What causes burnt pistons, and are there any major problems of having them? The reason I'm asking is...I pulled my motor apart to change the rings, and noticed that the pistons were burnt. They are JE 9:1 pistons and there's no way Im buying another set.

 

Are you sure it's not just carbon on top of the pistons? Is it on all the pistons?

 

the carbon raises the cr a bit and doesnt really hurt untill it stars blocking valves, use some HD degreaser and they will look new again

 

Check out the SafeGuard knock controller: http://www.safeguard.20m.com

If you have time, here are some threads about burned pistons from an MR2 forum.
http://www.board.mr2faq.com/showthre...ighlight=J%26S http://www.board.mr2faq.com/showthre...ighlight=J%26S

 

Describe what you mean. Is it black carbon deposits or does the piston top look slightly brown and burnt like?

 

The machine shop cleaned the pistons to the best of their abilities. I know the difference between carbon buildup and burnt pistons . I was worried because I know that the carbon deposits could just be cleaned off, but when a piston is burnt, there's nothing you can do (as far as I know).

 

What causes pistons to burn is generally running too lean, possibly detonation, possibly excessively retarded ignition.

 

As long as the pistons have not warped or changed dimensions you are ok but find out why the pistons are discoloring (too lean or detonation) and FIX the problem.

 

if the piston is not in perfect form... i wouldnt use it... just scrap them... u can get new ones for 500

 

THIS is a burnt piston.






[Modified by SiR Kid, 3:19 PM 11/20/2001]

 

good kill!

 

U were running lean. U melted a part of the piston, just to make sure check Ur Injectors and make sure the fuel and air is mixing properly. Send them to RC for a good cleaning.

 

D A N G .

 

That's stock LS pistons in a B16a, with stock injectors trying desperately to run 11 psi with only a 6:1 Vortech Fuel Pressurizer

Didn't work too well.

LS pistons for the record in a B16a net a compression ratio of about 8.3:1, and they have valve clearance issues to boot. Notice the nice shiny crecent moons on the outer edge of the valve reliefs. NEVER make this mistake, PLEASE!


[Modified by SiR Kid, 3:44 PM 11/20/2001]