp and neither was Rob from what I read. Unless I read his posts wrong I understood he was looking for similar perfromance as I was. . What we both appear to be after is throttle response, and that is somethiong that could be a difference of opinion of what is really good response. Lets leave that there I suppose. As for your statements, I cannot agree or disagree with any, as I do not know what you have done. What you have said is you apppear to be after more than 500+HP. Too many peolple get caught up in this high Hp number game. So what! My car has 800+HP, mine has 1000+HP. I've heard it all before many times over. Most of the time, the only times these cars make this Hp is on the dyno. I'm not into paying for something, and having something that does not make usable HP.
I am not here to find fault with what you say, but I do not agree with anything you say about the EFI applications. How you can say that for street systems the use of TPS v RPM is the way to go I just do not understand. Most sytems I know of, mine included are MAP base with a TPS correction, the TPS function used for bosst control among other things. In a Turbo application, you can have the same TPS and RPM, but way different MAP. I expect you just made a mistake in your explaination here.
What do yoy mean by "it doen't matter unless for racing" The EFI doen't know if its racing.
My note regarding the Ignition was the use of CDI over Inductive systems. The use of Inductive Ignition on these big hemi chambers is a poor choice. I am not sure what you are using. It has nothing to do with the amount of advance you are running. What I do know is the amount you state will most probably give a higher idle. The difference between batch or grouped injectors and sequential Injectors at Idle and at low levels of throttle is huge. This I know from first hand experience. Again, I suppose its comes down to what we both think good throttle response is, right. The EFI system Performance Developments used on my engine was sequential and has 6 channels of CDI ignition. In their tests they originally tried group fueling and Inductive. I am using the 403 grey nozzles I think. The ones I have needed the O ring kits fitted on top if I remember.
I wanted to use the ball bearing type. It works great. Its oil cooled and will flow enough air for 550 HP. In fact, these Turbo's are now becoming the common choice for amny tuners. Maybe you are thinking of another size. As with most Turbo's, wheel size etc is very important as you state. This is an area I do know something about. Its my daily grind. As a applications engineer for a major Turbo manufacturer here in LA., I deal in Turbo sizing all day. Yes these Turbo's are normally water cooled, but oil can be used. Its just a plumbing exercise. As for reliability, so far so good.
If the 3.2 manifold works for you great. As I said, I am very happy with my engine and its outcome. That is the main thing here. When I choose PD to do the work, the fact that they built the quickest car Road and Track tested 0- 100 -0 , did sway my thinking. In fact I recently saw their time was just beaten by Posche again. But the 0-100 time still stands as the quickest. I think only the new Enzo privately tested shows quicker times. Not bad for a 5 speed car. In all of the hype, real true track testing by Road and Track does cut thro the BS and prove who is real and who is not. My car is far from the one tested, but it does show what this company can do, and this did give me good feeling about what they could do for me.
I am glad we can discuss this who;e issue here. It gives me further ideas and show me how others do things. This is really good. PD is presently building a 944 Turbo engine for me, so I am really hopeful this turns out as good as my 930 did.
08-24-2003, 10:10 AM
#57
Nordschleife Master
M42Racer,
I want to make sure we are talking about the same thing. Throttle response and engine response are two different things. I would define throttle response as the crispness or lack thereof of an engine when going from one load to another (idle to part throttle, part throttle to full throttle, idle to full throttle, etc.) Engine response is the entire package and its ability to start making power and get going.
If we are talking about engine response, I would agree with you that there are so many turbos out there with poor engine response. From what I've seen, the major components to engine responsiveness in order would be turbo sizing, compression, cams, and of course my favorite, proper gearing to make it work. Herein lies the issue, in order to make large hp 450 and above, you need to have a fairly large turbo. Until very recently with Kevin's k27 hybrid, these turbos don't make boost until 3500 or so, so if you try to accelerate out of a corner and you are at 2500rpm, the car will indeed feel dead and unresponsive. This is why a CIS car with SC cams, 3.4l p&c with a k27 makes a great street car package.
We also have several 450-500hp cars with batch injection 44lb/hr injectors running 3.2 Carrera manifolds and they work very well. In fact, we have a 2.1l twin turbo built and ready for racing that has a 3.2 Carrera intake. As you know the port size between a 3.2 Carrera intake and the early smaller N/A displacement heads is quite different. We expect full boost by about 2500rpm with excellent engine response.
I also agree with you that 500hp is a lot of power and more than you really need for the street. For racing it does make a difference, although I think that 650-700 is probably sufficient for most of the tracks.
Regarding a pressure based fuel table vs a TP based fuel table, I believe I said that I much prefer a pressure based fuel table for most cases, certainly on a street driven car. With a pressure based fuel table the TP sensor is used for acceleration enrichment only. On a TP based fuel table like you would need for individual throttle bodies, the TP sensor is used as the primary measure of fuel, and the MAP sensor is used to compensate for boost pressure based on a mathematical formula that basically states "double pressure, double fuel". TP is also used for acceleration enrichment. I also went further to say that the throttle responsiveness between a pressure based fuel table and an alpha -N TP based fuel table is minimal on a turbo car and you'd really only notice it for racing. Remember that under vacuum conditions, the intercooler is a huge restriction in the inlet system. In a N/A application, I would almost always run a TP based map for the increase in throttle response that it provides.
Regarding ignition systems all of the cars I've mention have different systems, from individual coil packs, to the GM wasted spark coil packs, to the 800hp car that has, believe it or not, a stock 964 distributor. All of these cars have an idle of 800-900rpm execpt for the individual throttle body race car that idles about 1100. There has not been a noticable difference in idle quality between large and small injectors, or batch vs sequential injection. Given the choice, I would always run sequential because of the fuel economy and torque gains I've seen. The 403 injectors you are using are 55lb/hr injectors and work very well for the 500hp cars in either batch or sequential fuel injection modes.
As for idle timing, 5-10 degrees is normal for a good 800rpm idle.
I want to make sure we are talking about the same thing. Throttle response and engine response are two different things. I would define throttle response as the crispness or lack thereof of an engine when going from one load to another (idle to part throttle, part throttle to full throttle, idle to full throttle, etc.) Engine response is the entire package and its ability to start making power and get going.
If we are talking about engine response, I would agree with you that there are so many turbos out there with poor engine response. From what I've seen, the major components to engine responsiveness in order would be turbo sizing, compression, cams, and of course my favorite, proper gearing to make it work. Herein lies the issue, in order to make large hp 450 and above, you need to have a fairly large turbo. Until very recently with Kevin's k27 hybrid, these turbos don't make boost until 3500 or so, so if you try to accelerate out of a corner and you are at 2500rpm, the car will indeed feel dead and unresponsive. This is why a CIS car with SC cams, 3.4l p&c with a k27 makes a great street car package.
We also have several 450-500hp cars with batch injection 44lb/hr injectors running 3.2 Carrera manifolds and they work very well. In fact, we have a 2.1l twin turbo built and ready for racing that has a 3.2 Carrera intake. As you know the port size between a 3.2 Carrera intake and the early smaller N/A displacement heads is quite different. We expect full boost by about 2500rpm with excellent engine response.
I also agree with you that 500hp is a lot of power and more than you really need for the street. For racing it does make a difference, although I think that 650-700 is probably sufficient for most of the tracks.
Regarding a pressure based fuel table vs a TP based fuel table, I believe I said that I much prefer a pressure based fuel table for most cases, certainly on a street driven car. With a pressure based fuel table the TP sensor is used for acceleration enrichment only. On a TP based fuel table like you would need for individual throttle bodies, the TP sensor is used as the primary measure of fuel, and the MAP sensor is used to compensate for boost pressure based on a mathematical formula that basically states "double pressure, double fuel". TP is also used for acceleration enrichment. I also went further to say that the throttle responsiveness between a pressure based fuel table and an alpha -N TP based fuel table is minimal on a turbo car and you'd really only notice it for racing. Remember that under vacuum conditions, the intercooler is a huge restriction in the inlet system. In a N/A application, I would almost always run a TP based map for the increase in throttle response that it provides.
Regarding ignition systems all of the cars I've mention have different systems, from individual coil packs, to the GM wasted spark coil packs, to the 800hp car that has, believe it or not, a stock 964 distributor. All of these cars have an idle of 800-900rpm execpt for the individual throttle body race car that idles about 1100. There has not been a noticable difference in idle quality between large and small injectors, or batch vs sequential injection. Given the choice, I would always run sequential because of the fuel economy and torque gains I've seen. The 403 injectors you are using are 55lb/hr injectors and work very well for the 500hp cars in either batch or sequential fuel injection modes.
As for idle timing, 5-10 degrees is normal for a good 800rpm idle.
08-24-2003, 05:33 PM
#58
seems the more we discuss this the more we do agree. Not sure what you mean by throttleresponse and engine response. The two mean the same to me. Push down on the throttle, engine accelerates. I suppose the 3.2 maniflod is a good choice when there was never another for EFI systems. I think PD has now added another choice (930) for those who wish to limit there Hp to around 500. I do know that PD does have a multi butterfly plenum system, but it is very expensive. I believe it was the type on their Road and Track car.
As for the choice of Ignition type, turbo's and came etc, it all comes down to the tuners choice and what the customer wants. The real clever part comes when the tuner can build the engine the customer wants. Typically, the tuner builds what he wants and we the customer have no choice. I know, I've been there. It was refreshing to have a part in my engine build, save money and still get what I wanted. Tuners who offer many different options are few and far between. What we did have to do was redo the fueling and Ignition type, as the original choosen types, did not produce the results required. We found that the engine was very lazy, had fuelingh issues at part throttle and in the transistion. Yes it did accelerate and get into boost and make power, but the reponse was slow in comparision to what I have now. From what I was told, the more cylinders the engine has the worse it gets. Fuel delivered in group mode is injected into the cylinder next to fire and on the opposite cylinder on the overlap stroke. This fuel can be trapped behind the Inlet valve and also on some cylinders past thro the open valves. As I have 55Lb Injectors (403) this made the crispness of the transistion very poor. Add to this the poor capabilities of Inductive Ignition (lower energy) all made for a lazy engine in response. Although at higher RPM's, all of this became somewhat even, my use and needs for this car dictated throttle response and crispness. The one area which also did make some difference with the grouped injection was the ability of the EFI system used by PD to change the TDC where the fuel was injected. Injecting it 1 TDC earlier helped at the lower RPM's, but hurt the higher RPM's. All this was taken into consideration when it was decided to change over to sequential fueling and CDI ignition. The use of group fueling and Inductive Ignition was a departure from PD's normal direction. I have never used coil packs or similar coils as you noted, as most of these are Inductive I'm told. Again, it comes down to whats available to most to use without the need to design new parts. The use of the 3.2 manifold falls into this category also I believe.
As for the choice of Ignition type, turbo's and came etc, it all comes down to the tuners choice and what the customer wants. The real clever part comes when the tuner can build the engine the customer wants. Typically, the tuner builds what he wants and we the customer have no choice. I know, I've been there. It was refreshing to have a part in my engine build, save money and still get what I wanted. Tuners who offer many different options are few and far between. What we did have to do was redo the fueling and Ignition type, as the original choosen types, did not produce the results required. We found that the engine was very lazy, had fuelingh issues at part throttle and in the transistion. Yes it did accelerate and get into boost and make power, but the reponse was slow in comparision to what I have now. From what I was told, the more cylinders the engine has the worse it gets. Fuel delivered in group mode is injected into the cylinder next to fire and on the opposite cylinder on the overlap stroke. This fuel can be trapped behind the Inlet valve and also on some cylinders past thro the open valves. As I have 55Lb Injectors (403) this made the crispness of the transistion very poor. Add to this the poor capabilities of Inductive Ignition (lower energy) all made for a lazy engine in response. Although at higher RPM's, all of this became somewhat even, my use and needs for this car dictated throttle response and crispness. The one area which also did make some difference with the grouped injection was the ability of the EFI system used by PD to change the TDC where the fuel was injected. Injecting it 1 TDC earlier helped at the lower RPM's, but hurt the higher RPM's. All this was taken into consideration when it was decided to change over to sequential fueling and CDI ignition. The use of group fueling and Inductive Ignition was a departure from PD's normal direction. I have never used coil packs or similar coils as you noted, as most of these are Inductive I'm told. Again, it comes down to whats available to most to use without the need to design new parts. The use of the 3.2 manifold falls into this category also I believe.
08-24-2003, 06:26 PM
#59
Nordschleife Master
Actually, in batch mode with our engines, all 6 injectors are fired simultanously THREE TIMES each engine cycle (720 degrees of crankshaft revolution). This is why you can use smaller injectors in batch mode than sequential mode. There are merits to batch mode, as the fuel sits on the hot intake valve it vaporizes, helping to make for a better mixture. Additionally, the smaller injectors allow for a longer injector on time at low rpm which makes for better atomization. Did you know Porsche uses batch mode in all 3.2 Carreras, and I believe in the 964 as well?
Last edited by Geoffrey; 09-04-2003 at 09:24 AM.
08-25-2003, 01:29 AM
#60
Geoffrey,
Your last post makes no sense at all. You fire the Injectors every 240 degrees? Where is the first Injection? As for smaller Injectors? How does this calculate? Seems to me, any calculations for Injector sizing done this way is a little hit or miss. How do you calculate your Injector sizes this way?How does fuel behind the Inlet valve Injected off phase make for better fuel mixture quality. And longer Injection time makes for better atomization? Better atomization is due to longer air mixturing from shorter duration time, or higher positioned Injectors, basically the same thing. You really are not making sense to me now. Please explain. Most manufacturers used grouped fueling until the federal Govt's emmisions requirments dictated better control.
Your last post makes no sense at all. You fire the Injectors every 240 degrees? Where is the first Injection? As for smaller Injectors? How does this calculate? Seems to me, any calculations for Injector sizing done this way is a little hit or miss. How do you calculate your Injector sizes this way?How does fuel behind the Inlet valve Injected off phase make for better fuel mixture quality. And longer Injection time makes for better atomization? Better atomization is due to longer air mixturing from shorter duration time, or higher positioned Injectors, basically the same thing. You really are not making sense to me now. Please explain. Most manufacturers used grouped fueling until the federal Govt's emmisions requirments dictated better control.