Anyone have logs of a 30psi pump gas timing curve? Curious, tried to search and couldn't find anything and was just wondering whats a safe number to run up top

Thanks

 

tell us.

 

Bump

 

I may be wrong but the timing curve for 30 psi will be the same for just about any other boost pressure. I'm speaking of the curve not the actual values of course. The idea of ignition timing is to achieve peak cylinder pressure at the point of best leverage for the rod to act on the crank. When you do this you maximize the power at that boost pressure and rpm. I think this is called something like minimum timing for best torque.

If you run too much advance, you will start to run into knock, or you may simply stop making more power because you are beyond the point of best leverage. On pump gas though, I believe a Evo will almost always knock before you go beyond best leverage (when on boost).

All things being equal, as boost pressure increases, timing must decrease.

As RPM's rise, timing can be adding because everything is happening faster, and therefore, you need to start the combustion process sooner to keep peak cylinder pressure at the same spot.

Peak torque generally means peak cylinder pressure and this is generally equivalent to peak boost. Therefore you will likely run the least amount of timing at peak boost.

In terms of timing it's all about creating peak cylinder pressure at the right point in the power stroke. But if cylinder pressure is too great, then you can start to get detonation. So it is a balance.

Increasing boost pressure yields modest increases in peak cylinder pressure but improves overall cylinder pressure greatly. Greater average cylinder pressure will give you more power than using timing to create greater cylinder pressure peaks. But at some point you will reach the limit of the fuel and adding boost creates just too much average cylinder pressure to make it impossible to get a reasonable timing value at peak boost.

This is how I understand things and I'd love to be corrected by the more knowledgeable on the board.

As for actual timing values at 30 psi on pump, it could be 1 degree at peak boost or it could be 5 degrees or it could be anything. The question is, what boost pressure is yielding the most, safe power. If you know how to monitor the engine properly, and understand what the engine is doing, then you won't worry anymore what timing other people run.

Remember though, altering the head, valves, exhaust manifold, turbo and various other parts will effect what boost pressure you can run safely. So don't be surprised if a fully modified motor can run more boost pressure safely.

 

There are very few who can say they've mastered this sort of tune and I highly doubt that they would divulge that information to you

That being said you would have to push the limits for your specific setup to find out just how much boost vs timing your car can take.

 

Spark advance does not depend soley on boost so what other people use is useless. It depends on where peak cyl pressure is which depends on afr, boost, cams, bolt ons, plugs. So the only way is to log your car and quit advancing from low timing until it stops making power.

If det threashold is lower (pump) you have to lower something else

 

I can't believe someone actually asked that question!!

 

I think your question leaves too many variables to be answered correctly.

 

hmm fair enough

 

It is obviously an uninformed question but I just figure why not discuss the point.

Are you laughing because this is a shock to you people think like the OP? Hmm.. thats odd. As it's pretty clear to me that any typical newbie to tuning would think or ask a similar question.

To the OP... I tried to explain some of the fundamentals of creating an ignition map for a car. You should understand though, every car is different, so it just depends on all the factors explained and some.

 

He’s asking about timing curves at 30psi. He can’t be THAT uninformed. If was asking about exhausts or intakes, yes I’d call him a n00b, but he’s not asking a n00b question.

So he asks this question without giving any other details is why I’m laughing.

Stock turbo or 35R or 42R?
Stock motor or built motor?
Stock ECU or standalone?
91 octane or 94 octane?

See what I’m saying??

 

That^

 

Here is timing on a FPgreen Evo 8, 28psi, stock ecu, 91 California octane (straight)



Obviously this does you no good because you don't know the supporting mods, level of porting, AFR, etc

 

Ahhhh I do understand now. You assumed he is informed enough to know to post more detail. Got it.

Razorlab nice graph there. 28 psi on 91 on a stock frame turbo people. We got a proper tuner here people.

 

double post! bandwidth shot to hell sorry.