HP upgrade??????
10-03-2004, 03:22 PM
#16
Geoffrey,
Would you tell us your engine displacement and the RPM you run. 0.7b and 550Hp. That must be some special Compressor? What is the Mass Volume your compressor provides at this PR.
Would you tell us your engine displacement and the RPM you run. 0.7b and 550Hp. That must be some special Compressor? What is the Mass Volume your compressor provides at this PR.
10-03-2004, 04:01 PM
#18
Not trying to do anything of the sort. To make the sort of performance you speak of at that PR, several things must be present. Compressor efficiency, engine displacement and RPM among the most important. Just would love to know how you do what so many cannot.
10-03-2004, 05:11 PM
#19
Nordschleife Master
Here is another customer car 3.4l @ 1.15bar. Corrected to flywheel, this is 651torque and 677hp. ON PUMP FUEL!!! Not so special, similar turbo. Dyno is a dynapack measuring RWHP. Its really not that hard.
10-03-2004, 05:25 PM
#20
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Simon
Why, according to you, these hp levels cannot be achieved? I must agree that Geoffrey's numbers are impressive, I can hardly get there with a 3.8TT, twin plug, Garretts, etc.. however I am interested to understand the limitations, aren't there compressors that can take you there with a 3.4Ltr at 7000 RPMs and 0.7Bar? I am not an engineer, but very interested to know what would be the formula showing it ?
Thanks
Why, according to you, these hp levels cannot be achieved? I must agree that Geoffrey's numbers are impressive, I can hardly get there with a 3.8TT, twin plug, Garretts, etc.. however I am interested to understand the limitations, aren't there compressors that can take you there with a 3.4Ltr at 7000 RPMs and 0.7Bar? I am not an engineer, but very interested to know what would be the formula showing it ?
Thanks
10-03-2004, 07:58 PM
#21
Yes indeed there is. Very common in large Diesel stationary applications where low or constant engine speeds are seen. Many of the larger emergency Power generators, pumps etc., work in these sorts of configurations. The problem is there is contributing factors that start to work against the goals, when used in dynamic applications. A Comp wheel and its Trim can achieve the highest efficency at a certain speed. Usually single providers which can supply enough air mass at the stated PR would be at a slower speed, large and would take some time to accelerate. In order to get the time down to something reasonable, the Turbine side becomes smaller, but the speed goes up and the efficency starts to lower. This is a basic view of why most providers are run in their higher limits and the matching of the Exhaust side is so important. Unfortunetly, in dynamic applications you cannot have your cake and eat it too.
The dyno report you have posted is at 1.15b not 0.7b. Thats a huge difference in air mass in some Comp config's. Also, the calc's when converting to BHP from RWHP is not a true science. That among the correction factors all paly into the error factors. If you can do then that great. I am amazed but if your engine is like the Dyno run you posted I see some numbers that are not to impressive.
What I see is a torque curve that holds peak torque for only 500RPM an then it drops off . In fact it shows it drops almost 140FTLBs in approx 1200RPM. Either that was the first run setting the brake or you have a very peaky Torque curve. Torque curves like this are not very good for overal performance, and I would expect someone with lower values but more area under the curve would drive around you on the track. It would be good to know what the exact Turbo config on both sides, and some of your engine configs. Did the Exhaust pressure rise dramically, or the Comp speed very high, or is your engine choked. Typical Torque curves like this one are often the result of poor flow thro the Head. Either Port flows are choked, or the Cam is too short and the Cylinder head air transfer becomes choked. Its like been constipated. You can get it in, but it cannot come out. Also your peak Torque is at 4700 RPM. This would tell me the approx size of your configuration. This does tend to point toward the engine more so that the Turbo. Not enough imformation, but none the less, great numbers anyone would be proud of.
The dyno report you have posted is at 1.15b not 0.7b. Thats a huge difference in air mass in some Comp config's. Also, the calc's when converting to BHP from RWHP is not a true science. That among the correction factors all paly into the error factors. If you can do then that great. I am amazed but if your engine is like the Dyno run you posted I see some numbers that are not to impressive.
What I see is a torque curve that holds peak torque for only 500RPM an then it drops off . In fact it shows it drops almost 140FTLBs in approx 1200RPM. Either that was the first run setting the brake or you have a very peaky Torque curve. Torque curves like this are not very good for overal performance, and I would expect someone with lower values but more area under the curve would drive around you on the track. It would be good to know what the exact Turbo config on both sides, and some of your engine configs. Did the Exhaust pressure rise dramically, or the Comp speed very high, or is your engine choked. Typical Torque curves like this one are often the result of poor flow thro the Head. Either Port flows are choked, or the Cam is too short and the Cylinder head air transfer becomes choked. Its like been constipated. You can get it in, but it cannot come out. Also your peak Torque is at 4700 RPM. This would tell me the approx size of your configuration. This does tend to point toward the engine more so that the Turbo. Not enough imformation, but none the less, great numbers anyone would be proud of.
10-03-2004, 08:35 PM
#22
Nordschleife Master
I showed this graph because it was the most recent (from last week) I have of an engine with a similar turbo as is on my car. Yes, 1.15bar not .7bar, and the car has GT2 EVO cams which are not all that aggressive a camshaft and fall of quickly. My engine configuration is a little different but produces similar numbers. This run was a 12 second ramp run which really isn't enough time to get a true picture of the turbocharger spool time and not what I was testing for, but was the only graph I had handy. In this case, the logging shows 1bar of boost is acheived at 4400rpm, but if I steady state hold the dyno, the engine acheives 1bar of boost at 3750. So a longer ramped run would show more area under the curve. This particular car has over 500hp for about a 3000rpm range which is very usable, espeically in a track environment.
The Dynapack dyno does not have a brake in the traditional sense and is one of only two chassis dynos that are capable of properly mapping an engine because they have the ability to control the car. The other being a Dyno Dynamics dyno. The Dynapack uses hydraulic fluid and the computer controls it instantly.
As far as RWHP and FWHP conversions, I agree with you, for the most part it is only a guess. I happen to know that my original engine tested on an engine dyno produced 521hp, when put on the Dynapack dyno in the car produced 444hp, which is exactly a 15% loss, so that is what I use as a conversion factor and feel it is very close to accurate. Yes, I know gearbox oil and temp, CV joint age, and a myriad of other factors can influence RWHP.
As far as turbocharger technology, I've been working with Kevin for years now and we have been through several different iterations to find a turbo configuration that works well for my goals. Additionally, it has Zero Clearance technology which helps some of the low speed efficiencies you pointed out.
FWIW, I have the boost turned down to stock because for what I do, my stock style suspension and chassis cannot handle more than about 550hp. Lap times at 1.2bar and 700hp are no faster than at 550hp so why run higher boost?
Not sure what you are after here.
The Dynapack dyno does not have a brake in the traditional sense and is one of only two chassis dynos that are capable of properly mapping an engine because they have the ability to control the car. The other being a Dyno Dynamics dyno. The Dynapack uses hydraulic fluid and the computer controls it instantly.
As far as RWHP and FWHP conversions, I agree with you, for the most part it is only a guess. I happen to know that my original engine tested on an engine dyno produced 521hp, when put on the Dynapack dyno in the car produced 444hp, which is exactly a 15% loss, so that is what I use as a conversion factor and feel it is very close to accurate. Yes, I know gearbox oil and temp, CV joint age, and a myriad of other factors can influence RWHP.
As far as turbocharger technology, I've been working with Kevin for years now and we have been through several different iterations to find a turbo configuration that works well for my goals. Additionally, it has Zero Clearance technology which helps some of the low speed efficiencies you pointed out.
FWIW, I have the boost turned down to stock because for what I do, my stock style suspension and chassis cannot handle more than about 550hp. Lap times at 1.2bar and 700hp are no faster than at 550hp so why run higher boost?
Not sure what you are after here.
Last edited by Geoffrey; 10-03-2004 at 11:05 PM.
10-03-2004, 09:45 PM
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EFI?
Geoffery,
Is your car EFI? What difference in driveability would this make? Also, what suspension mods would you have to make in order to take full advantage of the 700 hp?
Could you tell me about the Higher effieciency turbo?
As well, what clutch setup is feasible for that type of Power? I found the clutch travel on my car is only about an inch or so. Miniscule to say the least. Very difficult to feather when needed.
Also, it would not make sense that the track times should be similar based in theory; on the straights, the car is in linear motion, the suspension typically should handle the power, only comming off of curves and corners would there be a hinderance, which could be compensated through driver control. Thus, a better ETA should be expected when applying the higher HP?
The only time you should expect a similar lap time is if the tries meeting the road are only capable of handling a certain amount of power and cornering characteristics; or if the track is very curvy and winding with less straights.
Is your car EFI? What difference in driveability would this make? Also, what suspension mods would you have to make in order to take full advantage of the 700 hp?
Could you tell me about the Higher effieciency turbo?
As well, what clutch setup is feasible for that type of Power? I found the clutch travel on my car is only about an inch or so. Miniscule to say the least. Very difficult to feather when needed.
Also, it would not make sense that the track times should be similar based in theory; on the straights, the car is in linear motion, the suspension typically should handle the power, only comming off of curves and corners would there be a hinderance, which could be compensated through driver control. Thus, a better ETA should be expected when applying the higher HP?
The only time you should expect a similar lap time is if the tries meeting the road are only capable of handling a certain amount of power and cornering characteristics; or if the track is very curvy and winding with less straights.
10-03-2004, 10:30 PM
#25
Nordschleife Master
I do wish I had more time to just test on the dyno, but a chassis dyno is not the best place because there generally is not enough data acquision to capture everything you'd want such as additional temps, pressures, and lambda. Additionally, since I just tune engines, and don't build them (with the exception of mine and a few others for friends), I generally don't have input into the design until afterwards when it doesn't perform to expectations. We've recently purchased some in cylinder pressure analysis tools which will datalog cylinder pressure for every crank degree of revolution throughout a run. This will enable us to better understand timing when we get a chance to work with it.
Kevin is the turbo expert, but in short there has been a lot of development in terms of turbochargers built on the K27 platform (K27HF1, k27HF2, K27HF3) which doesn't have any of the oiling issues the Garretts have. I run a Garrett based turbo, but it has modifications to allow it to live in an oil cooled only environment. Kevin has also developed some wheel combinations that are very efficient and then has applied his Zero Clearance process which allows the compressor wheel to run as close as .001" to the housing unlike a standard turbo which has around .012" clearance. This is where the 90-95% efficiency comes from.
My car is EFI, as are all the cars I deal with, including the non Porsche cars I've been doing for Grand Am racing. The difference in drivability is substantial over CIS. This is mainly due to being able to very tightly control the timing so that torque is maximized throughout the entire range the engine operates at. Anyone that wants to is welcome to come drive my car...at least while I still have it, hopefully it will be sold soon.
In order to take advantage of higher HP, I'd need to really put wider tires on it which would mean a wide body kit, also the car would need a cage to stiffen the chassis and support a proper coilover suspension. You'd need to lower the car and address the roll centers, most likely with the ERP 935 setup. Don't get me wrong, the car handles great and has some really good SRP bars on it and I'm happy with the way it turned out. It is also much easier to drive than a standard turbo becuse there is no turbo lag and I enjoy it a lot. However, at the end of the day, it is still a heavy street car.
I'm not real hard on the gearbox, I don't dump the clutch to spin the tires or anything. I am using a Kennedy Products Stage 1 pressure plate (12lbs) and a Porsche early turbo spring centered disk. Again, nothing special. I've not had any issues with sippage, but then again, I don't street race the car.
RE your theory, you may be right and perhaps I'm just not as good a driver as the car demands.
Simon, I've also seen some of the pictures of your car, or old car, I can't remember, and it looked great.
Part of the torque drop is from the turbo being maxed out and going from a peak of 1.15bar to 1bar.
Kevin is the turbo expert, but in short there has been a lot of development in terms of turbochargers built on the K27 platform (K27HF1, k27HF2, K27HF3) which doesn't have any of the oiling issues the Garretts have. I run a Garrett based turbo, but it has modifications to allow it to live in an oil cooled only environment. Kevin has also developed some wheel combinations that are very efficient and then has applied his Zero Clearance process which allows the compressor wheel to run as close as .001" to the housing unlike a standard turbo which has around .012" clearance. This is where the 90-95% efficiency comes from.
My car is EFI, as are all the cars I deal with, including the non Porsche cars I've been doing for Grand Am racing. The difference in drivability is substantial over CIS. This is mainly due to being able to very tightly control the timing so that torque is maximized throughout the entire range the engine operates at. Anyone that wants to is welcome to come drive my car...at least while I still have it, hopefully it will be sold soon.
In order to take advantage of higher HP, I'd need to really put wider tires on it which would mean a wide body kit, also the car would need a cage to stiffen the chassis and support a proper coilover suspension. You'd need to lower the car and address the roll centers, most likely with the ERP 935 setup. Don't get me wrong, the car handles great and has some really good SRP bars on it and I'm happy with the way it turned out. It is also much easier to drive than a standard turbo becuse there is no turbo lag and I enjoy it a lot. However, at the end of the day, it is still a heavy street car.
I'm not real hard on the gearbox, I don't dump the clutch to spin the tires or anything. I am using a Kennedy Products Stage 1 pressure plate (12lbs) and a Porsche early turbo spring centered disk. Again, nothing special. I've not had any issues with sippage, but then again, I don't street race the car.
RE your theory, you may be right and perhaps I'm just not as good a driver as the car demands.
Simon, I've also seen some of the pictures of your car, or old car, I can't remember, and it looked great.
Part of the torque drop is from the turbo being maxed out and going from a peak of 1.15bar to 1bar.
Last edited by Geoffrey; 10-03-2004 at 11:08 PM.
10-03-2004, 11:33 PM
#26
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Thanks!
Geoffery,
Great post. You guys give alot of informative tips and tech advice.
So maybe you can directly answer this becuase I am trying to figure it out for myself.
I just bought this car, 1985 Euro model, 930. The suspension was lowered and it is running great when it wants to start.
I was told it has a modified engine with documentation of a dyno where the car is putting down 465RWHP on a CIS system. Hopefully the dyno was for this car specifically.
When I looked over the engine, it was very clean. It has a custom set of headers and exhaust. As well, the turbo is supposed to be a higher end turbo.
The boost gauge reads 1.0 bar at about 2700 rpm.
As well, I raced my friend who owns a Z06 with some mods. In every try, I kicked his ***. So, to see if it was driver ability, we switched and the results were the same.
I also took it up against a Stradale. I kicked his *** in every try.
The car if defiantely moded, but I am unsure as to what has been done. The orginal owner works for Haliburton and is heading up some operations in Iraq. Plus, he is very difficult to get in contact with. He also never returns my calls. He used a dealer to sell his vehicle for him on comission. The dealer has very limited information and has a difficult time contacting the original owner as well.
Just so you know, I drove the car and went over it with a fine tooth comb. It is immaculate. This car was babbied from day one......
So, what could you surmize? That is why I want to pull the engine. It needs updating and I really would like to go EFI for drivability.
As for the clutch, what do you make of the pedal engagement range? It engages at the very top with a throw of about of an inch or two. Difficult to feather.
Thanks,
Paul
Great post. You guys give alot of informative tips and tech advice.
So maybe you can directly answer this becuase I am trying to figure it out for myself.
I just bought this car, 1985 Euro model, 930. The suspension was lowered and it is running great when it wants to start.
I was told it has a modified engine with documentation of a dyno where the car is putting down 465RWHP on a CIS system. Hopefully the dyno was for this car specifically.
When I looked over the engine, it was very clean. It has a custom set of headers and exhaust. As well, the turbo is supposed to be a higher end turbo.
The boost gauge reads 1.0 bar at about 2700 rpm.
As well, I raced my friend who owns a Z06 with some mods. In every try, I kicked his ***. So, to see if it was driver ability, we switched and the results were the same.
I also took it up against a Stradale. I kicked his *** in every try.
The car if defiantely moded, but I am unsure as to what has been done. The orginal owner works for Haliburton and is heading up some operations in Iraq. Plus, he is very difficult to get in contact with. He also never returns my calls. He used a dealer to sell his vehicle for him on comission. The dealer has very limited information and has a difficult time contacting the original owner as well.
Just so you know, I drove the car and went over it with a fine tooth comb. It is immaculate. This car was babbied from day one......
So, what could you surmize? That is why I want to pull the engine. It needs updating and I really would like to go EFI for drivability.
As for the clutch, what do you make of the pedal engagement range? It engages at the very top with a throw of about of an inch or two. Difficult to feather.
Thanks,
Paul
10-03-2004, 11:48 PM
#27
Nordschleife Master
I would be very surprised if the engine was putting out 465rwhp on CIS. I've not seen one yet with that kind of capability. It takes serious 3.3 head modifications, good cams, turbo, intercooler, exhaust, and additional fueling. Additionally, if your turbo is spooling up to 1bar@2700, it probably cannot flow enough air up top to support the hp. You'll also need more fuel than the CIS is capable of. I don't doubt the car is fast, faster than a Z06 or Ferrari, most CIS cars are.
EFI is great, but bring you checkbook...
Not sure on the clutch without seeing it. Stephen Kasper (PorschePHD) from Imagine Auto would be the best person to contact regarding 930 mechanicals.
EFI is great, but bring you checkbook...
Not sure on the clutch without seeing it. Stephen Kasper (PorschePHD) from Imagine Auto would be the best person to contact regarding 930 mechanicals.
10-05-2004, 12:40 AM
#29
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As I figured..
Geoffery,
I was figuring as much. I mean, the car is quick, but I didnt think it was putting down those number with CIS. The car defiantely had alot of engine work done on it, just not as to what. Still a work in progress on that.
I spoke to Steve on the phone and I was planning on sending my car to do the CIS and turbo upgrade if need be. Then, I spoke to my real good friend who said to me, "I tought you bought the car to tinker ? " I did, plus he wants to get his hands dirty, so I might make a go of it.
Where is the best place to learn EFI? I really would love to read a tech manual. Doesnt any compnay make a tech manual for Porsche 911 turbos?
For as long as this car has been out there, wouldnt you think?
Geesh, my Hemi car has tons of engine building secrets books out there. Almost overwhelming.
Paul
I was figuring as much. I mean, the car is quick, but I didnt think it was putting down those number with CIS. The car defiantely had alot of engine work done on it, just not as to what. Still a work in progress on that.
I spoke to Steve on the phone and I was planning on sending my car to do the CIS and turbo upgrade if need be. Then, I spoke to my real good friend who said to me, "I tought you bought the car to tinker ? " I did, plus he wants to get his hands dirty, so I might make a go of it.
Where is the best place to learn EFI? I really would love to read a tech manual. Doesnt any compnay make a tech manual for Porsche 911 turbos?
For as long as this car has been out there, wouldnt you think?
Geesh, my Hemi car has tons of engine building secrets books out there. Almost overwhelming.
Paul
10-05-2004, 09:58 AM
#30
Nordschleife Master
There are very few good EFI books out there. This particular engine has some design deficiencies which needs to be addressed if you are looking for real power. This affects both the physical engine build as well as the EFI installation. However, I teach a series of EFI classes around the country. There is a basic 2 day class and then an advanced class where you spend the day on the dyno with a laptop and as a class tune the car. Currently we have a 924 Porsche with an Autronic system on it that we use. Check out www.efi101.com where you'll find a schedule and information about the owner - Ben Strader.