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2,513 Posts
Discussion Starter · #1 · (Edited)
01/24/2009 edit: I have launched a new website for this project:
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05/03/2009 Edit: April 2009 newsletter was released today.

03/30/2009 Edit: March 2009 newsletter released

Original post:


EDIT: I have decided to create this FAQ due to questions I am receiving. I will continue to update this FAQ in the future, so please re-check this post periodically if you have questions.

1) Why are you using the Northstar (N*) V8 and gearbox and not some other one like the Audi V8?

Originally, I wanted to find a V8 engine and manual gearbox that would fit the MR2 mark2 chassis without a lot of cutting of the frame (unibody) or firewalls. Preferably, something that required no cutting at all. I looked at the prior attempts to install a V8 into the mk2 and found that they had to cut the chasis and frame so much, they were sacrificing all the strength and structural integrity. Since the rear suspension attaches to the rear main crossmember which attaches to the chasis just aft of the engine, cutting the frame at the engine would create a very dangerous car. If the frame is cut, then it needs to be built back up again somehow, with new bracing.

I started with measuring my 93T 3S-GTE turbo motor and E153 transaxle. I found that the 3S is 20 inches long at the critical dimension?Crank pulley to the interface (face) where it meets the transmission. The E153 is 16 inches from that joint (face) to the left most edge of the case as it sits in the car. So, the whole powertrain is 36 inches and has about ? inch of space to the frame rails on each side of the car. I started out on the internet looking for lengths of various V8?s Of course, I considered the Chevy Small Block (SB) and LS series first.

I found the following:

Chevy SB = 28.75? long x 24.75?
Chevy LS1 = 27.0? long x 26.5? wide (with AC, but no alternator), 30? with Alt
Toyota 1UZ-FE = 26.8? long x 26? wide
Cadillac Northstar = 23.0? long x 27? (made to be transverse!)
Cadillac 4.9 Aluminum V8 (pushrod, predecessor to the N*), 23.5? long x 26? wide
Ford 4.6 SOHC = 23.5? long x 28 wide (note?starter in the way on transverse application)
Audi PT, ABH, and ABZ V8 = 20.6? long x 29.0? wide (starter, block skirt, and oil pump drive in the way on transverse applications)

These measurements don?t include any headers that stick out further than the heads/valve covers. I assumed I would be able to modify or build from scratch, block hugging headers. I assumed in every case, that an adaptor plate would be needed.

I did not measure the width of the 3S, but I did measure the empty engine bay of the mk2. It is roughly 30 to 31 inches wide (depends on how high up you put your tape measure), and 36.5 inches wide at the center of the engine bay, ? way back between the front and rear firewalls, where the centerline of the engine crank would be. The width of the engine compartment varies depending on where you measure. It gets as narrow as 35.3 inches at the shock towers.

So, I found that even if I used the Audi, and assume an adaptor plate with at least .5? thickness, and using the E153, I found that cutting would be required. So then I had the idea of seeing what the Fiero guys were using for a gearbox, as they have been doing V8 swaps for many years. The most prolific V8 kit for Fieros is made by V8 Archie. I checked out his site. I found that as recently as 2007, he started using GM F40 6 speed transaxles from the 2006 Pontiac G6. He said they were strong, and most of the gears (except 1st) were suited for the lower RPM?s of a V8. He manufactures a kit to join a LS series to the F40. I also found out that the F40 was only 14.3 inches wide at the critical dimension. That is almost 2 inches less than the E153! To add icing to the cake, 2006 F40s in NEW condition were available on eBay for only $400 !

Again, I assumed in every case, that an adaptor plate would be needed. It turns out that this was a mistake?more on this later. The SB or LS both required 1.0 inch thick adaptors.

I went to the wreckers and looked at a 1991 Audi PT V8 (3.6L). I found that if I were to turn the engine sideways for a transverse arrangement, the starter, oil filter/cooler housing, and front of the block would be in the way of an intermediate shaft. I also found the Motorgeek Audi performance forum, and found a project by Andy Hill where he put an Audi ABZ V8 into his 1984 Lotus Esprit NA,, but longitudinal, not transverse. He used an Audi gearbox. He documented every detail, and all the problems he solved, and how he did it. It was a fantastic read. I thought I could deal with Audi V8 transverse problems, so I bought a 1997 ABZ (4.2 L, rated for 300hp and 295 ft-lbs). I also bought an F40. This was Dec 2007/Jan 2008. During the course of the next year or so, I thought about and planned how I was going to deal with these problems. I discovered that removing the oil filter/cooler was easy, and those items could be replaced with aftermarket coolers and filter relocators.

I then discovered that the intermediate shaft (axle) would run into the block where the oil pump was located. I found that the ABZ does not have parallel block skirts! There was not really any room for the axle CV joint on the passenger side (right side) of the car. I also thought there might be a problem with the axles interfering with the rear suspension mount points on the rear main crossmember. Relocating these is not really an option, as that changes suspension geometry?a very bad idea.

These problems, along with the starter mount problems made me doubt my decision to use this engine. Later, while making a temporary adaptor plate, I found that two critical bolts to hold the adaptor plate to the engine (tranny to engine bolts) are inaccessible as they would be inside the bellhousing of the F40!

I decided at that point to re-think my project.

FAQ continued below.

2,513 Posts
Discussion Starter · #5 · (Edited)
Northstar bolts right up to the F40. Only one bolt does not line up, and that is easy to fix with a fabbed small bracket. This combo has been in use by the Fiero guys for a couple of years. I should add: it requires some large notching on the internal webs at the top of the bellhousing, to clear the N* starter nose. It also required some smaller notching on one side, on the outside if the bellhousing, to clear the N* water log thing on the back of the block. I also cut off some extra material on the water log. These mods are documented on the Pennock Fiero forum.

When I bought my ABZ, I did not know the N* bolted up to the F40.

The powertrain fit a little better than expected. If it weren't for axle/suspension interference, it would be possible to put this powertrain into the car with NO cutting! However, due to the design of this transaxle, cutting is definetly required. HOwever, it won't be a lot of cutting.

In the photos above, the powertrain needs to be raised about 3-4 inches. Currently, the trans is hitting the frame, preventing me from raising it furthur.

I have to make the tranny notch on the left side of the frame larger to match the tranny I am using, as the notch only matches the E153/S54. ONce I make the notch larger (I am going to attempt to do this by hammer rather than cutting), I will be able to raise the powertrain. I am planning on cutting the pass side frame a bit as well. Currenlty, there is only about 1/4" clearance between the front pulley and pass side frame.

DonnieStar and the other guy that tried the 1UZ + E153 cut a HUGE chunk out of the pass side, but in my case, I think 1/2" - 3/4" is all that is required on that side. The extra metal attached to the shock tower on the pass side must go as well (the stock prop rod plugs into this extra metal I am talking about).

I have now reached the point where I believe this V8 swap is realistic and possible, and I am going to proceed with the permanent modifications (frame cutting, modifying my brand new $700 axles, etc.).

2,513 Posts
Discussion Starter · #6 · (Edited)
FAQ Continued from post #1 (recently edited).

I went back to the Fiero forums and did some more reading. It turns out that the N* does NOT require an adaptor plate for the F40! It is also possible (not verified yet) that the older pushrod aluminum block Caddy 4.9 V8 ALSO bolts up to the F40! I went back to the wreckers and measured the N*. While I was there I also measured some other engines, like the 4.9. I included those in the above list.

In addition, it turns out that I originally measured the N* wrong (the dimensions cited above are corrected), and thought it was another ? of an inch longer than it really was! Suddenly, the N* looked a whole lot more attractive.

In Oct 2008 I obtained another mk2 (91na) for a song, and planned on using this shell as my ginea pig. It actually ran/drove, but needed some TLC. I pulled the motor/trans and carefully remeasured the engine bay. Up until now, I had only rough measurements with a lot of error. The engine bay dimensions I gave above are the most accurate version I have right now.

I discovered that if I were to use the N* + F40, my total powertrain width (crank pulley to outer edge of tranny case) would be 37.3 inches.

Remember the 3S +E153 is 36 inches.

So, my initial thought was that I need to buy about .6 inches on either end, however, it turns out that it is more complicated than that?more on that later.
My thoughts were:

I could try to solve the problems with the Audi, but I would still need an expensive custom adaptor plate, and I would have to cut the stock left and right most engine mount ears off the car. No way around that.

Or, I could use the Caddy N*s which were designed for transverse application (no starter issue, or axle clearance issues), and they BOLT UP TO THE F40 without an adaptor, and simply cut the car about .5 inches on each side. No expensive adaptor required!

I decided to switch to the N* and CUT THE DAMN CAR.

2) So even though you already bought the Audi ABZ, you bought a N*?
Yup. Know anyone that wants a 1997 Audi ABZ 4.2L with only 70K miles?

3) If I want to do a V8 into an MR2 mk2, what kinds of tools/skills will I need?

Obviously, you should have experience working on a car beyond oil changes, etc. You should have some experience with pulling motors out and putting them back in and making them run correctly. You should also have skills in welding. This project requires cutting the car frame, and welding it again. You will need to fab/weld custom engine and tranny mounts.

You will need to be able to specify how you want the axles shortened and re-splined. I plan to use an Axle specialist shop that modifies hardened axles. You will need to know how to add a stand alone engine management system to the engine. The Cadillac PCM is NOT an option right now. A custom wiring harness will need to be made. Possibly a hacked LS1 PCM is the way to go, or a good aftermarket unit.

You will probably need to have a custom carrier bearing and bracket made for the intermediate shaft, or weld/fabricate/modify the G6 or Saab bracket. Possibly this part will need to be machined, so you will need to be able to spec this part out to the machine shop. I am considering creating a manual on doing this swap for sale, and IF(big IF) I do, I will have drawings of all the parts that need to be fabbed.

4) What Cadillac N* year should I get?

The 94-99 N*?s are all pretty much the same, but there are two flavors. Using the GM VIN from the car the motor was in (you should always get a VIN and run a Carfax on it, so you can get records for that engine), look for the rarer VIN 9 code, with hotter cams. This is the eigth digit in the VIN. The VIN Y Northstars are more common. The difference can be found on Wikipedia, so look it up and do some reading. Also check out the biggest Cadillac forum.

I haven?t verified this, but I think the 94-95 have a cast aluminum intake manifold (easier to boost), but the later plastic manifolds work for boost, if they have some simple mods. The 2000+ Northstars are different enough to be avoided for now. The reluctor ring is apparently weird (and cannot be swapped), and they are Coil On Plug (COP), which aftermarket ECM?s can?t deal with yet.

They have other differences, like worse flowing heads than 94-99, so at least for now, stay away from them. Be aware that the 94-99 N* has its share of issues, like headgasket/headbolt failures, using oil, leaking oil, and if you remove the headbolts, you will, 100% of the time, strip the threads. Inserts are required, or re-boring the holes, and re-threading. GM used permanent locktite on he head bolts

5) Do I have any other V8 choices?

Possibly the Cadillac 4.9 bolts up to the F40?not sure yet on that. Starter in a different location than the N*. Check out Pennock?s Fiero forum for answers. Remember that the 4.9 is another .5 inches longer than the N*, and makes a whole lot less power, and is not really that much more compact in spite of having pushrods. Not really a good option. However, the Caddy forums have a section for turbocharging this motor.

6) I searched eBay for a Northstar and came up with JDM Cadillac Northstars? WTF?

I guess there is someone pulling N* from Cadillacs sold in Japan. Probably at the 40K mark due to Japanese emissions laws. I am not sure. I bought mine using searching under Eldorados.

7) What are my transaxle choices?

The GM version of the F40 from the 2006 Pontiac G6 sports sedan, I think the GXP or GTP version?not sure. The 2007 version of the F40 will also work, but it has different ratios. Also, there is no surplus reseller for this trans. Saab originally created this trans for their 2003 9-3 and 9-5 cars. Do NOT use this trans, as it has a different bellhousing bolt pattern.

8) Why is the F40 so cheap on eBay?

There are 1 or 2 resellers on eBay selling a surplus of these transaxles. Believe it or not, the Fiero guys started using the 2006 F40 back in 2006 simply because it bolted up to the N*, and they needed to keep things short to fit the Fiero better. This was back when they cost $1800 from GM. The rumor goes that in late 2006, GM decided to change the ratios of the F40 for 2007, so they sold off a bunch of 2006 F40?s as surplus, as they were not going to use them in the 2007 Pontiac G6. Someone that is a eBay reseller snapped them up, and they have been selling them one at a time ever since. Recently (Dec 2008), the price on these was $300 + 100 shipping. Interestingly, if you buy a 2006 spec F40 from GM nowadays, it?s around $1800.

9) How much has this project cost?

Final cost has not been figured yet, as this project is still under way.

Audi ABZ: $2500 with shipping
G6 axles: $700 - $800
G6 shift Cables: $75
G6 engine mounts: $100 (probably will end up not using one of the 2 mounts).
G6 tranny (F40): $500 with shipping(New), now around $400 with shipping on eBay (new)
1996 Northstar , 40K miles with AC compressor, $1675 with shipping
MR2 mk2: $900
Clutch I did not use for the ABZ: $160
Does not include misc nuts, bolts, raw materials, etc.
Also, the 2003+ Saab 9-3 axles might be cheaper. Not sure yet on that one. Fortunately, they are much more common than G6 axles, and can be purchased used. See FAQ #10
I hope to recover possibly $1500 for the ABZ. Crossing fingers on that one.

2,513 Posts
Discussion Starter · #7 · (Edited)
10) Those axles are hella expensive! Isn?t there a cheaper choice?

Yes, possibly. You can buy used Saab 9-3 and 9-5 axles. The Fiero guys are still trying to figure out if the Automatic Trans Saab axles are the same as the manuals. Possibly they are (not verified).

The 9-5 is a wider car, so the axles are longer, making it easier to shorten them for the MR2. The 9-3 is roughly the same track (width) as the MR2, so I am not sure if they can be used. I think (not sure) that the G6 axles are stronger. They are also longer. Be aware of that the G6 axles and Saab axles cannot be mixed, with the exception of the left side (driver?s).

The intermediate shaft of the G6 is MALE on BOTH ends. The intermediate shaft of the Saabs are male at ONE end and FEMALE AT THE OTHER. The Saab probably (not verified) uses the same axle for the left and right side of the car. This makes sense from a cost/manufacturing standpoint. Also, the Saab intermediate shaft is HOLLOW making it easy to shorten (just cut and re-weld).

Possibly the left/right axles are hollow?please find out for me. If they are hollow, its a little trickier to shorten them, because the outer spline will be wrong to plug into the stock MR2 turbo Rzeppa outer CV joint. YOu have to use the MR2 outer axle stub in any and all cases, as its compatible with the MR2 hub, esp if you want MR2 ABS.

The G6 axles are different for the left and right axles. The right axle has a FEMALE spline to join the intermediate shaft. All three parts are solid and thicker than the MR2 Turbo axles. I will probably just shorten my G6 axles as I already have them, and re-selling the ones I have is not a good option (too rare).

Another option is axles from the Colbalt SS and Saturn ION Redline. Be aware that they must be the SS or Redline version of these cars, as these cars are supercharged, and have a different trans and axles than the regular cars. I hear the SS guys are breaking stock axles (the shaft and not the CV), so there is one company offering aftermarket axles for around $700 (no intermediate shaft).

2,641 Posts
If you decide to mod the engine and want fuel rails, I have a few sets machined that I made back when Bill started his Northstar gig ...

Looks pretty cool to me! A good read for sure. Do you know the weight differences between this engine tranny combo and say a 3S setup?

All the best,

2,513 Posts
Discussion Starter · #9 · (Edited)
11) Weights of the Motor and Trans?

I don't know these for sure, but I hear that the N* is around 460 lbs. The F40 is around 140, but seems lighter to me (I have muscled it around quite a bit lately).

I have heard that the 3S is around 600 lbs, and I am not sure if that included the E153 or not. I hear the E153 is around 125 lbs.

The Audi V8 is reported to be 460 lbs.

From the weights and Measures of engines link poste in the MR2 V8 sticky:
Cadillac Northstar V8 484 (71)
Cadillac Northstar V8 403 (79) (bare, no accessories)
Cadillac Northstar V8 464 (80) (dressed)
Cadillac Northstar V8 404 (155) (without accessories)

(71) Car Design & Technology, May 1992
(79) Automotive Industries, July 1992
(80) Automotive Industries, December 1992
(155) Machine Design, June 11 1992

Given the dates of the sources, they might be for the aluminum manifold version of the N*. THe plastic manifold, I am sure, is lighter.

2,641 Posts
Between you and Gouky, I have serious "swap envy" these days as my damned 3S keeps exploding on the track ... The weights don't look too bad. What is the final drive for the F40? Any idea if there are any LSD options?


2,513 Posts
Discussion Starter · #13 ·
Thanks for the Link Bill, do you know of any other Nortstar performance companies?

FAQ Continued:

12) I want to know more about the F40 transaxle!

2006 F40 (MT2) --- NOTE: the 2007 F40 is called the MU9
Type: transverse front wheel drive, six
speed manual transaxle
Engine range: 3.9L
Maximum engine torque: 245 lb-ft ( 333 Nm )
Maximum gearbox torque: 295 lb-ft ( 400 Nm )
Gear ratios: MT2
First: 3.77
Second: 2.04
Third: 1.32
Fourth: 0.95
Fifth: 0.76
Sixth: 0.62
Reverse: 3.54
Final Drive 3.55
Maximum validated gross vehicle weight: 3527 lb ( 1600 kg )
Case material: aluminum
Center distance: 197 mm
Fluid type: Castrol BOT 0063
Transmission weight: 56 kg ( 123.5 lb )
Fluid capacity (approximate): 3.1L / 3.27 qt ( dry )
Power take off: no
Applications: Pontiac 2006 G6

Here is a cut-away photo of the 2007 version of this trans:

Ok, for a comparison, here is a G6 intermediate shaft, installed into an F40, and the carrier bearing is is a machined block that is part of the V8 Archie kit. This is a Chevy Small Block. Note the location of the end of the axle relative to the block (relative to the front pulley). This is where the CV joint is approximately located.

There is an aftermarket Quaife Limited Slip differential available for the Saab F40, which internally is the same, and it has been verifed that the LSD will fit the GM F40. At the time of this writing, it is over 550 british pounds (about $1100 usd), and shipping is on top of that, along with Britsh Value Added Tax (VAT the UK name for Sales Tax).

Also available from Quaife USA for around $1500:


2,513 Posts
Discussion Starter · #14 ·
FAQ Continued.

Another shot of the V8 Archie kit inter-shaft:

Complete G6 Axles:

Complete Cobalt SS axles. Note the diamter of the inter-shaft.

The F40 uses a hydraulic TO bearing.

This needs verification, but the hydraulic hose assembly from RockAuto for the older Pontiacs will work on the F40 TO bearing, which has a fitting as part of the TO bearing. Then, a way to splice this hose assembly to the MR2 stock hydraulic line just needs to be fabbed. I do NOT know if the MR2 Master Cylinder is going to work with the F40 TO bearing.

2,513 Posts
Discussion Starter · #15 · (Edited)
F40 Ring Gear:

F40 shift Cables.

I have obtained a pair of cables from the 2006 pontiac G6. I bought them new from GM for around $75 or so (Can't remember). They come with the ball-snap ends that go on the trans, the stock mount bracket, and the other ends have a plastic threaded stud. I haven't thought about splicing them to the stock MR2 cables, but during my original test fitting of the drivetrain, I fouund that the stock MR2 cables on my 91na are not long enough to reach the shifter on the trans (it points upwards, and rearwards). I don't think splicing them will be a big issue. The stock bracket will need modification, of course, because its designed for cables that run directly aft of the trans. The Fiero guys worked this out. V8 Archie offers a cable lengthening service for the Fiero. I plan to lenthen mine myself, using the G6 cables.

Shifter end of Cables:

Tranny end of Cables. They come with the bracket.

2,513 Posts
Discussion Starter · #16 · (Edited)
This is just FYI. I haven't worked on anything domestic for some time now.

Removing the Power Steering pump from the Northstar

Today I removed it. I had to buy a special puller for the pulley which must be removed first. The pulley is plastic with a metal hub. The puller pulls only on the hub. I lucked out and found the right puller from Harbor Freight on sale for $7.00 !
THe pulley must be removed first to get at the two bolts that hold the PS pump to the engine.

2,513 Posts
Discussion Starter · #17 · (Edited)
I have heard a rumor that there is a Northstar aluminum flywheel available from Spec. WOuld someone look into this? Find out what clutch kits are available. The F40 uses a 1.00 inch diameter, 23 tooth spline on the input shaft. Same as Porsche.

The above mentioned CHRF has an 11lb steel flywheel. I am going to find out if its small enough in diameter for the F40.

Anticipated issues:

Passenger side motor mount. There is NO provision on the front of the block. I am not sure how GM mounted this motor in Caddys. Possibly they used the bolt holes located near the front (right end, aka pulley end) of the block, under the heads, on the sides of the block.

The Differential case on the F40 is a lot wider than the E153/S54. Hopefully, this is due to a wider (stronger) diff gear. That said, this causes a problem with the left side axle. The axle seal on the F40 would be roughly 2 inches to the left, more than the E153/S54, assuming the trans is placed in roughly the same spot as the E153/S54 in the car. Interestingly, the Fiero guys have exactly the same issue with the F40 vs the stock Getrag Fiero trans.

This means the axle on this would need to be that much shorter. The problem with that is that shortening it this much would cause problems with axle travel as the suspension moves up/down. My plan to deal with this is to cut the frame on the right side first, and not cut the left side yet, and check the engine fitment at that point. Moving the whole kit-and-kaboodle to the right would help the left side axle.

Possibly the mounting point for the lower control arm and the stock rear crossmember will be in the way of the transaxle. Not sure yet, as I have not been able to raise this end of the whole powertrain up enough to be in its final location. This is my the step I am working on now, so I will have these questions answered soon.
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