2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Compression different on ported engines?

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Old Jul 31, 2005 | 08:42 AM
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Compression different on ported engines?

Is it much different on street ported engines to stock?

-nick
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Old Jul 31, 2005 | 09:39 PM
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From: Indiana
Beats me...

I just tested my TII engine today....

Hot compression , street ported exhaust / intake, new housings on RA seals, and 330 miles

100 psi all faces both rotors.

James
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Old Aug 1, 2005 | 12:24 AM
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From: Rohnert Park CA
No, on side port engines; compression is only effected by rotor and housing
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Old Aug 1, 2005 | 12:25 AM
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it is only slightly because more air is drawn in, not enough to make a noticable difference though.
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Old Aug 1, 2005 | 12:29 AM
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From: Rohnert Park CA
Originally Posted by Karack
it is only slightly because more air is drawn in, not enough to make a noticable difference though.
No, porting is the same as using a higher profile cam on a piston engine. It only changes the amount of mixture being drawn in, not the actual compression of the mixture.
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Old Aug 1, 2005 | 01:08 AM
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i have noticed differences when opening and keeping the throttle plates closed so i guess we can agree to disagree.

same difference, there is more air entering the engine and so compression is increased, i always do compression tests with the throttle open because varying amounts of carbon buildup on the throttle plates can affect results.
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Old Aug 1, 2005 | 05:09 AM
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From: Phoenix AZ
hmm thanks guys. I just got into rx7's, can someone link me to the proper way to do a compression test on a t2?

thanks
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