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Discussion Starter · #1 ·
Good day, everybody!
I'm new to the group, although I keep bumping into it online while searching for info. Figured it was time to join. 馃槀 I own a first gen 1990 trooper LS. It's my forever truck and I'm currently making the 2.8L all it can be. Pulled the motor to just replace the leaky main seal but found a bunch of items needing TLC. Now I'm upgrading the camshaft, match ported the heads, previously added a 4.3 tbi, 1.6/1 rockers, K&N filter etc. It's slow going because I work two jobs, but it's gonna get there eventually. Got a full gasket kit and I'm gonna start reassembling the engine soon! Wish me luck!

Matt
 

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HI, Matt, welcome to the Planet! If you're not too far along in your reassembly, here's a tip that will greatly enhance the performance of your GM 60-degree Little V6 That Could:

Get a 3.1/3400 crankshaft kit with matching main and rod bearings. The 3.1 has the same bore as the 2.8, just a longer stroke. The 3.4 has a redesigned block with larger yet bore, and the same stroke as the 3.1. Cranks are physically interchangeable across the board, with exceptions noted below.

Pick up a set of new pistons for a 1991 Camaro 3.1, or a '91 Isuzu Pickup or Rodeo. The 3.1 has the same bore as the 2.8, just the crankshaft is stroked. So you can turn your engine into a 3.1 with those components.

I'd recommend Sealed Power H562CP "Coated" pistons, the anti-friction coatings on the skirts prevents scuffing and they run quieter. Assuming your block is Standard and not worn out, a set of Std pistons should work nicely. Install the new pistons on your good 2.8 rods.

Here's a standard set on eBay for $115 shipped: Sealed Power Piston Set #H562CP Standard - 3.1L Chevy (6 PCS) | eBay

One caveat: Check your bore sizes so there will be no surprises. Standard bore size for 2.8 and 3.1 is 89mm.

You should be able to get a crankshaft kit from your local auto parts store. They'll probably be happy to take your 2.8 crankshaft as a core, since good 2.8 cranks are getting scarce. Plenty of FWD 3.1/3100/3.4/3400 crankshafts out there. Doesn't matter if the crank has a reluctor wheel or not; later FWD models and the Camaro 3400 have crank sensors for the distributor-less ign, and that requires a wheel on the crank. Since we're using an old-school distributor, the reluctor wheel is moot.

Regardless of displacement, your V6 will benefit from improved exhaust. You can do a 2-1/4" cat-back, and if you really feel Sporty, you can chop out the exhaust Wye and use an upgraded cat for a HUGE improvement in performance. The wye is very restrictive and getting rid of it is a definite improvement.

Use a cat with dual 2" inlets. The V6 downpipes are run right into the cat. Lucky for us they happen to also be 2" pipes!

These cats usually have an O2 sensor bung right on the cat body, this runs the sensor hotter than sitting in the wye, which means faster warmups into Closed Loop, and better operation down the road.


For a 2.8 or 3.1, you'll have to use a reducer on the 2-1/2" inlet, down to 2-1/4". You don't need any larger pipe than that. I have 2-1/2" on my 3.4, but even it probably doesn't need that big of pipe. You'll have better low-end with smaller diameter. But starting from 1-7/8" stock exhaust, the performance difference is remarkable.

I used a Dynomax Super Turbo muffler and it sounds great. Doesn't drone at hiway speeds, either. You can tuck it up into the frame a bit more for better clearance and a straighter run. Don't know why ZuZu made the piping going to the stock muffler so convoluted.

2-1/4" size Dynomax: Dynomax Performance 17747 Dynomax Super Turbo Mufflers | Summit Racing You might find a cheaper one on eBay with free shipping, or better availability.

Back in 2006 I build a "2.8 Stroker" '89 Trooper for my folks. I was really surprised at the good low-end torque the 3.1 had, way better than my old 2.8. It got pretty good mpg, too. I used a Delta Cams (Tacoma, WA) "torque" regrind but otherwise it was stock. My Stepdad passed away in 2011 and my Mom gave the Trooper to my Nephew and he's still enjoying it to this day.

Anyway, hope there's something in there that you'll find useful.

Good luck with the project and post some pics when you get a chance...........ed
 
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Discussion Starter · #3 ·
HI, Matt, welcome to the Planet! If you're not too far along in your reassembly, here's a tip that will greatly enhance the performance of your GM 60-degree Little V6 That Could:

Get a 3.1/3400 crankshaft kit with matching main and rod bearings. The 3.1 has the same bore as the 2.8, just a longer stroke. The 3.4 has a redesigned block with larger yet bore, and the same stroke as the 3.1. Cranks are physically interchangeable across the board, with exceptions noted below.

Pick up a set of new pistons for a 1991 Camaro 3.1, or a '91 Isuzu Pickup or Rodeo. The 3.1 has the same bore as the 2.8, just the crankshaft is stroked. So you can turn your engine into a 3.1 with those components.

I'd recommend Sealed Power H562CP "Coated" pistons, the anti-friction coatings on the skirts prevents scuffing and they run quieter. Assuming your block is Standard and not worn out, a set of Std pistons should work nicely. Install the new pistons on your good 2.8 rods.

Here's a standard set on eBay for $115 shipped: Sealed Power Piston Set #H562CP Standard - 3.1L Chevy (6 PCS) | eBay

One caveat: Check your bore sizes so there will be no surprises. Standard bore size for 2.8 and 3.1 is 89mm.

You should be able to get a crankshaft kit from your local auto parts store. They'll probably be happy to take your 2.8 crankshaft as a core, since good 2.8 cranks are getting scarce. Plenty of FWD 3.1/3100/3.4/3400 crankshafts out there. Doesn't matter if the crank has a reluctor wheel or not; later FWD models and the Camaro 3400 have crank sensors for the distributor-less ign, and that requires a wheel on the crank. Since we're using an old-school distributor, the reluctor wheel is moot.

Regardless of displacement, your V6 will benefit from improved exhaust. You can do a 2-1/4" cat-back, and if you really feel Sporty, you can chop out the exhaust Wye and use an upgraded cat for a HUGE improvement in performance. The wye is very restrictive and getting rid of it is a definite improvement.

Use a cat with dual 2" inlets. The V6 downpipes are run right into the cat. Lucky for us they happen to also be 2" pipes!

These cats usually have an O2 sensor bung right on the cat body, this runs the sensor hotter than sitting in the wye, which means faster warmups into Closed Loop, and better operation down the road.


For a 2.8 or 3.1, you'll have to use a reducer on the 2-1/2" inlet, down to 2-1/4". You don't need any larger pipe than that. I have 2-1/2" on my 3.4, but even it probably doesn't need that big of pipe. You'll have better low-end with smaller diameter. But starting from 1-7/8" stock exhaust, the performance difference is remarkable.

I used a Dynomax Super Turbo muffler and it sounds great. Doesn't drone at hiway speeds, either. You can tuck it up into the frame a bit more for better clearance and a straighter run. Don't know why ZuZu made the piping going to the stock muffler so convoluted.

2-1/4" size Dynomax: Dynomax Performance 17747 Dynomax Super Turbo Mufflers | Summit Racing You might find a cheaper one on eBay with free shipping, or better availability.

Back in 2006 I build a "2.8 Stroker" '89 Trooper for my folks. I was really surprised at the good low-end torque the 3.1 had, way better than my old 2.8. It got pretty good mpg, too. I used a Delta Cams (Tacoma, WA) "torque" regrind but otherwise it was stock. My Stepdad passed away in 2011 and my Mom gave the Trooper to my Nephew and he's still enjoying it to this day.

Anyway, hope there's something in there that you'll find useful.

Good luck with the project and post some pics when you get a chance...........ed
Thanks for all the advise Ed! As much as I would like to stroke the 2.8, the bottom end is super healthy. No gouging or scuffs on any cylinders, no slop in the bearings, so I opted not to break it down that far. I am replacing the timing chain/gears though, and I'm installing the comp cams 206/206 high energy cam lifter kit. With my higher ratio rockers, this should end up a touch bigger than the 212/212 cam they offer. Hopefully it's not too lopey, if it is I'll just swap back to stock rockers and it should be fine. I have match ported the heads and did a lot of blending on those. Polished and lapped the valves, new water pump, smog pump and maybe EGR delete, electric fan conversion, and I just ordered the Heddman 69370 headers which I'm hoping to fit with minor cutting/welding/rearranging. I'll be sure to check your numbers when I get to the exhaust, since I'll probly have a muffler shop build it from scratch. Maybe MSD Ignition? I've heard of awesome results using those. I know I could squeeze a V8 into my Trooper for less than what all this will cost, but I just want to see what that 2.8 is capable of I guess. lol
 

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The cam should help, along with the other performance enhancers you're adding. Be sure to replace the timing damper, they get old and the rubber "slipper" shoes harden, after that they break, causing the chain to go metal-on-metal with the damper frame. After that, Very Bad Things happen! Cheap insurance.



The headers might take more than a bit of chopping to fit, but if you're able to make them work it'll definitely be an improvement. If you're planning on retaining a cat, you should be able to plumb the headers right into a dual-inlet cat.

Or custom-fab a free-flowing wye and dump that into a large single-inlet cat, that would work, too 馃樃 . In that case you should be able to find a single-inlet cat with O2 sensor bung built in. Or your muffler shop could add a bung to the custom wye.

I've had the same MSD Blaster coil on one V6 or another for more than 20 years, I can't say there's a huge boost in performance but at least it's a good steady spark. Summit and Jegs, among others, sell the 8226 coil and it's a bolt-on exact replacment for stock. Otherwise you're looking at multiple spark setups and IDK if there'd be any appreciable gain in one of those, for this application. I've had different V6's with the Blaster rev to 6000 with no spark-related issues, so take that FWIW.

And yeah, an LS would have so much more power and get better mpg doing it, but a fair amount of work there, too. The stock pan won't clear the diff, so you either have to modify the pan and/or body lift the rig, maybe even an SAS.

The hot-rodded 3.4 in my '90 LS got about 15mpg this past Jan when I was taking my daughter to work in sub-zero temps, with ice and snow. So I can't complain about that. It has plenty of snap for what I need it to do, far beyond the performance level of my old hot-rodded 2.8. Maybe that'll be your next engine build, you never know, eh!! 馃樃

Cheers..........ed

p.s. see attached pics of custom-built Gen I V6 headers, from one of our members.

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I am in middle of a 2.8 to 3.1 stroker , comp cam , new springs , valve's , HV oil pump ,and timing chain. Staying with a 4.3 TBI and would like a set of the headers if i can fit them on my 89 LS . Any info would be kool.
 

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I am in middle of a 2.8 to 3.1 stroker , comp cam , new springs , valve's , HV oil pump ,and timing chain. Staying with a 4.3 TBI and would like a set of the headers if i can fit them on my 89 LS . Any info would be kool.
Hi, sounds like a good build, you're doing all the usual mods that work well. Be sure to use the coated pistons, as in my previous post. They'll run tighter clearances and will have no tendency to piston-slap, plus your oil control will be better and you might even squeeze some more hp out of it from better cylinder-sealing.

Our Canadian buddy Geoffinbc says it's a worthwhile mod to get the top of the exhaust valve guide cut to accept a Viton valve stem seal, instead of using the Old-School "umbrella" type seal which just rides up-and-down on the valve stem. Gives a more positive seal, same as what's already used on the intake valve. A good machine shop will have the cutting tool that's used to shave the top to accept a seal. Pretty much same as what they do with a Small Block Chevy.

Get the TBI holes in your intake manifold bored-out to 1-11/16" to match your 4.3 TBI. Much-improved airflow by doing this.

Header-wise, you're either gonna have to custom-build your own or modify an existing set. Maybe something from a 3.4 Camaro could be hacked-up to fit??

My 3.4 with the 2" stock down pipes running into a dual-inlet cat, and 2-1/2" exhaust/turbo muffler back of the cat, breathes Plenty Good. Maybe too much, the big exhaust did take away from the low-end a bit. It sure shows no restriction at the top end, the engine revs willingly to well over 5000.

Your built 3.1 ain't gonna need a 2-1/2" exhaust, either. I'd go with 2-1/4" max if you want to keep your low-end. But with the Stroker, you will get a very nice improvement in torque over a stock 2.8.

I have a collection of 3.4 swap files which also include a small amount of info on a 3.1 build. Send a private message (i.e. "start a conversation") with your email address and I'll forward the files. You may find something useful in there.

Cheers...........ed
 
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