compression test

[Dicko]

i did a compresion test last night. not convinced myself the vaues are as good as they should be.

engine upto temp

#1=155
#2=162
#3=157
#4=163

head has recently been rebuilt and had blyderstein stage1 work.

compression ration should be 11:1, any know the exact value of that in psi? i think its 158psi?

the head had a nats bolock skimed off for the stage1, which kinda compensates for how much they take off by cleaning/blasting.

on wet test the results went up 20-25psi.

[Avon]

I HAD 240 PSI IN MY CYLINDERS THINK THE ENGINE IS STANDARD

[Dicko]

haha

ok mate thats helped me alot.

and btw 240psi sounds WRONG for a std engine

[bad_boy_nova]

This is a guess dicko

159.5 psi

[rgv_stu]

iirc my 1400nv was about 140psi per pot

i have no idea how you work out the ratio from that figure ??

[Stuart]

umm there is no effective way to calculate the compression ratio from a compression test, as the "book" figures are calculated from static volumes, when the engine is spinning the CR varies due to air flows not being 100% accurate etc.


i assume you have the throttle fully open lol

and they are all within 7or 8 psi so theres not much to worry about.

all you need to do is stop worrying about your engine, get it mapped, either on rollers or let one of three people loose on it on the roads.

your getting munchausens syndrome but with yer engine lol

[Aragorn]

dan had 220psi from his engine and he recons it should be about 11.5:1

so id expect 11:1 to be around 200ish

as camb said - u did have the throttle open right?

[Dan]

lol for a starters i dont reckon anything, i just assume as no real way of telling as we all know. When we thought it went pop on interpro rollers with engine hot we did a test and got 235 across the board, i have done when engine cold recently and got between 225 and 230. i always thought a good engine should be showing at least 170-180 + on a n/a car. could be a load of rubbish tho lol

[Dicko]

throttle wasnt open but some people say have it open some people say have closed, will test with it open later.