3.1 power options

[Colorado Pete]

Hello,
I have an old Isuzu Trooper with a GM 2.8 v6. I have heard that I can swap in a 3.4 from a 93-94 Camaro. This will provide the power I am looking for, but this also involves quite a bit of conversion detail including drilling and tapping the block to swap the starter to the opposite side.

Another possibility is to get a used 3.1 from an early Isuzu Rodeo. That engine will already be set up for an Isuzu truck installation (starter position etc.). However in stock form it does not appear to be much better than the 2.8, except for the longer stroke. It does appeal to me for the stroke reason and because it should be a simple long- block swap job.

My question is, what kind of mods can I make to a 3.1 beyond selecting a better camshaft, that will increase torque significantly in the low to mid range? The truck as is has very little of both torque and HP, especially below 3000 RPM. I want to generate as much of both hp and torque between say 1600 rpm and 3200 rpm as I can.

Thanks for any advice,
Pete

[candychevy87]

pistons, heads , sfi intake manifolds, the 3.1 can dish out some power but i would use a cam, ported intake, ported heads, and ported exhaist manifolds, see what power you make from there, if thats not enough add juice

[Colorado Pete]

thanks...

The cam was the first thing I thought of. Not sure how much rebuild $$ I want to put into a 3.1, if the $$ add up I would be better off putting it towards just using the 3.4 and doing all the extra conversion work. Funds are limited, and I am trying to come up with a fairly simple solution. Still haven't made up my mind yet!

[Superdave]

Almost nothing is simple in the 60v6 world.


i'd pull your 2.8, swap in a set of 3.1 RWD pistons/rods and the 3.1 crank.. then slap on a 3400 FWD top end. Slide in a Crane or Comp 260 cam and enjoy 200 ish HP and 200+ ft-lbs of TQ.

[Colorado Pete]

Now SuperDave that's interesting. I hear you about the 'nothing is simple' part!

Already rebuilt the 2.8 once, it has 338,000 miles total (150k on the rebuild), so don't think I should mess with it any more. Plus, time and cost would be a factor. It is my primary commute-to-work vehicle (need a 4x4 roomy vehicle, the '85 Supra won't cut it) and the mechanic (not me) would have to be able to complete the swap job within a week or so. Rebuilds take lots of time.

I would like the power of the 3.4 but would also like to avoid the extra complexity and cost of the 3.4 swap by using a 3.1 from a Rodeo, which should be more of a drop-in.

I was already thinking about getting the right cam. With new heads as well on a 3.1 you can get that kind of power? Wow. Can I still run the original throttle body or should I go to the 4.3 liter unit? Will the original rear-mounted distributor still work?

I'd be happy with about 150 hp and about 185 ft-lbs. of torque peaking no higher than 3100 rpm with a fat torque curve in the 2000's rpm range. Don't want to re-engineer the whole fuel system either, won't have the time, money, or know-how, have to do the KISS way. I figure I'd get the motor, add what parts are necessary in my spare time, then when I get a break from work (which happens here and there) have the swap done by a guy I know here locally. With an engine already out of an Isuzu the swap should be a straightforward proposition.

Thanks!

[candychevy87]

A 4.3 lower unit is for a 90* block, it wont work to well......... at all

[Colorado Pete]

Candy, you've got a touch of dyslexia...3.4 60 degree, not 4.3....Although I would LOVE to get a 4.3 in there! Would require a swap from front IFS to solid axle though, NOT.

[bszopi]

I think he was referring to your mention of the 4.3 TB, which would be installed on the 60V6 manifold.

As far as swaps into Troppers, check out the engine swap area, as there have been at least 2 guys who swapped engines in the last couple of months that might be able to chime in.

[Colorado Pete]

Thanks Brad that helps.
The 4.3 TB on a 60 deg. v6 is one of the standard mods when swapping the 3.4 into a 2.8 Trooper. The 2.8 intake manifold bore is machined out to the larger diameter of the 4.3 unit, but as far as I remember it does bolt on.

[candychevy87]

fark me in the arsh, i didnt read it right i thought he was talking about the 4.3 lim

[geoffinbc]

If your on a strict budget then here is my suggestion. Find a 3.1, 3.4L, 3100 or 3400 of ANY variety and just grab a good crank and take the rest back for scrap or sell it off. Once you have that pull your engine and start the rebuild process. You are going to need new set of 3.1L RWD pistons. Once you have that strip it down and clean it up. If you have the tools then you can measure all the clearances yourself. If not you will have to get a machine shop to do it since they will have to balance the rotating assembly anyway. If everything is within spec do not waste money machining any surfaces that already spec out. Don't forget the heads too.

Bring it all home and throw it together with new bearings and gaskets. A Comp 252 cam installed in a 3.1L should get you in the area of 200lbs at 2000RPM which is pretty damn good. It will move your Trooper like the 2.8L never could. Horsepower wont be much over 160 but its all about the low end grunt when your on trails and hills. The throttle body mod is a great one and so is a set of 1.6 ratio rockers. If you spend your money wisely you should come in under $2000 all said and done.

Aluminum heads and SFI will net more power but there is no way your going to make that all work in a truck set up for TBI and do it all on a strict budget. Especially if you have to rebuild the engine too.

[Colorado Pete]

Due to my being away for weeks on end on jobs using my truck, and being back home between jobs for relatively short and unknown periods of time, I probably won't have the time luxury of rebuilding my current 2.8. Can't afford the down time for the truck.

I am thinking of getting a moderate mileage (~100,000k miles) 3.1 from a Rodeo and building it up when I can on my between-jobs breaks, which will keep my truck operational. Then when I can get at least a week break I can have the swap done which should be fairly straightforwards and not drag on too long - a few days at worst. Given my work situation this is the only solution that will fit. New cam in the 3.1, maybe putting on a 4.3 TBI and boring out the intake manifold to match.

[geoffinbc]

Yea that sounds like a good plan to me. Its nice to have a spare motor to tinker with.

[pushrod]

i have a Q. how high kms should you push a 3100 before a total rebuild is the best? comeback, ive got 220.000

[pushrod]

why o why

is there no custom grind cam that will work with the way the obd 1&1/2 is set up, im gettin real pissed with the comp thing, im old school tryin to learn, but to many road blocks, the best ive had xplained is i have to get a stand alone ecm, programable with a lap top, more bucks, what ever happened to stickin cam and related in, time it and burn rubber!!!!!!!!!!! pushrod