Siamesed Runner TPI Questions...

[Bruce]

> Hmmm, I was under the impression that the difference in rpm potential
between
> two identical intakes compared on a 350ci and a 400ci would be
approximately
> 500 rpm, as in the 350ci should see approximately 500 rpm more air etc. Is
this
> close?

I did alot of back to back work with a 305 and 350.
It was uncanny how close they were.  It just seemed the 305 was 12% down
compared to the 350.  As far as CCC carbs went, they took the same darn
jetting, and chip to perform at their best.   Same eaxt operating
characterists.  Thou in the 305 the same amount of cam sounded nastier.

> As Bruce knows I'm happy with my power curve and rev range the way it sits
with
> the dual plane and the carb. I'm primarily looking for better economy and
high
> altitude performance, but if I can gain something in the switch to EFI
I'll
> take it (either a mid-range bump with TPI or better top-end with a
> single-plane/TBI or MPI or Mini Ram).
> Looking at the curves from the dyno runs below it seems as if the TPI
intakes
> made power to 6K rpm or a little better (on a 350ci crate motor). Would I
be
> correct in guessing that they would pull to 5500 rpm on a 400ci?
> If so with my current power peak at about 5150 rpm it might not be so bad?
I
> generally shift at 5500 rpm or so and my shift recovery rpm is 3100 rpm in
> first to second (3.06 to 1.62), and 3450 for second to third (1.62 to
1.00). To
> me if I can improve torque from 3000 rpm to 5500 rpm I go faster, yes?

For street motors I like 2,500 to 5,000.  Makes for long life, and reliable
operation.   Also, if I can't get **it** done with that, well there are
always bigger dogs around

> The Super Ram increases the plenum volume a lot over a TPI, is this what
> supplys the extra air for higher rpm work?

Combo of shorter runners, bigger plenum, and I do believe the runners are
noticebly large in diameter
Bruce
>
> Thanks...
>
> Doug
>
> Bruce wrote:
>
> > Naaaa,
> > IMWO, it varies on a case by case evaluation.
> > For a new guy TBI will always be easier to build from the ground up.
> > For a very large displacement engine, MAP is the answer, and cam/rpm
will
> > guide my response.
> >
> > 5+7 are mute in my opinion, most of the problems for them are cross
> > fire/ignition.
> > On a wet manifold, ya there can be problems, but generally at the higher
rpm
> > levels.
> >
> > I'd watch getting too short of runner.
> > Heck, I advocated the connected runner idea for a long time now,
> > What I would do if I were you is start measuring things out for the
plenum
> > volume and see where you are
> > Bruce
> >
> > > This thread over here too?
> > >
> > > Its not for everyone... but it is possible to extend the range of the
TPI
> > > more to popular liking...
> > >
> > > Think of how the siamesed runners shift the curve. Now say "what if"
the
> > > runners were siamesed all the way down?  more shift. Now... hmmm..
what if
> > > the siamesing was extended all the way INTO the base?  no need for
large
> > > runners or a ported upper intake now... cause you're drawing from 2
runers
> > > simultaneously!  reversion is a concers, especially with #5 stealing
fuel
> > > from #7 in the cycle of things but cam overlap management can help
here.
> > >
> > > Here is Mike's URL with dynos of some different TPI intakes..
including
> > the
> > > siamesed-base.
> > > http://www.eecis.udel.edu/~davis/z28/winter01/dyno/
> > >
> > > again.. not for everyone... just another idea for the mix.. complete
with
> > > dyno data.
> > >
> > > Oh.. the siamesed-base dyno will be re-done soon. A problem was found
with
> > > the motor setup and is now repaired.. the dyno comparisons illustrate
the
> > > mod well enough (a zero dollar mod I might note) .. but the next set
> > should
> > > show more of an appropriate comparison. stay tuned! ;-)
> > >
> > > -Dave Z
> > >
> > > 89 Iroc - '730 - 383 large tube MAP TPI, ZZ3 cam ,dry NOS 50 shot.
> > > 12.79 @106 / 12.08 @ 112.   www.delanet.com/~tgp
> > > 92 25th annev convertible  305 / T56.  268 mph in a perfect vacuum.
> > > ----- Original Message -----
> > > From: Bruce <nacelp at bright.net>
> > > To: <gmecm at diy-efi.org>
> > > Sent: Tuesday, May 29, 2001 5:15 PM
> > > Subject: Re: Siamesed Runner TPI Questions...
> > >
> > >
> > > >
> > > >
> > > > > Researching EFI updates for 71 Vette with 406/400. 218 @ .050 110
LSA
> > > flat
> > > > hyd
> > > > > cam with TFS Twisted Wedge heads and headers etc, currently a
> > > well-dialed
> > > > Q-Jet
> > > > > and Performer dual-plane (hood clearence). Power peak is at 5200
rpm
> > and
> > > > the
> > > > > torque peak is about 4000 rpm.
> > > > > So, since TPI stuff is cheap I was wondering how siamesed runners
> > would
> > > > effect
> > > > > the power curve?
> > > >
> > > > Just the oem stuff.
> > > >
> > > > > A stock or big tube TPI (with big manifold base) will kill power
over
> > > 4500
> > > > rpm
> > > > > with a 406ci, but I'd think that the siamesed runners would behave
> > more
> > > > like
> > > > > the shorter runners of the Lingenfelter/Accel Super Ram as they're
> > > > partially
> > > > > open etc. What do Ya'll think?
> > > >
> > > > Still no plenum volume.
> > > > If you happy with what you have how about, a TBI?.
> > > > Maybe a  Weiand 7527, or 7546 manifold, then up grade one of them to
TPI
> > > if
> > > > you want to progress further.
> > > >
> > > > > Would a Big Manifold Base/TB Siamesed Runner TPI set-up be able to
> > > support
> > > > a
> > > > > 406ci through 5600 rpm?
> > > >
> > > > Would be a real push to even try
> > > > Bruce
> > > > > TIA...
> > > > > Doug
> > > >
> > >
> >
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