Mr Helmholz - simple model

[Gary Derian]

Doesn't cutting the collector change the standing waves and therefore the
place where you want to cut it.  Maybe an iterative process.  I have no
technical explanation  for this either.  I don't know why pressure waves
would cause the paint to burn.  What if you had high temp paint that didn't
burn, or low temp paint that burned all over?  Do you have to hold a
constant rpm?

Gary Derian <gderian at oh.verio.com>

> I have heard exactly the same for an H-Pipe.  Paint it, and where the
paint
> has blistered up is where the crossover needs to go.
>
>
>
> >The way I was taught to roughly but effectively 'tune' my exhaust system
> >on my 4 stroke v-8's engine's is to bolt about a 2 or 3 foot pipe to the
> >header collector paint it black with some spray paint (preferably BEFORE
> >installing the pipe) then do a run down the strip...
> >
> >After runnin the car at WOT for a 1/4, there will be a point on the
> >'tuning' pipe where the paint has been burned off, and a point further
> >up towards the header where the paint isn't burnt at all!
> >
> >At the point where the paint begins being burnt is where ya cut the
> >pipe.. Whalaa instantly tuned exhaust...
> >
> >I've never heard a technical explanation of why this works or even if it
> >helps or hurts or is just a guess at the correct length of exhaust
> >pipe...
>