hey all. i got a compression test done on my new rebuild engine. i took it to a mazda dealer and watched them like a hawk!

the engine has a large street port and fd rotors, and 2mm oem 2 piece seals.

the results were..
Rotor 1
83
82
86

Rotor 2
83
82
86

is this normal compression on fd rotors? what do you guys think.

 

If that's PSI, tht's very low. And FD rotors are the same as s5 TII rotors, nothing too special. Was this done with the throttle held open? Cold/warm?

 

Isn't compression usually a bit lower after a rebuild?

 

yes its psi. engine was warm. i am not sure about the throttle being held open.. ill have to call the dealership 2morrow and ask..

 

i have about 1400km on the engine.

 

How many Km's on the engine? If really low Km thats par

 

for 900 miles, it should be higher than that. Who rebuilt it?

 

a local rotary guru. i am not worried about his work. he's very good at what he does.

it starts up fine. idle is very good. i may just get another test done in a few weeks.

still going to give the dealer a call tomorrow and ask if the test was done a full throttle.

 

I find it very odd that the psi readings are identical between the rotors. Even in the same order.

 

^ whoa, I didn't see that... That is pretty odd, lol.

How many miles are on the rotor housings?

 

i am not sure. i saw both before they went in and were in extremely good shape.

 

i have the result sheet infont of me. and there is some other info on it..

Rotor1
283 - engine rpm
4.51 max. rotor 1 - min. rotor 1
0.251 max. rotor 1 - max rotor 2

rotor2
281 engine rpm
4.016 max. rotor 2 - min. rotor 2

 

any idea what "4.51 max. rotor 1 - min. rotor 1" ?

 

that is a little low my rebuild has 300 miles and is well into the 90's, waz the battery well charged

 

impact, sounds like it's indicating the variance between the different rotor faces...the highest face has 4.51 more psi then the lowest. If you look at your PSI figures, that makes sense (highest is reported as 86, lowest is 82).

85 PSI at 250RPM is the minimum pressure according to the shop manual (for a '91 at least)

 

aight, thanks for the info. may go get it done at another place, just for a second opinion