ive heard that you can damage a valve by sucking cold air upon deceleration and ive heard not to use the engine to slow the car down...

any info guys ?

 

The onlything thatis going to get damaged are your ear drums, or your wallet if you get fined for excessive noise.

 

Alih both myths as far as im concerned. never seen any damage from either. if you think about it look at almost all purpose built race cars and the super short header lengths some of them use. its not something id worry about or be concerned with. the engine can be mated to various length headers to change power characteristics but valve problems as a result are just non existent kurt

 

not open headers, however, if u have a big exhaust leak at the header/head junction the cold air here can cause problems like u described. but im pretty sure it would have to be a huge leak... not one ud likely run ur car with. open headers is fine though, the headers take the collection tube far enough away to not have to worry about it

 

The fire in a cylinder can reach1800 deg. The exhaust valves can reach temp of 1200. That is to the point you can effect the heat treat of the valves. If cold air hits these valves it will cause a form of oxidation and micro stress cracks . If it happens once or twice or even a few dozen times it may not effect how the valves function. If you do it every day the valves will have a limited life.

Long tub or standard header will most liklyprotect your valves. Heat willrise and be trapped in the top of the header so cold air will not run up the tube. Unless, as stated above,there is a leakat the top at the gasket. Short header and stock manifold do not offer as much protection. These stress crack are easy to see under a microschope andquick cooling of the steel is about the only thing that will cause it.

 

yeah i have long tube headers, i was also worried about the heat that it puts out

but i will have to run it like this until friday when i get new mufflers