Mitsubishi Eclipse 3G Club banner

1 - 7 of 7 Posts

·
Registered
Joined
·
48 Posts
Discussion Starter #1
i have heard that if you turbo the 3.0 v6,that at 5psi the pistons will crack and then i have heard that others have been running 8 to 10 pounds safely..i would just like to know cause i do not want to build the whole motor if all i want is between 8 to 10 pounds..thanks
 

·
Resident Asshole
Joined
·
5,940 Posts
The general consensus is that about 8psi is the maximum boost level you can run before blowing your pistons sky high. Jbasol proved everyone wrong and ran a solid 15 psi on his twin turbo custom kit. The bottom line is that you need to know what you are doing with this car. It is not easy to boost this car and if you are serious you need to have the time, money and knowledge to do it right. 8 psi on a so so tune will let you ride around for a while until you detonate hard and blow the ring lands off the pistons. Of course, many people did this and were still able to drive around for a while. If you actually know what you are doing and have a proper setup and very good control of your tune you can run higher. Be aware this requires constant checking of your fuel trims to make sure everything is in order.

If you have a GTS, it's been proven over and over again that it doesn't like turbo boost in stock form. The GTS seems to adapt better to the SDS than a turbo kit. In all forms of FI, the GTS will blow up sooner and harder compared to the GT.
 

·
New daddy
Joined
·
3,352 Posts
Wow I was just going to link rezlo's info on why the 6G7* blows up, but the link is dead. :(

Basically what it comes down to is piston design, the amount of gap between the ends to the top piston ring, and heat. First top piston ring is set relatively high on our motors. This is done for emission reasons. However, this leaves a pretty small thickness of aluminum from the top of the 1st ring groove to the top of the piston. This is called the ring land.

2nd the gap between the ends of the piston ring is set for the amount of heat a N/A motor generates. For the best power, best emmissions, and cleanest oil you want the smallest ring gap possible.

Then comes the fator of heat. Going F/I makes more heat. This causes the rings to expand in length to the point that they touch. The harder they ends push together the more the ring will buckle and push up on the ring land. When the small ring land of the piston cannot take the pressure and it will break away, and start bouncing aroung in the motor.

The descrepancy between the amount of safe boost people have run comes down to tuning. There are a several ways to decrease the amount of heat. Either you can run a richer A/F ratio which cools down the overall combustion event or run less timing. Both have draw backs, but it is better than ruining your motor. Always benifical is to lower your intake temps through intercooling.

Where people really get into trouble is with detonation. Detonation mainly occurs from too low of octane fuel for the ammount compression and amount of boost. Detonation removes a very thin layer of gas (boundary gas layer) from the top of the piston. This thin layer acts as an insulator to the piston. Remove the insulator with dentonation and the piston and rings will REALLY heat up.

The lower the static compression of the motor the higher the amount of boost you can run without detonation. Therefore the GTS with 10:1 compression will blow up before the GT with 9:1 compression.

Below is a very good article about detonation:

http://www.germanmotorcars.com/Detonation.htm

To work around the problem most people install forged pistons with a lower compression ratio, larger ring land, and gap the rings wider. However, once you get into rebuilds there is a lot more to the subject on things you can do to increase power/reliability and why.
 

·
Registered
Joined
·
738 Posts
However, once you get into rebuilds there is a lot more to the subject on things you can do to increase power/reliability and why.
and where might I get this info from? :bigthumb:
 

·
Registered
Joined
·
48 Posts
Discussion Starter #5
thanks guys that really helped me out alot..i think know i will just do simple bolt ons and make it more powerful that way..just sounds a lil safer.plus this is the only car i have at this time and dont really feel like blowing it up..but thanks for all the info..:twothumb:
 
1 - 7 of 7 Posts
Top