t.b.i. builds. it is possible

recently in the march 2012 issue of chevy high performance magazine, eric patton from hiram, GA sent in a question regarding his 86 el camino tbi4.3 liter v-6. Eric wants to swap the 4.3 mill for a superior 400 *** small block while retaining the use of throttle body injection and the vortec status. Eric wants to know what heads he should use and what type of camshaft amongst other things. He was told in his reply that while he had a great idea, the use of tbi with a performance build is near impossible. Well Eric i can safely tell you what you want to do is very doable. i am doing the same thing to my 95 chevy c2500 pickup although be it a 383. i will share with you what i know to be true. while tbi is outdated and very often overlooked by the hot rodding community, they are a great setup to have on any motor. they are computer controlled but there is  ways around this. Any company that sells vortec heads i.e. patriot performance gm performance or edlebrock will work with the tbi intake be it stock or the upgrade that edlebrock sells for 265.00. These two intakes work with all vortec heads and rest assured will outperform the stock tbi 305 or 350 heads. As far as cams go, there is a limit to how much bump you can have in your stick. Comp cams has a set of extreme energy cams that will work in 87-95 fuel injected motors. they are better than stock and have the numbers to match. they are a bit pricy. you cant go overboard with high lift because without machining the vortec heads wont allow it. also the pesky knock sensors that most of the tbi vehicles have, wont know what to do with itself with too much lift therefore thinking the engine is misfiring causing all kinds of problems. one problem that eric will face is the ecm computer that all tbi engines have and need to run. a 4.3 computer will not work on an 8 cylinder so you need a new one. i recommend going to a junk yard and finding one out of a tbi 350.however even with the new brain most people think "outdated technology, i cant tune this to what i want." oh how wrong you are. There is a company based out of tennessee called Motorvation, that builds brand new ecm computer chips tailored to your needs and specifications. Recalibrating fuel needs and whatnot. Also as an fyi, even the lowly tbi is not judgemental. meaning the throttle body and computer doesnt discriminate cubic inch. it will work on a 502! Ok enough said. thanks for hearing me out. anyone with questions dont be afraid to ask as i wont be afraid to ask you. do your homework with your projects.  

No offense, but I would say finish the build before youd say "for sure" it works.  I agree its a viable option when done right for a mild motor.....but not so much a cheap and easy option by any stretch for a high performance engine.

Here is the problem.  The hot rodding community ignores the TBI because a stock TBI is severely limited.  Forget the factory heads and cam and compression and manifold.  For sure....all of that stuff can be improved upon.  No doubt about that.

But at the end of the day if you're using a stock TBI, your dealing with a teeny tiny throttle body that only moves around 425CFM or so on the small blocks and fuel injectors that dont move anywhere near the volume of fuel needed to keep up with a high performance engine.

As far as the knock sensor goes....  it doesnt have anything to do with lift.  Valve lift(be it more or less) doesnt create a knocking sound.  Symmetrical cam lobes with high seating velocity, slamming the valve into the seat is what creates noise.

This is why the comp line of extreme energy hydraulic flat tappets are always said to be noisy.  Symmetrical lobe with very high seating velocity.  What you hear is the valve snapping shut on the seat.

The map sensor is your limiting factor.  It relies on engine vacuum to work the TBI properly.  You add a large cam, vacuum is degraded and the map sensor cant figure out what to do with itself.  Reprogramming can be done...but it has its limitations as to how far you can go.  The cam selections are mediocre at best.

I didnt get to see the article in the mag so I have no clue what the guys goals were.

I can say this though.  One horsepower per cubic inch is a very mild build.  So...a 400 horsepower 400 small block would be a mild, driving engine.

Even with everything changed on the engine....the TBI unit itself will struggle to feed enough air and fuel to handle 400 horsepower.  By the time you change injectors and work on or change the throttle body, burn a new chip and everything else....the investment becomes pretty large.  This is why people avoid them because there are much better options in the same price range or for much cheaper.  

mo doubt there. its pretty expensive. and no one is going to build a high performance t.b.i. but for a mild performance 383 or 400 your going to have a lot of torque out of both of these motors. and thats what people want on the streets are motors that built torque. the knock sensor isnt really an issue its only there for engine harmonics. but you are right about the maf/map sensor. but i think you can have that eliminated with a performance chip im not sure though. but everyone including me needs help and guidance with things. so that being said, you seem like a knowledgeable guy and id appreciate it if i could pick your brain if i run into some issues  

Sure Id be willing to answer questions.   I must warn you though my knowledge of fuel injection is limited so I may also be limited in what I can answer.

I will tell you this though, concerning a high performance TBI....it does exist.  Companies like holley and FAST have essentially what is a high performance TBI.  They bolt on to a 4150 style flange(which is your typical holley carb flange), meaning that they can bolt to just about any existing aftermarket manifold for a square bore holley type carb.

Throttle bodies are around 900cfm and the injectors are large enough to support 600 horsepower.  They dont give nearly the grief with a large camshaft either.  

Two of these units are "self learning" and do not require tuning.  I know some people very satisfied with them.  

ive seen those, they are very expensive. my thing is im putting this motor in a 95 pickup with a 4l80e. im trying to avoid some hassles with the wiring harness like if i rip it out and switch to a carb   what kind of issues would i run into  

the big deal is going to be the transmission controller.  That trans depends on the computer to control everything such as shiftpoints and converter lockup.

the controllers do cost a fair amount, but this is also your biggest hurdle assuming emissions isnt part of the picture.

Next in line is ignition.  The easiest way is to just drop in a non computer controlled HEI or aftermarket ignition.  You basically just need something that isnt going to depend on a computer to control timing.

And yes you're right the fuel injection units can be pricey.  right in the 2000 dollar range.  But depending on specifically what you try to do with the factory TBI....it could be a little pricey also.  Ive never priced one but I figure bare minimum you need the better chip and you may need a better set of injectors as the motor grows stronger.  That alone has to have a bit of a cost penalty.  Then if it needs further modified in any way....I could see it starting to add up in cost.

Probably still not as much as some of the aftermarket fuel injection stuff, but not necessarily cheap either.  Id say it really depends on what you want the end result to be.  

For a mild engine the TBI with mild upgrades could fit the bill just fine.  If you really wanna extract a lot of power from it...it might start going up in cost enough that the flexibility of the aftermarket fuel injection doesnt look as bad.

me personally...I like carburetors.  They arent as adaptable, and you'll never get quite the cold start capability out of them, but other than that....a carb can work every bit as well.  It often takes a lot of effort...but it can be done!

In the end I think this is how any project should be approached really.  Decide what you want the end result to be up front, then explore all the options so that you know what you need or if what you have is up to the task of meeting your goal long before you start.  

Sometimes that can be frustrating though.  I dont have a huge budget to throw around, yet I dont wanna cheap out on quality or anything....so projects tend to take a while to do them just as I want them without sacrifice.  The end result is usually worth it though.  

im actually a carb guy tooo. i just wanted to try and do what some say cant be done. now im seeing why they say it cant be done lol.