For unknown reasons my car just died while cruising to work. I was hoping to be something minor, but unfortunately, it wasn't.
The belt skipped some teeth and now I have 2 broken valves and 14 bent.
I really wanted to know what happened to prevent it next time and the only clues I have are that there was oil somewhere on the belt due to some seal and I had my 60k service done late last year.


Anyways:

I will have to either buy OEM valves or Aftermarket SS valves.

Which route would you guys go?

OEM were quoted to be $500 while aftermarket about $200.

I want to get the best (durability) valves for street use regardless of the price.

btw I'm running e85, S2 cams, GSC springs & retainers. plus the supporting mods. 400whp 398ftlb


Any thoughts, thanks!

 

Go with the aftermarket ones. Just as well made as the OEM at a fraction of the price.

 

aftermarket, I recommend GSC's valves, go +1mm while you're at it and do new valve guides and valve seats. Make sure u don't have anything broken in the chambers

 

appreciate the input. I will be going with Aftermarket valves.

Also there were two small nicks on the pistons. any chance something bent as far as rods or anything that the shop is not able to see since they only took the head apart.

they recommended not running e85 anymore, but i'm not liking that idea

 

What? Recommended not running E85? Why in the world would they recommend not to run E85

There are people in other states (CT!!!) digging in their own backyards in an attempt to extract E85 out of the ground and this shop tells you not to run them

Just a question... Did you take your evo to a reputable shop? Do they know what they're doing? If yes, then they should tell you the state of your engine...

 

Doesn't E85 come from 85% corn though? No digging required

 

If you research a bit on here you will find some posts and information regarding what you are asking. Basically, the oem valves are a nice design, some will argue that the sodium filled design are superior to aftermarket as far as extracting heat. Some will also say that aftermarket valves have a better design to allow smoother airflow.

When I researched this in deciding what to go for I contacted MAP and GSC. Both recommended aftermarket valves. GSC stated many benefits found in aftermarket valves, not just their own. To each their own, honestly I don't think you can go wrong either way. Me personally I went with supertech nitrided intake/ Inconel exhaust valves.

 

I hope you didn't take my statement literally

 

Im fully aware of how Ethanol is produced.

 

I took it to one of the best shops in Socal. My main concern is not knowing what caused the timing belt to slip, so that i can prevent it in the future. A different shop did the 60k service 10k miles ago but didn't use OEM parts on everything, so i'm not sure if anything would be related to that.

But I still plan on running e85, I don't think i can go back to 91.

 

Which injectors were you using when you ran E85? A lot of shops out here recommend RC, but imo FIC injectors are better suited if you want to run E85. They sometimes require a little more time to setup and tune from what Im told, which may be another reason shops out here prefer RC.

 

True. Two shops recommended me the RC1000s, so.... I went with the FIC1100s (high Z)

 

belt jumped because it was too loose. belt tensioner was not setup correctly during the 60k mile service. there isnt anything else that would cause belt to jump.

factory valves are made to withstand turbocharged heat for many many miles. they come black nitrided to reduce stem and seat wear. and the exhaust valve is sodium filled which keeps that valve running cooler. most aftermarket valves you buy are a cheap replacement without these features. supertech valves are nitrided. but to get a filled valve is over 35 per valve. the factory filled valve is 18 last I checked. makes it a pretty good deal really. my personally would prefer to use a nice set of used factory valves before I used stainless or inconel with no nitriding.

also bigger valves will not necessarily flow more. the exhuasted gas is being pushed out around the exhaust head. so making head bigger does not help. on the intake side the valve is already shrouded pretty heavily. so without a proper port job it will likley flow less. evo X valves are like 3mm smaller than 4g63 valves. even after making cylinder bigger by 1mm.

 

Thanks, yeah i was looking at the OEMs but they all say it wouldnt really make a difference. I personally would go with OEM since they have been working fine all these time, but they are $30 a piece and aftermarket do they equivalent job, or so I hear.

 

MAPerformance sell them for $26 a piece, that should save you a noticeable amount. I'm sure you can find them for less.

But I believe that a lot of people are running aftermarket valves without issues so I'm pretty sure they can withstand the extreme exhaust temperatures.