Question about compression

[dj_lennon_franz]

i already ran a search...to no avail...didnt find the answer i was looking for...so here goes

what compression should an SR be at cold?? (i was pushing 135 all the way across at cold...engine hadnt been started all day...so it was basically ice cold) im not sure if thats good or bad (ive been told its good compression for a cold SR) with oil it went up to 195 (which i think is a bit high)

i dunno if fuel compression has anything to do with it...but the engine has had fuel problems due to the gas tank being bad (long story short...i could never get the gas tank to seal properly...so the engine hasnt had proper fuel pressure for a while now)

so yah...lemme know

[silvia-junkie]

i believe 155 is ideal. sombody corect me if im wrong

[nissanrcer240]

yeah that sounds about right, i think the more important thing is that the number is consistent all the way across.

[deCksy]

as long as they're 5psi from each other it should be cool

[spider_slayer]

i'm pretty sure that 155 is when the engine is running warm isn't it?

[Nismo_Freak]

160 should be warm compression.

135 on cold doesn't sound too bad to me, I recall a few engines having that and running just fine.

On your oil test, you put too much oil in.

[compression]

Your gas tank is not related to the fuel pressure your engine sees. Fuel pressure your engine sees (at the fuel rail) happens after the fuel pump, and is a result of the fuel pressure regulator restricting flow of gas back into the (unpressurized) tank via the fuel return line. If a fuel tank was pressurized to your fuel pressure (40-60 psi), it would most likely explode.

Your tank does develope some minor pressure from the thermal expansion of the fuel and such, but it is vented to atmosphere (through a charcoal canister) so those pressures dont build up.

In short, your fuel pump could be sucking from a 5 gallon bucket in your back seat and it would work fine. Your fuel return line would dump into the same bucket.

[jdm_master_X]

according to the Austrailian SR Manual, ideal compression is within 140-160 PSI range. doesnt mention anything about temperature tho.

In terms of most cars, generally speaking, to play the compression game requires AT LEAST 125 PSI. anything below that then you are out of luck.

-Robert

[daz1320]

when i got my motor it tested 60,90,110 and 133.when i got it running it read 159,162,161 and 161.It ran perfectly and did a 13.2 in the 1/4.

[luv2spedup]

i believe 155 is ideal. sombody corect me if im wrong

150 thru 155 across the board is good

[jdm_master_X]

wow your car ran 13.2 quarter mile? so did mine! shows how cool STOCK SRS are! wOOT!

[xero1]

how much boost does it take to run 13.2 in a quarter mile?

[tony/ka24de]

my conpression is 160psi across. But I can't figure out why i blow so much black smoke. How can I test my o2 sensor?

[daz1320]

I was at 12lbs dropping to 10 in high rpms.