Bypass valve versus blow off valve

[Marc Swanson]

> I am looking for an understanding regarding which one is the best solution
> for an MC-1.  I all ready have a bypass valve so the decision is made

good choice

> but I
> know someone running a blowoff on his 4KTQ rally car and inquiring minds
> want to know.

For a CIS powered car, forget about it.
Running a blowoff valve with ANY car designed with a fuel system which meters
all incoming air (be it CIS or even "mass flow" EFI systems) means that when
the bypass valve opens you've just altered what the computer thought it was
receiving for air and thus you've created a very rich condition in your
engine.  Sometimes you'll see flames shoot out the exhaust because of this.
Neat to watch, but it won't get you across the finish line first :-)

"Speed density" EFI systems can run blowoff valves with no adverse affects
since the actual volume of air is calculated rather than measured based on
things like intake temperature and manifold pressure.


HTH

-Marc-
87 4ktq
88 90q