I'm mostly just curious about it, but I want to know what kind of hell would I expect to make a 383 TBI work. I bought a TPI intake only, no harness, no sensors, not even any bolts. I got it in pieces. My buddy has a 383TPI and it was nice but honestly I want to be different from everyone else around here lol.

 

Hey Roadkill,

I think there may be a little confusion here...

TBI = Throttle Body Injection. It looks like a normal carbureted motor, but has a 2 barrel throttle body with one big injector above each barrel of the unit.

TPI = Tuned Port Injection. This came on certain IROCs / Z28s and has the long 'tube' style runners going from an upper plenum to the lower intake. This style has 8 fuel injectors.

The two systems aren't compatible. You either run a TBI system or A TPI system.

That having been said, here's my opinion, and I'll state it as politely as possible so as to not offend anyone.

1. The TBI guys here are very loyal to their preferred form of EFI. If you decide to go that route you will definitely have support. That's a good thing.

2. The TBI system was an economical, basic, reliable fuel injection system for the time. I've seen 300,000 mile TBI motors that still had the cross-hatch in the cylinders. If you want to build a mild 305 / 350, it's not a bad choice. You get EFI and don't have to spend much money.

3. If you want to make the most horsepower possible - any 2 barrel system will be a significant restriction - regardless of whether it's the stock throttle body, the Holley unit, or the 454 TBI that came on the Chevy trucks. As proof - go take a look at what Holley rates their TBI bolt-on systems to. You'll find something like this...
- 4 barrel system: ~600 HP
- 2 barrel system: ~300 HP
There's no getting around that limitation. Many may disagree with me, which is fine, but a 2 barrel system is NOT the way to make horsepower. Nobody runs 2 bbl carbs do they? (I'll note that I did experiment with TBI on a mild 350 and the effort vs. reward wasn't worth it).

4. A TPI system is capable of supporting much more hosepower / flow, but requires modifications as well - such as the addition of a larger intake and runners and injectors. These modifications aren't cheap.

4. All of the above statements are made 'worse' by your desire to build a 383. If a TBI system can make peak power at 5,000 RPM on a 350, it will peak even lower on a 383, again, because you're choking the motor. Ask yourself this: would I spend all the money on an awesome stroker, then stick a cork on top of it and sacrifice horsepower?

If you want to be different, maybe you don't mind the sacrifice. But I think you'd rather go fast

 

Here's what I would encourage you to do before you spend another dime...

1. Write a list of your goals with this car. Street? Strip? Show? Horsepower? Total Investment? Etc. Once you put together a plan of what you want the car to do for you, then it will be easier to make subsequent decisions. Going online and saying "what motor should I build" is much easier if you know what you want the motor to do and how much you want to spend.

2. Seriously consider starting with the basics. Regardless of whether your car is TBI or TPI right now, you can throw on a carb and an HEI distributor and learn the basics of tuning. I didn't buy into this reasoning until I spent a couple summers tuning carbs and setting timing. Once you understand the fundamentals of tuning a motor and you know what it wants, you can think about experimenting with fuel injection. A carb, distributor, and wideband-02 sensor are cheap compared to what you could spend on TPI or TBI.

3. Don't cut and hack up your wiring. EVER. If you can leave the connectors in place, do so. It's always easier to go backwards if you need to.

4. Read. Read. Read. Buy a copy of "Power Secrets" by Smokey Yunick and read it like the Bible. Building your own motor can be VERY rewarding.

If you have more questions, you're welcome to PM me. I'll always do my best to reply and be helpful. I don't know everything, but I've built my share of motors.