My buddy owns a 98 Prelude and lately sicne premium costs ur firstborn child, he put in some regular. what does that do to the engine? and whats the compression ration on the prelude?

 

It might be better for me not to try and answer... but what the hell.... it's just the internet.

I think the compression on a 98, which is a H22A VTEC engine, is about 10.5:1. I also think I read someone say that for that high of a compression that 90 or higher is recommended. My car only has 8.5:1 compression... so I don't need super premium... but I either put in 89 or 93 from sunoco. I try at least once every 2 months to use something extra good like 94 sunoco with a cleaner/treatment.

 

Sure you can use it. But the engine will run rougher and not as powerful. Any compression of over 9.5 should have at the minimum of 89 octane. Does it have to? Of course not. Do you have to eat vegetables? Of course not. You can eat nothing but pizza and hot dogs if you want.

 

if you dont run high enough octane your engine will pre-detonate wich can cause seriouse probs. spend money to save money.

 

the H22A features 10.1:1 compression. it requires at least 1 octane fuel to run properly.

as for lower grade fuel, you can run it safely as the engine features a knock sensor that will detect minor detonation and back off the timing to prevent engine damage.

Honda knew someone would put the wrong gas in so they took preventative measures to ensure engine life.