[Diy_efi] TBI or TPI?

[Rick McLeod]

The late John Lingenfelter was one of the most highly
respected SBC authorities, he wrote a book detailing
modifying the SBC in many fashions, TBI, TPI, RAM-Jet,
LT/S versions, etc, including bolstering oil systems,
fuel, etc. I recommend getting a copy or borrowing one
from the library if doing any SBC work, it saved me
many headaches building both my TPI's.

BTW, TPI is Tuned Port Injection, a form of multi-port
injection using a long runner design that was
originally optimized to the 305, but adapted to the
350 with good sucess. It falls apart at high RPM, mine
virtually quits at about 4500, but at 1000 rpm it will
put a moderate hill without downshifting, and cruises
at 75 to 80 at 30MPG at about 2400 RPM. This is torque
at it's finest!

To make your choice, it depends on your needs, are you
going to drive it much, if not don't spend the
time/money on TPI, but you'll really like what it
brings if you go that route.

BTW, I run a 700 trans w/ a 2400 stall converter,
really comes off the line hard and strong since it is
well on top of the torque curve at launch, but w/ the
lockup converter it doesn't impact MPG (read claim
above).

Hope this helps. 

--- Ashley Evans <hoshy at hoshy.co.uk> wrote:

> 
> Thanks, I even fully understood your description.
> 
> So what is TPI?  is that direct injection?
> 
> The discussion on low end torque being better on
> TPI, is that related to
> the manifold length?
> 
> Does anybody have links to the equations and theory
> etc related to
> manifold design, volume, length etc.  And info on
> the resonance flap
> used by some manufacturers?
> 
> I'm sorry to hijack the thread with so many
> questions :-/  Feel free to
> ignore me.
> 
> Regards,
> Ashley Evans
> 
> On 14/9/2005, "Rick McLeod" <dunvegan at sbcglobal.net>
> wrote:
> 
> >you're correct, TBI is Throttle Body Injection,
> which
> >usually is the use of a carburetor body w/
> injectors
> >to replace the atomization function under computer
> >control (other primitive means are used also).
> >Therefore, most all intake manifolds are relatively
> >easy to conver to TBI, and I believe companies such
> as
> >Holly and Edelbrock and others make simple kits for
> >this.
> >
> >--- Ashley Evans <hoshy at hoshy.co.uk> wrote:
> >
> >>
> >> Sorry for the n00b.  question.  I mostly lurk
> here
> >> to read and learn.
> >>
> >> TBI and TPI mean what??
> >>
> >> I thought that TBI means Throttle Body Injection,
> or
> >> am I sorly mistaken?
> >>
> >> Regards,
> >> Ashley Evans
> >>
> >> On 14/9/2005, "Rick McLeod"
> <dunvegan at sbcglobal.net>
> >> wrote:
> >>
> >> >Clearly TBI would be an easy swap, replace the
> >> carby
> >> >w/ a TBI unit, add some computer, wiring, and a
> few
> >> >sensors and you're off and running.
> >> >
> >> >TPI is a much nicer solution, hence why GM went
> to
> >> it.
> >> >It's long runner design lends to very good low
> end
> >> >torque, but in stock form has limited top end
> RPM
> >> and
> >> >HP drops off toward the top end. That shouldn't
> be
> >> a
> >> >factor in your application, actually TPI would
> be a
> >> >great way to go. It is frequently dubbed a
> >> tow-truck
> >> >motor. There are a couple ways to even leverage
> it
> >> >more but in stock form would be great. There are
> a
> >> >couple aftermarket companies that have nice TPI
> >> >packages, but with a little work salvage yard or
> >> ebay
> >> >should yield all the necessary parts and leave
> you
> >> w/
> >> >just wiring. The main issue is fuel lines, as
> >> you'll
> >> >need a return line and a high pressure pump
> which
> >> are
> >> >not requisite of a TBI, and I would suggest from
> >> >experience to go w/ a Painless wiring harness
> >> rather
> >> >than fighting w/ a factory loom and making it
> work.
> >> >You'll appreciate having spent the extra in
> >> >elimination of frustrations and it being plug'n
> >> play.
> >> >
> >> >Good luck
> >> >
> >> >
> >> >
> >> >--- Mike <sonoma at shaw.ca> wrote:
> >> >
> >> >> I was thinking of adding TBI or TPI fuel
> >> injection
> >> >> to my  83 Chev 350 (M) which is in a 11000 lb
> GVW
> >> 1
> >> >> ton chassis.
> >> >>
> >> >> Has anyone setup both types of fuel injection
> are
> >> >> the costs for TPI a lot greater.
> >> >>
> >> >> What are the advantages and disadvantages of
> TBI
> >> and
> >> >> TPI
> >> >>
> >> >> I'm considering  going with FI because I'm
> hoping
> >> to
> >> >> get better fuel economy, better drivability,
> more
> >> >> torque and horsepower if possible.
> >> >>
> >> >> I don't want to change the heads on the engine
> >> just
> >> >> the intake.
> >> >>
> >> >>
> >> >> Any ideas or suggestions would be appreciated
> >> >>
> >> >> Thanks...>
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> >> >
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