TBI on blown small-block?

[Walter Sherwin]

> >
> >
> > If Whipple listened to his engineers, he may have gotten to
> > have a decent
> > product.   It seems that they never did get the cals right or
> > they would
> > have sold alot of the kits.   In other words they didn't get the fuel
> > management right.
>
> And that's what worries me about this potential project;)  Thanks for the
> info, Bruce.  I've never seen a Whipple TBI install up close (heck, I
think
> I was barely out of junior high when they came out), so I don't have a
clue
> about their method of sensing MAP and providing PE.  It seems like a neat
> way of doing a pressurized TBI system, but I'm scared that there's a big
> unknown lurking out there.
>
> Anyone out there have knowledge of these systems?  I'd be happy to learn
the
> *wrong* way of doing this, just to know what not to do.
>
> Eric Bryant
> mailto:bryante at ghsp.com
> http://www.bryantperformance.com
>




Hey Eric.  The Whipple suck-thru 1bar TBI setups work VERY well, and IMO
they have excellent products, especially when comparing them to the rest of
the playing field.  They offer a vast array of kits, and their reputations
and sales volumes speak for themselves (......no I'm not affiliated with
Whipple).  Talk to them, and take a close look at the workings of their
external TBI fuel control setups.  They're pretty good.

Their external setups accomplish what is needed, and the cylinder
distribution/mixture winds up where it needs to be so long as you understand
HOW the system works and HOW to address complimentary engine mods.  I've run
many miles with their screws in suck thru form with both their external fuel
setups (without PCM program mods), and with my own custom 2 or 3 bar Delco
MAP sensor arrangements downstream of the screws (with corresponding PCM
program mods).  The later were together with obligatory TBI fuel hardware
mods.   Both work well.  Just depends upon your level of comfort and desire
to experiment and desire to house all of your boosted fuel and spark control
in one "box".

TBI fueling, whether boosted or unboosted (up or downstream - centrifugal or
roots or screw or turbo), tends to be less sexy sounding than MPI, so many
have discounted it without understanding it.  But, almost anything is
possible if you go down the TBI road.  Just make sure to stay away from the
Holley TBI units, because they have almost zero injector pressure tolerance,
and you'll quickly find that you can't get enough pressure and/or delivery
to feed anything with a significant appetite.  Been there, done that.

Think of all the ways to use Rochester TBI's together with boost...... Suck
through 1 or two of them, or,  Blow through 1 or 2 of them.  A GM ECM/PCM,
plus an external injector P&H driver box that offers one 4/1 amp driver per
TBI injector, and away you go calibrating to your heart's content.  Two
modified BBC TBI's atop a roots/screw can easily feed 1000+ HP, with gas, if
done right.  Two BBC TBI's below a centrifugal can feed just slightly less
due to the hydraulic injector pressure limits.  Of course you need other TBI
specific fuel system hardware & modifications to support such endeavours.  A
lot of this has been discussed in the bowels of the DIY/GMECM archives in
the past, so you can look there for ideas.

Here's a thought starter that gets to the heart of the TBI fuel strategy
"thinking"  http://www.aces.edu/~gparmer/efi/tbi_adjust.htm  .  Remember,
whether using external FMU's, or 2-3 bar MAP's, or even if simply NA with
huge displacement, you must first address the underlying mechanical TBI
flow/pressure delivery considerations.  Stay below 70psig injector pressure
with 4/1 amp drivers with most TBI injectors, and bench check your exact
injectors at your intended pressures before use, just to make sure.  Looking
for an all round/robust TBI injector?  I really like 17084304 (engraved)
17112560 (service) @ 75 #/Hr gas each nominal @ a fuzz over 10psig.  Offers
up over 200 #/Hr gas each @ 70 psig, with a 4/1 amp driver.  Is readily
available from your GM dealership, or your local junkyard.  Hard anodize (or
coat)  your TBI castings, and use the same injector, and you can use
meth/eth anol if so inclined.......


Walt.

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