Iwanna928

Those are awesome results! Big kudo's to you and John for building a 928 BEAST. Nothing like having a safe tune with those incredibale numbers! Enjoy the 928TT!

ptuomov

I don't know. Because I don't know, I just bought a spare GT gearbox, just to be on the safe side! ;-)

Any ideas how to make the fuel temperature as constant as possible in different conditions before it makes it to the fuel rails? The stock fuel cooler cools the return fuel only, maybe do something on the pre-regulator side as well?

IcemanG17

Is the fuel boiling a side effect of the higher flow pump? I would guess all the fuel running through the heated fuel lines, then back to the tank & back eventually heats all the fuel quite a bit?

Still impressive Dyno #'s.....all that torque down low must be a BLAST to drive..... I can just imagine what Bill would do with that

Dennis K

Congrats Tuomo! I've been following your build w/ interest on here and through Jim. Those are some great results! And it's only the first stab at tuning . . . wow. Really impressed by the low end spool. What are the specs on the turbos again? GT3071R wheel? What housing & A/R ratio?

Dougs951

.......

I don't know what to say. This is wild.

Darien

CONGRATS...welcome to the "boosted" community

ptuomov

At low rpm/load, the pump is pushing thru over 100 GPH thru that small return line. That's why everything heats up.

I'll probably pull off some of that mid range torque next time, and up the torque at the top end. It'll make the car knock less, make traction more consistent, and make the "headline" peak hp higher.

The car is begging for more boost in the top end. And for a dyno operator that doesn't chicken out at 6500 rpm...

The craziest thing about this whole ordeal is that if you have a 928 in a good working order, then all that is required to get over 500 hp out of the car is a phone call and some cash. So far I've proven to the world that I have both a phone and some money!;-)

The turbos are the largest units that will ever be fitted in that location. They have a gt2871r compressor with a surgically altered compressor housing. The turbine has a gt30 wheel fitted inside a housing that has t25/t28 external dimensions.

Compressor and trubine maps below. The blue top line of the turbine map is what we have.

dprantl

Someone was eventually gonna ask... how much $$$?

Dan
'91 928GT S/C 475hp/460lb.ft

Imo000

Here's my guess............"If you have to ask........"

AO

Fixed it for ya.

auzivision

Ball park figures can be found here:

http://www.kuhnperformance.com/prices.php

I rode in Johns a few years back... amazing amount of power... rubber is the weak link in the equation.

ptuomov

I am spending +Inf per month on the 928 stuff. That's mostly R&D and drunk-bidding on the ebay.

In terms of what's actually bolted on the car as of today, here's the breakdown:

The base '87 car in a very good condition: $16.5k
The rear fuel system upgrades: $1k
Spec 3+ clutch "upgrade": $1.5k all in and it still sucks
Twin turbo base system: $11.5k
System upgrades, exhaust, installation, etc.: $8.5k
Total: $39.5k

If I weren't planning to change the whole engine, the smart way of doing the same thing while getting the basically same results would have been:

The base '87 car in a very good condition: $16.5k
Some clutch upgrade: $1.5k
Twin turbo base system $11.5k
Installation: $1.5k
New exhaust: $2.5k
Total: $33.5k

I don't think John will ever make the base system for $11.5k + $1.5k for installation again, though. At least not when he does his cost accounting.

Brett Jenkins

Tuomo, check out Mike Simards hydraulic release bearing system with nascar type clutch. Might be able to hold more power.

http://www.simardracing.com/Flywheel.html

Benton

When you think about what it costs to get most new cars today, that's not a bad deal for an awesome beast like that.

Benton

I would strongly recommend against trying to use a clutch like that on the street. For the track, that is the perfect setup (one that I may purchase one day).