The key to top end power lies in the almighty Cosworth plenum

 

Some dynos will show power that carries out further as well....just one more variable.

 

Here is Tims car with SFR twin plenum intake manifold with twin throttlebodies.It is a stock motor,SFR twin turbo system,SFR dual 3" exhaust system and the rest is stock.It even has stock cams! I think the dyno pick-up was off since it hit the stock rev limiter but you can see the power was climbing.This was at 7.8 psi of boost

 

How would this work with a setup like the GReddy intercooler (ie, 2 in, 1 out)? Or does this twin plenum intake manifold necessitate the use of a new intercooler? Also, how does the second throttle body work? I'm on their (SFR's) site right now, and it appears as though it uses dual OEM electronically controlled throttle bodies. How does the ECU control this? I've been intrigued by this thing for the longest time, but it hardly ever comes up in conversation on here, so I guess now would be an appropriate time to ask.

 

I think he even offers the same manifold with different layout of pipes which utilizes one tb.

 

Interesting...

 

 

Doesn't turbo sizing also affect power curves (ie a bigger turbo will be able to make power further into the rpm band). My car makes power through the whole power band all the way to redline. I figure this is due to my setup having a fairly decent sized pair of turbos.

 

another HUGE variable is the amount of power. at 400 hp, i can make a graph climb straight up the whole way. at 650 when pushing the limits of a motor, its a little more difficult.

 

What are exactly the limits of a built motor (non stroked)! Are you saying 650 is what you believe the upper limits of the motor are?

Luie

 

alot depends on the heads & cams .....efficient cylinder filling is key to generating usable top-end power...

 

.... i think he was tryign to say that the higher the boost the harder it is to get the power to make it all the way up..not that 650 is the limit of the non stroked engine(i hope he isnt saying that)

 

Also race gas timing difference is big vs pump gas timing up top. That can certainly affect the curve-some may not agree but I think the TQ curve is affected more by this up top.

 

I agree. You start to surpass the air flow efficiency of the heads and cams as the power levels go up.

 

No joke, that thing is touched by the hand of God himself. It's not a mod to be trifled with.

 

I don't know a whole whole about the heads on our cars, but I have a friend with an heavily modded Evo that was experiencing something called "valve float". Is this a problem that affects our heads?

 

I think what he means are air flow limits. Many variables will play parts in how long power holds on including, intake flow, turbo flow, exhaust flow, and timing curve. There is no defined "limit" of any built motor let alone all of them as a whole.

 

Is see! I was thinking just about the motor it self with all the other variable taken out! i.e the true tolerances of a built motor in a perfect world.
Thanks for your input!

 

It could depending on RPM and the presence or lack of upgraded valve springs. Though the RPM levels were speaking of here <7000rpms the stock valve springs shouldn't have any problems.

 

Valve float is generally due to too high of an rpm for the spring pressure you are running. By that I mean, the springs aren't stiff enough to keep the valves closed, so the valve hovers open a little bit thus not getting full comression in the cyclinders.