I have 2 951 engines. I am thinking about a billet head for one of them. I have one with 49cc domes for a bore of 89.5mm. SD spec for domes is 51.8 +/- .6. For a slightly modified engine is 49cc too small? I want to run 91 octane. Per ADA, the 50cc dome the compression is 155 and for 48cc its 172. I would guess 49cc would be about 160. Is this too much? Should I find 50 cc domes?
Miller Billet Head 951
- Thread starter Boyd12
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I intend to do a rebuild at the same time.
"130 psi is stock so you really shouldn't go over 155 on pump gas." That was my understanding. I am concerned if I went over 155 it could create some unnecessary issues and I dont think the quality of fuel now is as good as it was 15 years ago. An engine I had back then was 160 with no issues. That was back then.
Thank you for your response!
"130 psi is stock so you really shouldn't go over 155 on pump gas." That was my understanding. I am concerned if I went over 155 it could create some unnecessary issues and I dont think the quality of fuel now is as good as it was 15 years ago. An engine I had back then was 160 with no issues. That was back then.
Thank you for your response!
No problem.
Keep in mind that 160 psi in one engine can be unsafe in others. 160 would be no problem on pump gas with a superjet or something like a 96' XP but the 951 is under more stress and typically run pretty hard so I would keep it lower to avoid detonation.
Keep in mind that 160 psi in one engine can be unsafe in others. 160 would be no problem on pump gas with a superjet or something like a 96' XP but the 951 is under more stress and typically run pretty hard so I would keep it lower to avoid detonation.
130 is stock? I have both cylinders at 135 and the engine has 184hrs on it...
Used 2 different gauges and both were very close.
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