[TwoTonic]

We completed an engine swap into a '91 FJ80 recently. We installed an Atlas I-5 from a Hummer H3... Although this may seem like a strange combo, it's actually worked out pretty well. The Hummer motor has 60% more power, 40% more torque, gets 30% better fuel economy and is quieter. Being a more compact engine, the fit was a breeze-- Being an I-5, there was no steering linkage or brake booster interference. It fits really well.

Here is a link to an album for the conversion-

Picasa Web Albums - HT - Hummer H3 Dri...

The one side-effect of the conversion is that the truck is a lot lighter-- we took about 200# off the nose. Are there suggestions as to whether we should cut down the front springs to lower the front a bit? Or, is it better to put a lift set-up or longer springs in the back. I actually like the clearance on the front, but it does look funny with the nose high. We actually didn't realize that the weight reduction would have such an impact until we had the engine conversion done and stopped to think about how much lighter than all-aluminum block-and-heads GM motor was. The case on the 4L70E is much lighter, too.

I've attached a photo of the rig... Any ideas on the best way to level it?

Thanks,
TwoTonic

[MLX450]

Nice work there! Add an ARB bumper and a winch, that should give you some weight in the front.
Where did you get those front seats? , and more info on the conversion, please

[MoJ]

What's the difference in height front to back? I wouldn't cut the coils. Look at adding height to the rear via different coils or adding coil spacers. If the difference is around 1" spacers would be the inexpensive way to do it.

[Atoyot1031]

You could level it fairly easily with the right set of OME springs. Light in the front, medium or heavy in the rear.

Nice conversion. What is the rest of the drivetrain? What is the displacement of the motor and published output?

Welcome to Mud

[Lka1988]

That's a pretty clean conversion. The I5 is only 3.7L. How does it hold up to a loaded truck?

[Lka1988]

I just googled the specs for the 3.7L: 242HP @ 5600 RPM, and 242 lb/ft @ 4600 RPM.

A stock 3FE puts out 155HP @ 4000 RPM, 220 lb/ft @ 3000 RPM. Lower RPM for max torque, but the 3.7 puts out more overall.

I'd be interested to see a dyno chart for the 3.7.

[mmml4]

You could swap in a pair of later model springs. IIRC the 93-97 springs are about two inches shorter than the 91-92. I am using a set of each for a build I am doing and one set is about 17" and the other is about 19".

[jeepocabra]

You could always lift the rear a tad with ome springs.

I have questions about your swap, mostly about the transmition.

How did you retain the stock shifter.

Also were you able to retain the use of the shift indicator in the dash, and the other gauge functions.

[TwoTonic]

Eye-balling it, I think we're about 2" high in the front (or, 2" low in the back). Where it looks really funny is to put a trailer on the hitch with 300-400# of tongue weight. Makes the thing look like headlights are pointed at the starts. I think we'll play with adding height in the back, probably with stiffer springs to start and some spacers. I have other tow rigs but I'll use this to pull 'toy' trailers once in awhile.

We got about 240,000 miles out of the 3FE before starting the conversion. That motor was still tight, but it hadn't gotten any more powerful after its 200,000 mile break-in period.

The Atlas I-5 is part of the GM platform used in the H3/Canyon/Trailblazer/Colorado/Envoy families. The H3 got the 5-cylinder and the plusher trucks got the 6-cylinder version.

We used a Mark's Adapter kit from the output shaft of the GM4L70E and it bolted up very easily. Retained the stock Cruiser transfer case. The gearing in 1st for the GM transmission is low enough that, in LOW Range, it will be reasonable off-road. Front and rear gears are the stock 4.11s.

We used the stock GM engine control PCM, which controls both the I-5 and the 4L70 transmission.
Tuning, other than turning off all the unused stuff (VATS security, fancy dash indicators), is pretty much stock all the way. We used a K&N air filter which might be good for a few HP. Cats were retained, of course, and emissions are ultra-low-- another plus over the old 3FE.

In practice, the power difference is stunning. I have one particular grade that I drive all the time-- the 3FE would be panting at 48MPH with my foot planted firmly on the floor-- the Atlas easily pulls to 75MPH. Having owned 93-97 FJ80s, this thing will run rings around a stock '96 with the 1FZ (which was spec'd at 212HP).

The big pick-up (in addition to driveability, of course) is in fuel economy. On the road, I drive a 300 mile mountain/freeway/town loop pretty often... driving the speed limit with the 3FE would net me about 13 MPG. With the new Atlas motor, I can regularly exceed 19.5.

I'm pretty happy with how it turned out-- better power, better torque, quieter, and much improved fuel economy. I think it's a great conversion for a daily driver-- which can still be taken off-road once in awhile.

[TwoTonic]

Originally Posted by Atoyot1031

You could level it fairly easily with the right set of OME springs. Light in the front, medium or heavy in the rear.

Nice conversion. What is the rest of the drivetrain? What is the displacement of the motor and published output?

Welcome to Mud

The Atlas is a 3.7L in a 5-cylinder form (H3) and 4.2L in 6-cylinder.
At 242/242 it trounces the 3FE and breathes better (with VVT) than the 1FZ-- Way more power where you can use it than the 1FZ.

I have another FJ80 that we are planning to put an LT1 into-- I'd like to compare the two. The fuel economy on this Atlas is a big plus.

[TwoTonic]

Originally Posted by jeepocabra

You could always lift the rear a tad with ome springs.

I have questions about your swap, mostly about the transmition.

How did you retain the stock shifter.

Also were you able to retain the use of the shift indicator in the dash, and the other gauge functions.

We ended up using the Hummer shifter, which includes a gear position indicator in it's mechanical sweep. We did sacrifice the dashboard lights for gearing (although I'm planning to add that back in when we do the tach upgrade.)

The Hummer shifter is all electronically-controlled and it wires directly to the PCM. The throttle is, likeways, all electronic-- it's an E-Pedal. I wasn't sure I would like that, but it rocks relative to the ancient transmission control in the 3FE and Toyota transmission set-up. E-throttle means much quicker downshifts and no 'hunting' to figure out the right gear selection-- it's one of the advantages of leveraging the GM tuning and engine control-- smooth shifts and you NEVER have the feeling you are in the 'wrong' gear. It drives really well.

[TwoTonic]

Originally Posted by MLX450

Nice work there! Add an ARB bumper and a winch, that should give you some weight in the front.
Where did you get those front seats? , and more info on the conversion, please

Thanks!

The front seats were out of a Saab 9-3 Turbo. We found them in a Saab specialist wrecking yard in LA... they were in awesome shape.

With power and heat, the seats dress it up nicely and are very functional.... we looked a long time to find some seats "thin" enough to fit in there. There isn't much height to work with the way the stock seats are mounted in an FJ80. The width is just right too, so we didn't have to mess with the console.
We made a set of custom brackets and they mounted well.

The second and third row seats are honest Toyota seats out of a wrecked Lexus LX450. They bolted right in, after swapping the seat belt tensioners too (which, oddly, are different between the Toyota Lexus versions )

[sandcruiser]

OME springs in the rear would lift you up. Or even just a simple spacer-ring. 1" rings are darn cheap. Then add a bumper or a 2nd battery and you should be close to level again.

[Lka1988]

Originally Posted by TwoTonic

The Atlas is a 3.7L in a 5-cylinder form (H3) and 4.2L in 6-cylinder.
At 242/242 it trounces the 3FE and breathes better (with VVT) than the 1FZ-- Way more power where you can use it than the 1FZ.

I have another FJ80 that we are planning to put an LT1 into-- I'd like to compare the two. The fuel economy on this Atlas is a big plus.

I still want to see how well it holds up with a loaded truck.

[TwoTonic]

Originally Posted by Lka1988

I still want to see how well it holds up with a loaded truck.

We did haul a buddy's boat up over the hill a couple of times already. It's got plenty of grunt with a big boat on-- and will take Cat Creek Summit at 75, which the 3FE could only do 48 on. I think it's got more usable power than the 1FZ, I'm convinced. Beyond that, though, only the dyno will tell the story.

Come up over the Idaho line and we'll compare. Or, I'll bring it down to SLC sometime to put on an AWD chassis dyno?

[AKcruiserfreak]

Very cool! Thinkin ouside the box. I can't believe people are ragging you about power considering the 3FE's reputation as a complete dog. Whatever. I'm curious what your MPG's are.

TK

[bpassmore]

I love creativity, so I love this conversion. Good job!

[TwoTonic]

I used to comment on the 3FE in my 91's in the context of how much of the time (in town, up mountains, up hills, up slight inclines) I'd have to have my foot clear to the floor to get it to move.

With the Atlas engine, I'm averaging 19.7MPG on a 300 miles town/country/interstate loop. I can get repeatedly north of 20 MPG on the country portions, which in this state have a 65 MPH speed limit. This compares to 12-14 with the same route in the same truck and the 3FE.

I was giggling the first time I drove it with the Atlas I-5, between being so much lower weight and having a more powerful motor, plus willingness to rev. It just felt a LOT lighter and quicker. Immensely so.

No offense taken on the power questions-- I admit that it's a non-obvious conversion. But, we are really happy with it. If I was towing more I'd have probably done the I-6 in the same architecture-- 275HP, 270 TQ-- and given up a little fuel economy. But this is ideal for a mountain truck and daily driver-- we've taken it skiing a lot with the family's gear, hauling kids to school in the snow, mileage is great, it's quiet.

These motors are cheap-- there's a good used one on Ebay right now for under $500 with low miles-- and the GM tuning brings it very up to date, especially with variable valve timing. It really takes off when it comes up on cam. Toyota's 'F" series motors were a fine design 40 years ago, but in this truck we wanted an updated drivetrain with the solid quality only the FJ series have. It's a nice combo.

TT

[TwoTonic]

Originally Posted by MoJ

What's the difference in height front to back? I wouldn't cut the coils. Look at adding height to the rear via different coils or adding coil spacers. If the difference is around 1" spacers would be the inexpensive way to do it.

Just measured the height disparity... it's exactly 2 inches higher in the front-- unladen.

[ThePookieBear]

Wow. I find this very interesting. Sorry if I missed it from the pictures, but what did you do with the engine and transmission mounts? Were you able to utilize the stock one? And was Marks kit specifically for this engine/tranny combo, or was it for the tranny?

[80t0ylc]

I'm impressed with the fit & finish of the conversion. Looks like a professional job all around. Numbers are impressive, too. However, I'd like to see how it holds up over time and normal (maybe even a little abnormal) usage. Call me a skeptic or whatever, but the 3FE and 1JZ engines have both proven themselves over time. Nothing is perfect and both these engines were far from it. Your conversion sounds good in all areas, almost too good. Let's see how it passes the test of time. I'd be interested in seeing the HP & torque curves for comparison.

[TwoTonic]

Originally Posted by ThePookieBear

Wow. I find this very interesting. Sorry if I missed it from the pictures, but what did you do with the engine and transmission mounts? Were you able to utilize the stock one? And was Marks kit specifically for this engine/tranny combo, or was it for the tranny?

Hey, Pookie. Love the tagline about Land Rovers-- I changed so many alternators on that Disco-1 that I started to wonder why it wasn't mounted with quick-release clips-- or better still, explosive bolts. I finally threw in the towel the day it took 3 hours to change a tail-light bulb.

We did have to use the rotary cutter to get rid of the original engine mounts for the 3FE-- and replaced them with universal GM mounts welded directly to the frame. The Mark's Kit was awesome (thank you Denny). I think it's their MFK-1195 (A?) for the Th350/4L60 series to the Toyota transfer case. We didn't have to use any of their engine adapters-- and used most of the GM accessories, which I'd gotten with the H3 engine, so used the GM accessories brackets and serpentine. The Mark's kit, thoughtfully, includes a bracket which presents the T-Case lever through the original hole. Can't tell the difference from up top.

We did get the Atlas motor complete with the transmission and torque convertor already mounted and ready to install-- we had to do some work at the tailshaft housing to mount the Mark's adapter and then the T-Case. No machining required back there, though, and it all mounted up perfectly.

I can post photos of the engine and transmission mounts sometime if you're interested.

The conversion did work out even better than anticipated-- tuning was a breeze, too. I'd just say that the classical SBC conversion might have a more modern alternative. For 250 HP, great driveability and better fuel economy this is a sweet combo.

[TwoTonic]

Originally Posted by 80t0ylc

I'm impressed with the fit & finish up the conversion. Looks like a professional job all around. Numbers are impressive, too. However, I'd like to see how it holds up over time and normal (maybe even a little abnormal) usage. Call me a skeptic or whatever, but the 3FE and 1JZ engines have both proven themselves over time. Nothing is perfect and both these engines were far from it. Your conversion sounds good in all areas, almost too good. Let's see how it passes the test of time. I'd be interested in seeing the HP & torque curves for comparison.

Points all well-taken. The 3FE (like the 2JZ) is a legend for being over-built. I kind of felt bad pulling that 3FE with only 240,000 miles-- compression was still perfect and I'm sure it would have run to 400,000 miles easily. But, we wanted to take a shot with the Atlas and so far so good. That same architecture has been used on a bunch of GM trucks (Canyon, Colorado, Trailblazer, Envoy, etc) and I think has held up pretty well, but we'll see how the long-term reliability numbers come in... I'm always amazed to see the FJ80s listed on Ebay with 450,000 miles and original engine internals. That's reliability.

I'm probably most worried about the replacement engine's VVT technology-- BMW got burned badly with VANOS when it first came out, so time will tell if GM got that right or not when they put it in Atlas.

The gear-driven cam on the 3FE was amazingly strong-- basically never see valve train failures in those motors if you keep oil in 'em.

[lt1fire]

Look clean and if you are happy with it that is the important thing.
A few years ago I posted up the question of whether or not he I6 out of the trailblazer would be a good swap (since I had a buddy that was parting one out) I got ripped to shreads by some about how dumb of a swap that could be. Glad to see some others think out side the box. I love my 3FE but at the same time there are plenty of motors that would give me more power and better mpg at the same time.

[dogcatch'n]

how fast a vehicle moves, say from 0 to 60 mph is based on one primary factor and that is "horsepower per weight"....

you have more horse power less weight...this is always good..

it has to move faster....

now that being said, only time will tell how long the I-5 engine will last...and that is another suject all together...

but I must say, that this looks like a good conversion ...IMO..

[TwoTonic]

Originally Posted by lt1fire

Look clean and if you are happy with it that is the important thing.
A few years ago I posted up the question of whether or not he I6 out of the trailblazer would be a good swap (since I had a buddy that was parting one out) I got ripped to shreads by some about how dumb of a swap that could be. Glad to see some others think out side the box. I love my 3FE but at the same time there are plenty of motors that would give me more power and better mpg at the same time.

I'm not sure there's an 'perfect' swap, either... Just depends on what you want out of the truck. I have other trucks for towing, so this is mainly a daily driver with better power, torque, fuel economy-- so I'm happy so far. These Atlas motors clearly don't have anything like the track record the 3FE or 1FZ do-- but the H3 has pretty good off-road credibility.

The Atlas is helped by a static compression ratio of 10:1 and a pretty under-square bore/stroke geometry. It gets a lot out of its 3.7L and light weight, especially with the VVT which doesn't trade off low-end torque for high-end power. I guess I'll know after a couple hundred thousand miles. (For comparison sake, the 1FZ has a 9:1 CR, which makes it a nice candidate for that TRD supercharger, and the 3FE in its final form was a soft 8:1.)

I have a lot of admiration for the Toyota engines, BTW, but we do plan to do a couple more swaps into FJs-- one a LT1/4 hot rod and one a Duramax tow rig.

Different strokes for different folks, as Tunnell said years ago.

[Lka1988]

Originally Posted by TwoTonic

I have a lot of admiration for the Toyota engines, BTW, but we do plan to do a couple more swaps into FJs-- one a LT1/4 hot rod and one a Duramax tow rig.

This one I gotta see. I would LOVE a Duramax in my 80.

[ThePookieBear]

I talked to a guy the other day that said I should throw a 7.3L Powerstroke in my 80. Hmmm... Axle upgrade? . But I think the Duramax's are lighter, and are like 6.9. That would be fun.

[concretejungle]

Originally Posted by 80t0ylc

I'm impressed with the fit & finish up the conversion. Looks like a professional job all around. Numbers are impressive, too. However, I'd like to see how it holds up over time and normal (maybe even a little abnormal) usage. Call me a skeptic or whatever, but the 3FE and 1JZ engines have both proven themselves over time. Nothing is perfect and both these engines were far from it. Your conversion sounds good in all areas, almost too good. Let's see how it passes the test of time. I'd be interested in seeing the HP & torque curves for comparison.

Don't forget, your tax dollars are going to help hold up the warranty for this puppy!!

[TwoTonic]

Originally Posted by Lka1988

This one I gotta see. I would LOVE a Duramax in my 80.

The motor's a DMax LLY that's been on the shop floor for awhile. 6.6L turbo. We're planning to go a little different direction on the transmission, though, since we have a new ZF 6-speed to mate to the DMax. Everybody asks about the Allison automatic, which is a nice transmission, but the ZF is incredibly stout and has a very broad set of ratios across its 6 speeds. Sixth is a 0.50 Overdrive, so we're wondering what kind of fuel economy we'll get in an FJ80 on 33s with that OD combo. DMax hits peak torque at only 1800 RPM, so we are hoping it will cruise on the highway in the 1600-1800 RPM range.
The 80 is a lot lighter than the HD series 2500/3500 GM iron the DMax was meant to pull around too.

The 80 differentials are pretty tough, so hope they'll stand up to the torque.
Clearance will likely be an issue, so are thinking we'll need at least a 4" lift.

To go to the ZF gearbox we'll need to add clutch hardware to the 80. Anyone have a line on a source for clutch pedal, linkage, and master cylinder for an FJ80? A manual was offered Down Under, wasn't it?