Altitude compensation compression test

[DEADRINGER]

Does anybody know what the altitude compensation is for our motors? I'm at 6000' got 100lbs in all four jugs. Boat is a 95 speedster. Dont know what the motors are at the moment. Thanks

 

[LouDoo]

What kind of boat/ski do you have, year and model???

 

[DEADRINGER]

Saw a tag that said 657x. Does that sound right? It was on the igniter box the one on the other motor was faded.

 

[LouDoo]

I still don't know what you have, since you're saying "4 jugs", I'm guessing its a boat, with 2 engines. Anyway altitude should have no bearing engine compression. I suspect you're guage is way off because at 100psi it shouldn't even be running. Compression should be 150psi, no lower than 135psi.

Lou

 

[LouDoo]

Sorry, I just noticed in your original post you did say 95 Speedster.

Lou

 

[DEADRINGER]

I cant find any info on this so through might math I've got some numbers. At 6000' there is 80% of the air available for compression so a new motor would make 120 psi compression. Mine made 100. that would mean at sea level my engines should be 130psi. What do you guys think? Sounds right to me. -DR