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Hi everyone,

First time poster. I recently bought an NA6 which I'm doing a little work on that's a bit out of left-field. One of the things I'm doing is converting the intake to an electronic throttle. Does anyone know of any electronic throttles that would bolt directly onto the intake manifold? Maybe off an NC or a late-model Mazda3? Or something from a completely different manufacturer? I'll be making my own throttle controller for it but I'd like to keep the fabrication work to a minimum as I want to keep the option open to return it to standard spec after this particular project is done (in case it fails).

Cheers,
Peter

I wouldn't imagine an NC or 3 TB would be a bolt up job. They are completely different engines.
What's the reasoning for going to drive by wire?

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My understanding is that it is possible to retrofit a late model Commodore throttle-by-wire actuator to just about any manual TB.

Call Haltech and ask. They are doing this more and more with their new ECUs.

Reasoning: university project - hybrid electric MX5. I thought the later TBs probably wouldn't fit but with such a big tuning community I thought someone might know for sure.

Thanks, good tip on Haltech. Will give them a call and see. I know it's possible to use GM/Ford/Toyota throttle bodies but because I'm not replacing the engine control software I'll be developing a throttle body controller that mimics the output of the NA6 TPS to feed back into the ECU. The primary consideration is to keep the TB diameter as similar to stock as possible and to minimise modification to the surrounding parts, because every modification means I need to buy a spare part to bring the car back to stock when I'm finished, and we're trying to minimise cost.

Any throttle body can be made to fit any manifold with an adapter plate. Basically a 20mm thick piece of aluminium that bolts to the manifold. The throttle body then bolts to the adapter via some tapped holes. It's easy enough to make yourself with a hacksaw, a drill and a tap however it's probably easier getting it made professionally.

Whats more important is that the throttle body isn't too large for the engine / manifold otherwise you'll lose throttle response.

Just google "throttle body adapter plate" for some pics.

PLB-389 wrote:Reasoning: university project - hybrid electric MX5. I thought the later TBs probably wouldn't fit but with such a big tuning community I thought someone might know for sure.

Thanks, good tip on Haltech. Will give them a call and see. I know it's possible to use GM/Ford/Toyota throttle bodies but because I'm not replacing the engine control software I'll be developing a throttle body controller that mimics the output of the NA6 TPS to feed back into the ECU. The primary consideration is to keep the TB diameter as similar to stock as possible and to minimise modification to the surrounding parts, because every modification means I need to buy a spare part to bring the car back to stock when I'm finished, and we're trying to minimise cost.

Just remember that manual NA6 cars did not have a progressive TPS.

zossy1 wrote:Just remember that manual NA6 cars did not have a progressive TPS.

yep, it's basically a "closed" "not closed" one rather than "closed" "open by 12%"

as for the electronic throttle part, and keeping the standard ECU happy, why not look into something that simply acts upon the existing throttle? like the Commodore one mentioned by Zossy, or even easier, the actuator from a cruise control system (I know a lot are vac operated, but surely there's electronic ones out there:?)

Yes the switch style TPS should make it a bit easier if anything! The electronic throttle controller will have a position output that I can put through an arduino to fake the NA6 TPS signal.

I would prefer an electronic throttle because a large part of the project is working with transient torques - providing driving torque while changing gears, for instance. The throttle actuation needs to be super quick and very precise for these otherwise you get lumpy torque characteristics all over the place.

Probably gonna head out to a couple of wreckers later in the week and go throttle body hunting. Any recommended ones in Sydney?

Update: I went to Formaz spares out at Smithfield today and asked to look through their throttle bodies. Props where it's due: to the guys at Formaz for letting me wander around their incredibly tidy and clean warehouse with a pair of vernier calipers, and for doing a good deal on parts when they found out it was my uni project. For the record - I've no affiliation with them, it's the first time I'd ever visited (or knew they existed for that matter).

I found a mazda6 throttle body that has the same internal diameter as an NA6 body (55mm). The bolt holes are quite a bit wider though, and the OD is also a bit (maybe 5mm) bigger, so I'll need to make an adapter plate on one side and stick a short silicone connection in the other. Also bought the electronic throttle pedal off the same car, which will fit on the pedal box in place of the original accelerator pedal fairly easily (will have to cut and drill the pedal box and weld a couple of threaded bosses on for the bolts).

Next up, controller development and bench testing.