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v8 powered mr2

153K views 535 replies 95 participants last post by  mister3 
#1 ·
I'm starting my new build in the next few weeks. The drivetrain arrives this thursday. Engine is a 4.2L v8 out of a 2001 audi a6, chassis is a 1991 USDM MR2. Transmission will be a 6 speed manual. This will be the most unique engine swap I've ever done, probably also the most labor intensive.

Here's the car:



And what the motor is going in (my 3vz-fe powered 3.0L v6 mr2):

 
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#77 ·
Slow progress due to school. I'll keep this brief and add a photo or two.

I found a nice set of rims for the car, I'll need to get two more tires and also paint the rims gloss black. I also took the torque converter off the engine in preparation for flywheel/clutch/bearings test fit.

I've been thinking a lot about the quarter panels and what I will be doing there to bring it back to life, nothing inspiring yet but I have a few ideas on how to make it pretty. I'm as well considering changing the venting in the front of the car so the air comes in through the bumper and rad and out through the frunk hood. This will allow me to upgrade to a larger rad, better fans, eliminate some piping, and hopefully streamline the cooling system to accommodate the v8. Have already researched and chosen larger front/rear calipers, rotors. Final decision has been a headlight conversion, most likely custom; and I have a few never-done-before ideas in mind :)

I know some will complain about the decision to stray from the oem mr2 design but my reasoning is that with the wheelbase stretch the car might look like a "funny mr2" and I can't have that. If i want it to look like an mr2 I'll buy another mr2. So instead I'd rather have people see the car and go "whoa, what is that? it looks cool". Hence a lot of things will be changed, but hopefully the end result is as awe-inspiring as I can imagine :)

Bought these used. The previous owner liked my build so much he threw me a wicked deal on them. 17x8.5 +41 and 17x10 +41. The offset is kinda high but the widths kinda make up for that fact. No stretch here either. They came with a good set of 235/40r17 Nexxens that I'll be putting on the front. I'm not sure what size to go with on the rear, I'm thinking 275/40r17 or 255/40r17 (I'm using these to aid my decision http://www.rimsntires.com/specs.jsp http://www.miata.net/garage/tirecalc.html , audi transmission is calculated for 205/60r15) Anyways here are the rims:


 
#78 ·
Didn't feel like doing any school work today because it's over ten degrees outside, so I put my engine in instead. Literally took like 15min, slid in place like a baby. This is the first test fit of the engine, the frame is done (save for the tension rod brackets). Looks like my measurements and calculations all came out well as there is still plenty of room for the fuel filler neck in front of the block. Next I'll test fit the transmission and get to modifying my crossmember.



 
#79 ·
Clearances:
The engine still has to tilt backwards a little bit, but as it sits I should have about 2" from the top of the covers to the slanted firewall:


Enough room for the filler neck once I tilt the block back and install the transmission. I'll need some serious dampeners to keep the engine from squishing the pipe though as I believe I only left 1" clearance between the block and neck:


Just need space for hoses over here probably, nothing really on this side though :)


Finally, the oil pan ground clearance with reference to the original frame. Hard to tell in this picture but I have lots of room.
 
#83 ·
I was just at "widebodystarlet"s place last weekend and the build looks amazing in person... the amount of work is insane !!

All the extensive mods to the back end are allowing this V8 to fit in nicely with room to work around it.

This MR2 is going to be scary fast on the street putting down that V8 power on the road !!
 
#84 ·
One exam left, which mean's I've got plenty of time to procrastinate and work on my MR2!! :) Today I put the transmission on the engine, also marked the new x-member where I'm going to need to cut it to clear the transmission. Axle alignment looks pretty good but I won't know until I've got the suspension on. Which means I need to make the crossmembers work. Just waiting now to see if I can borrow a plasma cutter again :) Pictures!






 
#86 ·
I'll take some pictures today of the gap between the engine and firewall, maybe I'll put the fuel filler neck in there for fun :p I didn't want to stretch the chassis too much as I wanted the wheel wells to fit inside the taillights and I also wanted to stay around the 104.5" wheelbase that seems to be so widespread among mid-rear supercars.
 
#87 ·
Its more about the ratio between wheelbase and track.

The McLaren F1 has a 107" wheelbase, but is much wider than the MR2.

My first car was a 84 Ford Thunderbird (non turbocoupe) and it had a 104" wheelbase, but I don't think anyone would consider it a supercar.
 
#88 ·
on page 27 of this book , it has a comparison table of wheelbase to track of a bunch of different race cars.

At the top (with the most "square" ratio) is the 100cc shifter Kart. 1.155
in the middle of the table is the Lotus 7: 1.600
at the bottom is the Peugot 205 Turbo 'Raid" 1.922

They do say the following in the book: "Wide wheels, together with major inset or outset alterations have a big effect on the ratio. Peugot's large increase was to accomodate long range tanks rather than for roadholding.
Generally, a small figure should reflect a low polar moment
[of inertia] and vice versa but, even then, distribution of weight within or outside the wheelbase may make a bigger difference than the actual ratio."

I added the part in square brackets. Polar moment of inertia determines how quickly a car can change directions, for example: in the slalom. A Lower moment is better, and hence why I love mid-engine sports cars like the MR2 over conventional front engine cars or front engine, rear transaxle (dumbbell cars like the 97+ corvette or Porsche 928--they have a polar moment of inertia 'profile' resembling a dumbbell for weightlifting)

Anyway, if you can create a car with a ratio closer to square and at the same time concentrate the mass to the center, you will get a better handling car.
 
#89 ·
The engine weight sits forward slightly of where the old engine hung, but now the rear wheels are further back, which means I've moved the weight closer to the center by relocating the rear wheels correct? I've been wondering about ideal track width based on the 104.5" wheelbase I now have, but I couldn't figure out how the tire width comes in to this calculation. But basically as I see it, you're saying since the wheelbase is longer the track width needs to increase just to retain the handling aspect? I see how that makes sense. My new tires are wider and I'm going to need spacers just for them to clear the suspension.
 
#90 ·
Had a few hours to kill this morning so I trimmed the new crossmember down to size. I test fit it as well. It looks like I can't make the mr2 crossmember and the audi one connect as one piece... too much work and no benefit I can think of. For now I just clearanced the audi piece so the control arm bolts can could go into the mr2 piece. Also jammed one of my new rear wheels in the back wheel well for fun. They will have much wider tires on them when they finally go on the car. Pictures again!

Some shots of the clearance between engine and firewall now that the engine is on the right angle:




This is where the fuel filler neck goes, lots of space:
 
#96 ·
Where did he say the motor was bad?

I must have missed it. I only saw that from his donor Audi car, the quattro trans was bad. That doesn't matter as he is using an Audi 2wd trans.

Also, if any part of the bottom end of an Audi v8 is bad, the whole bottom end must be replaced as a short block. Audi will not sell rings, or crank bearings, among other things. They only sell head parts.
 
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