Intake & Exhaust Questions and info regarding various aftermatket exhaust systems for the G35 (Headers,Y-Pipes, and Cat-Back Systems)

MD Isothermal or just regular?

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Old Jun 27, 2006 | 04:15 AM
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MD Isothermal or just regular?

I notice there is a basic spacer and then theres the isothermal one... the website says the isothermal reduces the effects of power robbing heatsoak. Is there a difference in performance? Basically, is it worth the 30 bux diff? thx!
 
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Old Jun 27, 2006 | 04:21 AM
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I plan on getting the copper one (most expensive) since it says its best if it ever snows in your area, and I'm in Buffalo NY so lots of snow here.
 
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Old Jun 27, 2006 | 04:22 AM
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hmm i live in seattle so it never snows here... i think the iso is good. I read now that the iso thermal isnt good for cold weather since it transfers heat it can freeze ur throttle body
 
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Old Jun 27, 2006 | 04:50 AM
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Copper = for snow area
iso thermal = no or reduced power loss when heatsoak becomes an issue. Hot places, stuck in traffic, track use, repeated hard runs, AC running.
basic= don't mind that some of the gained hp can be lost due to heat soak

heatsoak causes intake air charge to become less dense because of heat, which means less power.
 
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Old Jun 27, 2006 | 04:52 AM
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hmm so.. might be worth the $30 dollars then.. might as well if im going to doing it to do it right.
 
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Old Jun 27, 2006 | 05:24 AM
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what is the coolant control valve for with the iso thermal plenum? From my understanding the iso thermal just reduces heat transfer to the plenum, so im confused what that valve is for. Thanks!
 
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Old Jun 27, 2006 | 05:54 AM
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I thought the iso thermal was the gasket you put on under the plenum? If so, it's well worth it... the plenums don't heat up as much with it on, definately a huge difference. I can put my hand flat on the plenum right after running the car hard now, as where before I couldn't without burning myself.

The valves or the copper plate, I believe are too keep your throttle body plate from freezing up on cold days since you don't have much heat up there anymore... not much of a problem for anyone in Cali...
 
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Old Jun 27, 2006 | 03:25 PM
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hmm so on days when it is cold in winter and I have to close the coolant control valve, when do i open it again? I live in seattle so it rarely is that cold except for winter.
 
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Old Jun 27, 2006 | 05:05 PM
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When the outside air temp is below 55F, you want the CCV in the open position. Other than that, you can leave the CCV in the off (no flow) position the rest of the time.
 
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Old Jun 27, 2006 | 05:43 PM
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what is that tubes purpose anyway i dont really understand?
 
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Old Jun 28, 2006 | 04:47 AM
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Originally Posted by Jining
what is that tubes purpose anyway i dont really understand?
There's coolant running through those tubes to keep your throttle body from freezing up and getting locked in any position on cold days (frozen open is bad...). It might sound ironic, but open your radiator sometime after you've been driving and you will find that coolant is not cold... The copper plate works constantly, since copper transfers heat better, and the other one you have to open like andy2434 stated.
 
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