Necessary Octane - V8 with 145 to 150 compression?

**baja200merk** · 06-27-2012, 08:47 PM

I'd be checking with 2 other gauges. We have gotten away with 145-150 on 93 but it lives FAT and HAPPY with the big prop and a heavy load. After a few yrs of abuse its down out of the danger zone now

**Li'l Toy** · 06-28-2012, 08:25 AM

Originally Posted by delawarerick

Ft Lauderdale at 14th street marina supposedly has rec gas in 93 make sure they still have it and price. I have 140+ in an inline with dome pistons I use rec gas 90 and sea foam.

Rick--if you know--Lauderdale Marina at the end of 15th Street, just north of the 17th Street bridge and across from Pier 66? Or something at the 14th Street Causeway in Pompano? I looked at PureGas.com, did not see them.

Have you bought from them--can you get fuel to a trailer, since nobody can run fast anywhere in Fort Lauderdale?

**rapidcraft22** · 06-28-2012, 09:35 AM

I WILL SAY I HAVE 4 HOLES IN MY BLOCK DUE TO BAD GAS I WILL BE RUNNING 25% RACING FUEL IN MY NEW POWERHEAD BIG MONEY TO FIX A V8

**Riverratt** · 06-28-2012, 10:09 AM

Originally Posted by rapidcraft22

I WILL SAY I HAVE 4 HOLES IN MY BLOCK DUE TO BAD GAS I WILL BE RUNNING 25% RACING FUEL IN MY NEW POWERHEAD BIG MONEY TO FIX A V8

What octane fuel were you running?

**STV_Keith** · 06-28-2012, 11:50 AM

Originally Posted by Instigator

Agreed

I'd say that's pretty good to get away w/that Keith. Might want to consider playing the lottery.

Monty builds a good motor! Been on the boat, running this way for 4 seasons now.

Originally Posted by Euroski

Isn't LV about 2000ft above sea level? If so octane requirements decrease vs sea level.

Lake Mead is currently at 1112ft above sea level, but Havasu is 446-450'. I run more in Havasu than I do in Mead.

**rapidcraft22** · 06-28-2012, 12:53 PM

I could only get 89 at that time never again will i do that But i will have a great motor now i got a brand new not rebuilt 3.6 liter

**Instigator** · 06-28-2012, 01:57 PM

Originally Posted by STV_Keith

Monty builds a good motor! Been on the boat, running this way for 4 seasons now.

No doubt. If he says it's so, it's so.

**STV_Keith** · 08-07-2012, 04:40 PM

Still running good...

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**kimswang** · 08-09-2012, 04:49 PM

I had to watch that video twice, normally I look at the ladies but those motors are just sexy.....

**JrCRXHF** · 09-04-2012, 08:51 AM

135-140 and 93oct here the motor has never had anything but 93 oct on it and when i took it down this winter it looked good i have not ran any sea foam or anything it it. I am running aftermarket coated pistons too.

**Scmarineperformance** · 09-04-2012, 10:45 AM

4.0s handel higher compression better then 3.6s with the same octane the heat transfer is better on a 4.0 but 145psi with 93 on a lighter load should be okay for some time as long as water and fuel is good.

**kimswang** · 09-04-2012, 12:44 PM

93 is what Monty suggested for my 150 psi motors he is building for me now. And the boat is a 34 footer.

**RUNWME** · 05-29-2015, 05:34 PM

I know this thread is a few years old, but figured I'd piggyback on it. I have a 1985 v8 275. Compression is 120-122 in all 8 cyclinders. I'm thinking that 50:1 and 87 octane is good for those compression numbers? What do guys think?