JCW JCW Hardtop compression test results
#1
JCW Hardtop compression test results
I need a bit of comparative data please folks.
Has anyone run a compression test on their B48 equipped JCW Hardtop?
Gollum IV was just tested at 92,600 miles, and returned (1-4) 150,145,145,145.
Nice balance, but seems a touch low for what I thought was a 9.5:1 motor.
Anyone else with data from this test?
Thanks very kindly.
Cheers,
Charlie
Has anyone run a compression test on their B48 equipped JCW Hardtop?
Gollum IV was just tested at 92,600 miles, and returned (1-4) 150,145,145,145.
Nice balance, but seems a touch low for what I thought was a 9.5:1 motor.
Anyone else with data from this test?
Thanks very kindly.
Cheers,
Charlie
#2
Compression pressure has little to do with compression ratio. Compression ratio is purely geometry based, while actual compression pressure is a function of geometry and valve timing.
Considering your pressures are all within 5%, I'd say your engine is probably pretty healthy. You might benefit from performing an oil analysis to further verify the engine health.
Considering your pressures are all within 5%, I'd say your engine is probably pretty healthy. You might benefit from performing an oil analysis to further verify the engine health.
#3
So I have learned, which is why I was looking for data from folks here -- having the B48A20B engine.
Apparently most folks do not make this measurement, which does not surprise me too much.
I'd love to find a BMW technical doc for that motor - including geometric compression ratio and a cam chart. No hope I reckon...
I agree the results look encouraging (92,600 miles).
Cheers,
Charlie
Apparently most folks do not make this measurement, which does not surprise me too much.
I'd love to find a BMW technical doc for that motor - including geometric compression ratio and a cam chart. No hope I reckon...
I agree the results look encouraging (92,600 miles).
Cheers,
Charlie
#4
A compression check is a pretty 'gross' measurement, where it will show if something has really gone bad vs a 'fine' measurement, like a burnt valve, leaking head gasket, broken ring vs just wear. I would add in a compression leakdown test to better gauge engine valve/ring condition. There are a lot of articles out there that describe the process, but basically it is just another 'tool' for engine condition evaluation w/o tearing it apart.
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