The do-it-yourself Lancer turbo kit based off of Evo components has definitely taken these forums by storm! I love dropping in and seeing another one pop up every week or so. I've had my kit on for a couple of months now and I love it! I'm running about 10.5-11psi right now. I've got my car perfectly tuned with ECUFlash and my stock injectors are way maxed out at over 100% IDC. Maybe I should put my WRX injectors in right about now...

My question is this: with ARP head studs (been installed for years), stock internals and stock head gasket, adequate fuel and a tune having 11.0:1 AFRs, what would be the breaking point? Everyone seems to have a different answer for how much HP the pistons will hold before breaking or how much boost the rods can take before snapping. I've got almost 130,000 miles on my motor and she still runs like she's got 130 miles. I was gonna see how much higher I could take the boost and not grenade my engine. Bottom line is that I don't care if I grenade my engine. I've got an engine in my garage with under 5,000 miles on it ready to go in. But what I would like to do is to see what we can max out our Evo 16G turbo kits at on our stock internals. I would rather find a suitable number and test it out than to just turn the boost up crazy high and have it bomb on the first pull.

I want everyone's input on this one. I'm the guinea pig here. I'm the test mule. I want a well thoughtout discussion here with some positive information. If you guys think that I should go no higher than 13psi, that's fine. I'll run 13psi all day long and let the logs do the talking.

Here's a starting point: from what I've read over the years, the 4G94 rods can't boost past 14psi without snapping. And everyone knows that the ring lands on the 4G94 pistons are weak. So from those statements I don't want to run more than 14psi.

With a perfect tune and adequate fuel would 13psi be the ideal max amount of boost we'd want to run on our 4G94's? Or is 12psi our max?

Cheers!

 

i'd think 12psi would be the total max. But even then I'd expect the motor to blow eventually. Between 5-9psi is really the most reliable to run at.

Seems kinda silly to blow up your engine though, its pretty common knowledge what our engine can handle. Why not just sell your spare engine and use the money to buy upgraded pistons or something?

 

I agree that it is common knowledge to what our engines can handle, but I've been running 11psi for about a month now. I've had zero knock and no problems besides the maxed out stock injectors. I'm gonna throw my WRX injectors in this weekend and re-tune for 11psi. The spare engine is going in after this engine goes. I am not trying to deliberately blow up my engine. I'm simply saying that right now I've been running 11psi with zero problems and my engine has 130K on it. I rarely see boost during the daytime. I drive very conservatively. But after work I let it rip. I've got no intentions to buy any forged internals for the 4G94. For the cost of forged pistons and rods, I could do a motor swap. The 4G94 is a very weak platform to get max performance from. So I'm trying to establish what the max performance would be.

 

If I recall, RRM was running about 12-13psi on their very first turbo kit years and years back and they grenaded a rod at 14 or 15psi. But they were running fine at 12-13psi on a piggyback. I would think that with ECUFlash the chances of keeping a higher boosting 4G94 engine longer running would be much better with all the knowledge we've obtained over the years.

 

I would slowly make my way up if I wanted to find out.

 

Definitely how I intend on proceeding. I'm guessing the overall answer lies somewhere between 11psi and 13psi. Of course we've always just speculated at what the actual number might be, but I'd like the chance to talk everything over to get max performance out of our stock engines.

 

As it has been disscussed in past FI threads PSI is different with regard to the specific turbo you are talking about. So using the RRM t25/28 12-13psi mark might be off when comparing it to a 11psi on the 16g.

Until someone does as you are suggest and runs it till it breaks we will not know the limits... not that I want to see that. To run safely though I wouldn't push it past 9, even though you are saying you run yours consistantly at 11... i can't see how that is good for the internals.

 

The additional factor I am trying to bring into the equation is that of having the ability to provide a better tune with ECUFlash. Granted throwing a turbo on an engine with a FMU and getting the fuel "about right" is kind of hit and miss. How much would having the ability to provide a perfect tune to a 16G'd 4G94 assist in keeping the internals in better shape? Which is the one to worry about first, detonation or stress? Our abilities to better tune our engines have evolved (no pun intended) over the years and I feel that we can use them to our advantage.

 

oh boy be carfull

 

Ok I guess my numbers were off on initial estimates. RPW recommends not running more than 12psi for the sake of the rods and no more than 15psi for sake of the pistons. They also state that anything above 7psi needs their decomp head gasket. RRM states that anything over 10psi on their kits is a gamble. So with all this on the table now I'm gonna leave my boost at 11psi and swap in my WRX injectors and see what we get. I've gone about a month on 11psi so far. I feel that proper tuning will play a huge role in my setup. My AFRs are a constant 10.9:1 - 11.2:1 across the board at full throttle with zero knock. I'll tempt fate and see where she takes me. Thanks guys!!

 

He has a second engine and doesn't mind. He will most likely blow his engine but is trying to find the peak boost. I think it be awsome if he did find out.

 

damn double digits of boost. ill prolly only single on my lancer..haha

too be safe i wouldnt boost more than 8 for daily driving 9 prolly for track or dynos. i hope your upgrading your injectors as well.

 

Well think about it, you're only in boost when you have the pedal to the floor. I still get 30-32mpg right now with 11psi. I have the 440cc WRX injectors but have yet to install them. I calculated my IDC and I'm past 100%. I'm gonna install them this weekend and retune my ECU.

 

I don't plan on exceeding 13psi at the most. And also since I'm using a MBC it would be 13psi peak and taper down to like 10psi. Right now my boost is 11psi peak and about 8-9psi with the taper. When I get on the pedal it is usually no more than about 15 seconds with shifting and then I let the temps cool down. I don't continuously get on it and get the temps way up. I ordered a hood scoop from CarbonTrix that I have yet to install also. It will do wonders with the underhood temps and keep my engine running cooler. It'll be positioned over the manifold and valve cover to allow air to come from the front, pass by the turbo and manifold and draw that hot air out the top.

 

Post pics of that scoop when you install it... I was thinking about doing the same thing only putting the scoop over the intake.