Z

Okay, so it is a picture of more than one car. It's a picture of two cars.








The dark blue car is the one whose dyno chart is posted at:

http://forums.rennlist.com/cgi-bin/r...=006577#000007

hacker-pschorr

Its even track tested.
Exiting turn 6 at road america:

JasonO

Am I going nuts or is everything in the red cars engine bay slanted?

-jason

GoRideSno

Z,
Is that the Spearco 4.5x4.5x10 IC core on Tim's car? or the 6x4.25x8.63?

And the red car, that IC seems to be 13x4x4 or so. What is the thing at the back of the manifold? Who belongs to this car?

Thanks for the pix,
Andy K

Z

The radiator makes it look like that in the picture. The position of the stock radiator, radiator fans, and fan shroud were modified.

I'm not sure about the exact intercooler specifications on Tim's car. He had it made to his specifications though. The one on the red car is a custom modification of a 951 intercooler. I'd say way overkill for most applications, but the intentions for that car are some pretty radical future modifications, and a lot more boost. The thing at the back of the manifold is the blow off valve. I'm not sure why he put it back there, but it's probably going to be moved to where Tim's is, on the other side of the intercooler. That's the better place for it.

John..

This forced induction on sharks is madness I tell you, but I'm so glad to have been hit by the bug as well. My setup is a lot more "hidden" because the goods hang real low.

My pics will be coming real soon. I put the heads, exhaust manifolds and turbos on last night. Tonight comes the intake and front side of the animal.

"How much Boost can you run in a 928?"

I will know soon!

Gregg K

What!? Call me a purist, but turbocharging with a belt is just plain wrong. Get that exhaust to do the work. I was hoping to see how one would accomplish a "real" turbo installation on a shark. Sorry, I'm not trying to be offensive, just that it is self defeating to take power from the engine while it's just throwing it away out the tailpipes. Argh!

hacker-pschorr

Well you can't please everyone!
I've been involved with Tim since almost the start of this project. Simply put, supercharging is simpler. How many years did Porsche spend trying to smooth out the turbo lag on the 911's and 944's? In my opinion, they never go it right on the 944's, reason why I bought a 944S. The couple of 944 Turbo's I've driven the lag was a show stopper for me, I'm just not used to it. Ok, blame driver inexperience.
The 928's are such a smooth engine, why ruin it with a sudden boost at whatever RPM the turbo kicks in? Tim's car is smooth as silk when he hits the throttle. Same reason why I'm sure Mercedes choose supercharging on their cars. You may be able to get more power with a turbo, but there is still room to go on the blown Mercedes motors anyway. They were going to everyday drivability, another question most interested shark owners bring up "How is it on as a daily driver?"
I'm sure John's turbo shark will be awesome, I can't wait to see the specs. I'm just not sold on turbo's unless you are building an all out race car where you are trying to squeeze every last bit of power out of the car. I'm sure Tim's car could make a lot more HP, but at what expense? I think he's found the sweet spot for these motors.

A friend of mine uses the 944's as an analogy for the 928's. A stock 1989 944 Turbo is rated at 250hp at the flywheel. A 1989 928S4, something like 320 I think. Bascially they are the same motor, one is jus half of the other. Why is the 928 making only 70hp more? Porsche was trying really hard to make the 928 as fast as possible without blowing the doors off the 930. If a 944 Turbo is reliable in the 250-300 HP range, why wouldn't a 928 be just as reliable in the 500-600 HP range? Maybe even more so since a 5.0 V-8 is a lot smoother than a 2.5 4-cyl? Just a thought.

Lagavulin

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">If a 944 Turbo is reliable in the 250-300 HP range, why wouldn't a 928 be just as reliable in the 500-600 HP range? Maybe even more so since a 5.0 V-8 is a lot smoother than a 2.5 4-cyl?</font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Wow, good point! Never even thought of that one...

John..

The big major difference in the 944 vs turbo is the sodium filled exhaust valves and forged pistons as well as ceramic lining in the heads.

I disagree with you on the lag. If the turbochargers are sized properly, and you have a competent driver the result is a smooth off boost car with great throttle response. All too often, the turbo is not sized properly, specifically in an aftermarket application. The 911 turbo always came on hard because the turbos were very large....this was done to minimize heating of the air by running an efficient compressor system. For the air cooled 911, those were the "proper" turbos. The 944 T feels like it comes on hard compared to a 928, because it is just a 2.5 liter copared to 4.5 liters plus.

A ride in my 928 would eliminate any concerns you have about turbo lag. I get boost as low as 1800 rpm and it builds smoothly from there on up. It is all about the A/R ratio and manifold setup along with the compressor wheel. There is a lot to consider.

If there is one major downside to turbocharging it is exhaust back pressure that can go sky high. A turbo is really like a steam turbine. More pressure and heat drop, more power to drive the turbine wheel.

I think the centrifugal blower is a cool setup, somewhere between a roots style and turbos. Certainly easy to install.

All setups have plus and minus factors. For maximum power and efficiency the turbo is king, but it is waaaaay more complicated to get it right.

Gregg K

Lag. Good point. When I built up my turbo, it was such that lag hardly existed. It's a looong way from those headers to the intake on a 928, probably. And I don't know how one would get the plumbing to work out anyways. Has anyone done an exhaust driven turbo installation on a 928? I'd love to see how they did it.

PCinDC

John, only the 1986 944 Turbo came with forged rods. From there on out they used cast rods, I would assume for cost-savings.
Even the 1988 951 S and 1989 Turbo have cast rods, and they are perfectly reliable until you really start upping the boost.

Other than that, I agree with you on all counts - It's all about getting the right parts for the application.
<img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />

Z

You mean by using a turbo to plug up the exhaust and heat the intake charge?

There's no way the age old debate is going to be settled here, and everyone's going to go the route they want to anyway. When one of the turbo fans states that their turbo doesn't take any power from the engine to run though, ask him to make it spin without starting the car. After all, if it doesn't take power from the engine to work, it should crank out plenty of boost without the engine even running, right? If any turbo fans figure out how to compress air without using any power to to do it, an awful lot of people would be very interested to hear about it.

Tony

So...
with the right CR and the right equipment(forged) and a bigger fuel pump , 600HP is definitley reachable id say. I know Tim and you guys have done a tremendous amount of work so far on your cars and i think it is really only just the tip of the iceberg. NOw you can start tweeking and growing from 500HP! <img border="0" title="" alt="[Eek!]" src="eek.gif" />

I think the reason we dont see more of this stuff in 928s from Mark A, MArc T, MArk K..Don H and our east coast racers is that SC'ing a motor takes the 928 out of certain PCA..SCCA..racing classifications doesnt it..therefore their resources and time are used to perfect the NA 928 engine? Absolutley no harm in that either!

All the power to you guys for charging a head and sharing the info for us street bound/ DE folks!

<img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />

hacker-pschorr

Hmmm, PCA - something I've been wondering about myself. Wonder what type of class a SC Shark would be in? Any PCA experts in the house?