turbo kit for my 91 tbi 350?

[superninja427]

In all honesty, I drive my truck everyday to work and back. I love pulling up next to a fox body mustang and playin.. I realized that I might want to twin turbo my truck. One reason being, have you ever seen an everyday driver 91 Chevy with twin turbos and a redneck behind the wheel? I personally think it would be cool...so how do I do this? I want to know what it takes to put twin turbos on my tbi 350 and it run at least a little safe. I prolly won't be running much psi. Anyone know?

 

[superninja427]

Maybe not twins, maybe just one turbo...but I'm definitely interested in turboing my truck.

 

[Tempted]

Doesn't matter how many turbos you add, the heads just aren't any good for flow. 5psi is about all you would safely be able to go. It really wouldn't matter that much if the motor held 10psi, the heads can't flow it. PSI is also a horrible way to express turbo boost. High psi does not mean high volume. An example is blowing through a coffee straw and a water hose. You get higher psi out of the coffee stray but way more actual air(volume) from the water hose.

That said, the turbos are easy to plumb. Grab some Ebay headers with a top mounted flange, a couple turbos from something like a SAAB or Volvo if you want twins, or something off of an older turbo diesel if you want a single. You will need to tap into your oil pan for the return line and you will need a spin on adapter for the filter to feed fresh oil into the turbo. Run the turbo intake into the stock location, an internal wastegate would be the easiest to use. The intake could stay stock, just use a carb hat or box. There are a few ways to actually run it. You can have a tune made for your stock computer or you can run a set of stand alone injectors ran by a boost referencing computer. You'll need to add another MAP sensor to do this.

All that said, I still wouldn't waste my time boosting a TBI motor.

 

[superninja427]

Oh yea,I have a set of vortec heads I'm putting on it along with an intake ill order from summit whenever I actually start buying things. And I'm not against putting a carb on this motor. My only two requirements are basically just not pulling the motor out again, and not absolutely killing my gas mileage. I understand the stock heads sucks and that intake and heads were gunna be swapped either way.

 

[Tempted]

I'd suggest you don't attempt turbos. Blow through carbs are not cheap. Not pulling the motor is a bad idea and adding any kind of forced induction is going to destroy your fuel mileage.

 

[454SSguy]

That's not necessarily true. The SS see around 2-3 MPG's when adding the whipple.

OP - First of don't get discouraged, I'm not trying to scare you away from working on your truck, I just want you to know what your getting into first. I don't think you completely understand how much $$$ will be involved in this. In all actuality that's why you don't see it very often, b/c the people who are willing to spend that much money usually are car (or truck) freaks. But if you do want a real idea of what it'd cost we'll try and lay that out for you. As mention before the heads are garbage. The bottom end isn't overly strong but for budget we'll say we are gonna use it till it pops (question of when, not if), we'll definitely need an intake, and at the very least an upgraded TBI, we'll also need a fuel system to feed that bad boy (we'll do this on the cheap too), then we got the turbo or turbos, hot side piping, cold side piping, intercooler, boost regulator, some kind of tuning software and the tranny is going to crap the bed pretty quick so we'll plan on that too, also there's no way it'll hook up after all of this so at the very least you'll need some wheels and tires. Soo here's a parts list and I think I speak for a majority of the site when I say that if you're still willing to do this we'll help you out all we can.


Sooo parts...

Heads $750 (that's cheap)
Intake $150 (single plane, low rise intake)
Cam $325 (custom grind for the turbo)
Gaskets and Misc $250
TBI $450 (ported 454 TBI)
Fuel Pump $150 (walbaro 255)
Fuel pressure Regulator $150 (Aeromotive 13301)
Fuel lines $175 (probably more than that really)
Turbo - Anywhere from $350 - $1500 each. Realistily $500 ea or $750 for one
Oil lines - $250 (for turbo)
Hot Pipe - $200 (if you do it yourself)
Cold Pipe -$200 (if you do it yourself)
Intercooler - $350 - maybe less used
Boost Reg - $250 wastegate (this is just a flat out guess)
Tuning Equipment - $450 EBL kit works nicely
Tranny - $750 for built th-400 more for anything w/ more than 4 gears
Converter - $500
Wheels - $400
Tires - $600

So you're lookin at upwards of $7,000. Now it would be flipping awesome if you did it, but do you got $7k sitting around or are you willing to start buying parts and spend all of you're extra money for a year or two before you have everything to start working on it. If so then you are retarded, just like me.
FYI my build is right at $8k for parts and I've already got $4k at the house waiting on me, but I'm in a special situation.

 

[MOBS]

Here's my $.02....after intake and heads changed....try it out NA, if you still don't like it, then get a single GM-8 turbo, have a welding/machine shop cut a flange that will bolt to it, along with a pipe welded to the new flange....now weld the flange into your exhaust(a Y-pipe, preferably a 3"), it'll be mounted somewhere around the passenger side seating area. Now run a 90-degree off the exhaust output side of turbo and connect to rest of exhaust. Since your truck is a 2wd, and you're seemingly wanting a turbo, then you'll be spending the majority of your time on the street(aka no mud or deep water). On the vacuum side of intake turbine housing, pipe your air filter assembly(either a CAI filter, or tubing run up and attached to the cab via spring hanger with a filter assembly of your choice). On the pressure side of intake turbine, pipe your intake tubing along outer side of frame rail(to avoid exhaust heat) or run it along inside of frame rail with heat shields on exhaust. Now run your piping up along the firewall and use an early vortec style breather to mount to top of tbi(or whatever fueling system you choose). After everything is fitted, you need to mount a boost sensor to your intake and have a handheld boost gauge handy. Now to tune your mechanical wastegate, you can either use a pull-type or compression-type spring for your setup, but the compression type is much easier to adjust your pressures with. You'll need to also mount a blowoff valve(set it to 2psi higher than your wastegate is set to, so it will pop during pressure spikes). You can get a turbomaster kit, or make your own using the stock vacuum wastegate controller. That's pretty much your basic turbo setup....I'm tired of henpecking so i'll let someone else explain the tuning aspect of the fuel system.

The reason i suggested a "higher lag" setup mounted further back: It keeps him from having to get an intercooler by using the older mechanical style of thinking........block the heat transfer. Speaking of which, heatsoak from the exhaust turbine won't have as big an effect due to turbo placement. Also, a lower lag system is kind of a waste since he'll be holding launch rpm's awaiting the green light.

Almost forgot, you'll need a dual-port(in/out port) oil filter adapter to pump filtered oil to the turbo and the return will come back and depending on design of adapter, will either continue on thru engine, or re-enter oil pan.

Also, use top-mounted hangers with springs and side-mounted hangers with rubber grommets....can never have too much support. Top-mounted hangers will be there to hold the weight, while side-mounted hangers will be there to reduce left-to-right sway of components.

 

[Tempted]

I wouldn't bother with an intercooler. The engine can't benefit from it anyway since the bottom end can't take much boost. Its overkill, a non intercooled system can provide more than what the engine can handle.

As far as fuel mileage, it does have more to do with driving style but typically you are going to eat more fuel. While it is true that you won't have to hit the throttle as hard due to the extra power chances are you will hold the throttle a little longer than before. Nothing better than hearing the turbo spool at light throttle, then the blow off valve evacuating the unneeded air. It can be done fairly cheap if you have some experience in custom system designing. The cars I did, for the most part, didn't have bolt on kits readily available. We made each system for that car. The hardest part is fuel management.

 

[MOBS]

I see you didn't delve into explaining the fuel system either.....get a blow-thru 600cfm and git er dun!!! They're $499 from Pro-Form.

 

[Tempted]

I mentioned that in my last post, but only in passing. Don't feel like describing a boost referencing carburetor.