Does anyone make Supercharger kit for early 16V L-Jet cars?
11-23-2003, 12:03 AM
#31
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Cory,
I used a Pro-M 75 mm Bullet MAF sensor, installed the IAT out of the AFM into the MAF, then feed the MAF output through a custom Split Second PSC1-009.
This PSC1-009 has a 2.5 volt offset added to the signal coming in and allows +/- 2.5 volts across a date table to allow you to tune in fairly nicely. It was custom made just for the Bastard based on actual MAF and AFM readings at various engine loads.
The whole setup was something like $500.00. Let me tell you that is money well spent, since the MAF sensors respond far more quickly than an old AFM could ever think of responding. For transient response, you can't do much better than an MAF, also because it is a measurement of air, not a calculation like MAP is.
I would steer way clear of MAP if you are keeping the L-Jet brain in tact. Just do a simple 1D voltage conversion to make the car run off like you want too. MAP will work well with a system designed for it, but the L-Jet has no throttle position sensor, so doing a MAP conversion with it would be nearly impossible.
I have a lot of hours in that MAF conversion, but I can tell you it works and works extremely well. I had to make a couple of wiring harnesses, but I am basically out of the woods with it and just doing the final tuning between the voltage curve and the fuel pressure.
I think L-Jet 1982 should be the same as L-Jet 1981, but I might be wrong. Both should be 8 volt systems. Here lies the difficulty of the calibration....you need a special signal calibrator like the PSC1-009 to get the MAF's 0-5 volts to send back a 0-8 volt like the L-Jet likes to see. Also, these AFMs are "Ratio Metric", meaning the signal is compared to a reference wire voltage....in my case this is set at 7.7 volts with some metal film resistors. The unit was made with an 8 volt reference, but I found the 7.7 volts to work better for me becase of the curve out of the MAF I am using.
What you really do is a graphical interpolation between points to make a smooth transient response curve the L-jet can read and then send in the required fuel. It allows you to run a larger injector and or higher fuel pressure and then re-shape the entire fuel curve for proper fuel delivery across the load range of the engine. It is a bit like installing larger injectors and cranking down the spring in the AFM, with the BIG exception of being able to define the slope of the transient curve and you also gain the respoonse of the MAF. The L-Jet brain is mapped around the response curve of the AFM.....which is lots of voltage change down low with little change up top.....the curve is steep down low and then flattens out as the load increases....I have it plotted if you are interested.
In my case, this conversion allowed me to place the MAF on the draw through (where it belongs) and replace my 1983 vintage intercooler with a much more free flowing unit. The whole setup worked out very well and it is by far the best mod I made to the car. My car actually had the AFM on the boosted side of the system.
My car now has the throttle response like my Audi turbo....crisp and right on the line. It has never responded better.
Warning though, it is not a conversion for the faint of heart....there were many times I was ready to scrap it all and go back to the AFM. Tuning it in takes a lot of time and patience and will really test your skills for sure!
For those of you thinking about blowing an early L-Jet car, I would highly recommend this setup....put it on the draw through side before the supercharger, then run a pipe down into the throttle body, where the AFM sits now.
Blowing through the AFM may work alright with the centrifugal because the higher boost comes in up top only, but still... the AFM can not properly compensate for density change in that setup, because the position of the AFM flap is a function of the density and the velocity of the air. In the case of the blow through AFM, the velocity is also a function of the density, so no matter how you look at it it won't be just right. AFMs are draw through devices. You can blow through a MAF, but it is still best to draw through for good signal and repeatability. Look at any factory blown car with an MAF and you will likely find it on the draw through side of the intake, it is certainly there on every turbocharged Porsche and Audi made today.
I used a Pro-M 75 mm Bullet MAF sensor, installed the IAT out of the AFM into the MAF, then feed the MAF output through a custom Split Second PSC1-009.
This PSC1-009 has a 2.5 volt offset added to the signal coming in and allows +/- 2.5 volts across a date table to allow you to tune in fairly nicely. It was custom made just for the Bastard based on actual MAF and AFM readings at various engine loads.
The whole setup was something like $500.00. Let me tell you that is money well spent, since the MAF sensors respond far more quickly than an old AFM could ever think of responding. For transient response, you can't do much better than an MAF, also because it is a measurement of air, not a calculation like MAP is.
I would steer way clear of MAP if you are keeping the L-Jet brain in tact. Just do a simple 1D voltage conversion to make the car run off like you want too. MAP will work well with a system designed for it, but the L-Jet has no throttle position sensor, so doing a MAP conversion with it would be nearly impossible.
I have a lot of hours in that MAF conversion, but I can tell you it works and works extremely well. I had to make a couple of wiring harnesses, but I am basically out of the woods with it and just doing the final tuning between the voltage curve and the fuel pressure.
I think L-Jet 1982 should be the same as L-Jet 1981, but I might be wrong. Both should be 8 volt systems. Here lies the difficulty of the calibration....you need a special signal calibrator like the PSC1-009 to get the MAF's 0-5 volts to send back a 0-8 volt like the L-Jet likes to see. Also, these AFMs are "Ratio Metric", meaning the signal is compared to a reference wire voltage....in my case this is set at 7.7 volts with some metal film resistors. The unit was made with an 8 volt reference, but I found the 7.7 volts to work better for me becase of the curve out of the MAF I am using.
What you really do is a graphical interpolation between points to make a smooth transient response curve the L-jet can read and then send in the required fuel. It allows you to run a larger injector and or higher fuel pressure and then re-shape the entire fuel curve for proper fuel delivery across the load range of the engine. It is a bit like installing larger injectors and cranking down the spring in the AFM, with the BIG exception of being able to define the slope of the transient curve and you also gain the respoonse of the MAF. The L-Jet brain is mapped around the response curve of the AFM.....which is lots of voltage change down low with little change up top.....the curve is steep down low and then flattens out as the load increases....I have it plotted if you are interested.
In my case, this conversion allowed me to place the MAF on the draw through (where it belongs) and replace my 1983 vintage intercooler with a much more free flowing unit. The whole setup worked out very well and it is by far the best mod I made to the car. My car actually had the AFM on the boosted side of the system.
My car now has the throttle response like my Audi turbo....crisp and right on the line. It has never responded better.
Warning though, it is not a conversion for the faint of heart....there were many times I was ready to scrap it all and go back to the AFM. Tuning it in takes a lot of time and patience and will really test your skills for sure!
For those of you thinking about blowing an early L-Jet car, I would highly recommend this setup....put it on the draw through side before the supercharger, then run a pipe down into the throttle body, where the AFM sits now.
Blowing through the AFM may work alright with the centrifugal because the higher boost comes in up top only, but still... the AFM can not properly compensate for density change in that setup, because the position of the AFM flap is a function of the density and the velocity of the air. In the case of the blow through AFM, the velocity is also a function of the density, so no matter how you look at it it won't be just right. AFMs are draw through devices. You can blow through a MAF, but it is still best to draw through for good signal and repeatability. Look at any factory blown car with an MAF and you will likely find it on the draw through side of the intake, it is certainly there on every turbocharged Porsche and Audi made today.
11-23-2003, 02:54 AM
#32
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John,
thanks for the write-up and for sharing. You're saving many of us much much pain and suffering. I think if this info was out a few months ago, my supercharged 16v would have survived...but oh well. Will have to contact you privately for more details on what you did, if you don't mind.
Now does this mean everything is tuned on your car now? next question of course: is it ready for a dyno run yet?
thanks for the write-up and for sharing. You're saving many of us much much pain and suffering. I think if this info was out a few months ago, my supercharged 16v would have survived...but oh well. Will have to contact you privately for more details on what you did, if you don't mind.
Now does this mean everything is tuned on your car now? next question of course: is it ready for a dyno run yet?
11-24-2003, 12:39 AM
#33
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How about a Roots type setup for the L-Jets...Is there a kit out there made for the Early 928s? What would be involved to do a setup like that?
Thanks,
Cory J.
Thanks,
Cory J.
11-24-2003, 12:57 AM
#34
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Cory,
There is no kit, not yet anyway. I have been offered an '80 as a test mule to develop a system with and plan to do so soon.
It will use an inexpensive OEM blower readily found on e-bay for $200 used or around 450 rebuilt.
It will use most of the existing manifold.
It will use most of the existing pulleys and belts.
It will use the existing AFM
It will have an ideal power curve for automatic cars.
It will be pretty darn inexpensive, probably around $2200 for the whole setup non-intercooled low boost, and about $600-800 more for a higher boost intercooled version.
Andy K
There is no kit, not yet anyway. I have been offered an '80 as a test mule to develop a system with and plan to do so soon.
It will use an inexpensive OEM blower readily found on e-bay for $200 used or around 450 rebuilt.
It will use most of the existing manifold.
It will use most of the existing pulleys and belts.
It will use the existing AFM
It will have an ideal power curve for automatic cars.
It will be pretty darn inexpensive, probably around $2200 for the whole setup non-intercooled low boost, and about $600-800 more for a higher boost intercooled version.
Andy K
11-24-2003, 01:47 AM
#36
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John..,
I think I've said it before, but you're got more patience than I do!
I was losing it just trying to set up my fuel pressure, ignition timing, and cam advance. It's easy to go full throttle, but to make it idle nicely... the neighbors must think I'm crazy.
But now that it's dialed in it's so nice to just drive and not have to watch the air/fuel meter constantly!
...
Andy,
That'd be cool if you have the 16 valve cars covered. I've seen now some of the restrictions of being 'normally aspirated'.
Are you thinking of putting in a 2300 at a angle, upside down, under the spider? Or backwards with a drive-shaft to the front?
...
Having deep down dirty torque is good for the automatics. I could see on the dyno the torque converter multiplication when the run first started.
On one of my first runs, in third gear, there was a flash up to 284 ft/lbs of rear wheel torque at 2200 RPM!
I think I've said it before, but you're got more patience than I do!
I was losing it just trying to set up my fuel pressure, ignition timing, and cam advance. It's easy to go full throttle, but to make it idle nicely... the neighbors must think I'm crazy.
But now that it's dialed in it's so nice to just drive and not have to watch the air/fuel meter constantly!
...
Andy,
That'd be cool if you have the 16 valve cars covered. I've seen now some of the restrictions of being 'normally aspirated'.
Are you thinking of putting in a 2300 at a angle, upside down, under the spider? Or backwards with a drive-shaft to the front?
...
Having deep down dirty torque is good for the automatics. I could see on the dyno the torque converter multiplication when the run first started.
On one of my first runs, in third gear, there was a flash up to 284 ft/lbs of rear wheel torque at 2200 RPM!
11-24-2003, 02:17 AM
#37
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PorKen,
The 2300 would be overkill and double the cost of the system for the older cars. The OB will use a smaller and much less expensive blower.
As far as positioning, most of the above. If someone wishes to put a blower backwards they will need a reverse spinning blower though.
Andy K
The 2300 would be overkill and double the cost of the system for the older cars. The OB will use a smaller and much less expensive blower.
As far as positioning, most of the above. If someone wishes to put a blower backwards they will need a reverse spinning blower though.
Andy K
11-24-2003, 02:33 AM
#38
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Shows what I know, I thought the 2300 was small!
I suppose I would retard the cam timing with a blower, to evacuate the exhaust faster? Hmmm...
I suppose I would retard the cam timing with a blower, to evacuate the exhaust faster? Hmmm...
11-24-2003, 03:26 AM
#39
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PorKen,
A very simple way of sizing blowers is a ratio of the amount of HP they can potentially make compared to the HP the engine has already.
For instance the 2300 AX can make 750 HP, the OBs have around 230 HP so the ratio is over 3:1 or a 200% increase. A 50% increase is reasonable and a 100% increase is very possible. The smaller the engine, the smaller the blower it needs to make the same % increase as a bigger motor.
HTH,
Andy K
A very simple way of sizing blowers is a ratio of the amount of HP they can potentially make compared to the HP the engine has already.
For instance the 2300 AX can make 750 HP, the OBs have around 230 HP so the ratio is over 3:1 or a 200% increase. A 50% increase is reasonable and a 100% increase is very possible. The smaller the engine, the smaller the blower it needs to make the same % increase as a bigger motor.
HTH,
Andy K
11-24-2003, 01:26 PM
#40
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Sounds like I need to build an affordable single turbo kit for the early 928s....oops what the heck was I thinking I am getting married in two weeks and I told her I would not have grease under my nails for the wedding.
Yes, I have it nearly tuned in right now...still small bits of tinkering, but it is close. If anybody wants more information on the L-jet MAF conversion, just let me know. It is the best way to go when you go forced induction.
Yes, I have it nearly tuned in right now...still small bits of tinkering, but it is close. If anybody wants more information on the L-jet MAF conversion, just let me know. It is the best way to go when you go forced induction.
11-24-2003, 02:35 PM
#41
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If you guys could make a supercharger kit for the early 928s I would definatly be interested in buying one and putting it on my car. My car has decent pickup but it could always use a little more.
11-24-2003, 08:19 PM
#42
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Originally posted by GoRideSno
Cory,
There is no kit, not yet anyway. I have been offered an '80 as a test mule to develop a system with and plan to do so soon.
It will use an inexpensive OEM blower readily found on e-bay for $200 used or around 450 rebuilt.
It will use most of the existing manifold.
It will use most of the existing pulleys and belts.
It will use the existing AFM
It will have an ideal power curve for automatic cars.
It will be pretty darn inexpensive, probably around $2200 for the whole setup non-intercooled low boost, and about $600-800 more for a higher boost intercooled version.
Andy K
Cory,
There is no kit, not yet anyway. I have been offered an '80 as a test mule to develop a system with and plan to do so soon.
It will use an inexpensive OEM blower readily found on e-bay for $200 used or around 450 rebuilt.
It will use most of the existing manifold.
It will use most of the existing pulleys and belts.
It will use the existing AFM
It will have an ideal power curve for automatic cars.
It will be pretty darn inexpensive, probably around $2200 for the whole setup non-intercooled low boost, and about $600-800 more for a higher boost intercooled version.
Andy K
Whike your at the design table - how about throwing something towards us Euro Guys w/S2's?. I'm still waiting for a line in. Hell, I'll even trade my F3 straight across for a kit w/out installation.
11-25-2003, 12:37 AM
#43
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The roots seems a good way to go. What kind of OEM Supercharger would you use, an Eaton M112? Being that I have an automatic...any kind of low end grunt would be good. Hope to here from ya Andy K when you have that test mule ready...so keep us updated on how things go with SCin these Early 16Vs.
Thanks,
Cory J
Thanks,
Cory J
11-27-2003, 12:05 AM
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I have another question that has been buggin me, how do you mount a roots type blower to the 928 manifold and still connect it to the AFM?
Thanks,
Cory J.
82 Weissach
Thanks,
Cory J.
82 Weissach
11-30-2003, 10:29 AM
#45
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