joeymia

iTrader: (6)

Would going with Wiseco 10:1 pistons provide better hp numbers with a stock turbo? What kind of gains if any would I see? I do not want to change the stock turbo but would like to get to around 400whp as safely as possible. I will be using EMS most likely AEM with this setup.

umiami80

iTrader: (1)

Too High of a compression IMHO. You may make less on WHP on pump gas as it'll detonate easier for sure. It WOULD however recuce lag and throttle rersponse, but generally not good on a turbo car


Run 9.0-1, that's fine.

Ted B

iTrader: (6)

No.

The nominal benefits of increased static compression will be more than offset by reduced boost tolerance, and you will see a decrease in power.

VTECH8TR

iTrader: (70)

Sure try it and let us know when you french fry your motor.... j/k

I have a Buschur stage 4, AEM, and running methanol and making 400 to the wheels with the TME turbo like TedB.

cruizinmax

If you were using meth injection and could run the same timing, boost with 9.0 and 10.0-1 how much more power would be extracted? Reason I ask is because I have heard of honda motors putting down over 800 to the wheels on race gas using 10-1 comp.

Ted B

iTrader: (6)

And those Honda motors are making that type of power at what rpm? This is significant.

A bump in compression of a full point (e.g. 9:1 to 10:1) will typically result in a boost in average torque of a few percent. Static compression is just how hard you're squeezing the mixture, while boost pressure affects how much air mass you're getting into the cylinder. There is a point where the tradeoff in raising compression becomes a losing proposition, and the position of that point will vary depending on several factors.

A motor that is set up to make peak power at very high rpm can get away with higher static compression because the loooong cam overlap will reduce cylinder pressures at lower speeds, where detonation is most prevalent. Less ignition timing, retarded cam timing, and richer mixture settings all factor into the equation favorably.

Also, since detonation is aggravated by load, vehicle weight and gearing play a factor as well. A lightweight chassis is more forgiving, as is lower gearing.

Other factors include intake air temps, bore/stroke ratio, rod/stroke ratio, head design efficiency and piston/chamber finish, etc.

So as one can see, it isn't only about static compression, but rather it is about what cylinder pressures and load the engine 'sees' within the bulk of its operating range, and the ability of the fuel to withstand those pressures without losing its 'cool'. So while a 10:1 comp ratio may look sexy on paper, a motor set up to make peak power at 10k rpm may not develop enough actual cylinder pressure at lower speeds to pull the skin off of a grape.