transverse V8 - Page 2 - MR2 Owners Club Message Board
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post #21 of 34 (permalink) Old January 31st, 2014, 06:54
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The SHO v8 bolts up to a mazda 6 gearbox. Definitely the 5 speed, not sure on the 6 speed but no reason it wouldnt...

just saying
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post #22 of 34 (permalink) Old January 31st, 2014, 15:00
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The 6 is the same as the avenisis/evora/eclipsev6
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post #23 of 34 (permalink) Old February 1st, 2014, 18:57
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Time for a new project?

Okay, so now I'm intrigued. I was unable to find the info on the ForMaha V8, and my eyes are getting tired from trying. As many crazy things as have been done, I feel this one should have been as well. Doubters and logic aside, what are the weight, length, width, and height of a SHO V8?
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post #24 of 34 (permalink) Old April 29th, 2014, 01:14
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I'm interested in this setup (LS4 + F40). But from what I've read the F40 is only rated @ 295 torque. Is there a gearbox out there that can handle say 350-400 and still allow you to mount transversely without intruding into the cabin or cutting into the frame?

Better yet, is there an F40 upgrade to allow it to handle more torque?
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post #25 of 34 (permalink) Old April 29th, 2014, 01:51
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The torque rating is also based on the weight of the Car. The Pontiac G6 GTP was around 3400 lbs, possibly a bit more. Even a 2nd gen MR2 weighed less, and with an aluminum engine, you lose another 100 or more pounds under a 3S equipped MR2.

So, the amount of torque the F40 can take would go up if the car were lighter. Less sticky tires would help too, but of course that's detrimental to performance.

As for upgrades to the F40, the only one I am aware of is a Quaife diff. There might be something else out there. Keep in mind the F40 was offered for only 2 years in the USA version, sold in low volumes, and the 2006 version was surplused out by GM when they changed the ratios for 2007. I strongly doubt upgrading internals to make it stronger is an option.

Stronger transverse manual gearboxes are going to be super hard to find. Just finding manual transverse transaxles is hard to do. The only ones I know of are made by Quaife, and they are not cheap.

You could upgrade an E153 (MR2 turbo) 'box to straight cut gears and dog engagement. Again not cheap. Ratios all wrong for a V8, but it would be stronger. http://www.franavehicles.com/dogTC.html
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post #26 of 34 (permalink) Old April 29th, 2014, 01:57
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Quote:
Originally Posted by JNRmr2 View Post
We got a winner. The perfect combo would be the LS4 engine with the F40 transmission. If you are willing to cut the frame (close to the tranny) you can use the E153 with the LS4 as well. The LS4 is very compact measuring an outstanding 23.25 inches, if we use it with the F40 which measures 14.30 inches that means both combine would come up to be 37.55”
http://forum.britishv8.org/read.php?6,37035,page=3

I'm not so sure about the LS4. I don't know what bellhousing bolt pattern it has. If its the same as the Northstar, then yes, it could work.

If it does not, then you have to figure the thickness of an adaptor plate in between the block and trans. That assumes you don't end up with a funky situation like the Audi ABZ, where some bolts would have to be INSIDE the bellhousing.

37" really is the maximum width. At this width, you will be required to pound dents into the MR2 pseudo frame rails on either side of the engine bay. At wider than 37", you will be required to cut. 3S + E153 is 36" wide, with only 1/2 inch each side clearance.

E153 has really bad ratios for a V8. THey are marginal even for a V6. Way to short unless you have some kinda small v8 that likes to rev to 3S redline

The northstar BOLTS UP to the F40 with the exception of 1 bolt that is easily handled with a simple fabbed steel bracket that took me about 30 min to make with a welder and bench grinder.

Last edited by cbulen; April 29th, 2014 at 02:03.
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post #27 of 34 (permalink) Old April 29th, 2014, 10:54
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Also something to note: While the N* bolts up to the F40 (except for that one bolt I mentioned), there is no off-the-shelf flywheel & clutch solution. In my case, I need to fab an adaptor (a spacer) for the Fidanza flywheel I have. This flywheel is made to mate the N* to the Fiero Getrag 5 speed, which has a much shallower dish in its bellhousing than the F40. It is not thick enough for the F40 bell.

The spacer solves this problem yet creates another: The ring gear would be further away from the engine and therefore the starter won't reach it.

So, with the LS4, the questions that must be answered are:

What is the bellhousing bolt pattern on the block (does it match the F40)?
What flywheels are available for it?
Are the flywheels small enough in diameter to fit into the bell of the F40?
Where is the starter on the LS4, I mean is it engine mounted or do typical LS4 applications have a transmission mounted starter (like the 3S-GTE/E153)?
If its engine mounted, what happens if you need to space the flywheel away from the block?
One potential expensive solution is a custom flywheel.
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post #28 of 34 (permalink) Old April 29th, 2014, 14:54
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according to the thread that was linked to earlier:

http://forum.britishv8.org/read.php?6,37035,page=1

Quote:
LS4 is the poor stepchild of the LS series. Used in FWD cars with transmission mounted starter. Small GM V6 bellhousing pattern.
not sure what the "small GM V6 bellhousing pattern" is, but it sounds like it might be the F40 pattern. http://en.wikipedia.org/wiki/List_of...using_patterns


So, you just gotta figure out the starter and flywheel.
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post #29 of 34 (permalink) Old May 3rd, 2014, 12:09
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I have two MR2s, one is a 93T with 3S-GTE/E153, aka the OEM drive train. The other MR2 is the Northstar/F40.

so I just pulled the E153 from my 93T to fix it. Just before I pulled it, I looked the space on the left side between the trans (5th gear cover) and psuedo frame of the MR2 unibody.

I also looked at the space between the right side psuedo frame and the 3S flywheel. I estimate there is about 1" of space on each side. This clearance allows you to pull the E153 without pulling the engine from the car. It gives you room to tilt the 3S while working the trans off the dowel pins and getting the input shaft to slide out of the clutch disk.

Bear in mind though that on the left side, there is a large depression, roughly the size of 1/4 to 1/3 of a helmet (imagine a sort of bowl shaped depression), in the frame rail. It matches the E153.

When I put the Northstar+F40 in my 91 MR2, I found that that depression was completely the wrong shape for the F40 on the left side of the car.

If anyone is interested, I could take some photos of my 91 MR2 engine bay, right where the F40 is up against the frame on the left. The Northstar/F40 are in the car right now.


If you put an engine/trans that is longer (I mean wider, side to side) than the 3S/E153, you will NOT be able to do clutch changes without dropping the motor/trans as a unit, completely out of the car. This is probably OK with anyone who is willing to do a V8 MR2, I am sure. Just something to be aware of. Changing plugs on the front bank of cylinders won't be fun either.
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Last edited by cbulen; May 4th, 2014 at 13:04. Reason: typo
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post #30 of 34 (permalink) Old May 4th, 2014, 09:47
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I'm still kinda new to the message board but I'll try to link this:

http://www.fiero.nl/forum/Forum3/HTML/000123.html

I think the F40 does bolt directly to the LS4. It's a matter of the starter mount having to be cut into the transmission (which this guy covers). I won't really know until I get my old engine out and the car completely disassembled.

Thanks for all of your advice. I'm sure I'll be needing all I can get when I start going forward with the car :-)
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post #31 of 34 (permalink) Old May 4th, 2014, 13:43
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That's a good thread to reference. That's what I did when I started looking into the Northstar + F40: I went to the fiero forums because they had done this engine combo.

Two things jumped out at me:

1) the starter he is using appears to be a standard starter, and therefore rotates the wrong direction. You must use a reverse rotation starter like a Toyota.

2) The Fiero does not have a passenger side engine mount all the way to the right like the MR2. I did not see any place on the LS4 in the photos in the above forum to attached a right side mount to. As I understand it, the Fiero uses a "cradle" under the engine/trans. Its a sort of subframe that mounts the engine/trans. You attach the engine/trans to the cradle, then lift all three as a unit into the underside of the car. GM FWD engines seem to have a mount on each side of the block, under the heads. In a transverse arrangement, the hard point would be at the rear right.

As most of you know, the MR2 rear crossmember is less "cradle-like" and is more of a large cross member that goes in after the engine/trans are put in.

You may need to fab something that attaches to the MR2 crossmember, near the passenger side, to pick up an engine mounting hard point at the rear right of the block.

In the thread you cited, he created a motor mount that attached to the rear head, all the way to the right of the engine. I'm not sure if you can do that in a MK2 chassis, as the right strut tower would be in the way.

Also, one other thing I saw in the fiero thread-- in one photo, he was fabbing a mount that attached to the F40, but it was being attached to bolts that hold the trans case together. This is an exceptionally bad idea.




These case bolts are way too small, and the tapped holed in the case are too small, and the amount of material (the cast case) that surrounds these bolts is far too little to take the stresses imparted by the trans on its mounts. They are meant to hold the case halves together ONLY, not to take the moment (torque) the trans imparts to the chassis. He is an EXCELLENT fabricator, and is way better equipped than most people (mill, lathe and welder), but he needs to consider the forces and loads involved, and the direction of the loads.



In other photos, he fabbed mounts that attach to the OEM bolt holes for the OEM mounts. This I approve of. THey are designed for the load they are expected to take. This location is on the rear of the F40. The equivalent in MR2 3S/E153 land is the rear mount that goes on top of the crossmember.




When building mounts, its extremely important to understand the loads and direction the loads are coming from.

For example, in the stock MR2 mk2, the left and right side mounts hold up the weight of the motor, and keep the motor from sliding sideways during cornering. They resist side-to-side movement of the drivetrain. In my own project, the right side mount (passenger side) on the car is no problem, since the MR2 already has the mounting ears stock in the unibody. The N* has no provision for a mount on the motor. However, I figured out where I could attach a mount to the block. I picked up as many bolt holes as I could for my mount.

The driver's side mount on the MR2 cannot be used with the F40. The stock MR2 trans (like the E153 or S54) have a mounting holes on top of the trans on the left side. The F40 does not. I ended up welding mounting ears to the underside of the MR2 chassis. THey are welded to the psuedo frame rails the MR2 unibody has.

They do almost nothing to resist rotation of the drivetrain. In engineering, this is called a "moment".

The front and rear mounts in the MR2 also hold weight of the drivetrain, but more importantly, they (together) are responsible for resisting 100% of the rotation of the drivetrain. I calculated that a bone stock MR2 turbo generates about 4000 ft-lbs of torque in first gear. This is during acceleration of course.

The front mount is trying to lift the nose of the car upwards. The rear mount is trying to push the rear crossmember downwards. Since its roughly in the middle, its trying to "Taco" the rear crossmember.

Engine/trans weight is shared by all 4 mounts, roughly equally. Compared to the torque generated by the engine, the weight is a much smaller force. This is why some FWD cars, such as Cadillacs that use the Northstar, use a "torque strap" on the top of the motor. Its for resisting rotation of the drive train. The OEM toyota MR2 mounts are more elegantly designed. The front and rear mounts just need a little help to make them less squishy. So, in my case, on my V8 car, and on my 93 turbo, I used urethane inserts in the donuts.

I essentially duplicated the Toyota mounts on my V8 project, because I recognized what the toyota engineers were doing, and why they did it (I'm a mechanical engineer in my Clark Kent day job). I strongly recommend duplicating the MR2 OEM mounting design philosophy as much as the LS4 will let you.

Whatever mounts you build, you need to bear in mind what loads your mounts are supposed to resist, and how they go about doing it.

Last edited by cbulen; May 4th, 2014 at 15:28.
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post #32 of 34 (permalink) Old May 4th, 2014, 15:36
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I don't have time to go through his entire thread to search for this, but one thing that is very worry some to me is that he does not seem to have a provision to resist side loads, such as during cornering.

I only saw this:


That is is modified Fiero cradle and 4 of his mounts. They are setup to resist the drivetrain moment (good), and drivetrain weight (good), but I don't see how they resist sideways movement (bad).

Another thing I saw that I really don't like: I don't see how the mounts in the above photo keep the engine from shifting forwards/backwards (bad). The way the mounts look in that photo, makes it look like a 4-link parallelogram, and the only thing preventing them from doing this is the strength of the bolted connections where the mounts attach to the motor.

At the transmission, this is less of problem, as his design of tranny mounts would resist forward translation of the transmission itself, but its introducing some weird torque between the motor and trans during heavy braking that should not be there.

GM FWD cars, and the Fiero had an OEM "dogbone" at the top of the motor to resist the drivetrain moment, but in his case, it would also help with the forward translation of the motor, and relieve the weird stresses his design is imparting to the bolted joints on the motor that I just discussed. If he has this, I didn't find it in the thread.

Maybe I should do a sketch of what I am talking about. It would be easier than trying to describe it.
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post #33 of 34 (permalink) Old May 5th, 2014, 01:59
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A very informative post Chris. I am looking forward to getting the old engine out and looking at the engine bay to get an idea of my options. You've obviously been there several times and know exactly what to expect.

I am fortunate to have someone that owns a garage within walking distance from my house and he has everything we would need to attempt this swap whether it involves fabricating mounts or a cradle or both. He seems to be confident that it can be done. He also has a dyno there

Vendetta and I have PM'd one another about this swap since he is interested in it as well. I was hoping to see what mounting system blueblur was going to go with even though he wasn't going to use an F40.

I looked at your N* setup (video) and was very impressed with your work. What is really appealing to me about the LS4/F40 swap is being able to increase the HP and torque to a more desirable level.

We will see. If this combo isn't going to work out I can always do the Toyota 3.5 V6 swap or just rebuild the 3.0 that is already in it.

Once again, Thanks and I appreciate all of your advice!
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post #34 of 34 (permalink) Old May 5th, 2014, 11:08
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Here's one of the diagrams I did some time ago to explain the Toyota OEM engine mount design.



crappy sketch I did of the OEM drivetrain
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