Crossover pipe keeps cracking
05-13-2010, 12:57 PM
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Crossover pipe keeps cracking
Just wondering if anyone has any tips in preventing an aftermarket crossover pipe from cracking on a race car. The headers I have are 321 SS. They comprise of a 4 into 1 slip fit, the cross over has a slip fit as well and the pipe going to the wastegate has an inconel expansion joint in it. The cracking occurs at the joint of the crossover to the waste gate pipe.
To be fair, the piece that cracked is 304 SS as we made a custom piece for the crossover. Perhaps the 304 is just more susceptible to cracking in general. Just wondering if anyone else has any good ideas on how to prevent this. I was thinking of mounting the waste gate on vibration isolators to allow a bit of travel??
Any help would be appreciated.
To be fair, the piece that cracked is 304 SS as we made a custom piece for the crossover. Perhaps the 304 is just more susceptible to cracking in general. Just wondering if anyone else has any good ideas on how to prevent this. I was thinking of mounting the waste gate on vibration isolators to allow a bit of travel??
Any help would be appreciated.
05-13-2010, 01:16 PM
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Just wondering if anyone has any tips in preventing an aftermarket crossover pipe from cracking on a race car. The headers I have are 321 SS. They comprise of a 4 into 1 slip fit, the cross over has a slip fit as well and the pipe going to the wastegate has an inconel expansion joint in it. The cracking occurs at the joint of the crossover to the waste gate pipe.
To be fair, the piece that cracked is 304 SS as we made a custom piece for the crossover. Perhaps the 304 is just more susceptible to cracking in general. Just wondering if anyone else has any good ideas on how to prevent this. I was thinking of mounting the waste gate on vibration isolators to allow a bit of travel??
Any help would be appreciated.
To be fair, the piece that cracked is 304 SS as we made a custom piece for the crossover. Perhaps the 304 is just more susceptible to cracking in general. Just wondering if anyone else has any good ideas on how to prevent this. I was thinking of mounting the waste gate on vibration isolators to allow a bit of travel??
Any help would be appreciated.
.
05-13-2010, 04:14 PM
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321 has an operating temperature of 1650 deg F, if your EGTs are that high you will melt the pistons. 304 is lower, around 1000 deg F and is more prone to sensitization during the welding process.
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05-13-2010, 04:43 PM
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EGTs of 1650 are pretty standard on a 944 turbo set up for street gas. Its not what you want - but it is what you get with reduced timing and rich mixtures.
05-13-2010, 06:05 PM
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You can see EGTs in the 1650+F on a 951.
05-13-2010, 07:47 PM
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I will check, I had a lot of other issues I was sorting out last race weekend so the EGT werent high on my list. I will have info for you next friday when I test and tune and dial in my AFRs.