HOW CAN I TELL IF I GOT LOW COMP PISTON`S OR NOT???
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HOW CAN I TELL IF I GOT LOW COMP PISTON`S OR NOT???
I was told by the chap i bought the car off that it had low compression piston fitted when it had a full rebuild.
How can i tell do a compression test or not ??
How can i tell do a compression test or not ??
#5
Norris Motorsport
A compression test will reveal nothing in terms of identifying compression ratio.
The only way to verify if you have modified pistons is to remove the head and burette the piston crowns for volume.
The only way to verify if you have modified pistons is to remove the head and burette the piston crowns for volume.
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I think i leave it at stage 3 then for now.Only done 5000 miles since rebuild.Can`t be fooked to take the head off to find out
Cheers for the info lads anyway
Cheers for the info lads anyway
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Tony, why dont you phone bluesprint motorsport. Im sure if you give them the car details and reg etc they will have a record of it. I know the previous owner was a little fussy when it came to rebuilding that engine Im sure he didnt do things by half
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#10
Norris Motorsport
No can do gareth.
Piston rings can leak fluid giving inaccurate results.
I can do it this way if its a dummy build whereby I have filled the top ring area with grease to prevent fluid leakage. However its easier to simply burette all volumes rather than a dummy build just to measure C.R.
Hence on an engine thats in car its a no go.
Piston rings can leak fluid giving inaccurate results.
I can do it this way if its a dummy build whereby I have filled the top ring area with grease to prevent fluid leakage. However its easier to simply burette all volumes rather than a dummy build just to measure C.R.
Hence on an engine thats in car its a no go.
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Originally Posted by AndyRST
Tony, why dont you phone bluesprint motorsport. Im sure if you give them the car details and reg etc they will have a record of it. I know the previous owner was a little fussy when it came to rebuilding that engine Im sure he didnt do things by half
The only prob mate it was a cash job no invoice .I spoke to joe @ BLUESPRINT But he can remember the car and rebuilding it but not a 100% sure what work was done on it.
He did tell me the previous owner was fussy as fook though.
As i do trust the guy i bought it off was telling the truth i just wanted to be 100%.
Look like i may have to take the head off
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Originally Posted by DOO
Originally Posted by AndyRST
Tony, why dont you phone bluesprint motorsport. Im sure if you give them the car details and reg etc they will have a record of it. I know the previous owner was a little fussy when it came to rebuilding that engine Im sure he didnt do things by half
So yeah i heard he was a little fussy
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You could still do a comp test 2 see what the figures are if there all the same across all cyls and are low or high will help denote health of engine and will help explain whether low comp or std it wont give a comp ratio but will help
#17
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Karl,
i was thinking baout the rings leaking!
Glenn5,
you gotta think about what effects the compression test, cam timing, cam choose being just two
i was thinking baout the rings leaking!
Glenn5,
you gotta think about what effects the compression test, cam timing, cam choose being just two
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sorry to jump on your post but its kinda related , would anyone in the know say thease are low comp pistons ?? as i was told by the last owner that they are but am not sure ??
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thanks karl thats all i need to know i hate having a enging that i dont really know the spec of , all i know is that it needs a set up and hopefully some one will be able to shead some light to the spec and what it caperble of ?
#26
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DOO= Does it matter? You can go well past stg3 on std comp anyhow if live mapped, and TBH if u was going past stg3 youd idealy wana whip the head off to fit a decent gasket anyhow.
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how can you tell with the head off? i'm away to buy a low comp bottom end 2! had a quick look at it a few weeks ago and the pistons were dished! how deep should the dish be? or would the pistons just sit lwoer from the top?
#28
Norris Motorsport
Glenn5, I'm affraid your attitude is pretty poor!!
A compression test is used to test for leaking/bent valves or damaged/cracked piston rings. It can give an indication of general engine health IF you know the compression readings when the engine was new.
It is a very crude test simply to help identify if the engine has any obvious internal faults which would then require stripping to investigate.
A compression test is used to test for leaking/bent valves or damaged/cracked piston rings. It can give an indication of general engine health IF you know the compression readings when the engine was new.
It is a very crude test simply to help identify if the engine has any obvious internal faults which would then require stripping to investigate.
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Re: HOW CAN I TELL IF I GOT LOW COMP PISTON`S OR NOT???
Originally Posted by DOO
I was told by the chap i bought the car off that it had low compression piston fitted when it had a full rebuild.
How can i tell do a compression test or not ??
How can i tell do a compression test or not ??
Simple really.
#30
Norris Motorsport
Glenn5,
You really don't get this do you. You're either stupid or have'nt read what I wrote above.
A compression test does NOT tell you whether your engine is high or low comp.
If you can't accept this I will give you an example that will help explain why it's of no use.
As I've said its a crude test to help identify IF a problem exists in the engine. The results do not indicate the C.R.
You really don't get this do you. You're either stupid or have'nt read what I wrote above.
A compression test does NOT tell you whether your engine is high or low comp.
If you can't accept this I will give you an example that will help explain why it's of no use.
As I've said its a crude test to help identify IF a problem exists in the engine. The results do not indicate the C.R.
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Re: HOW CAN I TELL IF I GOT LOW COMP PISTON`S OR NOT???
Originally Posted by Glenn5
Originally Posted by DOO
I was told by the chap i bought the car off that it had low compression piston fitted when it had a full rebuild.
How can i tell do a compression test or not ??
How can i tell do a compression test or not ??
Simple really.
The question wasn't how do i determine ratio's just the compression.
Is anybody on this post to help or are we here just to bitch at each other?????
#37
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Glenn, I think you'll find he wants to know if he has low compression pistons or not, meaning a low compressin ratio as opposed to how much actual compression there is in there.
#38
Norris Motorsport
Not to mention stu the cam timing could be well out from factory, due to variances in manufacture, head height, and even the odd case where people have got the cam a tooth out!! lol
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Originally Posted by Stu @ M Developments
Glenn.
If you do a copmpression test and its low at say 120PSI. How will that tell you its a low comp set of pistons?
How do you know the valve's arent leaking or the piston rings not worn? Maybe even the followers are knackered and causing a low reading.
If you do a copmpression test and its low at say 120PSI. How will that tell you its a low comp set of pistons?
How do you know the valve's arent leaking or the piston rings not worn? Maybe even the followers are knackered and causing a low reading.
so i don`t think anything would be wrong.
so is it worth doing a comp test or not