Trying to fine out compression ratio! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

sam's 72 · 05-12-2003, 12:08 AM

My son has a 87' chevy truck, with a stock fuel injection engine in it. I am wanting to know what the compression ratio is in this truck, and what size heads it has. I am thinking about putting the L98 heads on this truck, they are 59cc on the combustion chamber, i dont want to install them if it is going to jack the compression ratio up so much that it won't run on pump gas. Any ideal what the stock compression ratio is?
What cc heads is on there with out tearing it down?
Sam

mikep · 05-12-2003, 12:45 AM

should be 8.5:1 nominal with 76 cc chambbers and dished pistons

sam's 72 · 05-12-2003, 01:07 AM

Thanks Mike, that is what I was thinking, what would it be if you went from 76 cc chambers ( being 8.5:1 ) to 59 cc chambers?
Sam

stelth2002 · 05-12-2003, 02:08 AM

Desktop Dyno is showing 11.5:1 so it might not be a good idea :S

chevyhouse · 05-12-2003, 02:33 AM

try this.....

http://www.smokemup.com/auto_math/index.php

sam's 72 · 05-12-2003, 03:07 AM

chevyhouse,
That site does not do me any good. Sorry, It ask for info that I don't know, the engine is still in the truck and it is running.
Sam

jimfulco · 05-12-2003, 03:20 AM

My guess would be around 10.2:1. Depends some on head gasket thickness though.

bigjimzlll · 05-12-2003, 08:21 AM

I come up with: 59cc chamber-12ccdish-4.100 bore gasket-.039 thick-.025 deck height=====9.47-1

05-12-2003, 12:08 AM	#1
sam's 72 Senior Member Join Date: Nov 2001 Location: Pasadena, Texas, USA Posts: 1,005	Trying to fine out compression ratio! My son has a 87' chevy truck, with a stock fuel injection engine in it. I am wanting to know what the compression ratio is in this truck, and what size heads it has. I am thinking about putting the L98 heads on this truck, they are 59cc on the combustion chamber, i dont want to install them if it is going to jack the compression ratio up so much that it won't run on pump gas. Any ideal what the stock compression ratio is? What cc heads is on there with out tearing it down? Sam __________________ 72 LWB chevy truck. Pasadena, Texas

05-12-2003, 12:45 AM	#2
mikep Used to have a truck Join Date: May 2002 Location: port orchard WA Posts: 1,552	should be 8.5:1 nominal with 76 cc chambbers and dished pistons __________________ No truck :-(

05-12-2003, 01:07 AM	#3
sam's 72 Senior Member Join Date: Nov 2001 Location: Pasadena, Texas, USA Posts: 1,005	Thanks Mike, that is what I was thinking, what would it be if you went from 76 cc chambers ( being 8.5:1 ) to 59 cc chambers? Sam __________________ 72 LWB chevy truck. Pasadena, Texas

05-12-2003, 02:08 AM	#4
stelth2002 Young Gun wth Fast Inline Join Date: Jan 2002 Location: Idaho Posts: 1,475	Desktop Dyno is showing 11.5:1 so it might not be a good idea :S __________________ 1967 Chevrolet LWB with built 292! 415 ft. lbs of torque, 4 speed :O with 27% overdrive too, 3.73 Posi. Frame and body done... getting painted!!!

05-12-2003, 02:33 AM	#5
chevyhouse BEER-Vacation in a can... Join Date: Jun 2001 Location: wichita, ks Posts: 444	try this..... http://www.smokemup.com/auto_math/index.php __________________ Kurt 03' Trailblazer 69' C10 "SPSHL-K", 388 stroker/BTO 700R4, 2400 stall, 3.73 posi, lwb, fleetside long box, 3.5"/5" drop, 18" Budnik 2000 Yamaha V-Star 1100 Custom For Sale-87' V10-4x4, 408/700r4, 4.10's PM for pics

05-12-2003, 03:07 AM	#6
sam's 72 Senior Member Join Date: Nov 2001 Location: Pasadena, Texas, USA Posts: 1,005	chevyhouse, That site does not do me any good. Sorry, It ask for info that I don't know, the engine is still in the truck and it is running. Sam __________________ 72 LWB chevy truck. Pasadena, Texas

05-12-2003, 03:20 AM	#7
jimfulco Registered User Join Date: May 2003 Location: Shreveport LA Posts: 3,170	My guess would be around 10.2:1. Depends some on head gasket thickness though.

05-12-2003, 08:21 AM	#8
bigjimzlll Senior Member Join Date: Dec 2001 Location: Redding,CA...USA Posts: 4,736	I come up with: 59cc chamber-12ccdish-4.100 bore gasket-.039 thick-.025 deck height=====9.47-1 __________________ It's called "drag racing" if they called it "tic..tic..WHAM!..BANG! F*&K!!!", they'd have to keep the magazines under the counter with the other men's publications click the clicky to join the site.... http://67-72chevytrucks.com/vboard/payments.php 67 lwb..first hotrod in 25 years..540 best ET is 9.45 @ 141.44 Anderson,CA



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