checking clyinder pressure
Thread Starter
TECH Fanatic
iTrader: (13)
Joined: Dec 2004
Posts: 1,264
Likes: 55
From: Hanover, Michigan
checking clyinder pressure I was wondering what the correct procedure is for checking this?
Is 200 psi what is considered normal?
What needs to be on/off the car when doing this? etc etc
thanks a lot
Is 200 psi what is considered normal?
What needs to be on/off the car when doing this? etc etc
thanks a lot
Spark plug needs to be removed (DOH!).
Good luck getting 200 psi!
I inject less then 40 lbs and look for uniformity across the cylinders.
If you got a leak it will show for sure.
Good luck getting 200 psi!
I inject less then 40 lbs and look for uniformity across the cylinders.
If you got a leak it will show for sure.
Thread Starter
TECH Fanatic
iTrader: (13)
Joined: Dec 2004
Posts: 1,264
Likes: 55
From: Hanover, Michigan
well I figured the spark plugs...OBVIOUSLY
Can they all be out? what about the exhaust? can it be off of the car?
I am not doing a leak down test...I have a screw in pressure gauge that goes into the spark plug holes to check for cranking compression.
I was wondering what the proper technique was and what kind of pressure I should be showing.
I thought around 200 psi was considered good.
Can they all be out? what about the exhaust? can it be off of the car?
I am not doing a leak down test...I have a screw in pressure gauge that goes into the spark plug holes to check for cranking compression.
I was wondering what the proper technique was and what kind of pressure I should be showing.
I thought around 200 psi was considered good.
I was KIDDING about the spark plug (ergo the "DOH").
If you are checking compression, you can look up some values, but the main thing if uniformity across the # of cylinders.
Doesn't matter wether exhaust or intake is connected.
All your doing is checking how well your valves are seating and if the leakage past the rings is ok.
I would remove all the plugs as it makes it easier to turn over.
Hope that helps
If you are checking compression, you can look up some values, but the main thing if uniformity across the # of cylinders.
Doesn't matter wether exhaust or intake is connected.
All your doing is checking how well your valves are seating and if the leakage past the rings is ok.
I would remove all the plugs as it makes it easier to turn over.
Hope that helps
Thread Starter
TECH Fanatic
iTrader: (13)
Joined: Dec 2004
Posts: 1,264
Likes: 55
From: Hanover, Michigan
I knew you were kidding...no biggie
I was gonna do it before I got the car back together after the h/c swap.
I should turn it over with the starter 4 or 5 times and take the highest reading? Take out the fuel pump fuse etc? all plugs out and exhaust off (makes it easier)
this sound ok?
thanks a lot
I was gonna do it before I got the car back together after the h/c swap.
I should turn it over with the starter 4 or 5 times and take the highest reading? Take out the fuel pump fuse etc? all plugs out and exhaust off (makes it easier)
this sound ok?
thanks a lot
When I was running 8.34 dynamic compression, I got 200 psi.
With my current cam (in signature), my DCR is 8.78:1 and my cranking psi is 245!
With my current cam (in signature), my DCR is 8.78:1 and my cranking psi is 245!
__________________
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
Trending Topics
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
Five Reasons the Camaro Was the Most Pivotal Player in the Pony Car Wars 2.0
Brett Foote
10.5:1 is your static compression ratio, they were refering to Dynamic Compression Ratio, so they are actually running more compression than you are. There are a lot of variable that effect DCR but they are probably in the neighborhood of 11.xx SCR.
Banned
Joined: Dec 2004
Posts: 2,636
Likes: 2
still dont understand, your LS1 has 10.25:1 from the factory. I have 10.5:1 why do i get 150psi from a compression check and you guys get 200+ ? Before you say mine is worn out, its new block, pistons, rings, heads, etc. and i was withing 5psi on all cylinders. *confused*
Originally Posted by Stanger88
still dont understand, your LS1 has 10.25:1 from the factory. I have 10.5:1 why do i get 150psi from a compression check and you guys get 200+ ? Before you say mine is worn out, its new block, pistons, rings, heads, etc. and i was withing 5psi on all cylinders. *confused*
The other problem is that you have a Ford and are on a GM board
J/K
Originally Posted by 4.8T
so what does it mean when you #1 and #3 hit 245 -250 but all others hit 190-200?
i think it said like 20 in my book but it is for 04 trucks not 02 vettes lol. but why would they all be consistant but the two. and those two had like oil on the threads of the plugs.?
Banned
Joined: Dec 2004
Posts: 2,636
Likes: 2
if you see a 40PSI variation you should be worried. take a turkey juice injector (whatever you chefs call it, works for me...) and squirt some oil in the low cylinders and test again, if the #'s shoot up, if so...rings...
my book didn't say thats what i'm trying to figure out. my compression is a little higher than stock though i have the felpro .045's or what ever can't remimber the exact number but they are the thin ones lol. i could smell fuel when i done those two i was wondering if the left over fuel in the rails could have leaked passed the injectors when i was cranking over the eng because the fuel pump relay was pulled but not the injector fuses. and the fact i found oil on the two plugs that were the highest. could a valve seal leak cause oil to get in the cylinders and cause a false high reading??
Banned
Joined: Dec 2004
Posts: 2,636
Likes: 2
4.8, when I checked my 5.0 1 cylinder was lower than the others (135ish). I put it all back togather and cranked her over for a few minutes and then pulled THAT plug and got 135 (all plugs now in, #'s will be lower) and then pulled the highest and it had 135 as well with the other 7 plugs in. Fuel on the walls can cause loss of compression during a check.
PS. it backfired like a 12 gauge when I cranked it the nexxt time
PS. it backfired like a 12 gauge when I cranked it the nexxt time