Tbi 350 to Vortec 350

[Blanco_obs]

The tbi motor I built left the dyno making 300hp/385ft-lbs. using the stock GM intake manifold, slightly modified tbi unit, and stock ECM.

There’s still some power that was left on the table I’m sure with some tuning could squeeze every bit out of it but that wasn’t the goal, a good bump in power and driveability was what we were after.

TBI’s have their limits but those limits are well beyond what the engines came with. Just have to combine the right combination of parts.


But if you just want to “sound cool” put a huge cam in, plop on a carburetor, and idle around rumpety rump. Don’t forget to hack off the exhaust somewhere before the cat and straight pipe it.

What all did you do to your motor


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[Gramps]

What all did you do to your motor


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Short version
TBI roller cam block .040 over stock type pistons.
Comp roller ecm friendly cam have to look up the number I don’t remember off hand
Stock vortec lifters, lifter retainer
Comp roller rockers(self aligning) (not needed but was nice)
Hybrid ENgine Quest heads - order them bare and put your own springs/valves in them.
Stock tbi unit with some of the “ultimate mods” done to it. 454 injectors, pod lifted and fuel pressure regulator tweaked to 14psi
17* initial timing.

 

[Craig Lange]

It’s barely driven I drive 3 minutes to work and home. Other then that we drive our family car. Lol.


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Maybe you should question why do the modifications if it’s only driven 3 minutes to/from work. I just finished a similar modification on my 91’. It’s a lot of work and money for a vehicle driven so few miles.

 

[Kris901]

Same engine would run better with a big block TBI and some PCM tuning.

well most of everything was free too me, and the TBI I pulled out was trash. Also truck barely gets driven so wasn’t super concerned on mileage or cold starts etc. also it was a slow build, I’ve got maybe 1200$ in complete swap and all materials caught a lot of good deals and makes decent power nothing on the engine went untouched. It’s nothing wild it’s a 4wd truck that hauls/pulls and maybe taken hunting sometimes.

 

[Sreinke]

Efi will not work with a cam that is lopey. I have built a few tbi engines for my trucks and a jeep. Vortec heads..with vortec carb manifold...tbi rebuild and mods and a 14psi spring. Comp cams 12-388-4 cam....420/.440 lift. Works good...if you use vortec heads you will need a tune as the vortecs flow much better. The air enrichment needs to be increased by 50% in the tune. Tunes are cheap 250$ and easy to install the newly tunes chip. Upgrade the fuel pump to an ep241 if you are going to stay tbi ep381 if you think you may ls swap the truck. I run the ep381 it has been a very reliable pump for the last 3 years in my work truck.

 

[L31MaxExpress]

Efi will not work with a cam that is lopey. I have built a few tbi engines for my trucks and a jeep. Vortec heads..with vortec carb manifold...tbi rebuild and mods and a 14psi spring. Comp cams 12-388-4 cam....420/.440 lift. Works good...if you use vortec heads you will need a tune as the vortecs flow much better. The air enrichment needs to be increased by 50% in the tune. Tunes are cheap 250$ and easy to install the newly tunes chip. Upgrade the fuel pump to an ep241 if you are going to stay tbi ep381 if you think you may ls swap the truck. I run the ep381 it has been a very reliable pump for the last 3 years in my work truck.

I have run 232/244 on a 108 LSA with a 93-95 Automatic TBI computer. EFI runs just fine with a lopey cam. Just have to tune it.

 

[b454rat]

My 406 ran with an extreme energy 268. It had a pretty choppy idle. Put 10-15k on it before sold it. Ran beyond awesome

 

[Darrin Weiss]

What all did you do to your motor


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Motor is still in the truck, what it is, is I'm concidering a motor with 300+ hp off E-Bay actually but I'm getting confused about the true hp capabilities of the TPI. Was wondering if I would be better off with a Vortec carberated replacement

 

[Blanco_obs]

Maybe you should question why do the modifications if it’s only driven 3 minutes to/from work. I just finished a similar modification on my 91’. It’s a lot of work and money for a vehicle driven so few miles.

Because I’m laid off and have nothing better to do lmfao.


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[Blanco_obs]

Because I’m laid off and have nothing better to do lmfao.


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Also due to my job temporary closing. And also I love the truck tbh it’s my baby.


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