Compression/pump gas?

[miller19j]

I know this has been answered before but I can’t seem to find it.
What compression can you run on pump gas and what octane gas do you need to run? For example if I run 9.5 to 1 compression what octane should I run? And what is the standard compression of a stock 454?
Any info you could provide would be appreciated.

[HammerDown]

Miller, that could depend on several things, Aluminum Heads vs iron, timing, Cam profile etc.
I'm at 10:1 Iron Heads 93 octain 35 degrees total timing...all's good. I (belive) I recall anything over my compression needed 96 or higher octane, come to recall...that was for an air cooled Harley motor...
As far as most standard comp. in a 454...I belive that would be just under, or at 8:1
All the advice I receved when doing my 468,049 heads, was not to push over the 10:1 mark. I didnt want to get involved in adding race gas to the fuel mix.

[West Coast Dave]

With aluminum heads 10.5:1 on pump premium w/ a split pattern flat tappet cam. I've heard some people have run 11:1 on 92 octane w/ aluminum heads but that is about max.

[MikeF]

My engine is right @ 9.6 to 1 w/ iron heads. Kinda wish I had aluminum to step that up to 10.6 to 1 for a little more. wink Would not be sufficient enough of a power gain to make much added thrust (speed) though. :rolleyes: :cool:

[77charger]

I have 11-1 i can get by with octane booster and retard the timing to 32 deg but prefer 100 and 36 deg.A boat engine runs alot cooler than an engine in a car so you can get away with a little more.

[LakesOnly]

I was running about an 11.25:1 compression ratio and ran pump gas one day (89 octane). Just look at my detonated pistons (center piston is the most obvious--see the top compression ring?):
http://a7.cpimg.com/image/35/64/15256117-007a-02000162-.jpg
Also, note the blistered head gasket just above the hole in the center piston. Couldn't hear the pinging through the water-jacketed thru-transom exhaust. Motor is currently all over my garage floor in bags and about to be reassembled...
LO
[ December 27, 2002, 08:02 PM: Message edited by: LakesOnly ]

[MikeF]

LO, That is where it usually happens. The piston cannot shed the heat fast enough right where it broke. The crown to ring land is thinnest in that section of the piston. frown

[LakesOnly]

Yeah, I noticed that upon closer inspection at disassembly.
DOH! :mad:
Oh well, at least I'll have a fresh motor...
LO

[Infomaniac]

I hate it when that happens

[miller19j]

I am planning on running 9.5 to 1 with my iron heads, so it sounds like I will be fine running the quality fuel sold at the lake.
Thanks for the info guys!

[Whipple Charged]

I would never run less than 91 octane if you have anymore than 30 degrees of total timing. Your just asking for trouble, if it's just slighly lean in some spots, you can kill it! A couple of things to help with running bad gas is to run richer air fuel, colder plug, lower spark, cooler engine temp.
Dustin Whipple

[Thunderbutt]

I use an additive with premium gas. 36 degrees, autolite 23 plugs with a Magneto, and keep the carbs (2-750's) a little fat. the motor runs at 180 degree water temp.

[Ian]

Lo, What headgasket is that. We are having problems getting our copper gasket to seal water.

[wfodude]

Ian:
Lo, What headgasket is that. We are having problems getting our copper gasket to seal water. What sealant are you using???