Don't worry about keeping heat IN the exhaust system-- you want to! More heat in the exhaust is more energy to spin the turbos.
An underhood temp sensor to run the fans is a very good idea.
Just an FYI, on my Subaru STI the ENTIRE exhaust from the heads to the turbo, the turbo itself, and then the downpipe from off the turbo until under the car is entirely covered in a sheetmetal "clamshell" heat shielding scheme. This is partly to keep the heat in the exhaust for quick catalyst light-off, but I'm sure it does a good job of keeping the exhaust heat off more sensitive components, too. However, after thrashing on it on a hot day (like today, 104F outside and I'm enjoying my drive home) it does get a wee bit toasty under the hood...
All the wrap and shields may not look as pretty as totally open headers, but cool running is better than cool looking in this case.
Another thing you should be concerned about, especially with the turbos and the underhood heat is oil temp. Do you have an oil temp gauge/cooler?
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1969 Chevelle
Old setup: Procharged/intercooled/EFI 353 SBC, TKO, ATS/SPC/Global West suspension, C6 brakes & hydroboost.
In progress: LS2, 3.0 Whipple, T56 Magnum, torque arm & watts link, Wilwood Aero6/4 brakes, Mk60 ABS, Vaporworx, floater 9" rear, etc.
Last edited by Blown353; 08-05-2005 at 05:46 PM.
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