Q&A

Mailbag: Finding a Transaxle & Turbo for a Lotus with a Ford Engine Swap

[Image/ Vauxford, Creative Commons Attribution-Share Alike 4.0 International]

Q: I have a 1970 Lotus Europa S2. It’s a mid-engined, rear-wheel-drive car.

With a little cutting and welding, I managed to take a Ford 302 (bored .30 over) and nestle it snugly behind the firewall. The engine runs like a charm, but now I need to find a transmission that will match the Ford engine and line-up with the rear wheels.

I know the Ford GT40 from the 1960s had the same drivetrain as my Lotus now carries, but I don’t recall what kind of transmission it had. Can you help me out?

Also, what engine components would I need to upgrade if I were to install a T3/T4 hybrid turbo with a 57-trim compressor wheel, kicking out 25-28 psi of boost? The engine is stock except for the overbore and matching rings.

A: That’s easily the most interesting combination we’ve heard in a while. The best part, is that the answer to your first question is also pretty interesting.

The De Tomaso Pantera was powered by a Ford Cleveland V8, and it used the same five-speed ZF transaxle as the GT40.

The ZF is very strong and has a limited-slip design. An 11-inch clutch plate is used with a hydraulic master cylinder for clutch linkage. If you can’t scavenge one of those, Ford Racing used to offer a GT40 transaxle (M-7003-GT), though it has been discontinued and would now likely cost well more than your project is worth.

As for the turbo upgrade, you’ll need to do a number of things.

The crankshaft needs to be replaced with a 4340 steel crankshaft, and the connecting rods need to be upgraded to H-beam rods. You’ll also need forged pistons, and you’ll need to drop the compression to 7.5:1 or 8.0:1 in addition to opening the ring gap.

Finally, you’ll need a camshaft designed for the turbo, and the entire rotating assembly will need to be balanced.

This is another in a series of weekly Q&A Mailbag sessions with Summit Racing‘s tech department, in which there are hundreds more. Click here to see them all

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2 Comments

  1. David Weakley says:

    Hi,
    I built a mid-engine sbc 41 Thames 1/2 ton in the 70s using a Corvair 4spd transaxle. I went through 5 of them over the years due to putting power to the glide side of the gears (running backwards). The kit car industry found my solution by using the 2002-2005 porche boxter S 6spd transaxle behind v-8 power. They go for an affordable $1500 and handle 400 ft-lbs torque . Use off road CV 300M joints.
    Enjoy your ride my friend.

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