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Vortech Inside
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389 Posts
Discussion Starter #1
Hi everyone, I'm a newly boosted member here and things were going pretty good. I had been using the stage one pulley for my supercharger for about a month now and then it got damaged somehow and makes the supercharger make weird noises in the shaft. My kit came with a stage two pulley as well so I decided to use that for a while until I could get my hands on a new one.

I've read all the dissaster stories on here pertaining to the GTS engine and stock pistons with larger amounts of boost so I knew I couldn't really beat on it. However, I decided to see exactly how everything looked so I used ecuflash and pulled timing in appropriate places for datalogging.

As of now, it peaks at 11 psi with at the most 4 counts of knock at the 4000 rpm range- granted this is after pulling 4-6 degrees of timing on the high end. AFRs look good too and are actually a little on the rich side.

Does this sound alright or are there other factors I should be looking at for the sake of my engine?
 

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New daddy
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3,352 Posts
The problem with the GT and GTS engine is the piston ring gap. If you get the pistons too hot the rings will get just as hot and expand. They can only expand so far until ends butt together. This butting rings will put so much force on the top of the piston that a piece will break right off.

Use colder plugs, don't boost for prolonged periods, use high octane gas, and keep detonation under control. If you have the boost cooler then use it. It will help to keep combustion temps down. To me it sounds like you have a pretty good tune. BTW, how are you measuring AFR's and what are they.
 

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Stage 1 SDS @11+ psi
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3,035 Posts
I've read all the dissaster stories on here pertaining to the GTS engine and stock pistons with larger amounts of boost so I knew I couldn't really beat on it. However, I decided to see exactly how everything looked so I used ecuflash and pulled timing in appropriate places for datalogging.

As of now, it peaks at 11 psi with at the most 4 counts of knock at the 4000 rpm range- granted this is after pulling 4-6 degrees of timing on the high end. AFRs look good too and are actually a little on the rich side.

Does this sound alright or are there other factors I should be looking at for the sake of my engine?
You've gone about it right tuning-wise. However, the more you retard the timing, the more you'll increase the EGT. That is what fasteclipse00 is talking about with increased cylinder temps. Good easy on the boost until you get your stage 1 pulley, or add a boost cooler and get your timing back (which again is what fasteclipse00 said :D)
 

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New daddy
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3,352 Posts
Well there is a difference between the exhaust gas tempurature, the in cylinder temperature and the tempurature of the pistons. Retarded ignition timing will cause higher EGTs which will heat up the exhaust valves more. More advanced timing will cause higher in cylinder temps (and pressure) and higher piston temps. However, detonation in the main enemy. It will cause the insulating boundary gas layer to be blown away from the top of the piston. This will cause a rapid increase in the piston and ring temps, which leads to piston damage.

However, if you were to retard the timing too much then the exhaust valves could possibly get too hot and pre-ignite the air fuel charge as soon as the intake valve closes. The knock sensor will not pick this up, it will remove the boundary gas layer, and the piston will be attempting to compress the expanding fireball. Pre-ignition a lot worse than detonation and it will destroy the pistions in a couple revolutions.

What are you using for tuing besides the ecu flash?

Also, I know a guy that ran a turbo GTS at 6 to 7 psi with no timing control and very lean A/F ratios. His engine was never damaged, even though he ran that way for several thousand miles and raced the car. He was just lucky I guess.
 

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Vortech Inside
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389 Posts
Discussion Starter #5
Thanks for the info, I forgot to mention I have Ripp's meth kit and have it set for max injection at 5 psi. I'm using ripps black box/brat box combo too. I use Innovate's LC-1 Wideband for afr and on average they go down to around 10 when I push it on the high end. So if I watch EGTs and don't boost it high for long period of time I should be ok?
 

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New daddy
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Now that I'm looking back at your post. A/F ratio's in the low 10's isn't really that good. More fuel does not always equal better. Too much fuel can wash oil off of the cylinder walls and contaminate the engine oil quickly. Really the only reason to over fuel is to keep peak cylinder tempuratures down in an attempt to control knock. However, the water/meth kit does a much better job of keeping temps down because of the latent heat differences compaired to fuel. You might be better off aiming for 11 to 11.5 AFRs.
 

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Vortech Inside
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389 Posts
Discussion Starter #9
Ya I know its running pretty rich, I was going to work that out after I was sure everythings going to be alright detonation wise. I'll try to lean it out and shoot for 11ish, thanks.
 

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Stage 1 SDS @11+ psi
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3,035 Posts
Thanks for the info, I forgot to mention I have Ripp's meth kit and have it set for max injection at 5 psi. I'm using ripps black box/brat box combo too. I use Innovate's LC-1 Wideband for afr and on average they go down to around 10 when I push it on the high end. So if I watch EGTs and don't boost it high for long period of time I should be ok?
So you do have a boost cooler and still had to retard the timing? Check the flow of that thing. You can do it with a 9 volt battery if you like.

fasteclipse00, I've always liked your explanations. I'll just add (not to debate) that higher EGTs do raise the temps of the piston itself, but not displacing that very important boundary gas layer.
 

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Stage 1 SDS @11+ psi
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3,035 Posts
So you're saying I'm not supposed to have any large amounts of knock with the meth injection installed?
I was just saying to check it and make sure the flow isn't obstructed. Water-methanol just raises your threshold for detonation. It can't totally eliminate detonation if the timing is advanced too much or if the CR is too high.
 
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