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Zed oh six
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Discussion Starter · #1 · (Edited)
Last night after work I was driving on the highway towards my house, and I saw a white Evo ahead. I stepped on it a bit to catch up, and something didnt feel right. My car sounded like a WRX and it didnt have a lot of power.

I was near my house and puttered home. When I got out and lifted the hood I could hear this weird knocking. I ran a compression test this morning, and sure enough, my motor is blown.

Cylinder 6 was the one. I knew it when I pulled the spark plug. It was all beat up and whatnot. The compression test only yeilded 70psi.

I have a spare block lined up that me and Tearstone are going to build. After that is complete, we will swap it in my car and take my blown one out to use as a core. It's shouldnt be too expensive. I am also going to get some headwork done in the meantime.

Our general consensus on the matter is that 8psi with a .48 exhuast housing is just too much. A .48 is too small and it built up too much heat. I knew this about a month ago when I had a pretty bad detonation after racing a Subaru. I had ordered a .63, but it was too late.

Wish me a smooth build :D
 

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958 Posts
I wasnt sure if you were going to post this on this board. I can already see where this is going to go... "turbos blew another engine"
 

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REDLINE ALL GEARS
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5,043 Posts
well tearstone already warned me about changing my turbine housing to .63 so that doesnt scare me. Could forged pistons prevented this also (just curious)
 

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Zed oh six
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6,234 Posts
Discussion Starter · #7 · (Edited)
thahnic1080 said:
well tearstone already warned me about changing my turbine housing to .63 so that doesnt scare me. Could forged pistons prevented this also (just curious)
Yes, it would. But it's still isnt a good idea to have heat building up in your cylinders, forged internals or not.

I debated on whether to post this here simply for that reason Ryan. But the reason it happened is just growing pains. Remember, we didnt have a company to back us for R&D in the beginning, so we had no one to tell us how things need to be done. Plus, after finding out this information, I couldn't leave Club3G in the dark. Now people know, and it shouldn't happen to anyone else.

We do this for the greater good :)
 

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REDLINE ALL GEARS
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Yeah you took one for the team. I saw it on club3gfl.com and wonder why you didnt post it on here. So what is your build and head work gonna consists of.
 

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Sorry to hear about that. But 40k isn't too bad and sounds like you have a good plan for the new motor. Good luck!
 

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Vortech > VTEC
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1,450 Posts
Not all of us SDS people want to start a Jihad when we see stuff like this. I personally wish everyone would stop all the my e-penis is bigger nonsense and work together on things that would benefit the entire boosted community.

Sounds like you have a good plan for the rebuild. Good luck with that and let us know how it comes out!
 

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Sebring 6G72
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518 Posts
Tearstone said:
Going to forged pistons is one of the ingredients for a proper forced induction conversion on a naturally aspirated car.

like i have been saying since i blew my stock ones with near perfect a/f.... its just a matter of time.

these stock engines arent made for any kind of boost.
 

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I'm out.
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88 Posts
Sorry to hear this Rulez, that's terrible. Glad to hear you have a good start on the next iteration.

Can you provide any data on exactly what happened? I understand if not, I've grown lax about keeping my datalogger running when driving lately.

Anything you can provide would be good info, but ideally things like EGTs, AFR, and ignition timing would be great to know. Even if you don't have them from the point of the failure, do you have any info about what they were at some recent point in simular load conditions?

-John
'00 Eclipse GT Twin Turbo
 

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Sebring 6G72
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518 Posts
most likely the piston ringlands had already cracked.... probably didnt happen last night.


just they finally came completely apart. So info on exactly what made them break off would be just the normal heat/pressure/to small of ring gap.
 

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WOW dude that really sucks to hear. Though its a good thing you have another block on hand. :D

BTW Just to point out, Tearstone has in fact been predicting this for a while. I was going to use a "stage 1" T3 .48 turbine housing, which would have had the same results as above, but probably 10x sooner.

Good looking out.
 

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Kampfbereit
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17,852 Posts
On Mike's behalf this is a technical examination of the situation:

* 40K in turbo charged miles before it finally went
* We identified early on that the .48 was too small for this engine at 8psi and Mike had his .63 on order and we still have not recieved it yet.
* Mike identified the .48 issue shortly after turning up the boost to 8psi and allieviating some exhaust leaks his car immediately started beating up spark plugs (a.k.a. chipping piston ring lands), hence why he ordered the .63.
* Once the first detonation occred (8psi with .48), he was only reduced to 160 in cylinder 2 and 160 cylinder 4. Not too bad for the first bad detonation, but this was the first damage that was ever done to the engine, and the engine still idled normally.
* I have checked his engine many times when he has brought it over and has read 180psi all the way accross the board for the past 2 years prior to bumping the boost up to 8psi w/intercooler, despite all the racing that we have done.

This is the same issue that we had with Steve's car, and it's due to the improper turbo size that we received from xtech way back when where it would build up excess heat and pressure between the turbine housing and the heads which caused detonation.

Right now we have made these changes to my car and to anyone else (such as Warsheep) who is running an xtech kit to use the .63 turbine housing at 8psi and so far neither one of us has had any issues despite the amount of comparable hard milage that we put on our cars as Rulez had done. See the racing section on club3gfl.com for a testament to how hard Warsheep has been on his car in terms of "beating on it".

Between all of our cars:
* Legacy xTech kits are tuned to a 12:1 A/F (Rulez and I use e-manage, some others use AFC with FMU).
* WOT EGTs on a 12:1 A/F ratio consistently run 740c, highway cruising gets up to 800c.

With the turbo kits that we sell, the turbo size is a full T4 setup which is proven safe at 10psi and allows for enough heat to be bled off through the wastegate and passed through the turbine to prevent excessive build up in the heads. (Along the same thought process as Rippmods has explained about scavenging heat away from the heads for lower cylinder temps).

But what it all comes down to, in order to perform a proper supercharger or turbo conversion on the V6, you should spend the money to do it right the first time and simply build the engine as if it were meant to be boosted to begin with. This not to say that it is not entirely possible to run forced induction on a stock engine, but constantly pushing the tolerences of the engine in N/A form is all we've been fighting about on this forum for years now. But this community I feel for the most part has begun to mature past working within the tolerences of a stock engine and really looking for the holy grail of big powah.
 

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I'm out.
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88 Posts
No arguments from me that forged interals are a big help. But I don't believe they are required for 'propper forced induction'. Detonation is bad. It can, and will ruin parts. Any parts...all parts. Cast or Forged. the only difference is the tollerance. Obviously the forged pistons will tolerate more detonation. But guess what? Your rod bearings are the next weak point. And trust me my friends, they will let you know when they've had enough.

One of my good freinds has his Stealth running 10 second quarters, making roughly 800-900hp in a full trim car. As you can imagine, he is running forged internals. Even changed his crank from a cast to a forged (Early stealths had cast, later came with forged). So he gets his motor all put together, and heads out to check it out. Had his boost controller set impropperly. Hit the gas, hit 28psi, for just a second till he realized what had happened. He lets off, and the bottom end is knocking like a SOB. Pistons were fine, Rods were fine (except for the little end on the cyl that spun the bearing). So is it safe to say that 28psi is too much boost for a 3S bottom end? Heck no. He hadn't tuned ignition for that boost. Too much timing and poof, disaster. Even with a 10.5:1 AF.

I'm sorry if I sound like I'm ranting, I really don't intend to. And I really don't mean to start any sort of argument. Tearstone, I have the utmost respect for you. I thank you for posting the info above, it is very much what I wanted to know. More data is always better, but any is better than none.

You are also 100% correct about getting the heat away from the cylinders. After the combustion has happened, the heat is worthless inside the cylinder. Better to use it to spool the turbo :) Has there ever been EGT readings taken on Rulez car? I'd be curious to see what they are. Mine are suspiciously low. I never see more than 1550F, which is great, if it's correct. :)

Understand the only reason why I always ask for hard data is that it's good to compile that info to see what the early problem indications are. If all the reliable guys with 12psi of boost have EGTs around 1400, and AFRs at 10.5:1, 20 degrees timing advance, and the ECU pulling none; than we have a picture of what a 'safe' setup is. Knowing only one of those things does not a safe setup make. Motors can still let go at 8psi (obviously), or 11:1 AF, or with any number of nominal readings. It's the one that's out of line with the TOTAL 'safe' picture that you want to catch early so you know something is afoul and can do something about it.

Again, not arguing, not trying to fight about forged/stock. Just compiling info. :)

-John
 

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Kampfbereit
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17,852 Posts
jbasol said:
No arguments from me that forged interals are a big help. But I don't believe they are required for 'propper forced induction'. Detonation is bad. It can, and will ruin parts. Any parts...all parts. Cast or Forged. the only difference is the tollerance. Obviously the forged pistons will tolerate more detonation. But guess what? Your rod bearings are the next weak point. And trust me my friends, they will let you know when they've had enough.
I agree completely, but this engine was designed for N/A and not for boost at all in it's stock form. The front bank runs hotter than the rear from what Ian has learned and the pistons are absolutely horrible. Albeit this is an ignorant question, but how far do you think Mitsubishi would get if they turbo charged this exact 6G72 out of the factory? Maybe the obvious answer is that they would not, as we have seen from the 3Si cars. They sold them with forged pistons at least, which with the kind of target whp that people are typically making in this car that should be a minimum requirement from the get-go ya know?

Basically what I am saying, to do a proper basic forced induction conversion on this car you should start out as if the car was built this way from Mitsubishi and that includes changing out the pistons at a minimum. On our race blocks we perform the following:

CP racing pistons
Speedpro rings
Clevite bearings
Fully balanced
Professional assembled
Race prep block (Magnafluxed, Cleaned, Decked and Equalized, Align-bored mains, New Freeze Plugs and Oil Galley Plugs)

Combine that with a turbo or supercharger kit, and you are going to have one happy and pretty much worry free 3G owner.

For over 40K miles of trial and error because there was no other company backing the turbo projects as we have done over the past few years since xtech folded we've been sweating from day to day on when the day was going to come that our engine was going to go. In my case I do not ever plan on going any higher than 8psi with my setup on a stock engine. Luckily now that we have the backing of Donny, his shop and his products we are moving forward much quicker with R&D and cranking out turbocharged 3Gs.

Really, I feel Mike had a hell of a run. If we would have gotten that .63 in there a bit quicker than he would still be running. But poop happens and he was itching to build his engine anyways so... it's for the best.

Now, if we are talking about taking the 3G to 600whp+ levels, than we are in a whole different school of thought. Right now, we are just focusing on the tolerences of what a N/A engine can take, and what should be done if you want to make the N/A engine safe and reliable for low boost applications where most people that want extra pep for their car fall into.

I'm not arguing at all, nor do I think what you posted as an arguement. This is a community here to freely share knowledge for the benefit of everyone involved. I spend hours in my inbox everynight on customer queries to our products based on how safe/reliable the 6G72 is for boost applications rather they buy from me or not. I have a strong compassion to make this platform successful :)
 
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