Done a compression test on the cossie and . . . .
22-10-2006, 01:52 PM
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Done a compression test on the cossie and . . . .
They were all bang on 120psi (isnt that a wee bit low?)
When I bought it off Pete Rs specialists it had just had a bttom end re-fresh. Rings and shells etc etc but he also said that he'd taken around 1mm off the top of each piston (this obviously affecting the PSI reading I will get)
Does anyone know what the correct C/R is.
Ta,Pete
When I bought it off Pete Rs specialists it had just had a bttom end re-fresh. Rings and shells etc etc but he also said that he'd taken around 1mm off the top of each piston (this obviously affecting the PSI reading I will get)
Does anyone know what the correct C/R is.
Ta,Pete
22-10-2006, 02:01 PM
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Originally Posted by chip-3door
You cannot tell the CR from a compression test.
I would have liked to see a bit more than 120, but at least there all the same
Bri.
Meant, does anyone know the correct PSI compression for a cossie lump 
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22-10-2006, 02:10 PM
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Originally Posted by chip-3door
Any slight change in cam specs or cam timing can have dramatic effects on the results.
22-10-2006, 02:11 PM
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Leakdown test? Would this be a test of how long compression can be held for?
Anyways I didnt have any worries it was running badly just wanted some piece of mind before the bosst goes up.
Anyways I didnt have any worries it was running badly just wanted some piece of mind before the bosst goes up.
22-10-2006, 02:13 PM
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Originally Posted by PeterLucas
Leakdown test? Would this be a test of how long compression can be held for?
Anyways I didnt have any worries it was running badly just wanted some piece of mind before the bosst goes up.
Anyways I didnt have any worries it was running badly just wanted some piece of mind before the bosst goes up.
22-10-2006, 02:21 PM
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opps i meant to write - Anyways I didnt have any worries it WASNT running badly just wanted some piece of mind before the bosst goes up.
22-10-2006, 02:32 PM
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well ok then. I got a set of .5 pistons upstairs anyhow! Im sure ill need em sooner or later.Just been flicking through tech Q & A's and someone has quoted at least 140 psi on all four pots!
120, or at least 140? which is it to be
22-10-2006, 02:37 PM
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Wouldn't worry about the exact reading, it'll be fairly random depending on the guage used engine temp etc. As long as they are all within 10% and don't go up much with a squirt of oil its all good.
You should really do it with the engine hot and the throttle wide open.
You should really do it with the engine hot and the throttle wide open.
22-10-2006, 02:45 PM
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Well my gauge was callibratd the other day so I can count on that, but I did it with a cold engine and forgot to open the throttle whilst cranking.
One of the reasons im questioning this is because the pistons have had 1mm taken off, so I would like to compare my PSI reading to manufacturers figures.
Fuk it im gunna end up stage.3 ing it anyway i know what im like!
One of the reasons im questioning this is because the pistons have had 1mm taken off, so I would like to compare my PSI reading to manufacturers figures.
Fuk it im gunna end up stage.3 ing it anyway i know what im like!
22-10-2006, 04:15 PM
#22
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Originally Posted by Bosch-Man
...my own built engine at 7.9-1 with grp a ported head and 16 in and 14 out had 155psi on every cylinder..good or bad 
22-10-2006, 05:53 PM
#24
As long as their pretty even then as said about a million times its ok
My standard engine'd cossie running stage 3 was around the 140psi mark but my last 1 that was low comp all cylinders were running abour 120psi like urs bar no4 which was only 100 psi so was obviously something up but didnt matter as it blew up in feb
My standard engine'd cossie running stage 3 was around the 140psi mark but my last 1 that was low comp all cylinders were running abour 120psi like urs bar no4 which was only 100 psi so was obviously something up but didnt matter as it blew up in feb
22-10-2006, 08:29 PM
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Now ive just got the dilema of . . . . do i stage.3 a perfectly driveable, economic, reliable saff and pay for the fuel and parts 
!
Or
Do I leave well alone and keep it lock stock standard
!
Stage.3 it is!
!Or
Do I leave well alone and keep it lock stock standard
! Stage.3 it is!
22-10-2006, 08:53 PM
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I have actually been looking into this mate, currently trying to buy a down pipe with an oxygen sensor hole! would also like to get his coil pack conversion stuff.
22-10-2006, 09:05 PM
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I guess PSI compresion depends on spec of engine then?
If 8.5bar/ 123psi is standard figures how come your getting 150 PSI!
and a few other posts ive read said theyve got 140 psi.
If 8.5bar/ 123psi is standard figures how come your getting 150 PSI!
and a few other posts ive read said theyve got 140 psi.
22-10-2006, 09:08 PM
#30
Originally Posted by PeterLucas
I guess PSI compresion depends on spec of engine then?
If 8.5bar/ 123psi is standard figures how come your getting 150 PSI!
and a few other posts ive read said theyve got 140 psi.
If 8.5bar/ 123psi is standard figures how come your getting 150 PSI!
and a few other posts ive read said theyve got 140 psi.Mark
22-10-2006, 09:16 PM
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All plugs out but forgot to throttle it (+it was stone cold, adn the fact its had a mil off each piston)
Fuk it if it breaks ill fix it. . .. . . again
(+it was stone cold, adn the fact its had a mil off each piston)Fuk it if it breaks ill fix it. . .. . . again
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