z25 octane

[KerrLake]

I read a previous thread about octane. I don't have an owners manual with my boat so I don't know what the recommended octane level would be. It is an 86 z25 454, the previous owner says 370hp. It doesn't seem to be running great on 87. I am wondering if the octane level could be my problem. Should I dump in a couple bottles of octane boost to see if it runs better? What would I look for to know that it is option 370hp and not the standard 330hp?

Thanks
Brian

[joel3078]

Define not running great.
The 370 horse is high output and needs premium. Should run 93 but can probably run 91. 87 is too low. Low octane would cause pinging, preignition, etc. Poor idle, rough running, etc. is not indicative of low octane gas. Again, define not running great.

[KerrLake]

Runs rough meaning that once the engine is at normal running temperture it dosen't idle as well and at lower rpms misses randomly. When the engine is cold it doesn't seem to have the miss and idles better. I've only had the boat a couple weeks so I don;t have alot of running time in it. If it is the high output would it say it somewhere on the engine? It has chrome Moroso valve covers, so nothing there.

Brian

[mjpcowboy]

My 500 EFI's run great on 87. I personally think you would be throwing your money away running higher octane fuel unless you have really high HP motors. Just my $.02