NoPistons -Mazda Rx7 & Rx8 Rotary Forum

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-   -   13b-rew (stock) Rebuiled (https://www.nopistons.com/rotary-engine-building-porting-swaps-55/13b-rew-stock-rebuiled-33262/)

FD3Sgasm 02-05-2004 08:28 AM

13B-REW rebuild with new housings, new seals ans apex, stock car, compr. check

have 2500 miles on the engine now after the rebuild and measured the compression today:



rear rotor:

874/979/837 KPa

front rotor:

929/905/931 KPa



1000 KPA = 145 psi = 10 Bar

http://www.chromatography.co.uk/Tec...er/Pressure.htm



so i have a difference of 0.94 Bar

any throughts about these numbers? everything looking fine?

FD3Sgasm 02-07-2004 11:27 AM

rear rotor:

874/979/837 KPa

front rotor:

929/905/931 KPa



anybody thoughts about these numbers?

93BlackFD 02-07-2004 11:33 AM

you still have some breakin- but pretty solid numbers



90psi is 6:1 compression, 110psi is about 8:1



130psi i think is the theoretical max for a rotary

jeff48920 02-10-2004 03:12 PM


Originally Posted by FD3Sgasm' date='Feb 7 2004, 09:27 AM
rear rotor:

874/979/837 KPa

front rotor:

929/905/931 KPa



anybody thoughts about these numbers?

874/979/837 KPa = 127/142/121 psi = 8.74/9.79/8.37 bar= 8.91/9.98/8.54 Kg/cm2

929/905/931 KPa = 134/131/135 psi = 9.29/9.05/9.31 bar= 9.47/9.22/9.49 Kg/cm2



KPa or psi or bar or Kg/cm2...The rear rotor looks to maybe have a leak in some single seal between the 874 and 837 readings. Of course these are really high numbers for any rotary engine...just something of a head scratcher as to why the lower numbers occur.



The manual calls for 690 KPa/7.00Kg/cm2/100psi at 250 rpm after a warm up as target numbers and presumes 8.0 and 6.0 as limits.



The manual also suggests a differential of < 150KPa/1.5Kg/cm2/21psi between chambers at 250 rpm as the limit for interchamber diffs. You have that 21 psi between the 874 and 837 readings.



Finally, temperature and rpm compensation tables are available in the manual if testing above or below recommendations.



Your numbers seem high, what were your test procedures?

jeff48920 02-10-2004 04:18 PM


Originally Posted by jeff48920' date='Feb 10 2004, 01:12 PM
Finally, temperature and rpm compensation tables are available in the manual if testing above or below recommendations.

That should read "altitude and rpm" not temperature https://www.nopistons.com/forums/pub...O_DIR#>/11.gif https://www.nopistons.com/forums/pub...IR#>/blush.png https://www.nopistons.com/forums/pub...1047683664.gif


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