alright i got an 1987 pontiac firebird 2.8 mpfi v6 and automatic transmission and as many people know the drive train sucks. i dont want to spend a lot of money on the v6 cuz its not gonna be in the car for more than a year or so. cuz eventually i am gonna stick a vortec 454 in the car. but thats not why i am posting on here. the reason i am posting this is cuz i want to give the v6 a little more power cheaply while its in the car. i have been looking for ways to cheaply improve it and one thing i read about on s10 and blazer forums is a 4.3 tbi swap. but is that an improvement over the stock mpfi? if not what other intakes will bolt onto my engine and boost power? i am not talking aftermarket, i mean stuff i can get at a junkyard.
thanx

 

NO 90* V6 PARTS WILL WORK ON A 60* V6. The 3.8, 3800, and the 4.3 are ALL 90* V6 engines. Nuff said. There is NOTHING in terms of intakes that you will find in a junkyard that will directly bolt to your cylinder heads that is actually an improvement, unless you stumble on one of those rare Edelbrock performance carb intakes. About the only parts you'll find in a yard are the 3x00 parts, which ARE an improvement.

 

your right a 4.3 intake won't fit on a 2.8 but a 4.3 throttle body will fit a 2.8 tbi intake. it has been done hundreds off times on blazers s10's and even Isuzu's with the gm 60* v6. one of the best sources for info on the swap is this one. but what i dont know is if that would be an improvement over the stock 2.8 mpfi intake. tbi intake usually are a down grade from mpfi. but with the larger bore and injectors of the 4.3 would that still be worse? i have read that it gives between 20 and 30 horsepower over stock 2.8 tbi intakes. how much more horse power doe the mpfi make than tbi stock on the 2.8?

some more info on the 4.3 throttle body and swap can be found at
http://members.shaw.ca/betterthanyou/newtb.htm
http://www.4x4wire.com/forums/showfl...&Number=445449
http://www.4x4wire.com/forums/showfl...t=1#Post415876
http://www.4x4wire.com/forums/showfl...t=1#Post928246

heres a 2.8 tbi next to a 4.3 tbi the 2.8 is on the left

 

I'm not 100% sure on this, but the TBI parts would just about break even on the MFI setup you're currently running, and may even give you about what HP you would gain swapping to a 3.1. For the money you would spend (between the TB, manifold, and the controller parts), I'd leave it as is and go hybrid if you're looking to do something for some bang.

 

i talked to a couple of yards and they said a complete tbi intake from an s10 or blazer is $130 and a 4.3 throttle body from astro van is $75.then a gasket kit from advanced auto is about $20. so this could be done for just over 200 bucks. and can be done in a weekend. i have no clue what a hybrid build or 3.1 swap would cost but i am gonna guess that its more than 200 bucks and cant be done in a weekend. maybe just swapping to a 3x00 intake could be done that quick and cheap but do those work with the stock heads and stuff?

 

... Except that you forgot the wiring, computer, chip, and the solenoids and other parts you will need to make it work.

And no, the 3x00 intake don't work without the heads. If you know where to get the parts, you can get them cheap. I got all the 3100 parts I need, and a lot I don't, for $50 because they were on a junk engine sitting outside a shop.

 

why would i need a different computer? and the $130 is for the intake manifold with wiring and sensors and brackets still attached and brackets and sensor also come with the 4.3 throttle body. the only problem i see is the larger throttle body and injectors could cause a high idle as the commonly do with this swap in the s10 forums but its easy to fix that by adding an idle set screw to gm throttle body.

what i still don't know is how much of a n improvement this would be over the stock mpfi. what is our cars stock horse power rating?

 

302 isn't a TBI ECM... Stock HP for the 2.8 is 135... I believe TBI engines are around 120-130, but I'd have to look that up.

 

why are talking about a 302 ecm? i have the stock 2.8 ecm

 

look at it this way. its a whole different system. not all the same sensors parts etc

id just spray the **** out of the vbanger and call it a day

 

why would i waste money on nitrous yes it boosts power but only for a few seconds then you got to refill it. its pointless on a street car. i know not all the sensors are the same thats why i am thinking of getting one with the sensors and wiring and all that stuff still on it. shouldn't the stock mpfi computer be able to hand the tbi? and it shouldn't be to hard to splice the wires to the sensors on the tbi intake.

 

well u want power. u didnt say for what.

 

s10s where rated at 125 HP and 150 Torque stock with the 2.8 tbi. but the trucks also had a different cam than our cars. ours as maverick said have 135 hp and 165 torque. so i am guessing this swap should give atleast 20-25 more horse power. i am still looking to see how much torque is gained or lost from this swap.

 

The 1227302 IS the stock 2.8 MFI ECM... I have 3 of them in my garage, one of which is attached to the dashboard out of my car. Car-Part.com reports that the stock S10 2.8 TBI ECM is the 1228062, so yes, you would have to replace the ECM as well. Not to mention you may have to tune the chip (because there is no factory chip for the setup you plan on running).

 

even the ecms are difrent why wouldn't the stock one work? and why would i need to burn a chip s10s work fine with this setup?

 

Because the stock one uses a MAF sensor and multi-port fuel injection, not a MAP sensor with throttle body injection. Which means you'll also need to get a MAP sensor.

 

the map sensor should already be in the manifold. but i don't plan to use it. maf is way more accurate.
i am gonna try to explain my plan for wiring this to you clearly. if you still think it won't work tell me why.

the sensors that are need to make the engine run are
ECU engine temp sender, fuel injectors, TPS, and Idle control solenoid, these i will splice the s10 sensor into the wires from the stock ones.

MAP or maf i will leave the s10 map sensor unhooked and the stock maf i will leave as is.
i know tbi intakes usually have an air cleaner rite on top of the throttle body like carburetors do. but i can also get a tbi hat from a 4.1 Cadillac and that will fit on the 4.3 throttle body. then i can run a hose from that to the maf and another hose from the maf to the air cleaner. now why would that not work?

 

The only reason the 4.3 TBI is popular is cause the V6 trucks were all carb or TBI, they all wish they could of had MPFI like the 3rd gen line.

Going TBI is a step backwards.

 

one more thing the tbi intake use a thick based distributor so i will get that off the s10 as well. another thing i plan to do during this swap is add an adjustable fuel pressure regulator, and an idle set screw so that way i can tune the engine.

also heres how to adjust the tps and iac.

 

yes it may be a step backwards but with the larger throttle body it will still be an improvement in power over stock. and its cheap and which is my motivation to do this.

heres an interesting article about tbi

 

What part of 2 completely different systems is so hard to understand? The MAF system will NOT work with the TBI, PERIOD. You can't just put the MAF onto the air cleaner and call it a day. Even if you could, just how would you go about wiring up the fuel injectors? The reason this swap is so popular with the S10 guys is because they ALREADY HAVE TBI and not much changes. With all of the money you're spending on the TBI crap, you could buy a simple camshaft or headers and intake system and already beat what you would gain out of the TBI parts. Not to mention there isn't any massive rewiring involved. TBI intakes aren't that great on torque, which is why the S10 series and the like had different camshafts. The longer runners on the MFI intake allow for increased torque.

:edit: Headers can be had for around $200. Cam and air intake for about the same price. Both can be put in within a couple of hours if there are no major problems (exhaust, mainly). Again, going TBI is not only going backwards, but also a major headache for the price of simple parts.

 

i guess i am the only person who sees any potential benefits from this. i know tbi is a step backward i know its a different system. i get that. but hey its cheap reliable and tunable. and the engine will be able to breath better increasing power and yes maf and tbi can work together. it to has been done before google it.

 

alright because nobody thinks this can work is there a way to put a larger throttle body on the stock intake? the main reason for doing this swap was to get more air and fuel in the engine well i know how to put larger injectors on. but i don't know of any larger throttle body's to replace the stock one. do you guys think that will work? do you know of any?

 

Some people, I think, use Ford 65mm TB's on their intakes, IIRC. But that would require porting the intake (designed for a 52mm intake plate). again, IIRC.

 

whats iirc?
porting the intake is not a problem. do the ford throttle bodies bolt on rite? what did they come on? do you have any info or links to it? thanx

 

IIRC = (If I Read Correctly)

 

That would be If I Remember/Recall Correctly...

:edit: They're aftermarket pieces, available from WOT-Tech. They have a 62mm (recommended for non-turbo applications) and a 65mm TB. I was thinking of the Thunderbird 65mm MAF sensor that the turbo guys like. Looks like Ford has a similar TB, but I can't find any info on what cars it came from. I'll search eBay next to see if I can find one.

 

will it bolt on the stock intake manifold?

 

That's the million dollar question. RedRaif has one bolted to a Trueleo intake, but I couldn't tell you if it uses a stock TB mounting plate or not. WOT-Tech sells an adaptor plate of sorts, but it seems that their replacement TB's just bolt onto the 3x00 parts. I'll have to check the fit of the 3100 TB again against my stock TB from the 2.8. As for the Ford TB, they're found on the late-80s/early 90s Rustang with the 302 (the GT models, I'd guess). I could check what he has when I get back to the JY, but I don't think he has a Rustang that old.

 

i was actualy reading a thread about redraifs tb and she had them build the intake so it would bolt to the ford throttle body. that and a thread on 60degreev6.com where a guy machined an adapter plate to mount the ford throttle body on his 2.8. so the ford throttle body wont work. how big are the 3100 or 3400 throttle bodys? and will they fit?

 

Hmmm....isn't a 4.3 just a 350 Chevy with 2 cylinders lopped off? I would just drop in a 350 at that point, but from a unique standpoint, a 4.3 would look kind of cool in there.

 

Yes the original designs were just that, same with the Buick 3.8 was just a Buick 350 missing two cylinders.

But funny how Turbo 3.8 can pump out 5-700+ HP with simple mods
but ya don't see that happen with the 4.3

Kinda puts thing in perspective on which V8 was a better power plant by basic design

Which a few people took notice of and found that a 2 bolt Buick 350 can push 500+ on all stock iron parts with a little grind work, and over 1000+ with forced air. Try that with an 80s chevy 2 bolt V8

 

it was never my intension to put a 4.3 in my car. just part of a 4.3 on my engine to increase power.and when i do get to replacing the v6 i got a 98 vortec 454 and t56 sitting in my garage. but thats not what this thread is about. this thread is to find ways to cheaply improve the 2.8.

 

3100 TB is the same size, 3400 slightly bigger. But they don't bolt up directly. You would need the WOT-Tech adaptor plate for them as the bolts are on the opposite sides and the idle air intake passage sticks out the top, which would leave a huge vacuum leak. So, either way, you need an adaptor plate.

 

can cast aluminium be welded the same as regular aluminium?
i read something a few days ago on i think 60degreev6.com about how throttle body spacers actually harm performance on mpfi intakes because the air has to travel further before it mixes with the fuel. or something like that. i'll look to see if i can find it again. but it said on mpfi torque would be higher with the throttle body closer to the intake. does anyone know if thats true? if so making a flange to mount a larger throttle body would impact performance the same way.

if it is true and cast aluminum can be welded i was thinking instead of making a flange to mount a larger throttle body why not get part of the neck of the intake that the larger throttle body came on and weld it to the stock intake manifold? do you guys think that would work?

 

the mustangs had a 50 something mm throttle body. late 90's explorers have the 65 mm throttle body. thats what a lot of people put on mustangs.
can cast aluminum be welded with an oxy acetylene torch?
i cant find the article i was talking about in the last post but i was reading a thread on a mopar website that was talking about how dry type intakes like our mpfi, will have better torque and throttle response with shorter intake runners. and wet intakes like carbs and tbi will be better with longer intake runners. so if i weld on a new throttle body i will do it as close to the intake as possible.

 

As far as welding goes, I had a shop weld a mounting ear on both my first T5 maincase and the 2.8 plenum back on. T5 case didn't hold oil because he didn't check it, and I got rid of the plenum because he somehow messed it up when I had him make sure that the TB face was flat (had to use a gasket and a half to seal the TB to the plenum ). So, yes, cast aluminum can be welded.