1990 Trooper owner here

[SeanF]

hey y'all, I did a little looking around, didn't find the answer I was looking for, so I figured I'd introduce myself and ask. My engine's fine, remanufactured with only 20k miles on it, runs like a top. I've been curious, though; is simply swapping out for a 3.4L really the best thing to do if you want more torque/hp? I'm wondering whether I could rebuild a 2.8L into something a good bit more powerful, without installation issues or having to fabricate anything external to the engine. I realize that any significant torque/hp gains would require a new crank/rods/pistons/cam, so it's not a small investment, plus machine work and installation, but apparently these things were designed to be embiggened down the line, and how would one go about that? I see where the original is undersquare, so a longer stroke seems like a likely start, and a meaner cam probably wouldn't hurt. And understand, I'm not talking about doing anything to the one I have, but rather finding another one and going to town on it.

Anyway, just another old engineer here, from Raleigh NC, love my truck, just like experimenting with stuff. thanks!

[SappySE107]

Welcome to our mostly dead yet still hanging in there website You could build a 2.8 if you wanted, using a 3.1/3.4 crank and 3.1 pistons to give you a bit more torque. The 2.8 is better for higher RPM, which isn't really a truck thing usually but it certainly can be. The iron heads will limit you on power and RPM, but its more work to do the aluminum top end and may not be something you want to get into. Its worth it for power and RPM and MPG if you have the time and energy for it, but there isn't a carb/TBI setup which i believe yours is now? Port injection only. Iron heads are my weak spot right now, though I hope to learn a bit more as I do some flow testing with the heads and also install a 91 MPFI setup into a 90 firebird. A 3.4 is the best to start with if you build another motor, and externally shouldn't be any different to your 2.8 block. There are a lot of cam options, and some piston options short of forged. I don't have a lot for iron head on wot-tech.com, but you can see I have listed if you want. The cams you will see on summit or otherwise are all designed for iron head engines, so you don't have to go custom to get something that works well for your engine. The Comp 260 grind comes to mind.

[SeanF]

Ben, thanks a bunch. Yeah, mine's got the TBI, iron everything. My main concern about using another block is whether it would mate with the rest of the drivetrain easily; I think the 4WD trucks are kinda picky about that. Exhaust options are pretty limited too, unless I wanna mod some headers to make them fit. This is all just preliminary research right now, but I'm trying to consider all angles. I understand that there's a larger TBI that would work with my ECM, but it doesn't really fit the intake manifold unless I do some drastic mod. Just considering options. Probably trying to make a silk purse out of a sow's ear, but it's interesting to research.

[SappySE107]

Same bolt pattern for all the transmissions so I don't think you will have an issue with a 3.4 block if you wanted to go that route.

[SeanF]

thanks again. Yeah, reading through one post where a guy swapped a '95 Camaro 3.4L in, looks like the starter's on the wrong side, the stock oil pickup tube is too short, the motor mounts don't line up exactly, something different about the flywheel...but it's been done plenty of times. I met a local once who'd done it to his, he liked it a lot, but I didn't get to talk to him long about it. I'm gonna check out 3.4L crate engines. Love that WOT site, btw.

[SappySE107]

Starter should be the same for all RWD. Did you see it swapped into a fiero? That is a FWD setup with iron heads. Flywheel does change for some years. You can use a FWD flywheel and pressure plate and throw out bearing setup as far as I know. The camaro flywheel is offset and extra heavy.

[45es]

The 1993-95 gen 1 RWD should be a direct bolt in. Starter is on passenger side. You should be able to use your existing flywheel as long as it is neutral balanced. Should you decide that you want to go EFI, then I would very much consider building the engine as a hybrid using generation 3 top end. Select the heads based on how you intend to use the vehicle. Not all engines have to be built for maximum rpm and horsepower. When I built mine for example, I chose the smaller generation 3 headed to suite the lower RPM / torque range that I intended it to operate in. The engine sits in an older Jeep and performs very well.. Ben helped me get the engine tuned in the beginning. I have since, tweaked the tune to better suit my needs.

[SeanF]

The 1993-95 gen 1 RWD should be a direct bolt in. Starter is on passenger side.

yeah, apparently it needs to be on the driver's side in the 4WD Trooper. The guy that posted pulled it from a '95 Camaro. What you're describing with the better torque at lower RPM is exactly what I'm thinking of. I'll probably have all sorts of questions for you in the future, thanks!

[SappySE107]

If you need it on the driver side, use a 3400 block and put your iron head stuff on top and the timing cover and such from your current engine on it. All the FWD engines have the starter on the driver side in a RWD application. I think its odd they would move the starter between RWD and AWD.

[SeanF]

yeah, the truck's in for paint right now, but once I get it back, I'm gonna take a closer look. Glad I asked y'all, finding detailed information on this swap is tough. All I've got to go on so far is the few detailed descriptions I've found on the web, and the authors typically don't include all the critical details.

[SeanF]

by the way, just flipping the breather cap over seems to make a noticeable different, maybe a little more torque? Not earth-shattering or anything, but it does seem to help. Pretty cool.

[Evan Walker]

Now, that's fantastic! Welcome to the forum!

[SeanF]

thanks, Evan! I put Comp Cams 1.6 roller-tip rockers in it a couple weeks ago, makes a noticeable improvement.