Did a couple of quick searches and scanned through the forum, didn't find anything conclusive... forgive me if this info is already available

I am replacing my busted 350 with a 305 tpi...

I know it's a little odd to switch TO a 305, but nevertheless...

have the proper harness, computer, etc...

is there anything I should know about switching to tpi? does the fuel pressure need to be kicked up? anything?

 

i would use the TBI intake and components for the new engine. TBI is much easier to play with and just as effecient. less mess. you wouldnt have to alter fuel psi, computer, anything. JMO.

 

I've been involved with a couple swaps and they are pretty much plug and play ran into a few minor issues,

easiest is to use the complete ecm harness and chassis harness off the TPI engine/engine bay

you need to change the fuel pump as well,

you'll be very impressed with the power increase even though you are going to a smaller motor

 

TBI is no where near as effecient as TPI, I call TBI a glorified carb with with poor performance, 350 TBI to 305 TPI would be an upgrade IMO

if the TPI is a MAF setup its far better for minor bolt on mods and small cams upgrades,
I've seen guys stab a cam in a MAP setup like TBI uses and the cars never run right again, they end up giving up or going back to a stock cam,
some of the smarter ones call me and I set them up with a custom chip

 

The TBI cars (I've had many) only had 170HP because of the setup. I think it is just an electric carb. I bet adding TPI to a TBI car would add 25HP. Were the TBI 305's the same exact engine as the TPI just without the TPI?

 

yeah, the fuel flow and pressure were what I was wondering about... thanks for the info...

as far as tbi goes, the old motor was no slouch, had a mild cam and some short tube headers... but the money to repair it would have been better spent on a lt1/ls1 swap... and then I came across this tune port 305 with comp, harness and trans for 500 bucks...

thanks again

 

I've worked on many TBI and TPI cars and trucks. the TBI is very friendly to work on and does haul ***. I remember this TBI 350 in a heavy silverado smoked the tires like butter. with no aftermarket cam. outran plenty of stock TPI camaros/firebirds. the TBI 305's and 350's from the chevy trucks use vortec heads and put down some serious torque. TPI is a pain to work on and is not all that rewarding. BTW, they do make chips for TBI also. but factor in that this guy is going with a 305. so he probably aint looking for a race, so if it is effeciency and low maintence, TBI hands down. TBI=easiest fuel injection system in the world.

 

No, the TBI trucks use swirl-port heads that were called vortech heads back then. The true late model vortech heads are the 1996-1999 truck heads with raised intake ports and 8 intake manifold bolts, instead of the common 12 intake bolts. The swirl port heads are not bad for a stock engine, but they are horrible for performance engines.
I consider the thousands of TPI engines in the 12's and faster much more rewarding than the handful of TBI engines in the 12's, but I guess my yardstick is different.
The best thing about the TPI setup is the computer is MUCH easier to tune and modify. The f-body and caprice 8746 computer has very little you can modify, its only 4 kilobytes of data compared to the 16k and 32k for TPI. It wasnt until GM went to the 32k and 64k TBI chips in the 93-95 trucks that TBI became much easier to work with.
Bottom line, if you want to switch, go for it. Just keep in mind its not something you can do in a day and its not something for a new mechanic to tackle. There is a basic tech article on thirdgen.org and many posts on thirdgen.org's forums as well that discuss the swap.
As far as the power gain, on my dad's 92 RS 305, he went from 158 HP and 220 TQ at the wheels with 28 MPG, to 177 HP and 290 TQ at the wheels with 30 MPG.

 

you ever driven a TPI car?

TPI is a far better truck motor then a car motor,

its a torque monster of a motor, peak hp is under 5500prm and torque is way down low on the power band

from my experience and my personal opinion, if I were to do FI, I would only go with a MPFI setup,
TBI might as well go to carb

my bro's very mild cam 350 TPI should make 350hp and 450ft.pd, but I just fired it today, still got to burn a chip for it then I'll get it on the dyno