De-cat downpipes etc

Gareth_GT_Hatch · Post by **Gareth_GT_Hatch** » Tue Mar 09, 2004 9:23 pm

I think the GT has the biggest inlet manifold and the G40 has the biggest (or best?) exhaust manifold. Im not 100% sure but the NZ might have the biggest throttle body...G40 has smallest Throttle body in any case

Krupa · Post by **Krupa** » Tue Mar 09, 2004 9:33 pm

Why oh why didn't they do a GT with an NZ throttle body and G40 exhaust manifold, and a G40 with a GT manifold.

It'd save us loads of work!

optima21 · Post by **optima21** » Tue Mar 09, 2004 11:34 pm

its s**t about the NZ throttlebody being bigger than the GT they're both the same size, while they will bolt the the inlet manifold the electrics are different and do are some of the vaccum connections.

having said that I beleive its possible to solder a plate on the side of the GT throttle body (where the throttle return spring is) to allow you to bore it out 4mm which will give an approimate 19% more airflow. Also new butterflys will have to be machined too

Gareth_GT_Hatch · Post by **Gareth_GT_Hatch** » Wed Mar 10, 2004 12:34 pm

Hey Dom, No need to use such foul language!

I did say I wasnt sure after all...Oh by the way Dan W, the inlet manifold is the same on NZ and G40 (or is it????)

optima21 · Post by **optima21** » Wed Mar 10, 2004 1:57 pm

what ya mean bad language, I guess people are too sensitive.

Anyway I just put that because people say they're bigger, I've now got a spare GT throttlebody and Dan's (got my NZ throttle body to see what he thinks).

Yeah the Inlet manifold off an NZ does appear to be the same as that of a G40.

The distributor is different though as the GT/G40 ones dont have a vacuum advance, but the NZ ones do

amstrange1 · Post by **amstrange1** » Wed Mar 10, 2004 2:34 pm

optima21 wrote:Yeah the Inlet manifold off an NZ does appear to be the same as that of a G40.

I forget who was telling me, but apparently there are different versions of the 3F inlet manifold - some are the same size as the G40 (PY engine) ones. Whether VAG fitted them with NZ/PY engine ones because of parts supply problems I don't know. I can't comment from first hand experience, because I've only seen a few GT inlet manifolds off the car and they've been the larger type.

The NZ seems to be a weird mish-mash between the older Polo engines and the 3F, with a vaccum advance dizzy - yet the same AFM as the 3F etc.

Here's a pic comparing the PY, 3F and NZ throttle bodies - nicked from Mark Hunter:

@Dom - Peter said he should be getting the GT TB back from Beavis soon, will get him to take pics of it to show you what's been done. I have no idea at this stage whether it's had a larger butterfly put in or not.

optima21 · Post by **optima21** » Wed Mar 10, 2004 2:53 pm

yeah pete's throttle body should be interesting to see, I dont think you can bore them out much unless you solder an aluminium plate to where the recess for return spring the secondary (big) choke is. Then I think its easy enough to bore them out 4mm. To solder to the castings you need something called "lumiweld" which I last used about 15 years ago, but at least you can still buy it. I'm not sure if I've already said that in this post, but I've definately said it on another polo site.
Anyway all my engine mods will be detailed on the other site with piccys as I do them.