Skunk Workz

600 hp in the Audi 2.2 is not pushing it....Try boring it,to get 2450cc,then the Audi 20V of KRB Trading pushed 916 hp @ 7600 rpm,949 Nm @ 6400 rpm on racefuel. www.krbtrading.no It also pulled a 10.038 at the quarter,with a race track setup (not drag). As for reliability,the engine has worked flawlessly all summer.

Skunk Workz

Ok...ever heard of the 951? It happens to have stainless headers...

Well...there are lots of people on rennlist claiming (and showing dyno's) of 420+ rwhp on 18 psi with loads of torque from 3K rpm....on 3-litre engines. Then an 4.5-litre+ engine running 15 psi with the same amount of tune should easily lay down 500+rwhp without sacrificing the low end torque. A puny little 60-1 (or something in that size range) should do that easily.

Herr-Kuhn

You actually beleive that 900 HP Audi engine will last...now that is funny! An engine at that power level may have 50 hours of life (on boost). Also you mention race fuel, of what 112 octane? Who want to pay for that at the pump anyway? Mine will be built to run 93 octane pump fuel and will be built to last, not some 30 psi kiss of detonation death engine. 600 HP on a 5 cylinder is in fact pushing it and it takes a lot of money to get there as well. You people seem to forget, the engine does actually have to last to be considered a success, otherwise if you are just after numbers strap on a bottle and go.

DFWX

I doubt that a stock compression S4 can run 30 psi even on racing gas, intercooling, water injection and seriously retarded ignition. The compression is too high. It possibly could do so on alcohol with careful tuning and therefore would be a monsterously powerful motor - but more than the drivetrain could withstand.
On pump gas, probably 5, maybe 7, psi is tops on a stock compression S4.
Why not add a second mini fuel tank and a simple switch valve for racing fuel for those few times you really want to go fast?

DFWX

A couple hundred $ for water injection would be a good investment against denotation.

Vilhuer

1.5L turbo monster engines in Brabham were based on M10 engine family. It's 4 cylinder iron block originating from sixties 00 and 02 series cars. M50 in M3 is totally different animal and more related to M20 six cylinders also used in 3-series etc. starting from late seventies. But M20 and M50 can also take huge boost levels when build right.

Fabio421

What the hell is it with this subject?

My Grandfather taught me that there are two things you should avoid discussing if you wan't to keep out of arguments, politics and religion. I think I may have to add "boosting a 928" to that list.

James-man

We like to argue. Arguing Rocks.

That is why the gods invented Off Topic.

MarkRobinson

"forged sintered steel" rods. It's in the manuals.

chris0626

Ok, you got me on the manifold (cast iron is still better).

So you think that the production of power is linear (as based on displacement alone)? Your nuts, it's not nearly that simple. Higher compression does not lend itself to higher boost pressure(s) nicely... that's where tuning comes in... (so the tuning wouldn't be the same either).

As someone mentioned, an Aquamist (or other) water-injection system would be very beneficial to decreasing the likelihood of detonation (say, have it come on at 7psi or so).

Skunk Workz

It has 400+ hours of running without a hiccup to this day,mostly WOT track driving...It runs ELF TurboMax,which is around 103 octane unleaded. 25+ psi on 93 (our 98 RON) is rather commonplace here. We'd built Mitsu 3000GT single's running 30 psi all day long on pump fuel. Was used for everyday driving,and the occasional track day. 600ft/lbs to the wheels. Why should it be so much harder on a 928,where you have loads of cu.in to make up for the lesser boost? A 5 litre engine is almost twice the displacement of the 3000,which had 571 AWHP @ 24 psi/6400 rpm...that means your '28 would not need much more than 16-18 psi to be there,if it is properly tuned. No race gas needed.

Skunk Workz

Ever considered using much longer duration cams instead of porting some big ol' holes to get the mixture in..? What happens then? ...yes...that's right...lower dynamic compression....which means you can boost harder on the same static compression. With proper intake and exhaust tuning,you won't get much blow-back/ short-circuiting,and the smaller ports increase low rpm torque and spool. But,if the drivetrain is an issue...build it the same way,just boost less. It feels the same as the stocker to drive,except for actually being really powerful on top. That setup worked on every other car engine I've laid my hands on,and I just can't see what makes Porsches special in that matter. Except they might not handle the power and start breaking ring lands/cylinder walls/etc...or the drivetrain.

Skunk Workz

Sorry...seen engines having better spool with an exact copy in stainless of the stock cast iron manifold (all measurements were the same),so I'll stick to stainless anytime.

I know it's not linear...lots of hp is just about tuning it for a given (high) rpm and make as much torque there as possible. Strangely then,I see people raising the compression on Supra's from 8 to 8.8,slap in much longer cams and see a substantial gain... (if the tuning is right...of course). But,they're just ricers...

SharkSkin

Just a thought here... if you want to interest buyers in the most states possible, you might want to also think about what you can do with 91 octane. If one of the requirements is 93 octane, folks in Calif. won't be able to play...

chris0626

That is of course, your perogative.

Of course there are substantial gains to raising compression and installing larger cams. However, they are that much closer to the edge of detonation as a result, tuning/timing has to be more conservative as a result. I do hope that the 'ricer' comment was a joke, not everyone with a Japanese car is a ricer. There are a LOT of folks putting down very good numbers on Supra's, Skyline's, MR2's, Z's without looking like extra's from the cast of The Fast and The Furious.

It seems as though we've gotten off-topic in this thread (imagine that?!)

As SharkSkin stated, tuning for 91 would seem to be wise so everybody can play.

I couldn't agree more. The engine has to last (and last and last and last)...