Quote:
Originally Posted by enkeivette
. . .
Hey Ben, my Mercedes tech buddy seems to believe that a 14-15:1 A/F ratio is dangerous for WOT. So I've decided to richen it up based on that.
You said that your A/F ratio was similar under WOT, why don't you richen it up to 12-13:1, you'd gain power obviously, it would be safer, and you might be able to get away with just 91 octane. I can't think of any reason not to bump up the fuel pressure.
|
It may be slightly different for DOHC engines than Pushrod, but I don't know. On Naturally Aspirated Gen III motors, 14:1 is about ideal for A/F efficiency. A bit richer at lower rpm (I'm close to 15 down low), would improve torque under the curve.
Running too rich (and I think 11-12 is too rich, even for your application probably), means LESS power, more hydrocarbon emissions (unburnt fuel) and and less mpg. Running too lean means you emit more NOX and run the risk of dangerous detonation (like bye bye engine territory).
It gets pretty complicated and I don't know all the theory for sure. However, it is my understanding A/F and timing is quite a bit different on Forced Induction motors than Naturally Aspirated. I suppose in the simplest terms, timing is often comparatively retarded and the A/F comparatively richer.
The point is that the same A/F and Timing curves are not equally well suited to different engines.
In my case, my biggest potential gain for power will come from timing. I'm only at about 18 at 4K. That's because it was tuned on 91 to avoid detonation. Because it's a fairly hi-comp motor, getting the timing up from peak torque, might punch it up a fair bit.