Highest HP Stock bottom end m20

[varg]

93 octane. Stock compression ratio.

[SLEEPYDUB]

93 octane. Stock compression ratio.

Well there is your answer. I can run much higher timing because of E85. usually 6-8* more then gas. I am probably little lower cr due to the 2.7/885 combo.

[varg]

Yes, you mentioned that earlier in the thread. The reason I replied it's a good amount of advance is because you said "not as much you'd think." It was right in line with what I'd expect. The lower compression ratio 2.7/885 combo may require more advance to make power, but due to the poor interface of the piston and combustion chamber it may be simultaneously more prone to detonation due to poor quench.

[SLEEPYDUB]

Yes, you mentioned that earlier in the thread. The reason I replied it's a good amount of advance is because you said "not as much you'd think." It was right in line with what I'd expect. The lower compression ratio 2.7/885 combo may require more advance to make power, but due to the poor interface of the piston and combustion chamber it may be simultaneously more prone to detonation due to poor quench.

Right. Flame propagation is trash compared to the normal 2.5 setup. I used to run much higher timing, and didn't see any issues with it, and only recently dropped my timing down for drifting purposes to conserve. I have seen some m20 maps with a lot higher timing and made great power on a similar setup. I have also read some discussions about how with m20s you can almost not run enough timing, especially lower compression and shit quench. Haven't heard of it being more prone to detonation though?

[varg]

With poor flame propagation you can reach the detonation limit of timing advance more quickly than you would with an equivalent engine that has the proper piston design to work with the head.

[cream_e30]

Ms2

Have any dyno sheets at 550?


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[SLEEPYDUB]

Have any dyno sheets at 550?


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I don't. The 550 estimate was based off of fuel injector calculations. I can tell you that at 30psi it felt just as fast as my 550whp 2JZ E30 at at 22psi. Again, that was just an estimate. I will have some true figures soon enough, but it will be on a built 2.9

[SLEEPYDUB]

With poor flame propagation you can reach the detonation limit of timing advance more quickly than you would with an equivalent engine that has the proper piston design to work with the head.

What would you consider too much advance on the 2.7/885 combo?
Say, 1 bar and E85?

[ForcedFirebird]

Naturally aspirated, MBT is about 27°.

[SLEEPYDUB]

Naturally aspirated, MBT is about 27°.

Thats about what I run at 100kpa, 27* at 5500rpm and goes up to 28 by redline. In boost, at 1 bar, I run about 18* at 3500 and slowly tapers up to 20* by redline.

For a boosted engine, E85, 2.7 bottom/885 head, what would you consider safe timing? What would you consider too much timing? Where would MBT sit at under boost?

[SLEEPYDUB]

Have any dyno sheets at 550?


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I did dyno my stock 2.7 bottom with 885 head before I pulled it out to go 2JZ + DCT swap. Head used a 280/274 bimmerheads cam.

21psi on E85, made 522whp


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[varg]

Big power. That was with the 6266? Where was full boost, 5,000rpm?

[4ce30]

Great numbers .. I’d like to also know where the powerband was

[SLEEPYDUB]

Big power. That was with the 6266? Where was full boost, 5,000rpm?

Sorry for late reply, I rarely get on here. I just finished up my 2JZ with M4 DCT swap and am about to post a build thread on it.
This was a 0.81ar T4 6266. Full boost on the log was around 4500rpm.