Turbocharging a TBI 350

[Mule89]

Hi everyone Im sill sorta new to the site. I am currently collecting parts and things I need to turbocharge my 1989 GMC C1500 with a stock TBI 350. The engine will be stock and only 5psi for now and im more interested in mpgs and light towing. I have already decided on the ebay gt45 kit and would be using EBL flash for the computer. Has anyone done this before? What do I need to do the trottle body for bost? What fuel pressure regulator do I need? Is there something that I might not know about? I really like turbos so im set on that and I kind like having something different. P.S. LS swap is not an option

 

[Lifted92]

Adding boost from either a supercharger or a turbo doesn't work very well with the TBI motors, all the guys I know that have used power adders took them back off within a year because the driveability suffered so much.

 

[TylerZ281500]

youd have to make it blowthrough and seal the throttle shafts etc. it works, vafpr necesary, different map, tuning of course. your now adding to components that are very picky on cam selection, tbi is super picky and to turbo something properly your looking at overlaps of 112 or better. the fantastic part of this is the k1102/3 works well in both applictions. id get rid of the heads on it though, and run towards a single plane

 

[retorq]

There is a reason no one is turbo charging stock TBI setups. You list you have 211K on your engine, surely you are not turbo charging that engine?

 

[Mule89]

The stock engine would be turbocharged for now and once that engine throws a rod, spins a bearing, burns a piston, or some other tragic reason to be pulled from the truck it will be replaced by a vortec 5.7 1996-00. Yeah the heads are junk and not many people turbo TBI's but that's why I'm asking. I know that it has to be blowthrough but what do I need to do to the throttle body specifically for blowthrough? Plus I don't want to dump $8000 dollars in a FI system a turbo and all the other little bells a whistles. I have seen a couple of turbo TBI third gens running around here but I think they have some kinda secondary injectors and a piggyback computer to control them but that is not the route I want to go but I know it is possible to turbocharge TBI. Im more interested in torque not horsepower so something like the LT1 or LT4 cams would be the good for what I want later on in the vortec but lets focus on the TBI test mule in the truck now. P.s. this is the Third engine and it has maybe 142xxx.

 

[superdave]

Why is an LS swap not an option? It's a better foundation for a turbo if that's your ultimate goal. Going the route you are suggesting sounds more expensive and more trouble than going LS.

As for daring to be different, remember that there are usually reasons that lots of people end up doing the same thing. There is a reason that a great many street rods of different makes are running small block Chevys. Yes, dare to be different and run a flathead Ford, and you'll have twice the money and half the horsepower. The LS swap versus the turbo tbi may be the same as the SBC versus the flathead.

 

[90halfton]

Third engine at 142k? What are you doing to that thing lol.

 

[TylerZ281500]

google blowthrough carb, use the same concept on your tbi. thats how i figured it all out. there was no one to give me directuon when i turboed a customers truck. i figured it out though. id suggest researching blowthrough, and then look into supercharging tbi as thats more common and can be useful background info as far as what map, fp, etc. . yes theres piggy back systems, theres utilization of tpi 9th injectors etc etc. not entirely needed. id be steppign up to a 454 throttle body though, boost reerence fuel pressure is your friend. ill tell you lt1 cams would be a poor choice, k1102/k1103 are decent for turbo applications. ditch the heads, straight up get rid of them, dont even try to utilize them. even if something is a test mule your setting it up for failure. but yea third engine at 142k? how the hell? vortec bottom ends arent that much superior all in all. the heads just flow better but tbi castings are better. your trade offs are minimal

 

[Mule89]

Third engine at 142k? What are you doing to that thing lol.

Well lets just say thats what happens when junk oil cooling lines and faulty oil pressure sensor does thats fixed now so is every other sensor is new or been checked out

 

[Mule89]

google blowthrough carb, use the same concept on your tbi. thats how i figured it all out. there was no one to give me directuon when i turboed a customers truck. i figured it out though. id suggest researching blowthrough, and then look into supercharging tbi as thats more common and can be useful background info as far as what map, fp, etc. . yes theres piggy back systems, theres utilization of tpi 9th injectors etc etc. not entirely needed. id be steppign up to a 454 throttle body though, boost reerence fuel pressure is your friend. ill tell you lt1 cams would be a poor choice, k1102/k1103 are decent for turbo applications. ditch the heads, straight up get rid of them, dont even try to utilize them. even if something is a test mule your setting it up for failure. but yea third engine at 142k? how the hell? vortec bottom ends arent that much superior all in all. the heads just flow better but tbi castings are better. your trade offs are minimal

Thank you for the info on the vortec I have a good tbi block laying around that has 4 bolt main and provision for a roller cam. I have been reading alot on all this and trying to see which cam would work well with the turbo. Can you please tell me more about this truck you turbo charged for a customer? Again thank you for the imput and info.