I have 150 PSI in each cylinder. Can I use 87 gas?
 

99 Ultra, 95" Screaming Eagle upgrade, 203 cams, CNC machined heads, flat pistons. Do I have 9:1 compression ratio or...?

You can damn near use kerosene! Only kidding!
At that compression I'd say that 87 octane would be absoluetly fine.:icon_beerchug:
Scott

Thanks. What is compression ratio? Is that stock compression? 9:1? Are flat pistons higher compression pistons?

Bud of mine has a 02 SE 95'' and he runs 87 all the time without issues. Mind you , I don't know what cam it has and sometimes this could have a play on what works too. Basically if it pings, then no.
Ron

Ran 87 octane in my bike with 205ccp this summer....ran fine and didnt even ping...suprizingly. That said i usually run 93 here as many places have it.

One atmosphere is about 15 lbs per sq inch. This number varies with altitude and temperature.

The way I figure this, and I may not be completely right, is whatever number you get, less 15, divided by 15. Round about.

so you do have about 9-1 compression.

An interesting side note.

Where I worked awhile back we had a BIG old air compressor that was single stroke for some reason. Used for a particular job.

Most this size are two or three stage with intercoolers but this one wasn't.

It pumped 115 discharge. Or about 6.5-7 compression ratio.

The temperture before the cooler was 450 Degrees. Always though about that.

So if you have 10-1 might be 650-750 degrees before the spark.

Don't need much