Blow off valve vs. By-pass valve (semantics aside)

[Ken Keith]

Fuel consumption and environmental/cat destruction aside, what 
are the performance ramifications of the momentary rich condition?

Wouldn't it have less power than if it weren't experiencing that 
temporary rich condition?

Well, I guess if it's hesitating and jerking, it's probably not good, 
right?

Thanks,

Ken

JShadzi at aol.com wrote:
>
>     I have been running an Audi/Porche/Bosch watchamacallit valve on my 80qt 
> now for a few months.  I have had it configured in blow-off mode where I am 
> feeding boost to the bottom of the diaphram, and also feeding boost via a 
> vacuum line to the vacuum nipple and restricting vacuum via a one way valve 
> so it will not open during idle.    Overall, it has run well like this, 
> making a sexy hiss between shifts (a nice touch if you are in a little stop 
> light race, as you are rapidly passing someone you can give them a little 
> hiss between shifts to really let them know they are being beat).  Of course, 
> the downside to this configuration is a very rich condition for about a 
> second, when throttle is lifted rapidly, and the mixture goes mostly fuel 
> because most of the air has been force out to atmoshpere. It causes the car 
> to hesitate and jerk, also wrecking havoc on your cat. converter (although 
> great for night driving, I could often see the flames behind me at night-also 
> a great touch when racing , icing on the cake along with the hiss =)
>     So the other day I configured the valve in by-pass mode.  Now boost is 
> being fed to the top of the diaphram, and is rerouted back into the intake 
> right before the turbo inlet hose in a metal-T.  I definitely recommend that 
> metered air stay that way, the car drives as it was intended, smooth and fast 
> with no rich-jerking anymore, but no more hisses or fireballs either.  Man, 
> growing up is hard to do  =)
> Javad Shadzi
> 80qt (now smoking other stop light dragsters quietly and maturely)
> 
> 
>