IcemanG17

can boost produce more hp from a 928 engine...for sure......

is it cheaper than rebuilding the engine or changing internal parts....yes

it all depends on what you want to do.....street car or race car.....how often will it be driven to the limit....and for how long (think Open Road Racing)....

Most boosted 928's are supercharged and street cars.....so they get short bursts of VERY high power....then go back to normal driving.....boost is great at this...

IF you want extended time at high load-RPM then there are large issues to overcome with supercharging...& turbos to a slightly less extent..... The most reliable high HP 928's are all strokers (increased displacement)....for a very good reason.....

Lizard928

I went with a custom mid mount. IMO turbo is the best way to go.

17prospective buyer

With regards to turbo setups, what about that Finnish guy that put his turbo right before his radiator and a bunch of convoluted plumbing to an intercooler? Never seen that offered by anyone so i figure he did it/engineered it all himself. He's on Rennlist. I think he said he used a Volvo truck turbo. Seems pretty badass to me.

Imo000

The Scandinavian's are a class on their own. I've see some many awesome, one off creations, come out of that peninsula that it truly is amazing. This is one of them. The turbo is after the radiator by the way.

928 at last

This is what can happen when people have a different view on life, and have waaaay too many holidays.....

andy-gts

I did carls raptor sc first , had 7 psi but didnt come on till around 3000 rpm and missed low end torque . If i went the the kuhn twin turbo first ( boost comes on earlier and with much torque) I never would have done the stroker.....
sc stage 3 7500
carls stage 2 6000
kuhn twin turbo 12 plus install and tuning 2500to 3000 more
stroker with itb , custom everything and oil control north of 50K

andy-gts

but I guess I can still twin turbo this and then do the texas mile.....for the win!!!!

FLIEGEN

If I did the Kuhn TT kit, where would it be power wise? I'm debating whether to keep this and mod it or trade my dad for his Vette. I already gathered it will cost 10-12k for the mods I want to do to it and it will make right at 500 at the wheels on motor and run low 10s in the qtr mile.

I know the 928 will never be that quick, but if it could make over 500 at the wheels safely, it's on the table (esp for the same mod money). I know they are different cars, I just want to make 21st century power. My last VW was as quick as my 928 is with just a computer flash upgrade.

rgs944

Personally i don't think you can get 500rwhp and do it reliablly, or at least not without a bunch of tuning and trial and error. My boost kit is probably around 400rwhp and does it easy without a lot of screwing around. Get past 400 and things will get quite a bit more involved. For a street car I have lots of top end power on reserve. I know some people talk about needing to get over 3000rpms before any boost kicks in on some kits, but with Victors kit I feel it immediatly when I touch the go pedal.

Imo000

As Mad Max would say.........there is not enough runnway.

Roy928tt

Gee a short visit to Kuhnperformance.com reveals his own car running 12psi claims over 570 whp, and that figure is typical of the 32 valve engine at that sort of boost level.

Colin's mid mount turbo is an amazingly effective and infinitely less complex installation.I personally dislike single larger turbos and particularly long hotsides, ie mid and rear mounts, but Colin's is hard to argue with.

I've actually been working on mine today, and I can't believe the enormous amount of detail work that goes into a Twin Turbo installation, that is why I'm quick to recommend Johns kit. It seems expensive but it took me untold hours to put mine together, it could have been cheaper to buy his kit or at least large chunks of it.

In my opinion Twin Turbos are the 'best' boost option, giving a wider rev range of torque increase, not suprisingly John points this out on his website. My own car starts to register boost at 1800 rpms and pulls like a train all the way to the rev limiter. I couldn't be happier.

In short it is the cheapest most effective means to achieve a most substantial power upgrade.

ptuomov

This statement makes no sense whatsoever. For the same USD and RWHP number, it is obvious beyond a shroud of doubt that forced induction motor will be more reliable. The main reason being that you don't need the high rpms to make the power with forced induction.

ptuomov

Isn't a 500 hp 928 about as stressed as a 250 hp 951? ;-)

The early S4 engine is basically unbreakable as long as you avoid very high rpms, avoid high g-forces, don't let it knock, and don't live in the Death Valley in terms of cooling. It can make 500 ft-lb of torque 3000-6000 rpm all day, all night.

AO

Fixed it for ya.

It is more involved. The higher the power the more complicated and costly it gets. No way around that.

If you want 500 at the wheels, I think the only options are Murfs Stage 3, or a TT system. I think the strokers are close to 500 but not quite there. My DR twin screw (extensively modified) now makes 490, but that's not quite 500...

I will say, there is a BIG difference between 400 and 500 on these cars. 500 gives you just enough power to feel a bit out of control if you're not paying attention. 400, while nice, just gives you a taste of what there could be.

I rode in a 800hp TT 928 last fall and OMG it was amazing. Very scary, but fun all at the same time. So maybe I just need to up my game and go to 600 HP next. It just costs time and money.

rgs944

Yea that's kind of what I imeant that if you do want to do it there is a lot more involved. Maf, greater tuning challenges, etc. For the average giuy with a street car who wants more usuable power I think it is good to stay around that 400 mark. In my case I would also need to update my clutch package which adds another few grand. I would love to have 500 though.