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TBI or TPI?

big94gmc

big94gmc

1/2 ton status
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For mostly crawling and slow style 'wheeling (very RARELY any muddin', street, or high wheel spin required), which is better, and WHY?


Tuned Port Injection, or Throttle Body Injection?

Which is better for low end torque, not high rpm. To let you know what I'm working with, here is the truck:

Crate 350, Edelbrock carbed right now
465
203/205 triple sticked
4.56's.

This truck crawls, doesn't do much high speed stuff - no 3500rpm clutch dumps if I can avoid 'em :D .
 
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tuned port

I prefer tuned port. It is more efficient and you will also gain a little performance in most cases. AND IT JUST PLAIN LOOKS COOOOOOLER :rolleyes:
 
I read someplace that for low end torque on a mild-mid HP motor you need to add short runners to a TPI to match a TBI. On the otherhand TPI made more power midrange and top end in every test I saw.

But that was somthing like 3 years ago and I might be confused. :confused:
 
I would just go with TBI
They build great torque.
Cheaper and easier to find
Simpler to install. You can even use your stock manifold with an adapter.
You may need to get a computer friendly cam. The crate engine cam may not work right for TBI. Prolly should get an adjustable fuel pressure regulator also.
 
I have both TPI and TBI available. Cost isn't an issue, other then 'what it'll take to get working'. I know I need to reprogram the prom, and match it to a (possible modification) RV cam.

I just want to make sure I know what to expect at the end of these possible swaps.
 
tpi

Tbi is deffinately easier to install. The performance gains just isn't as good as with a TPI system. Also if future performance mods are in store you can get all kinds of upgrades for the TPI that you can't get for the TBI. Both good working systems but I guess I'm just partial to the TPI.
 
Power output at lower ranges should be better with TPI, simply because fuel staying in suspension with slow moving air charges doesn't matter, since the runners are "dry".

TPI was designed towards getting a fairly heavy vehicle moving fast. In other words, low end torque. Especially with quite a bit of disregard for upper end power.

Not using throttle, I'd assume a TBI and TPI motor would act the same on an incline, since both would just adapt to the increasing load. Actually trying to accelerate in that situation, TPI should beat the TBI hands down.
 
For what your describing you'll never notice the difference. If you have the TPI use it. The RV cam will not be a problem with either. What ECM do you have? The 1227730 is a speed/density and is easier to get a chip for, this is what we use with TPI and MPFI systems. If the TPI is a MAF system it can be changed out to not need the MAF sensor.
 
TPI is good for low end. Long runners are better for low end. I am puting a LT1 intake manifold on my TPI setup for better higher RPM power. Just need money to finish the setup.
 
For crawling and slow stuff I would run TBI. It is less complicated and more user freindly. I have TPI on my truck and it is awesome. But for a pure low speed low HP requirement then TBI is the better choice in my opinion.

Harley
 
How about this > TPI was originally intended for the 305 cuz Chevy designers at the time didn't think they needed a 350 anymore. So, seeing as TPI gives up the ghost at a mere 4800rpm, i see no reason why someone can't build a stump puller Tune port. John Lingenfelter made almost 500lbs of torque from one almost 7yrs ago. I've been trying to figure out how for just as long. :D
 
Hopefully I get the S10 ready and TPI on the 383 by September. School has a chassis dyno :D :wink1:
 
Actually, the tpi may be a bit small unless u get the SuperRam top and ported TPI Runners. But good luck anywho!! and btw, my buddy mikes blue s10 ran 12 second quarters with his tpi. granted hes got a corvette tpi though.
 
TPI on a Corvette is no different to my knowledge.

And as for the SuperRam, overpriced nothing I'd say.

www.lt1intake.com **doh, presently under reconstruction**

Ported heads, LT4 Hot Cam, and a LT1 intake, not getting my hopes up but I can't help it at times.

HOpefully won't lose a bunch of torque to the intake, if I do I'll swap for a stock TPI intake, can't give up a bunch of torque for a few HP.
 
Corvette = Higher Compression and better cams. though i must agree, the superram is a little overpriced.
 
TPI has great low end torque. My stockish motor with stock TPI has PLENTY of lowend torque. I am not saying it doesn't. But for the question that was asked TBI is probably the better setup. TPI is more expensive to get into and setup. TPI is also a little more complicated then TBI. Also lots of trails are in more rural places and parts stores are much more likely to have the parts to fix a TBI setup as compared to TPI.

I love my TPI but it is not for everyone's budget and needs.

Harley
 
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