michaelmount123

Here's a tip for 2V 944/951 guys: I use an upgraded (increased tension) inner valve spring on the 2V heads. Its primary purpose is to allow much higher RPM by keeping the followers controlled by the cam lobe. Many of you know, an over-rev (selecting wrong gear, missing a gear, etc.) all too often bends exhaust valves since the followers lose contact with the cam profile. The result is ruined race, ruined weekend, ruined bank account $$$. These inner springs allow (most) over-revs without ANY engine damage. They simply replace the Porsche inners; plug and play. They are also perfect for boosted 951's since the 951 factory valve spring tension is reduced by any additional boost (think about this, 951 guys). It's another no-brainer, must-do, really. I've got several sets laying around. $88/set plus $6 shipping. Make 'em disappear. It's a better deal than GEICO.

Reference: Ask anyone that uses them if they've zinged their engine and what the result was!

Paulyy

I've zinged my engine. I have new aftermarket springs and innersprings. Nothing happened

blade7

I've bumped the rev limiter once or twice, no kittens died .

Thom

I had a valve stem seal pop off while driving at 23psi of boost on a GTX3076R with a relatively aggressive aftermarket cam coupled with stock springs, and am pretty sure it was caused by valve float at upper rpm.

While stock springs work well most of the time with stock cam profiles, I would say that stiffer springs are definitely needed with much-modified engines.

Paulyy

What guides do you have? and how did you notice a stem seal popped off? my stem seals where hard to get off.

michaelmount123

I believe you're missing the point. Re-read my initial post!

lee101315

Not enough people here have been on the track to understand. Sometimes When braking and downshifting for a corner, you select a gear that is too low for the speed you are going. The engine may momentarily see 8500+rpm... and where normally you'd bend a few valves, these will save them.

If you have the engine out, I'd upgrade the rod bolts for the same reason! They tend to stretch on severe over revs

Thom

My post was a diplomatic way of saying that your valve springs won't be needed for anything close to the stock set up, over revs or not. But there you go.

michaelmount123

With all due respect, are you suggesting there's little or no value in using these springs in a stock engine on the track? Do you do DE's or race? Do your buds? How many have been trailered home because they stuck their shifter in a wrong gear, zinged the engine to the moon, and bent all their valves - stock or modified?

If there's a better place to offer solutions to 944 issues, I'm all ears. I've had to repair way too many 944 cylinder heads with bent valves; most I'd have never seen if they had used these inner springs.

Tsmith84

I built my first engine at 16 yrs old. I had to learn some things the hard way, like what valve float was. A summer full of hard work at minimum wage quickly turned into the head of a valve shoved into a piston, cracking it and punching a hole into the cylinder. Some people learn things the hard way, some people will just buy the valve springs from Michael! Stock or modified, a money shift can only turn out Ok with good springs and rod bolts.

David Floyd

Paypal sent

Droops83

So, you are saying that these will save my valves if my engine loses timing?





Just kidding.

I wish I had known about these last year when I had my head apart. I'll keep em in mind for my spare engine.

Thom

Sorry but the people around here I know who track their cars hard using the stock cam profiles, and that includes endurance races, never had an issue with stock valve springs and over revs. If most of the folks you come across have never spotted the 6400 rpm limit on a stock engine and/or are too ham-fisted to change gears correctly then what should they be told short of RTFM?

Again I think replacing valve springs makes a lot of sense when using different-than-stock cam profiles. Makes a lot more sense than swapping the stock springs for supposed security, unless they have become soft/worn out to the point of needing replacement.

blade7

I have no issue with MM, never bought anything from him and still may in the future. He's built some impressive looking engines. Maybe I'm mistaken but I get the impression he usually posts to promote his business or when he has something to sell ?

Eric_Oz_S2

It appears you are missing the point. Over revving has nothing do do with rev limit. It is when you down shift or miss a gear. A rev limit only controls spark and/or fuel. It does happen and has happened.

Secondly, and of no relevance to the point of this thread, but if you have raced and never bumped the rev limit, then you haven't really raced.