TPI Vs TBI

[aitch]

I've been wanting to get away from the 4 bbl and into a tbi or tpi set-up.
I've read a bit on the tpi but know little about the tbi.
What are the advantages and disadvantages of these two systems.
I've read that the tbi systems are easier to work on.
Thanks for sharing your experience.

[krue]

TBI from what I have gathered here is more of a computer controlled carb than a true injection like TPI. TBI has less electronics=> easier to work on and tune. TPI is more complicated, but is more efficient. That's all I know. I'm sure we will all get a lesson from the experts.

[aitch]

Thanks for the concise explanation. I'll await further information.

[Russell]

Krue basically hit the nail on the head.

Both are very reliable injection systems, but a TPI will be slighter better on gas, and make more power than a TBI.

TBI is far simpler to work on though, having a lot less electronics, and wiring to worry about.

TBI is also far more common to find, whereas TPI is a bit more exotic, and costs a fair bit more to install.

Really, both systems work well, and get great milage while making great torque, it really depends on if you want to go a bit more exotic, or just stay fairly mild. TPI won't out-perform TBI by much on a 350, due to the long slender runners, which make massive torque, but not nearly as much high end power as most carburated guys make. Expect to be hitting the red-line at 4800 - 5000 rpm depending on your elevation, porting work etc with a TPI. It just won't draw in enough air. TBI suffers from a small two barrel throttle body as well, so it doesn't perform much past 4800 - 500 either. Only real performance gains with a TPI is found in the massive low end torque it makes as compared to a TBI.

[neonlarry]

You can get more power and RPM on a TPI system by using aftermarket runners and manifold or a LT1 manifold. Both of the above setups will get you to around 7K with the right engine.

[Russell]

While this is true, you definitely loose a lot of low end torque doing either of those upgrades

My engine is built to make power while the TPI is able to breath. If you've got an engine built to rev higher, then you'll benefit from an LT1 intake, or some other intake

[dirtboy488]

I put a mild lt-1 in my truck (ie cam, rockers, forged bottom end, ect.) it is a little more stout than the lt4 and I get between 14-18mpg depending on how I drive. The swap was pretty easy also yes it does have a little less bottom end than the old 355 but after about 2500rpm it pulls alot harder all the way to about 6000rpm.

[aitch]

Originally Posted by dirtboy488

I put a mild lt-1 in my truck (ie cam, rockers, forged bottom end, ect.) it is a little more stout than the lt4 and I get between 14-18mpg depending on how I drive. The swap was pretty easy also yes it does have a little less bottom end than the old 355 but after about 2500rpm it pulls alot harder all the way to about 6000rpm.

dirtboy, did you install a throttle body or tuned port?

[Russell]

I think dirtboy may be talking about the old LT-1 small block chevy. It isn't the same as the new LT1, and usually they are carburated

Then again, I may be blowin' smoke rings, haveing no clue what actually is under the hood of his truck, lol

[dirtboy488]

It is originally a 1995 lt1 out of a z-28 it is still tuned port injected, I sent the factory harness to lt1wiring.com so that there was only about 8 wires to hook upto the truck. I cannot say how well it will pull stock but my buddy has on in his 88' pickup and he said it pulls harder than the old TB. His 1/4 mile times went from a 16.8et @83 to a 15.3 @ 90. all he has is exhaust and an intake. My 1/4 mile time as it sit now is a 13.87@ 99 and with the 100 shot it is at 12.96 @ 108.