Damn, what a bad Friday....It was running better than ever before!

Here are the details that we know now.
http://www.shoptalkforums.com/viewtopic.php?t=74056

I'm sure we lost a part, probably a rod- will know next week and will share some pics of some of the carnage..

This is our first failure in 3 years, and this one was a doozey, I doubt anything is salvageable!

Ouch man..

I guess we learn from our mistakes right? So you have to make a mistake to learn!

(not saying you havent made a mistake.. its just this is one of the only one's we've heard of...)

Sorry to hear this, but I hope you find a way to make it stronger, better, faster.

Andrew

Someone made a mistake along the line... Either the manufacturers of the parts, or me and my crazy risk taking way of assembling things...

So, your saying the parts should be able to handle this kind of abuse, you just think that since this is a super high end engine, it must need everything to be perfect, and someone screwed up somewhere...

Andrew

These parts had been handling the power just fine for 3 years... Nothing was changed except the cam and it was just modified with a newer billet and modified lobe centers.

I made changes to the combo to increase the powerband another 800 RPM. The extra revs and added CR found a weak link somewhere. The engine previously would pull to 8K, but would not make power that high... Now the new combo would make power at 7,800 RPM.. It went 1 rev too high and scattered..

My bet is the rod bolts broke, they cost 30 bucks each!

At these kinds of revs anything can happen.

You can always learn from your mistakes. It is more difficult to learn from your successes. That is a law of nature. Sorry to hear that it blew up. We know the next generation will be all the better for it.

It blew at 7500 rpm. Wow I get nervous when I get north of 5500 rpm. Type 4 must sound wild at those kind of rpms

The engines powerband STARTS at 5500 RPM! Driving one at high RPM is one thing, but the dyno is even more scary up that high..

My street car turns 8300 no sweat..

I'll bet the marine training helps there. Nerves of steel when under fire. You have guts, that is for sure.
Too bad the car will not have an engine for a while. That is the real problem. It is not like there are sufficient parts ready on the shelf and it can be put together during an all-nighter.

Jake,

What is the connecting rod ratio of your high reving type IV's? I know when a stock rod length is used in a BMW 2002 the ratio is 1.6875. Which means the motor will live at 6875 RPM's all day and ask for more. But when pushed over 7000 rpm's the crank speed and the piston speed become unequal. This results in the failure of the rod at the small end. It is literally jerked apart as the wieght of the crank and the speed of the piston work against each other. To increase the rev's longer rods are used with a custom piston. If your moving the rev's and power up 800 rpm's you may want to follow the BMW theory. Just something to consider... I respect your work and knowledge of the type IV's. Your the expert not me.

Nevermind... I just read the othe post. My question is too engine specific.

Jake, What kind of rods are you using? Since I went to carrillo rods 20 years ago, we haven't lost a rod or rod bolt. I always shift at 8,000 to 8,500 in my F/P 914.

Rich, the FP engine uses the stock 1.8 connecting rod ratio which is 1.95. Not a bad ratio for such RPMs, slows the piston speed considerably. Rules don't allow any change in the ratio.

Carrillo has had a bad batch of rods in the past, but they are indeed one of the best available.

In my opinion three seasons on those parts is a long time to run them. Maybe too long. How many hours did the motor have one it?

Bummer dude. I'm sure you'll learn a lot when you examine what happened.

Fiid.

Jake,

You should be bragging about that motor, i.e., three seasons. My buddies running hot 6's on the track are getting 25 hours total and you know what that rebuild costs!

Randal