Frederic Breitwieser/turbo discussion, design Q's

[Frederic Breitwieser]

> Turbo engines respond to all the same tuning tricks as atmo engines.  Tuned

yes they do.  The only thing I would append to your comments if I may is that
with a turbocharged system, you want the exhaust system to have as little
restriction as possible, because the turbo itself is a big spinning CORK.  You
want little, if any back pressure pre and post turbo, especially with the larger
turbos.

> headers included.  Conventional wisdom states that a 4-2-1 header gives
> better mid range and a 4-1 gives better top end.  There is lots of racing
> engines that use 4-2-1 designs  With largish tube diameters and appropriate

What would you recommend for low to mid end then?  I am curious, for I'm
building a 383 Mopar B block stroked to 431 cubes (or more if I can figure it
out), using the EEC stuff to manage it.

What I ended up with, since the vehicle is a truck and not a race car by any
means, was either to make shorty exhaust manifolds that go forward, attach the
turbos there, and blow up into the intake system I'm almost done fabricating.

Also, even with turbos, and H-Pipe offers better performance.  I am clueless as
to why this is the case, I believe it has to do with exhaust pulse
reverberation, however the H pipe does make a difference.  Original testing on
the Buick before we ended up with bizarre headers, the tried the H pipe before
the turbos, and after the turbos.  Post turbo offered slightly more power and
less turbo lag from idle.  We used a 3" H pipe.

BTW, I had called up to the shop, and found out that I was completely mistaken.
The 180 degree headers are in fact 3 to 1 headers, however underneath the dry
sump oil pan there is an "X" where the left side feeds the right side, and the
right side feeds the left side, in conjunction with their own side.  My friend
said conceptually, its the same advantage as an H pipe, however being an "X"
rather than an "H" the crossover points are somewhat aligned with the airstream
versus the H pipe which is a 90 degree bend of course.

See, I made this and I didn't even know what it was LOL.  Hope that clarifies
what we did, and makes sense to some of the discussions.

Hey Bruce, can I borrow your cone shaped hat for standing in the corner for 15
minutes?


--

Frederic Breitwieser
Bridgeport CT 06606

1993 Supercharged Lincoln Continental
1989 HWMMV w/turbocharged 500cid Caddy
1975 Dodge D200 Club Cab soon to have 431 stroker + turbos
2000 (I hope) Buick GTP (Mid-Engined Sports Car)