Octane Rating Needed?

TXFlyGuy · #1 10-07-2017, 06:03 PM

For you RV guys with high compression ratio engines, what is the minimum Octane Rating that you need?

High compression being 10.7-1.

As we have found a good source for 91E0 fuel, just wondering if that would cause any detonation or preignition issues?

We wish to avoid 100LL as much as possible.

Kyle Boatright · #2 10-07-2017, 06:58 PM

You'd do a lot better asking your engine builder. There are many factors in play other than C/R.

rv7charlie · #3 10-07-2017, 07:26 PM

And specifying the actual engine.

If it's an a/c engine with giant bores & sub optimum combustion chamber shape, you probably will have problems. If it's an automotive engine with optimized combustion chamber shape and an engine controller that monitors air/fuel ratio & knock sensors, and manages mixture & timing, it might not be a problem at all.

RV3bpilot · #4 10-07-2017, 07:27 PM

On this site below gives the compression and pressures for engines. Just type in your engine size and you can find the compression ratio and the fuel octane needed to keep it from pre igniting or detonation.

http://www.turbofast.com.au/javacalc.html

TXFlyGuy · #5 10-07-2017, 08:09 PM

The engine is a LS376/480 Chevy. Max rpm will be limited to 4500, which equals 400hp at sea level.
Seems like GM says 92 Octane is recommended.

rv7charlie · #6 10-07-2017, 09:14 PM

Well, if you're using the factory (street rod/international) controller, you've got your answer. :-)

I think we've covered this before, but in addition to numerous Lyc drivers, a *lot* of alt engine guys just use pump mogas, even with ethanol. The aluminum tanks and fuel lines are fine with it, so as long as you're using teflon lined flex line, you should be good to go.

TXFlyGuy · #7 10-07-2017, 09:30 PM

Quote:

Originally Posted by rv7charlie

Well, if you're using the factory (street rod/international) controller, you've got your answer. :-)

I think we've covered this before, but in addition to numerous Lyc drivers, a *lot* of alt engine guys just use pump mogas, even with ethanol. The aluminum tanks and fuel lines are fine with it, so as long as you're using teflon lined flex line, you should be good to go.

Yes, similar topic visited before. Thanks for your input!