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Author Topic:   Motor blew and we found someting ODD?
Ego Racing
Dirt Forum Champ
Total posts: 724
posted April 29, 2005 09:09 AM  
A motor in a friends car (built by a prof engine builder) started to loose power very quickly and then popped. We called the builder and he told us to bring it buy. When we pulled the heads off we found one piston cracked. When we went to pull the bottom apart 3 rods were twisted about 90 degrees from the pin to the crank. Two were still together and the third was the cracked one. The crank and block were still in good shape as all the block needed was a light honing to bring it back.
We thought the rings grabbed and twisted the rods but there was no evidence of it.
The only thing we had to replace was three rods and 1 piston, we replaced a full set of each though. Put it back together and it has had no problems for almost 12 races.
The builder has built over 300 of these motors and has had no problems with great results. He has been building race motors for over 20 years and this was the first time he saw something like this.

dirtywrench13
Dirt Freak

Total posts: 324
posted April 29, 2005 11:51 AM  
I USED TO WORK IN A MACHINE SHOP, BUT EVEN I HAVENT SEEN THIS! I'VE SEEN ONE, BUT NOT THREE! WERE THE HEADS OK?

Ego Racing
Dirt Forum Champ
Total posts: 724
posted April 29, 2005 12:11 PM  
The only thing we "lost" was the three rods and pistons. We had the 5 rods left checked for length and twist and all were still good. The heads were still in great shape as the pistons were flattops and were down in the bore to start. He got a new set of pistons and rods ballanced to the crank and bolted it back together. The motor had about 80 laps on it at 6500rpm max. The rebuild has about 240 laps.

leapinlizard
Dirt Freak

Total posts: 402
posted April 29, 2005 02:34 PM  
Got pics?

Ego Racing
Dirt Forum Champ
Total posts: 724
posted April 29, 2005 06:53 PM  
No I wish I did have some pictures of it though.

b00
Dirt Maniac

Total posts: 152
posted April 30, 2005 07:47 AM  
acording to oliver
it is a harmonics problem??
only seen it once

Ego Racing
Dirt Forum Champ
Total posts: 724
posted April 30, 2005 10:06 AM  
I would belive anything but like I said the new rods were ordered for the same weight and so were the pistons and after they were checked everything was bolted back together and has been run every weekend, almost 1 season.

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