There's a lot of guessing on how octane effects a moderate compression ratio engine or if it effects it at all. I believe they mention the the compression ratio on the engine they tested to be 10.7:1. I hope posting this video is OK.
Troubleshooting SBC overheating issues
- Thread starter MaltbyPenn
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I don’t know the exact compression ratio, I probably should do a compression test just verify. But I bought it from a guy who had a reputable builder build it. Talked to both of them and they said regular unleaded, but could give me an exact ratio.
I didn’t know that too much octane would make things worse. I just went higher to eliminate knock.
The video offers interesting effects of different octane fuels and different types of fuels on the same engine. A compression test wont 100% accurately verify your compression ratio, but it might get you an idea. It may give you a good guess using the atmospheric pressure on the given day you do the test. Imo, with your timing set at 36* and your using a higher octane fuel to compensate for pinging tells me your timing is probably too far advanced. Running a higher octane isn't going to hurt anything, but pinging will.