What's the highest compression ratio I can run on 93 pump gas with iron heads?

 

A lot of people have run fairly high c/r successfully. But a lot of it depends on you spacifically. IE- tuning, mods, conditions, etc etc

But i will move this over to 3rd Gen since it looks like that is what you are working with and this is more a general question.

Thanks bud.

 

ID just Stick with 10:1 so you wouldnt have to worry about pulling timing out of it b/c of detonation (low octane)

You could probably get away with 11:1 On 93 And it not being 110 Degrees on the bottle. Probably have to always mess with timing too, not worth the extra 5 horse power differnece from the 10:1.

 

With cast iron heads I wouldn't go any more than 10.5:1. Thats about the maximum I would say. I am somewhere around 10.1-10.3:1 and I get a large amount of spark knock under hard acceleration.

On the other hand if you had aluminum heads you could easily run 11.5:1 compression on 93 with relatively no tuning issues.

For the full point in compression from 10.5-11.5 You would probably gain 15 hp. But then again, that could be a low side gain.