89 928 turbo

Adam,

I thought we talked about 10-12....

no warranty implied........

jt

special tool

UUUhh - yeah - that is excellent, dude.

That is an exceptional powerband for a rear mount which OBVIOUSLY has a smallish turbine/housing to compensate for location.
It is not easy to ground break with these engines - a turbo 928 is rare and speculation makes LITTLE horsepower, you actually have proof!!!
Imagine that....Porsche hp that ain't bull****.
Good job fellas.

Kaz

Very exciting, you should know a 2007 997Turbo Triptronic Transmission just recently ran a 12.27@119mph with a first time driver. This car had an X50 option and traction control which the owner did not use on that particular run. Temps were 80's and humid. Good to be within spitting distance and you're not even fully sorted and tuned yet.

atb

jt wrote:

She'll hold together.

Wade T

Very nice! Deffently needs an IC reguardless of the passive cooling effect from the long charge pipes. On one of the my other cars, upgrading from the stock intercooler to a large aftermarket unit made a HUGE difference.

special tool

haha - wait till you see what happens when you put an intercooler on there.

Imo000

At such a low boost, you don’t really need an IC. It can help but it’s not necessary. There were cars made in the 80’s by several different manufacturers that were turbocharged and had no IC at all. As far as I’m concerned, anything bellow 8psi does not need an IC.

JEC_31

"Necessary" is a variable. It was very necessary for OEMS in the '80s to cut costs and/or complexity on their low-boost specials, but it could possibly be considered necessary for the hot rodder boosting an NA-design motor to A) take steps to help protect against detonation, and B) make more power with same boost level.

Then we must plan for when that hot rodder is going to be turning up the boost level as the addiction sets in...


Wade: did you read Imo000's bad intercooler experience?

Imo000: did you ever try a different IC setup?


I've read many Expert Opinions, 928 and beyond, that vary the cut-off point above which IC becomes "necessary" from 6 psi to 12 psi. Of course there's 10,00 variables for every application.

James-man

Wouldn't heat-sink type vanes on the long pressurized tube under the car offer some degree of intercooling or would that only be effective if they were also within the tube? (I definitely wouldn't want to rube-goldberg anything within the tube, but externally seems risk free except for the squirrels and rabbits that may be impaled or minced on these things).

Seems like we would want to take advantage of cooling opportunities that may exist outside the engine bay.

Great turbo results BTW!!! This is one of those things that looked easy on paper but challenging to pull off - Glad to see your persistence toward a positive outcome!

Imo000

Yes, that’s very true but at the same time the manufacturers had to keep the cars reliable and cost effective. If it wasn’t possible to get away with IC and keep the engine reliable, they would not have done it.

Here is the dilemma. If the exiting turbo is already running out of air at the top, an intercooler will make this an even bigger problem. The boost would have to be slightly turned up to compensate for the pressure loos through the IC, so if the turbo is already running at maximum efficiency, this might not be possible.

I’m my case the dual core intercooler experiment was a semi success. I don’t think I posted pics of the final dual core Volvo IC with the custom aluminium end tanks, but it sure looks good! The IC is good but not for an engine as big as this and with a supercharger like mine. Also my Paxton was already spinning at max impeller speed so I could not compensate for the pressure drop in the IC. With a different SC that can be spun higher (pretty much any other SC can go at least 10 000 prms higher) the pressure loos would have been adjusted with a smaller SC pulley and the effects of the IC would have been beneficial. BUT this was not meant to be in my application.

JEC_31

Good point. But they're still designed for boost, and low-ish boost at that.


True, it would have to be a small IC to minimize pressure loss and then woouldn't be as effective - but it would still help.


I didn't know you had maxed the Paxton. Good to know you haven't toasted it with a smaller pulley.

Wade T

Well, if I were ramming boost into a 10:1 engine, I'd want a cool dense blast. The benifits are two fold, even at lower boost. One is, it save the engine from dentonation and the second would be more HP. Keep in mind when I upgraded to a bigger IC on the Supra it was at 10psi w/ the stock turbo!

Wade T

Negative. Infact, I've never heard of down side from intercooling execpt a tad more lag at low rpms.

Imo000

I believe you are probably more familiar with turbos. Superchargers don’t have lag but they have limits of how fast the impeller can spin. If you have a unit that is running at max impeller speed (at red line) and if the addition of an IC takes away a pound or two of boost, then the benefits of the cold air will be less than if the system stayed non intercooled. This is exactly what happed in my case. The setup is a low boost ~6.5psi and loosing 1.5psi to the intercooler made the overall results less than before the IC went in. Therefore I pulled the IC and went back to the non IC setup. This is not to say that the car is slow. It is pretty fast for what it is. Estimated FWHP is around 400 and is capable to pulling solid high 12 sec runs ant the drag strip. This is a perfect case of “sometimes more is less”

Wade T

Strange. My setup acutally gained 3psi from the IC upgrade not to mention 3psi just from an exhaust upgrade! I guess that's turbos for ya. But back up a few posts, my comment was about the turbo setup posted on the thread.