[scrub]

Ok i did search and couldn't find nadda.

I've got a 89 S10 with a TBI 4.3, i want to convert it to MPFI what all would i need to get, i have open access to a JY with tons of these trucks i Need to know what all i would need to grab to convert it over from the TBI.

thanks
-Matt-

 

[rat]

What are the goals of the setup? What mpfi are you looking to get, and why?

 

[scrub]

What are the goals of the setup? What mpfi are you looking to get, and why?

More power, better mileage, and personally i dont like the TBI setup.

I'm not sure which setup i should be looking at that is what i'm asking.

-Matt-

 

[rat]

The tbi isn't that bad. The thing that holds it back big time is the camshaft, and the heads. The cpi cam has duration #'s of 208/208, your tbi is in the 179/### range, with very small lift numbers.

I highly doubt you see more than 5hp from swaping just the intake manfiold. Also, you are going from a tbi, shared with v8's, easy to get bigger injectors for, ect. All of the multiport injection setups on the 4.3's use goofy popet injectors not used on any other engine. The '92-'95 ones are very prone to leaking.

So, to answer your question. At a minimum you would need this:
Computer, tuned to whatever cam you run
'92-'95 cpi intake manifold will bolt up to your stock heads
Fuel pump

To make it a "true" '92-'95 cpi in addition you will need
Camshaft
Heads

^^This setup is batch fire by the way. Stick to the early computers, as it is an obd1, mid '94-'95 they had obd1.5, and your ignition stuff won't bolt up to it.

Or, you can do the '96 up route. Here you will have to do some thinking about where you are going to get your crank position input, you would be better off just getting the whole motor, computer, and harness. Might need to have passlock turned off in the ecm. This intake manifold will not bolt up to the older heads. The all of the '96 up comptuers are sequential.

 

[scys]

Hey Rat,

I have a question for you.

My truck is a 93 Jimmy, the motor was replaced with a 96 (both 4.3 vortec). What part's are different? How about the distributor/shaft?

I have posted this in the past and had no luck with responses.

Cy

 

[rat]

There is a lot different, what exactly did you want to know?

'96 and up have vortec heads with 8 bolts that point streight up, and taller intake ports. There are 6 individual injectors instead of the one cpi thingy. The distributor has a "flat" cap, with the connections horizontal, the timing is set by the computer, and is not adjustable. The '93 would have HEI, and the timing must be set with a timing light.

 

[tippmann243]

Ok i did search and couldn't find nadda.

I've got a 89 S10 with a TBI 4.3, i want to convert it to MPFI what all would i need to get, i have open access to a JY with tons of these trucks i Need to know what all i would need to grab to convert it over from the TBI.

thanks
-Matt-

converting to a "true" mpfi system isnt going to be possible with parts found at the junkyard

 

[scrub]

Ok, so would i just be better off upgrading the injectors in the TBI?

If so what would be the best donor to get better injectors out of?

Thanks for the Help.

-Matt-

 

[Teeleton]

Ok, so would i just be better off upgrading the injectors in the TBI?

If so what would be the best donor to get better injectors out of?

Thanks for the Help.

-Matt-

350 injectors (55lb/hr) would be a good start, and you can go as big as 454 injectors (90lb/hr).

Here's a color code chart for you.
http://www.diy-efi.org/gmecm/component_info/tbi_injectors.html

You'll need a custom chip to use different sized injectors, though. For the record, mine has 85lb injectors in it.

Teeleton

 

[brock1949]

alright here is the problem maybe i missed what going on with your build in another post but i can start of telling you this.

The injectors in your truck are not maxed out as they sit, I personaly ran 4lbs of boost on a stock tune with stock injectors and upped my hp from 126RWHP to 172RWHP without even tuning it what so even.

If you were to get the bigger injectors from a 350 or 454 on a stock tune you will run rich all the time and will probably end up washing the pistons. I ran my truck with a stock chip and 350 injectors once after building my motor to see if it was close enough to drive it home,... and it was crazy rich to the point we shut it off instantly. You would have to get a custom chip for your truck to run right with the bigger injectors. www.tbichips.com could take care of it....

That was on my truck with a edelbrock 2114 intake with holley tbi conversion plate, 2000 vortec heads worked over with oversized undercut manley stainless valves, edelbrock tubular headers, and a .500 lift cam with 260 ad duration on full roller rockers...

Now if your looking for a better running truck all around without doing alot of work, call brian at TBI chips he is working on my tune with my truck right now. just goto www.tbichips.com and tell him brock sent you lol thats the easist fastest upgrade to your truck to get another 10-15hp maybe out of your tune.

now other low buck for the bang items on a tbi motor

coil factory one is horrible get a msd drop in gm one or go big and wire it
air intake, get a open element filter to replace all that steel and routing crap.
exhaust, free flowing cat and muffler
Good NGK plugs and some Accel or msd wires

next level
y pipe its horrible..
better valve springs, so you can wind it out past the 4400 rpm area its at now
cam, .. comp and crane have some nice ones - timing chain to support the extra valve spring force and rpms
Headers
adj Fuel pressure regulator
350 injectors

Next level yet, (where you would start to need 350 injectors)
Vortec heads from a 96+ with or without some work on them (requires alot of work to make this conversion. though)
2114 edelbrock intake and holley conversion plat for tbi
Full roller rockers
MSD 6a or 6al or crane box

Then... where the bottom drops out..
Supercharging bolt on kits from www.wynjammer.com
Fuel pump
More tunning from TBI chips

depending on miles on the motor a rebuild with forged internals...
Meth injection
etc etc

So depending on what your goals are you will be 100% better off just putting the money into upgading what you have. I am running TBI and plan on running it until i have some kinda big problems or see major gains going to somthing else.

The biggest gains in fuel injection to be had past tbi is just getting a 2114 intake with 6 real injectors controlled by a 96+ ecm and harness so it will have the ability to run a 2 bar map for running boost later on.

Should give you some ideas!

 

[brock1949]

teeleton how hard are you running those 85lb injectors? I have 55lbs on mine right now and i'm only pushing them up to 18psi of fuel pressure, but i am getting to about 75% duty of them with only 4-5lbs of boost. However meth injection should be installed and running tommorow with the higher boost...

 

[91S104x4]

On Horsepower TV, they did a MPFI conversion from TBI on a V8 truck and it gained 20 rwhp. Since our V6s are 3/4 of what a v8 is I would guess you would see 15 rwhp?

 

[tippmann243]

On Horsepower TV, they did a MPFI conversion from TBI on a V8 truck and it gained 20 rwhp. Since our V6s are 3/4 of what a v8 is I would guess you would see 15 rwhp?

i tought it was 30 hp, and the bad part is no one makes a kit like that for the 4.3, you have to have an intake custom made

 

[91S104x4]

i tought it was 30 hp, and the bad part is no one makes a kit like that for the 4.3, you have to have an intake custom made

20-30, is still a lot for a new intake manifold and fuel injection system!

 

[rat]

That isn't exactly an even test. How was the tbi tune? Also, you change the intake manifold, that is another variable, maybe the new intake manifold breathes better on the top end. Maybe the tbi needed a little more throttle body.

 

[Teeleton]

teeleton how hard are you running those 85lb injectors? I have 55lbs on mine right now and i'm only pushing them up to 18psi of fuel pressure, but i am getting to about 75% duty of them with only 4-5lbs of boost. However meth injection should be installed and running tommorow with the higher boost...

My TBI 4.3 has a rather healthy build on it. It also has a fairly large cam and exhaust on it, so the scavenging I get in the upper RPMs tends to pull some of my intake charge through the exhaust valve. As a result, I have to make up for that lost fuel. I'm actually only running the equivilant of 73lb injectors right now, since they're only running at 15psi (they're 85lb holley injectors which are rated at 20psi, I think GM injectors are rated @ 13), but I'm in the process of bumping the pressure to 20 so I can get my AFR down some more. Above 4000 RPM, the AFR slides up to about 13.2:1, and no matter what I do in the tune it won't go any lower, so I think I've maxed the injectors out. Also, about this point the horsepower plot changes from a smooth line to an erratic one which again tells me that the injectors are at 100% DC. Even with all that, it still made [email protected] (the bump at 5400 was the TCC lockup).

Teeleton

 

[brock1949]

Thats really impressive !,
What kinda fuel pressure reg are you running? I am such a big fan of my aeromotive FPR with the 1:1 deal its dumb.. I am just kinda wondering if you were to use a setup like that to try and get that extra fuel up top.

Get this though, with my truck heads, intake, cam, blower. 55lb injectors i went from 20MPH WOT through 2nd shifted out of 2nd at 80mph exactly at 5500rpm, ran third to about 130mph WOT the hole time and my AF ratio stayed between 11.4 and 11.8. It was so consistant through all the low to high RPM and gear changes it was hard to imagine... now we started getting some weird spots again but were chalking that up to the tr55's getting burnt off and starting to make a little to much heat, actually after i pulled them out today.. i must have been out of it when i gapped them.. they were gapped 55 lol i installed tr6's at 45 today.

teeleton what heads are you running ?

 

[Teeleton]

96 vortecs that I ported & polished. The FPR is just the unit that comes with the holley TBI. When you try to go beyond 15psi, the adjustment bell contacts the diaphragm and the pressure shoots up very fast with very little adjustment. I'm working on making some shims so I can raise the spring rate. I probably should just break down and buy a new FPR, but when I can just shim it for about 50 cents, I'm going to at least give this a try first.

I'm running 3.73s on 255/50/17s in the blazer, so I run out of gear at 120.

Teeleton

 

[scys]

The 96 motor came without a distributor shaft, so the one from the 93 motor was put into the 96 motor. I seems to run fine.

Thanks,
Cy

'96 and up have vortec heads with 8 bolts that point streight up, and taller intake ports. There are 6 individual injectors instead of the one cpi thingy. The distributor has a "flat" cap, with the connections horizontal, the timing is set by the computer, and is not adjustable. The '93 would have HEI, and the timing must be set with a timing light.