Turbo? Supercharge?
07-05-2001, 11:05 PM
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Turbo? Supercharge?
Is it possible to supercharge, or tubo my 85' 928? Who makes or does either? Cost? Any other MODS needed? Also look at my other TOPIC i posted PROBLEMS!!!!
07-06-2001, 01:06 PM
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Barring you have a 16V car and not a 32V car (can't remember when they switched), find 2 cheap 951's (doesn't matter if they run so long as most parts are intact and not destroyed) take the heads, rods, and pistons, turbos, and intercoolers off of them. Get custom piping made to/from the turbos/intercoolers, and set up a turbo for each bank of cylinders. Swap engine internals and heads (O ring them and use wide fire head gaskets) from the 951s, run full engine management with a MAP sensor(i.e. electromotive or motec), tune the fuel maps, run 15 psi of boost, and you have a 500-600 HP twin turbo 928 that should run as reliably as a 951. Swap better turbos (garrett comes to mind), upgrade intercoolers, make sure everything is opened up, run 20 psi and you could probably make enough horsepower to snap the crank and destroy the transmission on your first 1/4 mile run. This is just a project I have been thinking about recently, and I wish someone would do it. If only I had a 928....
ribs, with V8 envy, 86' 951
[ 07-06-2001: Message edited by: ribs ]
ribs, with V8 envy, 86' 951
[ 07-06-2001: Message edited by: ribs ]
07-06-2001, 03:33 PM
#4
Ribs,
I already have 944(16v) heads on my car and I am in the process of adding an Electromotive Tec II with a MAP sensor and knock sensor.
Do you know if the manifolds will bolt up to these heads(851/2 944). I don't want to run more than 8psi of boost(I like engine longevity). I have thought of supercharging but I am unsure of the direction I want to go. I'm not sure supercharging would be any cheaper than going with the turbo system like you mentioned expecially if I use rebuilt 944 turbos. If the manifolds have to be custom built, supercharging would definately much cheaper. I'm thinking if the engine already has 400+ hp, the returns should be around 600hp with a conservative 50% increase in power. I already have the forged pistons and Tec II so I've got a head start. Bolt up the turbos, run oil lines, and custom tubing and I'm there.
Jim Nowak
I already have 944(16v) heads on my car and I am in the process of adding an Electromotive Tec II with a MAP sensor and knock sensor.
Do you know if the manifolds will bolt up to these heads(851/2 944). I don't want to run more than 8psi of boost(I like engine longevity). I have thought of supercharging but I am unsure of the direction I want to go. I'm not sure supercharging would be any cheaper than going with the turbo system like you mentioned expecially if I use rebuilt 944 turbos. If the manifolds have to be custom built, supercharging would definately much cheaper. I'm thinking if the engine already has 400+ hp, the returns should be around 600hp with a conservative 50% increase in power. I already have the forged pistons and Tec II so I've got a head start. Bolt up the turbos, run oil lines, and custom tubing and I'm there.
Jim Nowak
07-06-2001, 04:42 PM
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Jim,
The exhaust manifolds should bolt right up, but unfortunately the drivers side manifold will be exiting to the front of the car. Some custom tubing will be necessary...do you plan on intercooling? I hope so. You would also need to fab heat shields so you don't cook your engine compartment. If you are running stock compression pistons, you probably wouldn't want to run more than 7 or 8 psi for fear of detonation, but your power should go up by 40-50% depending on how cool you are able to keep the intake charge at those boost levels. Let us know when you make headway...this sounds like a very interesting project.
The exhaust manifolds should bolt right up, but unfortunately the drivers side manifold will be exiting to the front of the car. Some custom tubing will be necessary...do you plan on intercooling? I hope so. You would also need to fab heat shields so you don't cook your engine compartment. If you are running stock compression pistons, you probably wouldn't want to run more than 7 or 8 psi for fear of detonation, but your power should go up by 40-50% depending on how cool you are able to keep the intake charge at those boost levels. Let us know when you make headway...this sounds like a very interesting project.
07-06-2001, 06:36 PM
#6
Drifting
Hey Ribs
Im thinking of a PCA club racer 928 (definatley not gonna be stock class if its turbo charged!)in a couple of years. Ask me about this idea of yours again in 2003 and i'll pony up a 16v 928 euro 5sp. A few local sponsors for cash flow, a lotta elbow grease and who knows...
John Krawczyk
I wish i spoke Dutch so i could translate that 928 race car site that Pat Edwards posted pictures of two weeks ago
Im thinking of a PCA club racer 928 (definatley not gonna be stock class if its turbo charged!)in a couple of years. Ask me about this idea of yours again in 2003 and i'll pony up a 16v 928 euro 5sp. A few local sponsors for cash flow, a lotta elbow grease and who knows...
John Krawczyk
I wish i spoke Dutch so i could translate that 928 race car site that Pat Edwards posted pictures of two weeks ago
08-21-2002, 11:29 AM
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very simple and effective idea....all the info does say a 944 engine is just half a 928....
use the 951 turbo parts transfer to 928...some custom work and simple...there you go, a twin turboed 928...
with a bit of cash it seems easily done...
use the 951 turbo parts transfer to 928...some custom work and simple...there you go, a twin turboed 928...
with a bit of cash it seems easily done...
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08-21-2002, 03:57 PM
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I talked to someone once that did try to make components from a 951 work on a 928 in order to make a turbocharged 928. They never came to completion on the project, did make it running though, but could not even manage to make the hood fit after the whole ordeal was done. I actually have most of a twin turbo setup sitting in boxes out in my garage, it however was being built for a front mount intercooler but that portion could easily be redesigned, it is the headers that are the big key to it all.
Your best bet is to do what we did with my turbo headers, which is what Callaway did and the one place(name slips my mind) in Australia did. That is to low mount a small turbo on the back side of the motor. If you have to have twins, then do a pair of T3 turbos, very common turbo to find, it is going to take some skill though to design/build a header that will fit on the drivers side and place the turbo in a spot it does not hit anything. Now if you would be happy with a single turbo setup then your best bet is to run something like a T04 on the passenger side back there, more room over there and this is how Callaway did their one single turbo 928 no less. Intercooling is really the biggest headache on a 928, just no where to really put one(two). To run a air-air unit, you pretty much just have the front of the air damn and one will fit there, but the tubing to from it is a whole other story, you pretty much have to go under the radiator support and that kills your ground clearances. What I was going to do with my twin setup, was run two Vortech aftercoolers, one per side and merge their outlets at the front of the motor then into a TB. I really wanted to fab up a custom intake with built in water-air intercooler, but funds prevented that idea from getting off the ground. When you do mount the turbo(s) back there though, you need to build a oiling system for them, going to need a catch canister for the outlets and a scavange pump for pumping the oil back into the system.
Your best bet is to do what we did with my turbo headers, which is what Callaway did and the one place(name slips my mind) in Australia did. That is to low mount a small turbo on the back side of the motor. If you have to have twins, then do a pair of T3 turbos, very common turbo to find, it is going to take some skill though to design/build a header that will fit on the drivers side and place the turbo in a spot it does not hit anything. Now if you would be happy with a single turbo setup then your best bet is to run something like a T04 on the passenger side back there, more room over there and this is how Callaway did their one single turbo 928 no less. Intercooling is really the biggest headache on a 928, just no where to really put one(two). To run a air-air unit, you pretty much just have the front of the air damn and one will fit there, but the tubing to from it is a whole other story, you pretty much have to go under the radiator support and that kills your ground clearances. What I was going to do with my twin setup, was run two Vortech aftercoolers, one per side and merge their outlets at the front of the motor then into a TB. I really wanted to fab up a custom intake with built in water-air intercooler, but funds prevented that idea from getting off the ground. When you do mount the turbo(s) back there though, you need to build a oiling system for them, going to need a catch canister for the outlets and a scavange pump for pumping the oil back into the system.
08-21-2002, 05:21 PM
#9
I like the idea of turbo charging, and Aaron and I have spoken about this at length earlier in the year. The actual use of turbos is not as well tested as the use of Supercharging. The SC layout is 100% easier, and really, you want to drive the car and not constantly be in the project, right? Yes, SC is not has efficient as turboing, but what the hell if you have 650hp either way?
My plan involves stages.
The kingpin in the whol eidea, and as Ribs originally mentioned, the EFI is the most important step. You can do very little (though some will disagree) with the 928 without circumventing the computer. The DTA computer from the UK is a great solution to this, and it will be my first step in the biuldup.
Later steps involve Supercharging (with a cog belt), and then a final rebiulding of the motor with a stroker crank and custom pistons. I am still quite indecided on the sleeving process. I have some new information that may allow a normal JE piston to be used in the regular bore without that messy iron coating.
For those that may be reading this topic and making thier own plans, please do check out a very informative and interesting site called
<a href="http://www.928developments.com" target="_blank">www.928developments.com</a>
This gentleman's main idea is that we can't really address serious power delivry in a 928 (32V or not) without first addressing the notion that the intake is a main restriction over say, 400hp.
Anyway, that is my dislocated and muttled attempt at a contribution to this thread.
BTW - 81 auto for sale. Baby on the way
But I am keeping my 89S4 5spd.
My plan involves stages.
The kingpin in the whol eidea, and as Ribs originally mentioned, the EFI is the most important step. You can do very little (though some will disagree) with the 928 without circumventing the computer. The DTA computer from the UK is a great solution to this, and it will be my first step in the biuldup.
Later steps involve Supercharging (with a cog belt), and then a final rebiulding of the motor with a stroker crank and custom pistons. I am still quite indecided on the sleeving process. I have some new information that may allow a normal JE piston to be used in the regular bore without that messy iron coating.
For those that may be reading this topic and making thier own plans, please do check out a very informative and interesting site called
<a href="http://www.928developments.com" target="_blank">www.928developments.com</a>
This gentleman's main idea is that we can't really address serious power delivry in a 928 (32V or not) without first addressing the notion that the intake is a main restriction over say, 400hp.
Anyway, that is my dislocated and muttled attempt at a contribution to this thread.
BTW - 81 auto for sale. Baby on the way
But I am keeping my 89S4 5spd.
08-21-2002, 05:40 PM
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I think the next big worry is then your drivetrain. These transmissions can only handle so much power, same with the torque tubes. Would be interested to see if the one person who claimed on Ebay to be developing a means to put in a C5/Z06 tranny, actually finishes his project. Seems that does give people a way to a stronger drivetrain, costly I am sure but when are things like this not ...
08-21-2002, 06:14 PM
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Aaron is right about the drivetrain. There is such a thing as too much power believe it or not. If you don't have limited slip, then the stock power is, at times, too much as I have found.
Next is the fact that horespower does not equal horsepower. If you have 650 horsepower peak but no bottom end you might as well drive a rice car. The beauty of the 928 is the broad powerband. It is what allows a 300 HP car to compete with cars touting much higher numbers. Ideally the most desirable power curve is that of an electric motor. Flat torque up to the break poing and then tapering off from there.
Because of this, and the fact that it gets messy, turbos probably aren't the most desirable thing to have. the supercharger has power immediately when you step on it.
Some of you are considering multiple turbos to counter this. That's a step in the right direction, but good luck with the plumbing. Sure it can be done, but is it worth it? You'd be able to buy a Ferrari when all was finished.
Anyways my 2 cents worth is that supercharging is the most desirable way to get more power out of the engine and retain reliability, driveability, and minimize clutter and headache.
Good luck either way, and keep us informed. Should be fun.
Next is the fact that horespower does not equal horsepower. If you have 650 horsepower peak but no bottom end you might as well drive a rice car. The beauty of the 928 is the broad powerband. It is what allows a 300 HP car to compete with cars touting much higher numbers. Ideally the most desirable power curve is that of an electric motor. Flat torque up to the break poing and then tapering off from there.
Because of this, and the fact that it gets messy, turbos probably aren't the most desirable thing to have. the supercharger has power immediately when you step on it.
Some of you are considering multiple turbos to counter this. That's a step in the right direction, but good luck with the plumbing. Sure it can be done, but is it worth it? You'd be able to buy a Ferrari when all was finished.
Anyways my 2 cents worth is that supercharging is the most desirable way to get more power out of the engine and retain reliability, driveability, and minimize clutter and headache.
Good luck either way, and keep us informed. Should be fun.
08-21-2002, 06:38 PM
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[quote] Some of you are considering multiple turbos to counter this. That's a step in the right direction, but good luck with the plumbing. Sure it can be done, but is it worth it? You'd be able to buy a Ferrari when all was finished.
<hr></blockquote>
Actually with the modern day design of turbochargers the "lag" rep. they developed in the early days has become more of a myth than anything else. You can get past slow spool up times via all sorts of means, properly sized exhaust housings, properly sized tubing comes into effect as well and then there are the various ball bearing options be it ceramic, single bearing or the exotic dual ball bearing units.
Really for a single turbo 928 to stay in the power levels the drivetrain can withstand, you would not even need to play with all the ball bearing options to get away from a "laggy" setup. With a twin turbo setup you definately do not need them(ball bearings).
I know of one 928 that had a pair of T3 front mounted(don't try this kiddos, because there is a thing called heat soak to accesories and the t-belt) .48 turbos. It made full boost by I think it was 2500rpms, a SC makes full boost usually when at max RPM of the motor(not sure if that is the case in a 6-8lb scenario though). Anyway due to those turbos being front mounted it had a TON of tubing for the air to go through before it made it to the back of the intake, yet it still spooled up pretty quickly, only problem is it flattened out around 5k rpms because really it needed .63 exhaust housings. Beauty of a T3 turbo though is the price is next to nothing, a .63 ratio T3 was a factory turbo on things like 5-speed Ford Thunderbirds(Turbo coupe) in the 80s.
Nice thing about a SC though is you can "cheat" and use a FMU with the factory computer. Since the boost from a SC is pretty static to the rpm/load on the motor, the adding of extra fuel pressure per lb of boost usually works out pretty good. An FMU on a turbo car(any make/model) usually leads to rich conditions at certain points. Due to that a aftermarket ECU, in my opinion, or at least some sort of "piggy-back" setup to the ECU to allow for tweaking.
If all one wants is more power, go with a SC or if you can afford it do a NA stroked motor. Turbos are something you just have to want. People can argue until they are blue in the face about how turbos are more efficient. However with the limitations of drivetrains, really all that is a mute point because a SC can give you just as much power to break parts as turbo(s) could, heck a big NA motor could too.
<hr></blockquote>
Actually with the modern day design of turbochargers the "lag" rep. they developed in the early days has become more of a myth than anything else. You can get past slow spool up times via all sorts of means, properly sized exhaust housings, properly sized tubing comes into effect as well and then there are the various ball bearing options be it ceramic, single bearing or the exotic dual ball bearing units.
Really for a single turbo 928 to stay in the power levels the drivetrain can withstand, you would not even need to play with all the ball bearing options to get away from a "laggy" setup. With a twin turbo setup you definately do not need them(ball bearings).
I know of one 928 that had a pair of T3 front mounted(don't try this kiddos, because there is a thing called heat soak to accesories and the t-belt) .48 turbos. It made full boost by I think it was 2500rpms, a SC makes full boost usually when at max RPM of the motor(not sure if that is the case in a 6-8lb scenario though). Anyway due to those turbos being front mounted it had a TON of tubing for the air to go through before it made it to the back of the intake, yet it still spooled up pretty quickly, only problem is it flattened out around 5k rpms because really it needed .63 exhaust housings. Beauty of a T3 turbo though is the price is next to nothing, a .63 ratio T3 was a factory turbo on things like 5-speed Ford Thunderbirds(Turbo coupe) in the 80s.
Nice thing about a SC though is you can "cheat" and use a FMU with the factory computer. Since the boost from a SC is pretty static to the rpm/load on the motor, the adding of extra fuel pressure per lb of boost usually works out pretty good. An FMU on a turbo car(any make/model) usually leads to rich conditions at certain points. Due to that a aftermarket ECU, in my opinion, or at least some sort of "piggy-back" setup to the ECU to allow for tweaking.
If all one wants is more power, go with a SC or if you can afford it do a NA stroked motor. Turbos are something you just have to want. People can argue until they are blue in the face about how turbos are more efficient. However with the limitations of drivetrains, really all that is a mute point because a SC can give you just as much power to break parts as turbo(s) could, heck a big NA motor could too.
08-21-2002, 06:47 PM
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considering the question of where to mount the intercoolers at on a twin turbo 928...why not do what RUF did with the CTR2? Put them near or after the wheel well. Or do what mercedes did on the 300D Turbo-Deisel and put vents on the very front of the fender and have the intercooler sit behind it. If you are concerned with space when it comes to the turbochargers, use K-24s like Porsche did with the 993; just run a hotter (bigger) fan in it like the little K-27-11 turbos (I think its the K-27-11).
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08-21-2002, 07:31 PM
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guys there's other ways around doing custom work to twin-turbocharge a 928. Companies LOTEC, Gemballa, Callaway and Koenig have made both forced induction type 928s (turbo and supercharged). I recall Lotec actually fabricating their own custom intercooler to fit in a 928...2 to be exact. Their design I believe was similar to what i said above, in fenders or wheel wells. If anyone can find pictures of a turbo 928 please post them.
<img src="graemlins/burnout.gif" border="0" alt="[burnout]" />
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