How to increase engine compression

[jc denton]

Re: How do you lower the compression ratio

This thread is beyond my feable mind.

I would like to know more about increasing compression though!

 

[pgarner]

Re: How do you lower the compression ratio

basically the opposite as lowering
skim the head slightly or fit higher compresion pistons

 

[obi_waynne]

If the compression ratio goes to high you will suffer from detonation or pre-ignition.

 

[jc denton]

You can adjust your ignition timing to compensate for that though, if you have a dizzy.
I normally crank my ignition timing right up, go for a drive & listen for pinking. If it happens, then back of ignition timing slightly & go for another drive & repeat until its as high as can be.

Also you may want to make a mark on the dizzy to remember the best position for different fuels.

 

[SLEEPER]

In your other recent thread you were saying your MR2 seemed tired and may have lost compression.
If this a question about getting it back by or raising it another way to compensate that then the answer is almost certainly NO.

Also if you have sorted the timing out by the "raise it and see if it pinks method " this was well be the cause of your problem.

 

[jc denton]

1: Crank it up untill you can hear it pinking

2: Back it off slightly & retest

3: Enjoy the few extra HP down low

Try different setting for different fuel.

PS: I don't have a problem with the way the MR2 is. I just suspect that its lost some compression over the years as it seems a bit down on power.

The reason I'm interested in methods to increase compression is that when I change the rings it might be a good time to go for some other changes. Adjustable cam gears? Lumpy cams?

 

[SLEEPER]

In that case its a good question.
IF it is apart there are a few thing that may be better than just raising the c ratio. (imho)

Low compresion could be leaking valves etc just as easily with that mileage so checking/improving head work would be a must for me if you are taking it apart to change the rings .
remember though compression will only return if rings are the problem

Alternatively just rebore it then you can have whatever c r you want - after all you only want to take things apart once . personally Id leave it a stock and fit different cams

cams change the power curve not the compression

Or of course you could pay someone to map the car properly. This is without doubt usually the best one way of improving performance and economy. Then you wont need to play with the timing and fuel ever.This would be worth doing even now.