General Compression test

[Rob-mint-mk1-uno]

Hello....

For thise of you that dont know i have a 1989 fiat uno turbo mk1.
The car has done nearly 70000 miles and according to the service history it had oil changes every 2-3000 miles, so the engine should be in good shape.
We got talking a while ago now about what boost i should run and how to get it, some one suggested i carry out a compression test.

I have my own tester and i have done these tests before but what figures should i be looking at on the engine ???
So ill carry out the test today and write down the figures and hopefuly you guys will help me by fining the right figures to compare it against.
Also if the engine is healthy is it ok to put a bleed valve on it, because some one said 1 bar boost is ok to run on a standard engine, if this is true how do it fit the bleed valve and how do i know how to adjust it to its safest correct setting, my mate had one on his rst and wound the boost rite up not knowing which way was which and suddenly BANG goes yet another rst.. lol
If you get a min read my light fault thread because i think i have cracked it but i need to know if when you turn your side lights on if your dipped beam comes on aswell, it should be just slighty dimmer than dip but i think my resistor has had it because my dim dipped and dipped beam look the same.
Let me know if u have a mark 1 turbo from 1987 on, yours should be a little dimmer than dipped beam.
Am i making sense, if not read the thread on sidelight trouble..

 

[the mk1 kid]

I think your results will be around 145psi. What you're looking for is a nice set of even results, 140 would be on the low side for this engine and 150 high IIRC.

You certainly dont need a degree to fit a bleed valve. Cut the vacuum pipe that goes fom the actuator to the compressor housing and insert the BV. Before fitting it wind the valve closed, well almost, perhaps half a turn open. Drive the car and watch the gauge on the dash carefully and repet if needed....

Tom

 

[Rob-mint-mk1-uno]

So is 1 bar ok on a healthy engine, if so what power will that make my turbo, the only other mod is a k&n air filter ...

 

[oldskoolmk1unoturbo]

I used to set mine at about 12 psi as if you take it up to 14 it drops down in the high RPM but if i was racing someone i'd take it up to 1 bar to give it a bit more power bottom end

 

[the mk1 kid]

The mk1 IHI will make about 140bhp max so less than that, perhaps 130. It might not seem a lot but you'll love the difference!

Tom

 

[alexGS]

The mk1 IHI will make about 140bhp max so less than that, perhaps 130. It might not seem a lot but you'll love the difference!

Tom

Yes, it certainly feels like a huge difference! And besides, 25 extra horsepower with no other change... that IS a huge difference With the bleed valve costing something from $free to $80 depending on how well you do the job (even a garden sprinkler tap could be used!) it is surely the most extra power for the price that it's possible to get.

I found that you need to conduct testing very carefully while setting the bleed valve, as it would be easy to exceed 1 bar during medium-speed high load (driving up a hill, for example). You may have to suddenly drive very gently or use lower gears until you can pull over and wind it back a couple of clicks. You would have thought that high revs = more boost, but you will find that this isn't necessarily the case!

I eventually managed to get mine so that it hits exactly 1 bar during acceleration. The boost then tails off slightly by full revs.

The next stage is electronically-mapped boost control, made possible by a solenoid valve and a microcontroller-based kit that I have - I haven't found a solenoid valve yet, unfortunately. The benefit will be that there is maximum control when needed (boost may come on more smoothly) yet there is minimum control (i.e. maximum possible boost) at high revs. You can even switch between two different maps - so one can be defined for performance and the other for wet-weather driving... I'm sure somebody reading this will know what it's like to have the tyres spinning up unexpectedly in the wet, not really what you need...

Cheers,
-Alex