7150rpm is enough for stock lifters.......imho

edit it a little.....for old version of stock lifters

 

This is not about the lifters, but it's a good vid to see some effects of high revs on springs and valves.

http://www.youtube.com/watch?v=_REQ1...eature=related

 

Just a FYI; it looks as though the 997 lifters are not immune to failure either. Todd K. at Proto just got a 997 GT2 in from Bahrain with one of the lifters on the verge of failure (galling).

It seems to be a rare problem, but so far I've heard of it happening to my car, a 997 GT2, a RUF VIN 996TT, 2 other modded 996's, and 3 bone stock 996s.

 

Is there a way to know that lifters are failing other than an internal engine inspection? I mean do they sound strange and/or does the engine have some particular behaviour when a lifter is going bad?

 

I'll ask.

 

Thank you sir..

 

So this is one of those "I hope it doesn't happen to me" deals? Because I doubt a lot of people go running to spend the coin to inspect these if it's such a rare problem, but if you're the one who gets bitten, it just sucks. If there is no easy way to check, it's hard to justify opening up the motor just to see. It's hard to justify opening up these motors at all unless you are going to throw a ton of power at it.

Seems like there were a LOT less problems just a couple of years ago. Where did all these problems start coming from? Seems like there are still many more of these engines running to 80-100+ k miles than are having problems.

What's a ballpark figure on checking this out?

 

Oil and/or filter analysis. That metal getting carved out has to go somewhere...

 

This is another good reason go with GT3 heads and their radius tappets.

 

Metal shavings can come from many different places, none of them are good!

This seems like a very rare failiure that's mostly caused by revving the engine higher than factory intended for this car. I wonder if the stock cars that failed were flashed at some point before being put to stock and experiencing the problem?

In terms of checking for this and trying to activelly manage it, I see no point in it - you can check for it today, but develop the problem tommorow, and I doubt anyone wants to make this check a part of their oil change routine.

I remember when I owned my old 600 AWHP 3000GT TT, and after I went through several stock motors, I was so scarred to lay into it anymore because I always thought I was hearing sounds..... I don't miss those days.

Ok, I digress, back on topic - good luck with the car, glad the collateral damage wasn't worse.

 

Are they an improved design, or just different and less prone to failure?

Since you're likely the resident expert on these things, are there any other reasonable alternatives, like a traditional solid or hydraulic option that does not use the variable lift? What do the Cup cars use?

 

I can't see why this couldn't be found using a blackstone oil analysis. This is a good thing to do to track bearing wear anyways. I would be interested to know if this is an over rev issue in itself or a combination of revs and parts manufacturing flaws.

 

They are designed for the higher rpm's. They are stronger, better designed and built.

There are have been different lifters made for different GT3 models over the year models. Some GT3 models (GT3 Street, Cup, RSR) had different ones in the same year. This gets a little tricky as the different lifters require different valve lengths as height of the lifters vary. Not an issue if you plan for it ahead. They all can work with a little planning.

Regarding the Cup cars ....... they have been made by Porsche with both solid and hydrolic lifters. I personally like the radiused top hydrolic lifters as opposed to the flat top ones for street use.

 

What could be the cost for gt3 heads,roughly?

 

For information only. Here is a 996tt cam housing versus a GT3 am housing. Not only will the GT3 housing allow bigger cams ....... they are far beefier.