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New first gen build

2K views 12 replies 3 participants last post by  MarkB.NV 
#1 ·
Hey guys ive been watching this site for awhile and finally decided to sign up ive got a 1991 isuzu trooper completly stock except for 31 mud tires and a stage two racing clutch 2.6 gm v6 with a five speed plan on doing a "storm trooper" theme black from the wheel body line down and above the body line in the hood and white all the rest of the way black steel wheels with 35s and a 3 inch body lift 4.3 swap black offroad bumpers and a roof rack with four kc lights i found a storm trooper helmet shift knob just to make it that much better :lol: i will post pictures if wanted and updates onthe build
 
#2 ·
Welcome to the Planet, newbie!

The GM V6 is actually the 2.8L motor ...the 4 cyl was the 2.6. Its a minor nit but the OCD in me couldn't let it pass.

PS: Where the hell are those pics and what's taking so long with the pics.

:)
 
#3 ·
MarkB.NV said:
Welcome to the Planet, newbie!

The GM V6 is actually the 2.8L motor ...the 4 cyl was the 2.6. Its a minor nit but the OCD in me couldn't let it pass.

PS: Where the hell are those pics and what's taking so long with the pics.

:)
Well, maybe he meant "2.8" vs 2.6". It's been at least a few minutes, where are those pics???? :drunken:

BTW if you do have a 2.8 GM V6, a much easier swap is to use a '93-95 Camaro or Firebird 3.4. The swap is well-documented and you can keep your stock transmission.

You can build a 3.4 to more HP than a 4.3, and with the right cam, it'll make a lot of torque as well. With stock 2-bbl S10 carbed manifold, the old GM 3.4 "Goodwrench" crate motor was rated at 160hp and 195 ft-lbs. The crate engine used the same grind as the Comp Cams "torquer" cam meant for the 60-deg V6.

Build your 3.4 with the torquer cam, Comp Cams Magnum 1.6:1 roller-tipped rockers, a GM 4.3 throttle body injection unit (with the 2.8 intake bored-out to match the larger holes in the 4.3 TBI), improve the air induction (larger air cleaner, CAI, etc), and upgrade the exhaust (2-into one Walker 15022 cat, 2-1/4" exhaust out the back, and Dynomax Super Turbo muffler).

It'll run hard, make lots of torque, be much smoother than a 90-deg GM 4.3, and look virtually stock from the outside.

Anyway, still waiting for those pictures! :twisted:

Cheers & Welcome to the Planet..........ed
 
#5 ·
Ed Mc. said:
MarkB.NV said:
Welcome to the Planet, newbie!

The GM V6 is actually the 2.8L motor ...the 4 cyl was the 2.6. Its a minor nit but the OCD in me couldn't let it pass.

PS: Where the hell are those pics and what's taking so long with the pics.

:)
Well, maybe he meant "2.8" vs 2.6". It's been at least a few minutes, where are those pics???? :drunken:

BTW if you do have a 2.8 GM V6, a much easier swap is to use a '93-95 Camaro or Firebird 3.4. The swap is well-documented and you can keep your stock transmission.

You can build a 3.4 to more HP than a 4.3, and with the right cam, it'll make a lot of torque as well. With stock 2-bbl S10 carbed manifold, the old GM 3.4 "Goodwrench" crate motor was rated at 160hp and 195 ft-lbs. The crate engine used the same grind as the Comp Cams "torquer" cam meant for the 60-deg V6.

Build your 3.4 with the torquer cam, Comp Cams Magnum 1.6:1 roller-tipped rockers, a GM 4.3 throttle body injection unit (with the 2.8 intake bored-out to match the larger holes in the 4.3 TBI), improve the air induction (larger air cleaner, CAI, etc), and upgrade the exhaust (2-into one Walker 15022 cat, 2-1/4" exhaust out the back, and Dynomax Super Turbo muffler).

It'll run hard, make lots of torque, be much smoother than a 90-deg GM 4.3, and look virtually stock from the outside.

Anyway, still waiting for those pictures! :twisted:

Cheers & Welcome to the Planet..........ed
I actually do have the 2.8 iapologize for that but i believe the 4.3 has the same transmission bolt pattern as a 350 smallblock and if this is true i have a spare allison transmission once bolted to a built 350 i used in another project and ive had my eye on a stock 4.3 for awhile my uncle has been wanting to get rid of i plan on doing a cold air intake racing headers with dual three inch flowmasters ran out just in front of the rear tires racing heads i have a after market distrubutor and "racing" plug wires i have a larger front and rear pumpkin ready to goin along with many other future upgrades
 
#6 ·
You're correct, both the SBC V8 and the 4.3 share the same 90-degree bell housing bolt pattern. Allison transmission should be an interesting swap.

The TBI system found on older 4.3's is similar enough that it shouldn't be a lot of trouble adapting. I'd imagine you'd have to burn a new chip or use a different ECM to run the 4.3. And of course a larger throttle body unit. The other thing I don't know is if a TBI-equipped 4.3 has (1) or (2) O2 sensors; the 2.8 uses (1) in the exhaust "wye".

Or maybe you'll just change the EFI system entirely! You'll need to if you have a Vortec 4.3 with SFI.

Do keep us updated on your progress; you could even start your own swap thread to document.

Cheers......ed
 
#7 ·
Ed Mc. said:
The TBI system found on older 4.3's is similar enough that it shouldn't be a lot of trouble adapting. I'd imagine you'd have to burn a new chip or use a different ECM to run the 4.3. And of course a larger throttle body unit. The other thing I don't know is if a TBI-equipped 4.3 has (1) or (2) O2 sensors; the 2.8 uses (1) in the exhaust "wye".

Or maybe you'll just change the EFI system entirely! You'll need to if you have a Vortec 4.3 with SFI
I did have trouble in deciding what to do with the o2 sensors i would have to do some research to figure out what to do ive had trouble finding any efi systems that arent stock for the trooper i could always find one off of an old 4.3 maybe ill head to a junkyard soon
 
#8 ·
91firstgen said:
I did have trouble in deciding what to do with the o2 sensors i would have to do some research to figure out what to do ive had trouble finding any efi systems that arent stock for the trooper i could always find one off of an old 4.3 maybe ill head to a junkyard soon
Maybe if you used the 4.3 ECM, I'd imagine there is another terminal for the 2nd O2 sensor. So you could either add that wiring independent of the 2.8 EFI harness, and connect to that terminal, or replace the 2.8's TBI harness for a 4.3's. Either way I'd think it should work, the first option being much easier than the 2nd.

I attached a few diagrams of the 2.8 ECM, maybe that'll help.

I also found at Autozone.com an engine controls diagram for an '88-92 S10 4.3, and Surprise! It only has one O2 sensor, connected to the same terminal (D7) as the 2.8. So maybe not an issue. Included that diagram (poor quality, though), too.
 

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#9 ·
Ed Mc. said:
.

I also found at Autozone.com an engine controls diagram for an '88-92 S10 4.3, and Surprise! It only has one O2 sensor, connected to the same terminal (D7) as the 2.8. So maybe not an issue. Included that diagram (poor quality, though), too.
That actually helps alot thank you for that the seperate wiring harness wouldnt be diffucult at all just need to find a wiring diagram which should be easy thank you for your help
 
#10 ·
BTW what year is your 4.3? I'm assuming it's a TBI-type, which would have had about 160hp and 200+ ft-lb torque. Would make a good crawler. Or soup it up with hot cam and roller-tipped (or full roller) rockers.

The "high performance" version of the 4.3, as I recall, made around 195 hp and used the SFI style of injection system. You'll note the engine controls diagram shows both configurations, so you have to ignore the stuff that's different from what you have.

What I would do is print out the 2.8 ECM diagram, and the 4.3's. Then you can lay them side-by-side and compare the differences. I think you'll find that many of the inputs/outputs at the ECM go to the same pin (i.e. same function).

In actuality, if you hooked the 2.8's injector harness to a 4.3 TBI engine, it'd run. But probably not run very well, because the 2.8 ECM isn't capable of adapting to that large of a displacement increase. But it would run and I bet would be driveable to some extent.

The 3.4 works OK (with larger injectors or the fuel pressure cranked up), because it's not way way out of the range of the ECM. A 3.1 Rodeo ECM is rumored to work better yet with the 3.4. I have one in my toolbox but haven't tried it yet. Guess I should!

But, I'd think that you could have one of the custom chip makers modify your 2.8 ECM to feed a 4.3. Then you wouldn't have to do anything to the rest of the wiring at all.

Since there's only (1) O2 sensor, you have to run both sides of the exhaust past it. One way to do that is with an "X" pipe. Another way is to install a dual-inlet cat such as what I did to my 3.4 Trooper.

This Walker 15022 cat has 2-2" inlets and a 3" outlet. Don't know what the diameter of the 4.3 downpipes is, but if larger you might be able to find a different dual-inlet cat. The 15022 has an O2 sensor bung welded into the cat's inlet chamber, so the sensor runs nice n' hot & all the exhaust passes by it. Just what you need!

I'd think a 3" outlet is more than enough to run a 4.3. The cat is rated for up to a 5.9L V8, so there you go!

http://www.rockauto.com/en/moreinfo.php?pk=128877

BTW, I looked up S10 exhaust at Rockauto.com and they use a "Wye" pipe which has one sensor bung at the wye. If you can make this fit in a Trooper, that would work as well. Then adapt a universal Catco cat & add the free-flowing muffler of your choice.

These cats are quite inexpensive on eBay: https://www.discountconverter.com/universal/index.cfm

Anyway, just a few more brainstorming thoughts!

p.s. Geoff ( "Geoffinbc" on this forum) is really up on tuning these Beasts and would probably have some good input on the chip stuff).

Meanwhile, here's some good reading at this site: http://tbichips.com/
"
 
#11 ·
Ed Mc. said:
BTW what year is your 4.3? I'm assuming it's a TBI-type, which would have had about 160hp and 200+ ft-lb torque. Would make a good crawler. Or soup it up with hot cam and roller-tipped (or full roller)
"
The motor that he has is actually the "high output" motor out of a 92 astro van so yes it is injected with the few minor upgrades (slightly more aggresive cam, tbi spacer, ported heads) should be about 190-200 horsepower and about 280 pounds of torque although im not sure how i feel about the strutless pistons they seemed to be the source of alot of problems with the motor my grandfather actually has a motor he was trying to sell me its a 350 with the blower off the old 571 diesels and corvette racing heads but i was afraid this would be to much horsepower without significant body stiffening and other various suspension tweaks and upgrades
 
#12 ·
OK, found a diagram for the '92 Astro Van 4.3 H.O. A bit different from the one above, and more legible.

So, if you do a line-for-line comparison between the 2.8 and 4.3 HO, you'll find that there is wiring that's used only for the 2.8, and the HO motor has other wiring and components specific to that motor.

But, there are some things that have the same function and the wiring in many cases goes to the same terminal.

IMHO you're gonna have to use the 4.3 harness and ECM. Hopefully you got that out of the van.

But before you rip out the 2.8 harness, I would look at every external input/output from the dash area, fuse box, and relay box. There are a number of cross-over items, and if you can retain the original function, all you'd need to do is pull that wire from the 4.3 ECM connector plug, and insert the appropriate wire from the 2.8.

Otherwise, you're gonna be pulling wires out of the dash & fusebox & re-running those leads. No sense in doing that if they can be re-purposed to the 4.3 ECM. I did a quick comparison and it looks like all the fused (hot at all times) or fused (switched) power can be re-used.

The 2.8 uses a "chopper" in the speedometer head to feed the speed buffer (VSS), whereas it looks like the 4.3 uses a VSS sending unit at the speedo gear in the tranny. I'd bet that it's the same signal and you could take the feed from speedo buffer and stick that wire right in the VSS signal position on the 4.3 connector plug. The VSS output goes to the same pin on either ECM.

Now, stuff on the engine like temperature senders, MAP, TPS, ect, will be picked-up by the 4.3 harness. And we don't care about the 2.8 wiring that corresponds to that stuff, since it's from the engine to ECM, not the hard-to-reach stuff.

BTW, wonder where the Astro Van mounts its ECM, in the glovebox? That might require some re-routing or extension of the 2.8 ECM switched Power/fused power wiring. Or maybe there would be enough length in the 4.3 harness to make it to the center-console location of the 2.8 ECM.

The 4.3 doesn't use a main relay like the 2.8, but it looks like you could retain that (it does serve other functions for HVAC, as I recall, that won't work if you disable it). You can re-route the power coming out of the main relay to do the same function for the 4.3.

The 4.3 doesn't use a backup fuel pump relay. From looking at the diagram, the backup relay pretty much becomes useless if everything is hooked-up as per the 4.3 wiring.

The oil pressure switch would have to be reconnected inline with power to the main fuel pump relay 'cause it's inline with the backup relay and that wouldn't work. But maybe the 4.3 harness will pick that up anyway??

The 4.3 O2 sensor has a heated element so you'll need to tap the heater line into switched 12V power.

Stuff like that! Just a cursory review but I'd think it might be too much of a pain to try and use the 2.8 harness and add wires.

The 4.3 has an Linear EGR Control, Variable Tuning Control (whatever that does!), and no external Electronic Spark Control.

It certainly looks do-able, just need to "Nuke it Out" before ripping things apart.

IMHO saving wiring out of the 2.8 harness that have the same or similar function for the 4.3 harness, would be the way to go.

Painless Wiring did sell a stand-alone harness for the early ('92-'95) Vortec 4.3, but I couldn't find the part # (60210) on the site.

Found it here for $612.06:

https://autoplicity.com/368976-painless ... mNOFITMENT

$486.99: http://www.streetperformance.com/part/p ... 60210.html

Here's the installation manual for that, lots of good info in there:

http://www.painlessperformance.com/Manuals/60210.pdf

Of course you won't need that if you have the Astro Van harness.

HTH.............ed
 

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#13 ·
Nice looking rig. The 4.3 is a decent little motor. If you can squeeze her in there and make her work, that truck should haul @zz.
 
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