MT2 (Isuzu) 5 Speed in a 3.4 Swap (Page 1/2)
gjgpff JUL 08, 11:26 PM
I have a 1988 2.5 manual transmission notch-back and I am at the very beginning of considering a 3.4L (L32) or a 2.8L (L44) V6 swap. Several pick-a-parts around my area have suitable donor cars with the L32. Reliable L44s seem to be very be hard to find and expensive. I have been poring over the more detailed swaps here and I have a couple of questions to start off that I haven't seen answered (maybe the answers are there and someone can point me in the right direction):
1) the L44 should be a very straight forward swap but I'm discounting that because it's really hard to find any engine for anywhere near the price I can get a 3.4 ($300). Am I looking in the wrong places?
2) I'm assuming that, after the 2.8, the 3.4 is the easiest swap for any year, and in particular, 1988. Is this the case?
3) I would really like to retain the MT2 (Isuzu) transmission, and I can't seem to get the final word on whether that is a good idea or not.
- V8 Archie says (said?) it generally works for V8 swaps
- One particularly detailed 3.4 swaper said that he once cracked open the MT2 and it's gears were half the mass of the Getrag 282. That's the only hard example I can find that gives me pause.
- There's tons of third hand reports of MT2s melting down after swaps, but they tend to lack detail and in most cases it's a LS, or a 3800SC.
4) Failing this, I'm wondering if the job could be accomplished in two stages, first swapping in, say the Getrag 282; mating it with the Iron Duke, getting that running, and later swapping engines. I like this idea because I imagine it is easier to swap in a transmission or an engine than an entire drivetrain. Nobody seems to do it that way, though. Am I wrong?

I'm only looking to bump the hp up to ~150, and want to go naturally aspirated to limit hotspots in the engine bay. If 2.2L ecotec swaps were mature, I'd just do that, but they seem pretty fraught.

Anyway, thanks in advance!

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Geoffrey Gibbons

Raydar JUL 09, 06:35 AM
The short answer is that the Isuzu will work with the 3.4. I temporarily swapped an Izuzu into my 3.4 car, after I shattered my (tired) Getrag.
It should hold up fine as long as you don't shock-load it. If you speed shift and such, its longevity will be questionable.
There is also a larger jump, between 1st and 2nd gear, with the Isuzu, than there is with the Getrag.
The good thing about the Isuzu is that they shift quite nicely, and they are relatively inexpensive and plentiful.

There was a guy here who bolted an Isuzu to a 4.9, and went autocrossing with it. It worked for a while, and then fragged 2nd gear. He did that several times, until he got tired of swapping trannies.
From what I've heard, 2nd gear is usually what dies first. I've also heard shift forks mentioned, but don't know anyone who has ever broken one.

A Getrag swap will be fairly easy to do - whether you do it now, with the 3.4, or later on.
The axles and shifter are the same (with very minor shifter differences.)
You will need a Getrag clutch kit (or at least the Getrag release bearing), the Getrag slave cylinder, and the Getrag shift cables.

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Raydar
88 Formula IMSA Fastback. 4.9, NVG T550

Praise the Lowered!

pmbrunelle JUL 09, 08:58 AM
I ran an Isuzu on a stock 2.8 for years without blowing it up... that included semi-regular 5k RPM launches. At the end I decided to switch to a Muncie as a precaution, not because of a failure.

Getrag has a smaller 1-2 gap, but larger 2-3 and 3-4 gaps than Isuzu.

Doing a trans swap first then engine swap makes sense... take bite-sized chunks of work. Verify that the Getrag shift cable routing doesn't interfere with the Duke exhaust.

In terms of hotspots, that largely depends on your exhaust routing. The ECU and firewall area on my turbo V6 runs cooler than it did with a stock 2.8 exhaust configuration.
gjgpff JUL 09, 10:18 AM
Thanks for the response and insights!
I had seen that the shifting ranges are different between the two transmissions. Is that published anywhere? In cars with the Getrag, does their "SHIFT" light (I hate that light) go off at different rpms/speeds?
Assuming it does, that's something that the computer controls, right?

I'm going to continue to research this, put another thousand or so miles on the car as it is (I have about a thousand miles on it since I got it), and try to get a better understanding of it.
pmbrunelle JUL 09, 12:14 PM
The shift lamp is controlled by the ECM.

In order to identify the current gear, the ECM is programmed with the transmission gear ratios. Then, from VSS and RPM, it can determine the present transmission ratio, and see which gear it corresponds to.

If you want the shift lamp to work correctly after a transmission swap, the ratios should be re-programmed in the ECM.

Rather than trying to correct the shift lamp function, I would suggest simply removing the shift lamp bulb, and using your ears and butt feeling to shift like on any other car...

It is very easy to replace/remove lamps on the Fiero instrument cluster. There is a plastic access cover on the front side of the cluster than can be removed to gain access to the cluster lamp sockets. You don't have to remove the entire instrument cluster from the car.
da.slyboy JUL 09, 12:52 PM
I've utilized the isuzu with my 3.4 for years without any issues. Even utilizing the dinky 2.5 clutch disk on it. (would suggest updating to the slightly larger stock 2.8). I've autoX using it, but am not overly abusive to it. Biggest issue I've experienced was the shift cable routing with the stock V6 intake tube.
Patrick JUL 09, 02:05 PM

quote
Originally posted by gjgpff:

In cars with the Getrag, does their "SHIFT" light (I hate that light) go off at different rpms/speeds?
Assuming it does, that's something that the computer controls, right?



As has already been suggested, the best thing to do in regards to the "SHIFT" light is to remove the bulb. In case you're not aware, the "SHIFT" light is to inform the driver of when to shift gears to help maintain the best fuel economy. Is that what anyone really wants, some incessant nanny telling you when to shift... over and over and over and over again?

I found it nothing more than a constant distraction. If a red light illuminates on my instrument panel, I want it to be indicating something important.

[This message has been edited by Patrick (edited 03-18-2021).]

gjgpff JUL 09, 03:53 PM
I was unaware of the existence of the "SHIFT" light before driving the car for the first time. Imagine the panic, after the mechanic checked it, test drove it, said it was fantastic, and I handed over my $3k to the previous owner. I'm on the road, trying to learn it's shifting, trying to find a gas station, and every time I think I should shift, this red light goes on on the dash, but it goes out before I can pinpoint it's origin! Eventually I caught on to what was happening and it was a relief!
hnthomps JUL 09, 06:10 PM
I drove a 3800 SC Series II mated to an Isuzu five speed manual transmission for a couple of thousand highway miles. It worked fine but I did not do any high rpm clutch dumps or other potential shock loading things. If I had I would expect the Isuzu to eventually die at the worst possible time.

Nelson
fieroguru JUL 09, 06:20 PM
I have ran the Isuzu alongside a 2.8, 4.5, and a 350 SBC... only broke one of them and it was with the 2.8 - pushed 5th gear out of the case at 135 mph. But I will also say I generally beat the crap out of that drivetrain for a couple of years before it let go. The other swaps came later and I practiced a little more restraint (but still did a lot of WOT rowing through the gears).

Longevity of the Isuzu is more up to driving style than engine it is used with.