MyE28.com

Duke, 100k miles isn't the issue, it's the age of the guides. After 20 years, the plastic get brittle. That's not what M635Csi is driving at here though.

If you take an equal m30 and s38, both producing the same horsepower, the m30 is operating under much higher stress levels than the s38 is.

I'm sorry, but the motor you built for your car to begin with would not have lasted 300k miles, there's simply no way. I doubt it would've made it past 150-200k miles, quite honestly. Most Alpina and Hartge motors don't make it very much past 150k from what I know.

His original statement was:

I believe a correctly built M88/S38 engine will last longer per unit output of horsepower than an M30 engine.

He may very well be right. It's actually rather easy (though not inexpensive), to get an m88/s38 to 600hp with turbo. Doing so with an m30 is probably possible as well. Compare the two side by side now. The M motor is running moderate boost due to the inherent efficiency of the 4 valve engine. The m30 has been tweaked and poked and prodded pretty hard, many parts are running at the limit of their tolerance.

I seriously doubt the m30 in this scenario would last as long as the s38 in this example.

Jeremy

M635CSi wrote:You statement "This would be the same whether theres (sic) a turbo or not", is similarly unqualified and does not withstand scrutiny.

That sentence doesn't withstand spelling and grammar scrutiny. You forgot the "r" on "your" and the apostrophe is incorrectly placed, which is really irrelevant since your use of it is superfluous.

M635CSi wrote:As an engineer you know wear does not increase in a linier fashion...

... nor does it increase in a linear fashion.

BTW, you left out a period at the end of that post. Just thought you'd like to know.

Shawn D. wrote:

M635CSi wrote:You statement "This would be the same whether theres (sic) a turbo or not", is similarly unqualified and does not withstand scrutiny.

That sentence doesn't withstand spelling and grammar scrutiny. You forgot the "r" on "your" and the apostrophe is incorrectly placed, which is really irrelevant since your use of it is superfluous.

M635CSi wrote:As an engineer you know wear does not increase in a linier fashion...

... nor does it increase in a linear fashion.

BTW, you left out a period at the end of that post. Just thought you'd like to know.

Thank you Shawn, I have edited my post to reflect those corrections. I do like to know these things so that I may be correct in the future. Years ago I witnessed a Harvard graduate be denied a position he had applied for. After attending multiple interviews and receiving a job offer, the thank you letter he sent contained a grammatical error. A grammatical error cost that young man his chance to work at a very prestigious investment bank. It's all fun and games until someone gets hurt...

In my opinion the s38 valvetrain is stronger when abused to high RPM levels because it have solid valve lifters and no rocker arms. All japanese motorcycles which go well beyond 15000rpm stock has the same type of valvetrain as the s38, so there is no doubt that this type will last longer. Actually all the japanese high potent engines share that valvetrain design (skyline gtr, supra tt ...)