?: F22a Highest Compression on 87 octane unleaded

[KillerCam282]

I'm surprised that no ECU tuner said it can be done. Simply because...it can be done. Now, if you were looking for a substantial gain in horsepower, you won't get much if any at all. If you go too high, you will lose power simply because detonation will be inevitable.

You see guys, his question is "whats the highest CR you can run on 87 octane unleaded?" If thats what your primary concern is, you need to find a CR that will not create temps that are substantially higher than your current temps.

We all know for a fact that the H23A1 from the USDM prelude runs on 87 octane. Well I have good news, that has a 9.8 CR and 160hp to show for it. That happens to be 20 more HP than the F22A6.

So, will you be able to pull off 11:1 CR on 87 octane. I say possibly, however you would have to fight detonation by retarding the timing and adding fuel. This can cause and engine to bog and be sluggish since the power comes from the exact opposite side of the spectrum. The power is made from a leaner mixture that has advanced timing.

Now to answer your put a number value on the question...I can't do that. No experience behind it, I can only give you speculation. Based on the fact that we can run 87 in the H23A1's 9.8:1 compression, I would safely speculate that you can do that up until 10:1. .2 points will not be much of a difference in engine temps. However, you will need a competent tuner, and definitely will have to take advantage of head upgrades as well as some bolt ons to see any dramatic improvement.

[d112crzy]

hmm, he had another thread asking something about compression.

I stated that he would only be limited by gas and he would have to retard timing a lot.

Phil, h23 has 9.8 cr. It does run on 87, but crappy. Runs much better on anything higher.

[KillerCam282]

hmm, he had another thread asking something about compression.

I stated that he would only be limited by gas and he would have to retard timing a lot.

Phil, h23 has 9.8 cr. It does run on 87, but crappy. Runs much better on anything higher.

I doubt that it would run crappy in 100% stock trim, P14 and all. Owner's manual says you can use 86. I validate your statement tho. In the early years of me owning my accord, it only ran properly on 93 octane. That was a stock F22A1. Anything lower, and it would bog and shut off on me. It might have to do with the condition and age of the components in the car itself...

9.8:1 compression is the correct figure, thanks Jose.

[MadSpleen85]

Is the factory compression ratio the best?

This is the same thing I have been wondering.. I heard somewhere on here that the stock compression ratio is tuned down for better fuel economy.. Maybe I just didnt understand what was being said then though.. Later