So I did a compression test tonight

[vr4goleta]

usually its 10% either way of the the specs.

with the water injection i have been told to just drill a hole in the manifold and fit a 5th injector, is this correct? ifso will the injector spray constantly off 12dc or does it have to be ac so it opens and closes, also how do you regulate how much water goes in so its not too much causing a hydraulic lock.
im veeeeeeeeery interested

 

[brisvr4]

Have a look at coolingmist.com and have a ood read on there.
You generally have to drill a hole in yoiu upper intercooler pipe or intake elbow and mount the water injector there. You will have to specify to them how much horsepower you will be making and they will supply the correct injector for you.
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[Jonson]

120psi is fair low. Did you have the throttle body open? take out all the plugs and have a good strong battery when cranking?

 

[vr4goleta]

all plugs out, and brand new battery. but i didnt know the throtle body had to be open

 

[mattrat]

were u testing it on a hot engine?
i didnt know you had to have TB open.. i still got 165 across all 4 tho

 

[jdm-vr4]

tim, i might come around to your place one day to test mine just for piece of mind as i don't think i ever tested mine lol.

 

[strudle]

i was running around on 80 for about 1 year b4 i finally got/getting it fixed. car still ran a treat, wouldnt have know with out doing the compression test. Only thing that stoppd me driving it was the clutch being burnt out by a missus.

 

[f1355spider]

does it make a difference if it is done when the engine is warm or cold?

 

[mattrat]

well yeh i suppose??? rings heat up and expand sealing the combustion chamber? lol physics?

 

[f1355spider]

True, makes sense. In that case, do most people do the test when the engine is warm? I did mine today with warm engine and I got 140 across all 4. Is that Good or bad for a standard motor?

 

[mattrat]

*calls gurus*

 

[EVO-00X]

Yes - engine warm
Yes - throttle wide open
Yes - 140 is still OK but dont be pushing the engine too much from here on in and start saving for a rebuild soon.

120 isnt 'really bad' but it is at service limit. Provided you dont want to make huge amounts of power people have been known to drive til they get to 100-90 before an engine rebuild which really is way past its date :lol:

 

[f1355spider]

Tim, sorry to go off topic in your post, I have just one last question.

Rob, thanks for the info. I cannot recall if the throttle was open or not (have to ask mechanic). Do you know roughly how much difference it would make having the throttle closed vs open?

thanks again..

 

[brisvr4]

Thats ok Jack

And for everyones info it wasn't the valve that looked all coked up that was the problem.... it was the one next to it!
The valve had pounded away at the seat until it compressed itself. This meant that it was always "open" no matter where the cam was.
I didn't rebuild the turbo head i the end, I used a 6 bolt GGSR head instead as it was in better condition to start with.

 

[MDK87]

Hey Tim, I hope it all goes well man.
So what would cause the valve to smash itself too hard back into the head?

tim, i might come around to your place one day to test mine just for piece of mind as i don't think i ever tested mine lol.

Hey man, I got one. You can test it this weekend if you want.

 

[brisvr4]

Thats ok Marek, I'll be doing the head on Saturday so bring yours round then if you can't get to Mahommads

 

[GVR40]

what time on saturday tim and where you live, i might pop round for a 'hows it going', got to do stuff with the mrs in the morning and night, but will have some free time in the arvo i guess

 

[brisvr4]

I should have the head back today
I'll shoot you a PM Craig.

 

[rob323]

So what would cause the valve to smash itself too hard back into the head?

Valve bounce, probably due to a very old and tired valve spring.

 

[EVO-00X]

Valve bounce, probably due to a very old and tired valve spring.

Take note those who still want to use after market high lift cams with stock springs