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The mkiv Supra Owners Club

is 160psi across all cylinders good compression


msupra1

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have a 97 RZ-S 6spd. Stock bottom block, 66mm turbo, head has upgraded gsc 269 cams and springs/retainers. It makes 700bhp.

Got the car with 68k miles (mostly stock), and now has 87k miles.

 

Had the car for 3 years and never bothered to check the compression numbers. Got the shop to check it for me.

Cylinder 5 read 158psi and the rest read 160psi. Motor had to cool down a bit but was still pretty warm.

 

 

Searching around I have been seeing numbers anywhere from 124psi to 180psi that are considered good. I just wanted to see if my numbers are good. Thinking to push for a bit more power but from what I've been sold motor is very healthy. And that having larger turbo/cams will affect the motor compression a bit / lower it?

 

cheers

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Thats a healthy engine, nice and close together. Thats the key really. Figures from the workshop manual :-

 

Standard pressure:

1,079 kPa (11.0 kgf/cm2, 156 psi) or more

Minimum pressure:

883 kPa (9.0 kgf/cm2, 128 psi)

Difference between each cylinder:

98 kPa (1.0 kgf/cm2, 14 psi) or less

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