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Compression test for 10:1 motor.

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Old Nov 14, 2018 | 08:43 AM
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Default Compression test for 10:1 motor.

Is it normal for a 10:1 motor to show 180 all across the board I know stock compression end up being somewhere between 220-240 I couldn't find this info anywhere. This is a brand new built motor.
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Old Nov 14, 2018 | 08:47 AM
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Seems low. My 9.6:1 made 210-220. But there are a handful of variables such as gauges reading different, was the motor warm or cold and was the throttle plate open or closed during cycling. So I wouldn't be overly concerned as long as all the cylinders are reading even.
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Old Nov 15, 2018 | 12:56 AM
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How many miles on it? My IP short block 9.5:1 shows 205-210 compression. That was after seating the rings. The same gauge showed 240 compression when I was stock.
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Old Nov 15, 2018 | 04:57 AM
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Originally Posted by soulicious
How many miles on it? My IP short block 9.5:1 shows 205-210 compression. That was after seating the rings. The same gauge showed 240 compression when I was stock.
Thanks guys the block is brand new not broken in yet but had 1-2 dyno tunes/passes would compression be affected by aftermarket cams?
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Old Nov 16, 2018 | 06:12 AM
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Originally Posted by Ludeboye1
Thanks guys the block is brand new not broken in yet but had 1-2 dyno tunes/passes would compression be affected by aftermarket cams?
Your pressures will increase when the engine is broken in New motors will rotate slightly slower when cranking. If your new cams have more overlap that will cause a slightly lower reading of your compression test too . Most important is variation or the lack of it
Repeat the test in a 1k miles or so I would expect 20x compression ratio or even very slightly higher on one of these motors
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Old Nov 16, 2018 | 08:25 AM
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They are turbo cams, so they should have a lot less overlap. Don't think compression would be effected anyway compared to stock s2k cams.
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Old Nov 16, 2018 | 01:48 PM
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My 10:1 motor was around 210 (CP pistons). If you have concerns, do a leakdown test.
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Old Nov 17, 2018 | 03:13 AM
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my 10.1 was about 180 across the board. depends on the PTW gap. mines built loose to make big BIG HP
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