I know this is a hard question to answer but is there a rough rule of thumb for what level an evo can be pushed to and stay reliable . Let me try to explain a bit beforehand.

Lets say I want to do three 30 min sessions on a 4 mile course 6-10 times a year. The car would be prepped with 100 Oct fuel and be able to keep coolant temps under 200 with a conservative tune to keep egt's manageable. The trans ( 5 speed, 4.11 gear) and ACD transfer case do not have coolers on them and will just get hotter and hotter as the session goes on.

400whp
450whp
500whp ?

Can I presume that the trans and tcase will develop problems at 500+? I'd like to hear from a few people that have actually done it.
I can build a 2.0/2.2/2.4LR and have enough turbocharger ( T3 flange) to make 400-550whp. The RPM's would be kept in check per engine ( Piston to rod ratio) and the necessary AMS pan and Kiggly hla would be installed as well as an oil cooler fan ( less then 240* hopefully) Tires are RS-3 so I don't think oil starvation on right hand corners would be an issue. Brakes are carbotech xp8, lines and proper fluid.
What other things need to be considered?

Any thoughts on the engine choice?
Is there solid data on what brand radiator is the best? Koyo?

 

You were correct from the jump, it's a hard question to answer because no two builds are the same. Regardless of your HP level, issues will arise--it's just the nature of the beast. Get out there, knock out a few sessions, and work from there.

Common issues are cooling, brakes and tires.

Personally, I'd go with a 2.3; more grunt than a 2.0 and can rev higher than a 2.4.

 

Unless you have years of quality seat time, id say youre making a big mistake.

 

Depends on do you have a very high quality parts-build and a very high quality tune. One is missing from here, you are doomed.
It's a race environment not a street.

 

I'm very detailed oriented so I won't overlook anything. I always run on the conservative side. Well, most of the time..
As far as making a mistake goes, I failed to mention that its a street car that will see the track every so often. I'm not building it to go racing, I'm building it to have fun.
If you are concerned about my skill level, don't worry about that. I've ridden streetbikes for 16 years including some track time without incident. My current bike makes 165whp weighs 444lb wet and has dirt bike bars for around town comfort/fun. I've also tracked an Ariel atom so I'm not a complete rookie when it comes to handling 'fun' cars.
I was hoping someone would chime in with something along the lines of.. "I had my car at xxx hp for 3 years without a hitch,then I went to xxx and all hell broke loose"

 

I raced for about 7 years with 350whp and then it went boom! You sure as heck do not need 400+ to typically be one of the fastest cars on track.

 

couple of years ago I was passed at the track by a pretty slow e30, that's when it hit me that my 335whp doesn't matter haha. seat time seat time seat time.

 

the closer to stock you stay the longer it will last honestly. i keep finding myself pulling boost out because it is making both me and the car more consistent. do basic bolt ons get a very tight tune for 23-24 psi and get some seat time.

 

When I upgraded my car from 350whp to the tune of 450whp I felt like I was making mistake after mistake. I have detuned mine to better align my seat time with what the car can deliver. BTW now that the car is 400+ I have lost all confidence in its reliability. I expect it to blow up every track day lol.

 

i make mistake after mistake at 340whp LOL.

 

If you want to be able to run 30 minute sessions, these guys all speak the truth about power levels. Mine's able to push 600whp but I don't ask it to go more than a couple laps. Longest it needs to survive is at PPIHC which is about 10 minutes if all goes well.

I don't expect it to blow up every time I take it out, but know that asking well over double the stock power levels means a greater chance of something bad happening.

Dave

 

For reliability go with a built motor on either stock IX turbo or FP Green / BBK Full. All other effort should be put in to cooling, brakes and suspension. A safely tuned 350 whp with a good overall setup of suspension and brakes should put you in the top 10% of the cars pretty much anywhere except the Nurburgring (and even there probably).

Usually the fastest cars are the reliable ones (professional drivers with purpose built cars excluded).

And in the long run - all that matters is seat time like it's been pointed out numerous times. And your car not breaking will lead to more seat time and money left over for even more seat time instead of paying repairs

With all that being said - I had my own car running at 350whp on the stock IX turbo and stock motor for 150k miles of daily driving and tracking/auto-x and it runs still.

 

At 500hp, I was able to hotlap the Nordschleife for 3 years with the only issue being high oil temps and high brake temps. The oil temp issue got resolved. Build your motor and prep according to your track and see how it goes. Again, it's hard to say everything will be ok because it may not. I raced with a guy who spun a rod bearing after his second lap--on a completely stock car.

 

There is a lot of good advice here.
I put 15-2500 track miles a year on mine with a 350 whp tune. Stock with bolt ons. It has proven to be stone reliable with the last 35,000 miles being track miles. Learn to drive it and you will be one of the faster cars on track.


Spend your money on good coilovers, brake cooling and the like.

 

Mo power, mo problems.