I'm converting a recently purchased g40 engine to a turbo but dont have all the g40 engine parts but i do have a full gt engine complete and just wondered to save money would a gt throttle body work?

cheers gaz

i'll have a G40 TB for sale shortly if you're interested?

What management system are you using, stock digifant or aftermarket?

I'm guna use stock g40 one but not yet got ecu and loom

Stick to the proper throttle body then with the two switches.

yes but that one has a boost release valve and i dont want to waste all that boost unless it can be blocked off?

it gets blocked off when you turbo

i no it closes at full throttle but i want the boost to be their all the time while the flap is open its still guna wear my turbo so that boost may as wel be used ant it?

You can use a TB from an NZ engined Polo CL. It's the same as the GT one, but instead of a throttle position sensor it simply has an idle switch (if memory serves...).

G40 TBs have an idle and a full-throttle switch, but if you're using Digifant to run a turbo you're better off replacing the G40 TB full-throttle switch with a pressure activated switch anyway. Set it to around 5psi, and you'll find you get betting running with the turbo. Then just use the idle switch on the NZ TB.

You can use a TB from an NZ engined Polo CL. It's the same as the GT one, but instead of a throttle position sensor it simply has an idle switch (if memory serves...).

NZ throttle bodies are larger than GT items and the switch is a full throttle switch

but would it work?

You can use a TB from an NZ engined Polo CL. It's the same as the GT one, but instead of a throttle position sensor it simply has an idle switch (if memory serves...).

NZ throttle bodies are larger than GT items and the switch is a full throttle switch

My bad, the setup I described is what Mark Hunter got working on his T40 years ago - so can only assume he got the full-throttle switch working as an idle switch instead.

Externally the NZ throttle body is the same size - hadn't noticed that the butterflies were larger than 3F ones! Should probably go and swap mine over at some stage.

Yep, the smaller of the two butterflies is bigger. Tried to swap it with the GT one but the shaft won't accomodate the throttle pot

easiest thing to do is to remove the boost return valve from the g40 throttle body elbow and block up the hole. I got a mate who does tig welding to weld a plate over mine. You can just about see it in this picture:

I've seen other people simply wire the boost return valve shut or just shove a bung into the end of the boost return valve pipe.

the throttle body is a normal g40 one bored out to 51mm with a bigger butterfly plate.

I have wired up a pressure switch like andy said above.

where do you get a bigger butterfly plate from ?^^^

well I bought the throttle body 2nd hand but it was originally done by pitstop. Any decent machine shop should be able to do it but it's not cheap because the throttle plate is quite a intricate thing with opposing chamfers on either sides. Pitstop used to charge £150 exchange (i.e. you give them your old throttle body).