Hey everyone. I am trying to narrow down whether after market motor mounts help or worsen the effects of cracking manifolds. I have heard arguments both ways and hear from certain fabricators that OEM mounts are to blame for cracked manifolds/dumptubes. Because of this, I am creating this thread to see what everyone is running for manifolds, what mounts they are running, and how long it's been running without cracking. I don't believe there is a thread like this, so it should be helpful. I'm also asking about built vs stock motor to see if maybe internal balancing has an effect on harmonics. I really hope to see a lot of feedback in this thread to help narrow down cause of cracking other than bad welding.

I will start with my own experience with last setups.

1. Built or stock motor - Stock
2. F20c or F22c - F22c
3. What turbo manifold - JSP
4. Is the manifold braced? - Yes, underneath to the motor mount bracket
5. What motor mounts and hardness? - OEM
6. How many miles without cracking? - 2000+
7. Where did it crack? - didn't crack
8. Horsepower - 733

1. Built or stock motor - Built
2. F20c or F22c - F22c
3. What turbo manifold - Sheepey
4. Is the manifold braced? - No
5. What motor mounts and hardness? - OEM
6. How many miles without cracking? - 400
7. Where did it crack? - wastegate flange weld and dumptube flange
8. Horsepower - 430

If you guys feel I should add another question please let me know. This thread isn't made to bash fabricators or builders but to help prevent these things from happening over and over. Thanks you!

Anthony

 

In the aviation world, we use 321 stainless for the exhaust. Some turbocharged engines, some not. The one thing that affects header cracking more than anything else is the balance of the engine (and in our case, the prop too) . A smooth running engine/prop combo will have an exhaust that lasts. A "shaker" will have regular failures.

Interestingly, aviation engine mounts are soft when new and get hard as rocks when old. Does not seem to matter much with regard to exhaust life.

I'd say the number one factor with regard to cracks on an S2000 is design, followed by material choice, followed by fabrication quality.

My previous car, a turbo Miata had cracking issues with my original design turbo header. I modified the design to include "double" slip joints from Burns Stainless, in 321. The header is still holding up well with the current owner, 15 years later. In essence, I copied how the aviation guys do it.

 

Stock motor
F22c
PLM sidewinder
Down pipe braced on the OEM header mount
OEM motor mounts
20,000 miles without cracking
440whp