I've searched for the following info, but could only get bit's and pieces here and there, and nothing that answers my question specifically. I'm curious as to what the general feeling is in regard to how much power stock bottom end and drivetrain(upgraded clutch only) evos can handle and not compromise long-term reliability. Providing I maintain the car properly, and don't abuse it, of course.

I'm thinking about a Buschur br440 turbo and supporting mods which should bring me to about 400whp. How many miles would you expect my stock bottom end and drivetrain to last w/this setup? This is a street car that I don't plan on racing. I'm a little worried about the transfer case thopugh, as a little bit of wheel hop now and then will probably be difficult to avoid at this power level, I know the bottom end is strong, just not sure for how long at 400whp. What do you guy's think?

 

Double your output, cut your life in half. I wonder how long it would last in stock form....

Don't forget that it also depends on how often you actually use 400 AWHP. Once a month or once per minute? That will affect things slightly.

 

This is a pretty heavy question, and it depends on the scope of your analysis completely. I can try to tackle a little bit of this...

If you only consider mechanical yield of major components (ie bent rods, sheared cranks, stripped gears, etc) you can do a simple fatigue analysis and get ballpark estimates assuming you know either the ultimate limits or the limits at some cycle time of the part in question.
Where this gets hard is with non classical mechanical failure modes....like piston melting, seal failure, etc.

There is a lot of crap that can go wrong besides yielding of metal. Anyways, lemme give some of this stuff a stab...

First off, this is not necissarily true. Steel parts have a unique property that at certain load levels (approx 1/2 of the ultimate strength, or half the force required to break the part in one cycle), the part will theoretically last forever. In practice, this does not always happen, but lets just say, they can last a LONG time. Now, lets say you increase the load from 1/2 the ultimate strength, to 9/10 the ultimate strength, youve just decreased the life of the part by a factor of 1000. Aluminum is a little different, the biggest difference is that there is no theoritical infinite life. Meaning, if you gently push youre finger on an aluminum piston, it WILL eventually break. It will take a LONG time, but it will break. A steel piece will NEVER break, theoretically.

Lets take some steel pieces in the engine as examples. Lets say the crank will shear at....idk....700 ft lbs or torque after 1000 cycles. Thats 15 secs of full torque if your torque peak is at 4k( i took 1 cycle as 1 revolution...this may or may not be the case depending upon the failure mode and loading criterion). Lets say your max torque output is....450 ft lbs. You are putting out 57% or the ultimate strength...that correlates to 300k cycles...or about 75 minutes of peak torque. Basically, that means, if youre car spends 75 minutes at or near peak torque, youre crank will fail. Thats a long time.

Now i just kinda made up as estimate for the failure strength at 1000 cycles. A better analysis is done by someone who can measure it experimentally.

Basically you would have to go through all the "suspect" parts like that to get the best answet to your question. I however, have a life, sorry.

The other method would be to wait for upgraded turbo guys to start wearing stuff out...that might take a while though.

If youre looking for exact numbers, idk man. No one does. Every car is different. every driver is different. If youre just talking steet duty, with an occasional run here and there, youre prolly looking somewhere on the order of 30% reduction in part life...thats just talking about deforming metal. Wear, heat transfer, etc...whole new ballgame.

IDK man, you pay, you play i guess. Good luck with that.

 

I'd bet that a sensibly driven BR440 Evo will outlast a stock Evo beaten to a pulp everyday by "drive like you stole it" sort of driver.

 

You also have to consider things like electronics reliability, environment conditions, etc.

I would fathom to guess the second you go to a new turbo and aftermarket ecu, etc...youre asking for a lot more minor problems than intake/exhaust/cams/flash.

Youl prolly get 5-10 odd-ball problems for every major part failure.

 

Possibly. Id go along with that in terms of major parts failures. But in terms of little knick knack things like....boost leaks, etc....a stock car should fare better.

But were talking about one driver here. A stock car driven by 1 person should last longer than an uprgraded one driven by the same person the same way.

If he gets the kit I doubt he would drive so drastically different that ^ will be a major factor.

 

Mercenary, thanks for the info, that was by far the most well thought-out and informative reply I've ever recieved.


It's also what I wanted to hear. Based on what you said,and how I treat the car, a theroetical 30% reduction in total engine life sounds logical and is, to me anyway, a worthwhile sacrifice for the fun of 400whp. Just think of the caliber of cars an evo like this would out-perform,then calculate how much it would cost to run,say just as an example, a GT2 for even 80k miles. Not counting the initial cost difference, it still seems like a bargain to me. Also, based on my experience so far, the evo has been as reliable a car as any I have ever owned. So far zero problems at 16K miles(zero hard launches and zero track days either FWIW). Just spirted street driving.

I wonder how long a sensibly driven stock evo would last? Someone else asked this and i am also curious.

 

I think the best place to find your answer is on UK forums where they have had the evo for longer than we have. Basically, in terms of lifespan in america, no one knows cus the cars only been here 2 years.

Most cars should last about 150k miles at least. Factor in we own a mitsu, but also factor in we own a very nice drivetrain package, and id say somewhere in the 150k range is reasonable. There are a lot of DSMs sill going strong after 10+ years out there.

Also, after a long time, usually you dont just get a catostophic failure. More likely, you will get reduced compression, worn turbo, etc. Stuff needing a rebuild. So when I ballparked a reduction, that just means youre gonna have to start doing more maintenance a little earlier. I think if you use DSMs for example, there are a lot of them running 400 hp or so that have 100k+ miles on them. So, like I said, every car is different but i think youl be OK.

Its much better to squeaze some extra power out of this car than many N/A cars out there.

 

I have 326whp now and will be knocking on 400whp's door very soon. I have almost 19k miles and have had really no issues...other than the clutch. I have noticed that any leak makes me worry though with that kind of power. I noticed some oil leaking or oosing out around the oil pan yesterday, but my oil level is ok tho. These cars should be reliable, they are 15 yrs into the R&D of this 4G63 motor we have.

 

I Open Road race with 345 whp. That involves 20 to 45 minutes of WOT.

I have a bigger turbo, cams, cam gear, bigger intercooler, 3 inch turbo back, EBC, and run 24 to 25 lbs of boost. I modded the car two years ago after buying it new. After two years of racing, 31,000 miles, still no problems at all. This car is driven far harder than a street driver. The only thing You don't do in ORR is dump the clutch. I replaced the clutch at just under 30,000 miles as a preventive measure, but the old one was fine.

What is the lifespan of the engine? I don't know. I reasonably expect to get two to three more years out of it racing. Stock head and bottom end. If something lets go I will just rebuild it.

I do run underdriven pulleys.

EB

 

bump

 

i have seen some evo's pushing 450+ at the wheels with a factory bottom with out any probs. now i have heard of some people putting 750+ with a factory bottom for a while but they ended up toasting a piston head during a tune and grenading the engine.

 

Hi, I want to have my cake and eat it, too.

 

i have seen some evo's pushing 450+ at the wheels with a factory bottom with out any probs. now i have heard of some people putting 750+ with a factory bottom for a while but they ended up toasting a piston head during a tune and grenading the engine.