Poll comments: What octane with what compression ratios? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

aintmisbehavinn · 10-24-2010, 05:53 PM

Searched around trying to decide what octane pump gas to run on original block and heads; rebuilt, torqued 350 w/ Holly carb; torquer cam; around 10:5:1 comp give or take :5. Been burning 93 but trying to decide if 89 is ok enough to slow foot it around town. What octane are you folks running and why; what motor?

Comments welcome; decision time

Beat68CST · 10-24-2010, 06:37 PM

I'm pretty sure that will lead to detonation.
I'm puttin my new motor in soon that will have flat top, 4 valve reliefs, so it should be around 8.7:1 or so and only gonna run 91 or better.

Both of my 327's came apart with cracked pistons from junk fuel.
I'd rather spend the extra few dimes a gallon then build, ANOTHER motor.

aintmisbehavinn · 10-24-2010, 06:43 PM

Thanks, this one has only seen 93 and runs smooth. May stick to 93.

cam.man67 · 10-24-2010, 06:43 PM

I'm trying to decide right now. 87 is giving me about 10-11 mpg, 89+ is running almost 13 mpg. Truck runs fine on the cheap stuff, though.

Mine's an almost stock '80s 350 with I think a mild RV cam.

llowlife · 10-24-2010, 07:56 PM

Short answer....I run the best gas I can find. .20 pr gallon times 16 or so gallons = 3.00 or so for a refill. I don't worry about 3.00 a tank.

Long answer, depends on what heads you have in conjunction with piston top design and quench area cam design. How about methanol injection?

I run measured 9.98:1 and can run cheap stuff ifn I have too.

Sorry to muddy the waters

Hubscrub · 10-24-2010, 08:13 PM

87 no problems 350 bored .60 no major mods

BADPURPLE70CHEVY · 10-24-2010, 08:29 PM

406 small block....93 all the way

aintmisbehavinn · 10-24-2010, 08:46 PM

Quote:

Originally Posted by llowlife

Short answer....I run the best gas I can find. .20 pr gallon times 16 or so gallons = 3.00 or so for a refill. I don't worry about 3.00 a tank.

Long answer, depends on what heads you have in conjunction with piston top design and quench area cam design. How about methanol injection?

I run measured 9.98:1 and can run cheap stuff ifn I have too.

Sorry to muddy the waters

Good point on price, that was my original idea; flat tops, not sure how much quench area, choppy cold smooth operating temp, no meth, that's on the GOAT.

Quote:

Originally Posted by Hubscrub

87 no problems 350 bored .60 no major mods

no ping at all on 87, hmmm...

Quote:

Originally Posted by BADPURPLE70CHEVY

406 small block....93 all the way

Any mods?

k5hart · 10-24-2010, 09:08 PM

93 is fine for me when it's a good brand. I've had problems with the cheap places. 350, 40 over, 10.75 compression roughly, aluminum heads. The aluminum heads and a tight quench is what's helping me.

Nova70 · 10-26-2010, 12:50 AM

I've always been told anything 10:1 or higher should use 91. Of course 91 here is equal to 93 around everyone else. 91 is our premium.

View Poll Results: Which octane rating are you using?
87 or lower	8	33.33%
89+	5	20.83%
93+	11	45.83%
Who cares; as long as it will run and it's cheap..	1	4.17%
Multiple Choice Poll. Voters: 24. You may not vote on this poll

10-24-2010, 05:53 PM	#1
aintmisbehavinn Registered User Join Date: Dec 2008 Location: Lawrenceville GA Posts: 64	Poll comments: What octane with what compression ratios? Searched around trying to decide what octane pump gas to run on original block and heads; rebuilt, torqued 350 w/ Holly carb; torquer cam; around 10:5:1 comp give or take :5. Been burning 93 but trying to decide if 89 is ok enough to slow foot it around town. What octane are you folks running and why; what motor? Comments welcome; decision time

10-24-2010, 06:37 PM	#2
Beat68CST Registered User Join Date: Oct 2010 Location: Buckeye Arizona Posts: 470	Re: Poll comments: What octane with what compression ratios? I'm pretty sure that will lead to detonation. I'm puttin my new motor in soon that will have flat top, 4 valve reliefs, so it should be around 8.7:1 or so and only gonna run 91 or better. Both of my 327's came apart with cracked pistons from junk fuel. I'd rather spend the extra few dimes a gallon then build, ANOTHER motor.

10-24-2010, 06:43 PM	#3
aintmisbehavinn Registered User Join Date: Dec 2008 Location: Lawrenceville GA Posts: 64	Re: Poll comments: What octane with what compression ratios? Thanks, this one has only seen 93 and runs smooth. May stick to 93.

10-24-2010, 06:43 PM	#4
cam.man67 Registered User Join Date: Jun 2010 Location: Jefferson, MD Posts: 2,397	Re: Poll comments: What octane with what compression ratios? I'm trying to decide right now. 87 is giving me about 10-11 mpg, 89+ is running almost 13 mpg. Truck runs fine on the cheap stuff, though. Mine's an almost stock '80s 350 with I think a mild RV cam. __________________ '68 Dodge Dart 270, 225, 904, 2.76--"Lucy" 1996 Gmc 1500 Z71, 350, 4l60e, 3.73s 1995 Jeep Wrangler Rio Grande 2.5, AX5, 4.10s 1989 Toyota Pickup 22re, auto, 3.73

10-24-2010, 07:56 PM	#5
llowlife Registered User Join Date: Jan 2010 Location: Elgin Mn Posts: 112	Re: Poll comments: What octane with what compression ratios? Short answer....I run the best gas I can find. .20 pr gallon times 16 or so gallons = 3.00 or so for a refill. I don't worry about 3.00 a tank. Long answer, depends on what heads you have in conjunction with piston top design and quench area cam design. How about methanol injection? I run measured 9.98:1 and can run cheap stuff ifn I have too. Sorry to muddy the waters __________________ In the beginning of a change, the patriot is a scarce man, brave hated and scorned. When his cause succeeds however, the timid join him , for then it costs nothing to be a patriot. I am a revolutionary...so my son can be a farmer...so his son can be a poet. If there must be trouble, let it be in my day, so my child may have peace... 72 short step w/ 388 /4l80e/ and 3.08 gears. Last edited by llowlife; 10-24-2010 at 07:57 PM.

10-24-2010, 08:13 PM	#6
Hubscrub Cruzin Join Date: Dec 2009 Location: on the road Posts: 2,835	Re: Poll comments: What octane with what compression ratios? 87 no problems 350 bored .60 no major mods __________________ Lime Wife's 67https://www.google.com/url?sa=t&rct=...wZEMODaS2d94u8 Back to the Fifties 59 https://www.google.com/url?sa=t&rct=...NAeStpydfrcj_U Proverbs 3:5,6 "Thanks to the Interstate Highway System, it is now possible to travel across the country from coast to coast without seeing anything."Charles Kuralt In memory of our first baby daughter, daddy and mommy love you. Danica Grace 6/26/14

10-24-2010, 08:29 PM	#7
BADPURPLE70CHEVY 406 Powered Join Date: Aug 2009 Location: waynesville,n.c. Posts: 877	Re: Poll comments: What octane with what compression ratios? 406 small block....93 all the way __________________ 70 GMC 68 c10 2002 silverado 72 4x4

10-24-2010, 09:08 PM	#9
k5hart Registered User Join Date: Nov 2002 Location: Charleston, South Carolina Posts: 1,370	Re: Poll comments: What octane with what compression ratios? 93 is fine for me when it's a good brand. I've had problems with the cheap places. 350, 40 over, 10.75 compression roughly, aluminum heads. The aluminum heads and a tight quench is what's helping me. __________________ 2006 Silverado CCSB, 1939 Ford Sedan, 1962 BelAir Wagon, 1976 Vega Panel Charleston, South Carolina

10-26-2010, 12:50 AM	#10
Nova70 Registered User Join Date: Jun 2009 Location: Dub VC Utah Posts: 364	Re: Poll comments: What octane with what compression ratios? I've always been told anything 10:1 or higher should use 91. Of course 91 here is equal to 93 around everyone else. 91 is our premium. __________________ '70 K10-- 4" lift on 35"s-- For Sale http://www.ksl.com/index.php?sid=733...iew&ad=4578305



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