Evilokc

im going to post this in the tbi and tpi section. i have 305 tbi car. its running fine right now but showing its age and im starting to plan an upgrade. right now im leaning towards a late 80s early 90s corvette motor. they can be had at a reasonable price and will respond decently well to a cam/head/exhaust/tune. my original plan was to keep the car as a tbi car. my tbi works fine and it would be an easier install and i wouldn't have to re wire anything. i know it would have to change the injectors ect ect. what i want to know is besides being the coolest looking injection out there is there a power advantage to swapping to tpi that i cant get from a modded tbi?

aliceempire

iTrader: (14)

I've had both in the same car with the same 350 underneath. If I were you and staying TBI I would get a vortec long block, vortec TBI manifold (you can use a carb one with an adapter plate too) pick a reasonable cam, change the computer to EBL (easy to do) and tune the car yourself (not as difficult as it sounds). In my experience that would be the easiest and least expensive way to make a ~300hp ~350tq combo. The TB itself is limiting higher power potential as it's relatively small. Even a big block TBI unit is smallish.

If you went to TPI as I have, then a donor car 90-92 f-body is the easiest. The wiring is literally bolt in and all the other odds and ends (cables, cruise control, hoses) can be pulled from the car too. I would still recommend EBL for tuning to keep things fairly easy.
Vortec heads start to raise higher costs with tpi. Vortec bases are more expensive (especially now that they're aren't in production) and the TPI manifold limits come up as fast as the TBI. Maybe even moreso. Being port injection though gives you a few good manifold options but all of them are going to start costing you more. In the end, you can go way more in power but what kind of power are you shooting for?

If you are going to vortec, keep in mind that the EGR would have to be replumbed to retain it (which I'm saying for legality reasons). The heads have no heat crossover so you need to plumb exhaust from the header to the intake.

Lastly, you need to think about axle gears, trans and torque converter. You'll get a huge bonus from those no matter what you change to even if you change the combo numerous times. Hopefully that's helpful and I didn't forget anything glaring.

Evilokc

i had planned a vortec long block so i could just move everything from my motor over to it minus intake of course. ive seen there are a few mods you can do to the tbi to get a little more power out of it. its a daily driver so im not worried about top end power. much more concerned with bottom and mid range for street. i started wondering about the tpi because i noticed the availability and cost of a running corvette motor of the same year complete top to bottom with tpi. as for rear end and converter i was thinking 2000-2200 on the converter and a 2.42 posi rear end. im not an expert of converters though so any input is always welcome.

dmccain

iTrader: (2)

I'm going to run TBI on an L98 engine i recently picked up. With a few upgrades i think 250-260 hp is not out of the question. Vortec longblock would do even better. I think TPI looks great i just wanted to keep my build simple and not looking for huge power just a nice strong cruiser. What are your goals? Get a shift kit and Use an S10 tc. Mine gave me a 2200 or so stall. 3.73s and posi makes it much more fun but 3.23-3.42s would have been a better choice.

Evilokc

I did an rpm simulator with 3.73 gears and decided that since my car sees its share of highway driving tjat 3.42s will be a better all around gearing. Hadnt heard of using an s10 converter though.

Evilokc

I did the rpm simulator as well and decided the 2.43 would be better because I drive a lot on the highway. im doing some research on stall converters and I think my 2200 stall might be a little conservative. might aim more for a 2500-2800 range. as far as my power dreams I think mid 300s will be the aim with a reality being low 300s. its a driver but I want it to be "peppy" and have the ability to throw me back in the seat.

aliceempire

iTrader: (14)

I'm guessing 2.43 was a typo and you meant 3.42. 3.42-3.45 is a good gear choice. That's the lowest gear I'd recommend. I have 3.08 on a 5 speed car and that's the highest gear I'd recommend for your theoretical combo. 2200 stall is probably fine but I'll let someone with more automatic knowledge give you advice on that. A vortec long block and a 212-218 duration cam will probably net you in the 300-325hp at the flywheel. If using a TBI unit I'd expect closer to 300. Which makes a nice easy driver that doesn't get slaughtered by any minivan with a soccer ball sticker in the back window.

dmccain

iTrader: (2)

3.42s are perfect. A 2200 stall which you can get out of a $150 S10 torque converter is also perfect for a 200-300HP engine.