can you give us your formula? i would like to do some calculations.

 

It's Hans' personal 997. I was there. Here's my post from another board.

Not an S, a 3.6. That car REALLY pulls hard. I mean 996 turbo hard. The German tech said that my 3.8 would gain the same hp as the 3.6, but mine would have more ft. lbs. at the bottom end, "significantly more" he said, I'd like to see that. I also learned that the published price includes all labor. I know it's a lot of money but damn, all that power and reliable too? Crap. It takes about four full days to install. You don't hear any whine from the supercharger and you really can't see too much in the engine compartment. Next time I'm there I'll take pics. I've thought seriously about getting the kit but am going to wait for the new turbo and have them sprinkle their magic dust on it instead.

 

((boost psi / 14.7) + 1) x motor compression = effective compression

 

JUST GOT BACK FROM RUF(DALLAS) THIS WEEKEND. WAYNE WAS NICE ENOUGH TO GIVE ME A RIDE IN THIS 997 KOMPRESSOR.. WOW!!!!!! AMAZINGLY FAST!!PULLS HARDER THAN MY GT3,HANDS DOWN.IF ANYONE HAS A CHANCE TO GET DOWN TO DALLAS,A RIDE IN THIS MACHINE IS WELL WORTH IT.GREAT GUYS WITH GREAT PRODUCTS(GROWN MANS TOY STORE)

 

It is north of 400 RWHP.

 

thx

 

Not a revelation being its "~9PSI"....my fearless prediction is you guys saw numbers in the 43Xrwhp range* With peak torque coming in at ~34Xrwt+ range. Easily faster than an X50 TT with I/E...

 

please post the numbers and dyno chart. if you're happy with the numbers, it certainly can't do anything but intrigue potential customers. anybody that would seriously consider this kit is going to want to see the chart anyway....

 

1999: what is the HP gain per psi on a 3.6 motor? i've heard approx. 20-25

also, what is the HP loss associated with lowering the compression?

is there a formula to guestimate how much RWHP this car should have?

based on 20HP x 9psi + an approx base HP of 275 should net a RWHP of 455 - minus whatever the lowered the compression losses are.

am i way oversimplying this?

 

You're looking at the power increase formula to simplicticly. There are only three primary ways to make more power ---- increase the displacement, increase cylinder pressure, or increase rpm. There are many things that effect the power increase in an engine as well as what the power curve will be. Forced induction is an easy way to, in a sense, increase the displacement of an engine. Adding more fuel to the increased, denser air in the cylinder will provide more power. However, timing has to be adjusted depending on the normally expected parameters of the engine's operation. What you do with the timing can have a drastic effect on the perfromance of the engine as well as what the power curve will be.

For instance, if you have a low compresion engine, as in the case of the RUF modified engine, you can run a higher (probably stock) timing setting and fuel/air mixture during low boost and slowly retard the timing as the boost increases. With an engine like yours that is starting at a higher compression ratio, the timing must begin to be retarded much sooner in order to maintain the same safety. Retarding the time is effectively robbing the engine of power. All this can be adjusted in various ways such as adjusting the fuel maps at various points in the rpm range.

Therefore, you cannot simply say that the RUF will be slower or faster than the EVO unit that is using less boost, even if the effective compression ratio is the same. Although the RUF unit will have less power without boost, timing can be maintained at an advance setting for a longer period in the power curve, possibly making up for any loss as soon as boost is present. Because boost is lower further into the power band, fuel mixtures can be adjsuted leaner for increased power.

This is all hypothetical as I do not know the setup of the RUF system. In short, simply increasing boost will not always increase power or performance. Increasing boost the wrong way can also cause you a loss in power. Boost increase must be done in conjunction with timing and fuel adjustment to take full advantage of the increased air available to the engine while maintaining a certain level of safety. Otherwise, you could get one of these:

 

that was good writeup. hope i don't ever see one of those pistons in person (knock on wood)


how much HP loss do you think is equated with lowering the compression in the RUF application?

 

The reason the RUF doesn't make more power than the evo is it needs added boost to make up for the HP lost due to the compression drop.

 

Whenever you lower the compression ratio of an engine without any other modifications, the power will drop at all points in the power band. But, as mentioned above, "other modifications" DO exsist in the RUF engine...the details which I do not know.

 

so why bother lowering the compression if you're not going for over the top HP?

unless of course they get a much bigger bottom end boost than the EVO kit with the added boost. that would be a great setup even if they didn't make more HP than EVO. it would be the best of both worlds between the EVO and the TPC.

 

The primary reason is for the longevity of the engine. However, I have run engines with a compression ratio less than 6:1 with 30+ psi of boost and I still prefer less boost with a higher static compression. You get a much better response throughout the power band. With improvements in materials and timing/fuel management, it makes it is a lot safer than it used to be.