tbi vs tpi which is better???????

[HELLBENT DESIGNS]

couple questions. lots of talk on here about tbi vs carb, not so much about tuned port injection? i know tbi is basicly a carb with injectors on it. not sure why the trucks never used a tpi setup even though both tbi and tpi were being produced at the same time? i would guess cost. given the same cost for the systems what would be a better choice for a 90% trail only rig, thanks

 

[mouse]

I will give you my opinion for the TBI vs TPI debate...I chose the TBI because chevy used it in our trucks and many replacement parts are available to help me swap it into my '77 blazer (i.e. gas tank with baffles). TBI supposedly makes power at lower rpms (like the rpm range I use most of the time wheeling), the TBI is cheaper and easier to install. Plus, I am staying close to stock with the engine, .040 over keith black pistons (slight bump on compression), slightly bigger cam, heavier valve springs are about it - so there shouldn't be any issues with the system handling it. If I wanted radical....then maybe TPI.

With that said, the TPI is a great setup, but will take a little more $$ and effort to get on my truck. I hate downtime, and the TPI didn't offer enough for me to go that route and spend the extra time. It does manage the engine a little better (each cylinder vs two injectors) and can handle higher horsepower levels.

You'll have to decide for yourself....so many options. Its almost like detroit vs ARB.....which one to buy?

 

[echos]

depends on amount of hp, which isnt as big a concern for rock crawling as torque. if i remember right the tbi is up too 220 hp (i think) tpi im not even gonna guess but it is better. I personnally would like to know what is good for 450 too 650 hp but not trying to hijack. expense and repair is also cheaper and easier via tbi by the way.

 

[Ryan B.]

tpi rocks. I swapped my engine over from carb to tpi in one weekend..
The difference was totally noticeable and worth the grand i spent on it.
If you search TPI there is a bunch of info on this site.. I did a write up in the advanced previews forum on my tpi swap and i collected all my part numbers in that post as well.
If you guys need any info or help later on with tpi swapping you can pm me.

 

[HELLBENT DESIGNS]

hp or torque are not the main issues, throttle response as well as off camber performance are. i doubt engine will ever see 5000 rpms.

 

[HarryH3]

Throttle response is instant with TPI. Mine's a TPI 383 and is a total blast to drive!

However, working on it sucks. Any work on top of the engine requires lots of patience and $20 worth of plenum gaskets. Those tubes are in the way of everything. Just swapping a single injector is a 2 hour job.

 

[HELLBENT DESIGNS]

tpi rocks. I swapped my engine over from carb to tpi in one weekend..
The difference was totally noticeable and worth the grand i spent on it.
If you search TPI there is a bunch of info on this site.. I did a write up in the advanced previews forum on my tpi swap and i collected all my part numbers in that post as well.
If you guys need any info or help later on with tpi swapping you can pm me.

ryan i read your write on the tpi lots of info thanks i am gonna get my my feet wet with tpi like it or not. i purchased a 88tpi injected corvette 350 for the wife's jaguar project. since i also bought a 88 tpi setup pulled off a transam gta. it is complete with wiring etc. in your write up you spoke about speed denisty vs maf, i thought about staying with the maf with the jag but considering a conversion to speed density on the trail rig for reasons you stated in the writeup. also i will be using a th350 tranny which doesn't sound like a plug and play type deal

 

[Russell]

TH350 will not be a problem, on one assumption, and that is that the kickdown cable will be long enough, and fit into the TV cable slot on the TPI's cable bracket.

I've got a TPI setup for my truck too. However, I'm on hold with it till spring. I just want to drive the truck now, and I'm sick of hunting for a `730 ECM with a chip included. Put the carb on this afternoon.

 

[beastofablaze]

Tbi is good up to 400 hp with computer tuning... and about 275 with the right fuel pressure running the stock tbi. Using a bigger tbi, and computer tuning you could probably squeeze 400 hp out of tbi but it is very rare. Only a couple guys on thirdgen(that i have heard of) are running tbi with those numbers. From what I hear tpi is good to over 425... just to clarify.

Throttle response (I would guess) is better on tpi becuase there are no injectors in the way of air flow but your also stuck with one manifold choice.

I went with the holley projection tbi and manifold and a prominator... throttle response is REAL good but it probably has to do with the fact that i'm running 10:1.

 

[MTMike]

I've got the Holley ProJection TBI system on my truck. Tuning that thing is a beyotch but other than that I'm very happy with it. When it's tuned right, throttle response is instant and with the ~10:1CR 383 Stroker it's got plenty of power & torque to move me through top-of-the-axle-deep snow at 2500rpms.

Off camber stuff is a non-issue also.... At Divide Ride there was 1 trail where the carb guys where stalling out on it because it was a steep descent, but I just kept right on idling down. Also, on side-hill stuff that my old carbed '79 was starving for fuel on, it just buzzes right along.

If you would actually call me when you come to or through Billings you could check it out

TPI should be a great setup as well, but I don't like being limited on my intake manifold selection. Good luck and keep us posted

Mike

 

[HELLBENT DESIGNS]

I've got the Holley ProJection TBI system on my truck. Tuning that thing is a beyotch but other than that I'm very happy with it. When it's tuned right, throttle response is instant and with the ~10:1CR 383 Stroker it's got plenty of power & torque to move me through top-of-the-axle-deep snow at 2500rpms.

Off camber stuff is a non-issue also.... At Divide Ride there was 1 trail where the carb guys where stalling out on it because it was a steep descent, but I just kept right on idling down. Also, on side-hill stuff that my old carbed '79 was starving for fuel on, it just buzzes right along.

If you would actually call me when you come to or through Billings you could check it out

TPI should be a great setup as well, but I don't like being limited on my intake manifold selection. Good luck and keep us posted

Mike

sounds like the holley stuff has a few tuning issues compared to thr factory stuff can't wait to see the truck mike, gonna have to pickup the extra jag motor at some point. will be nice to see a truck that runs and drives instead of one i have to push in and out of the garage

 

[MTMike]

sounds like the holley stuff has a few tuning issues compared to thr factory stuff can't wait to see the truck mike, gonna have to pickup the extra jag motor at some point. will be nice to see a truck that runs and drives instead of one i have to push in and out of the garage

I just bought a cable for my laptop that I can plug into the Holley unit and monitor things with WinALDL to help with tuning - my problem now is finding the time to do it

 

[beastofablaze]

What did you find so hard to tune with the holley unit? Mine works great... just need to monitor the fuel pressure which is a little bit of a PITA but its nothing to be concerned about.