Quote:
Originally Posted by Nate@IND
I would not anticipate an increase in sound since the OEM headers are already catless.
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Yeah, no additional volume, but in my experience with headers on other cars the tone may change.
Quote:
Originally Posted by Kyoshi71
Everything you say makes a whole lot of sense. However, header wrapping is not only to reduce underhood temps. The reason for wrapping, as I always understood it (other than a lucrative record deal  ) was:
1) Keep the heat in because hot exhaust gas moves faster thus creating a better exhaust system.
2) Maintain a constant temperature at exhaust ports because temperature fluctuation kills exhaust valves.
3) Underhood temp reduction.
4) Create a wonderful itching sensation in the hands for about 2 days after installation from the fiberglass  |
Yes, hot exhaust gas does indeed move faster but it is not always beneficial to have it as hot as possible. Most (I mean most but of course not all) of the cars that you used to see using header wrapping on were old school lower revving V8 engines. The problem with the S65 is that since it turns so fast the EGT's get high as a result of so many combustion events happening with so little time in between for any exhaust valve cooling to take place. There is a big difference in an engine spinning say 5K or 6K RPM compared to 8.4K RPM. Also since the S65 has lower torque compared to larger displacement and FI engines it spends a whole lot more time in the upper ranges of the tach than most anything else on the road.
So I do agree that hotter EGT's mean better flow however, with the S65, keeping combustion chamber temps down slightly compared to quicker exhaust flow from hotter header temps is better for performance. Maximizing timing is the #1 thing you can do on an S65 for added performance and all of PG's dyno testing of 100 octane and Shiv's use of WM on an otherwise stock engine proves it.