Yeah, I remember Carl's thread about his homemade intake manifold that he got ballooning under boost, and his was pretty thick aluminum as well. I think all he needed to do was to add some spans across the top, and that fixed the problem. So if it does happen, it probably won't be a huge thing to fix.

 

Erik (and Todd in case he happens to be reading this) --

Love your project. Also thanks for posting those photos here, I think a lot people are getting a ton of enjoyment from them. It's good for the entire "team 928" have big-idea projects being posted here, give us something to root for. This, Simard's 7.0, Ott's whole car, Sterling's variocam, etc. Never mind that some of these projects must cost so much that only a person who invented crack cocaine and after getting out of the game invested all the profits in Microsoft's IPO could afford to replicate any of them on a pure customer basis!

Here are some comments and questions about the project. As you may know, my car is getting Kuhn's twin turbo kit on it, with a lot of little extra customizations. I am very interested in the different design choices in this car relative to mine. This is not about so much what is better, but just for me to better understand the trade offs.

1. Why two pumps instead of one big one? I put in the big fuelab unit, and it does about the same as two 044's at high pressures. Furthermore, the speed can be controlled with a pwm signal. One pump allowed me to put in pre-filter next to the pump and another filter inside the right fender compartment. Is the idea with two pumps to operate with one pump at normal times and turn the second pump on only when there's demand? That will require two check valves, one for each system, which I think the system has.

2. What are the pressure conditions in the air intake in the front fender, have you guys measured those? I think there's a small low-pressure area in the fenderwell caused by the air rushing by the side of the car and another one created by the spinning wheel. The Kuhn system has a intercooler in front of the fender, which exploits the high-pressure zone in front of the bumper and the low pressure zone inside the fenderwell. The air intake in my car will be close to the stock location, in the middle in front of the radiator.

3. That intake manifold is going to make some real power. I am envious. Now, as others have pointed out, there's a risk that it'll imitate a blowfish at higher boost levels. The force is area times pressure, and that's a lot of area. I think that's why many turbo intakes are designed from two smaller plenums connected with a balance pipe. A version of this manifold should sell like hot cakes for the normally aspirated applications as well, as long as all the detials are thought out. Does the stock stress bar fit with this manifold?

4. Autronic and coil on plug will beat my stock ignition system hands down. Is this done on the principle "just because we can" or are you going to actually use the high-boost, high-rpm capabilities of this ignition system? If you are, I am double envious.

5. The intercooler is deep. I think I can see the design philosophy here. This may not be the best intercooler for a long high-boost operation. But it looks like a massive heat sink, so I would guess it will work brilliantly in any sort of 30 second attack. On a sustained basis, it's going to require a couple of superchargers to blow the air thru -- as you wrote, you have those fans! Absent big fans, I think the dual fender-mounted setup that exploits the nautral pressure differential is better.

6. On turbo placement and manifolds: This is an interesting comparison. Kuhn's system has smaller radius turns in the exhaust manifold, but this allows placing turbos closer to the exhaust ports. Moving the turbo further downstream will allow for straighter paths, but the exhaust cools off a bit. Also, you can fit (after a lot of mods) bigger turbos if you modify the chassis, and with bigger turbos you can make quadruple digit power.

One thing that I would have some concerns about is the angle at which the wastegate downpipes are reintroduced to exhaust flow. Is this flow tested? Not saying that it wouldn't work well, can't tell fluid dynamics by eyeballing. Just that I haven't seen anything like that before. (And I can't see inside the Y with branches, who knows what's inside there!)

A side point on heat: Earlier, you wrote "Especially on a turbo car which will have a tendency to heat up the heads more so than the supercharged car would." This not always the case. For the same crank horsepower, a supercharged car needs to burn about 20% more fuel. If the turbo is chosen to be the right size, as in your build, the effect of exhaust back pressure on the head temperatures is going to be smaller than that of the extra burned fuel. Your point is absolutely valid for "overboosted" factory cars with their tiny turbos.

7. I agree with you on the ceramic coatings and Swain's in particular. We're applying those liberally to everything before the cats. (Yes, I'll be running cats. Legal in spirit if not in letter. A couple of 3" inlet-outler steel cats which outflow the Random Tech flowbench which can't maintain the test pressure.)

8. Has anyone found the limits of the stock fuel rails yet? This might be the car to find them. We're going with stock rails as well, and if they work at your power level they'll for sure work at our power level. We've made some progress fitting non-restrictive fuel dampers to the system, which may or may not be necessary. Someone said that the last injector is likely to run out of fuel first, which I don't think is obvious. It's a battle between friction related pressure loss and then kinetic vs. static pressure.

9. Is the bypass / blowoff valve before or after the intercooler? Also, is it a bypass or blowoff? If the intercooler gets good air flow, it's probably better to vent a bypass out from after the intercooler into the compressor inlet. If the intercooler doesn't get good flow, and is just a heat sink, maybe the arrangement of bypass before intercooler makes more sense. Blowoff valve you probably always want to have before the intercooler not to waste the intercooler heat sink. What do you think?

10. Last but not least: What are the long block specs? Dying to know what those bad boys are feeding!

Thanks again posting the photos and the details. Reading about these kinds of projects is I am sure a great pleasure to many of us. To me for sure!

Best,
"The Internet Engineer"

 

Ah Greenbay... The Fox Valley, a great place to grow-up! How many 928'ers are there in the Fox Valley?

 

Has there been any progress on this project? BTW, I really like that intake manifold.

 

No idea of any progress, but I met Todd this past weekend and saw and heard his S4. To say I'm impressed by Todd's skills and his 928 is a a gross understatement. WOW.

 

Most recent update is the harness is almost complete.
I'm cleaning up the website to streamline it a bit.

To clarify, the red supercharged car.
The twin turbo is still on the lift at his shop.

The next time you are in GB with more time to look around, a stop by his shop is in order.

 

I talked with Todd this week, he asked me to give you guys an update.
He said he is 98% done, which means all the R&D & fabbing & fitting
& designing etc, is done.
If you looked at it right now you'd think it was actually done.
Now he will disassemble everything, finish up a few welds here and there,
clean, paint, & coat things then reassemble it and start it up.
Remember, he is not trying to make maximum power right now with this motor
that is in it now (original 1988 S4 w/59K mi ) he is just getting all the new pieces to work together for the first time and get a proper tune on it.
He is not trying to see how much power it can make before it blows up, he
already knows what boundary's are, he wants to learn how to get a really good
and safe tuneup on a turbo motor so when he builds the permanent, purpose
built motor he won't be doing any on the job training ..
He feels that what he has learned from the supercharged red car project that
he will safely be able to get this one up to 25 psi boost and the next purpose
built motor will get 33 psi of boost.
I'm not on this site as much as some of you are, so any question you may
have might be answered by Erik ? or wait a few days for me to check back in.
I've anticipated a few I thought you might have like the boost level and
whats that blue thing hanging down next to the radiator fan -- its a 2 speed resister for the fans & whats that stainless valve with a hose coming out of it
-- its a pressure transducer for the methanol injection thats controlled by the
Autronic SM4 version 1.09 Eng Mgt System.
The alum tank that is in the spare tire well has two chambers, one is for the motor 100% meth, which is injected at the throttle body when the ECU says
all systems are safe for a brief spray, the other chamber is 30% meth - 70 % water which is sprayed into the front of that mammoth A/A intercooler by
6 spray nozzles.
The coil on plug, coils are a GM LQ9 part, same ones the Toyota Supra guys
use.
The turbos are > Garret GT3076R with Tial V ban turbine housings.
The single pipe exhaust is 4" diameter.
Enjoy

 

Here's the rest ..

 

& see post # 90

 

Should be an interesting spring. I suspect the earth's rotation may be affected.

 

Yep, day light savings will come early this year in Green Bay

 

stock up on tires.....

 

How do you beef up the transmission enough to handle it all.....or ....is he doing a special transplant tranny.???

 

He has learned how to make the trans live with around 650 ish whp in the other car.
With this one there probably won't be a problem, but with the next motor he will have
to do some upgrades to the trans, something along the lines of what Steve Cantenneo does
when he makes one of his heavy duty versions.