How big is yours...!! (Throttle body question)

Victor Meldrew · Post by **Victor Meldrew** » Sun Jul 16, 2006 7:52 pm

I have bought an alloy throttle body on Ebay.. 56mm..

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... %3AIT&rd=1

The stock plastic item is 48mm
The majority of the alloy ones advertised are 52mm.
Then there is the 56mm one.. dont know what its off originaly?

I think the 56mm still works ok, with an additional breather filter (in the sellers description so dont shoot if i am wrong).

The question is, what size is the hole on the inlet manifold? There is no point in having a 56mm throttle body with only a 52mm hole.. there would be a sharp edge in the air flow which would cause turbulance and could reduce potential flow.

The manifold I have is the VVC alloy type as fitted to the mk1 135. Does anyone know the inlet hole size? If its less than 56mm is there enough meat on it to have it ground out to match the throttle body to give a smoth flow path?

Rich H · Post by **Rich H** » Sun Jul 16, 2006 11:55 pm

Turbulence isn't such a big problem with such a large area, the plenum will sort it out anyway. (And causes laods more I would imagine) Best bet would be to smooth the entry into the plenum or as you say your 56mm will turn into 52 etc. If you can smooth it then the airflow will speed up through the narrow bit anyway.

The only problem I cn see with large throttles is the low settings being more sensitive, ie for a small throttle movement you will get a larger amount of air flow. So could be difficult around town.

HTH
Rich

Victor Meldrew · Post by **Victor Meldrew** » Mon Jul 17, 2006 12:12 am

RICHARDHUMBLE wrote:The only problem I cn see with large throttles is the low settings being more sensitive, ie for a small throttle movement you will get a larger amount of air flow. So could be difficult around town.

HTH
Rich

If it makes it more twitchy, then Lesley wont like driving it.... two problems solved at the same time..

Rich H · Post by **Rich H** » Mon Jul 17, 2006 12:13 am

Victor Meldrew · Post by **Victor Meldrew** » Mon Jul 17, 2006 12:30 am

when you look at the pic, it has a hose connection on the side, I asume this is where the breather hose should go, but in the sellers description..

"YOU WILL HAVE TO PUT A OIL BREATHER FILTER ON THE ROCKER COVER(can be seen in picture),AS THE 56mm DOES NOT HAVE A CONNECTOR"

So, slightly confused.......

mac · Post by **mac** » Mon Jul 17, 2006 12:42 am

The spigot you see should be attached to the IACV to allow the car to idle (bypasses the throttle butterfly)

Mac

Victor Meldrew · Post by **Victor Meldrew** » Mon Jul 17, 2006 12:45 am

mac wrote:The spigot you see should be attached to the IACV to allow the car to idle (bypasses the throttle butterfly)

Mac

Now see, youve lost me already....

(me)

mac · Post by **mac** » Mon Jul 17, 2006 12:55 am

The IACV is a round thing about 1/4 of the way along the engine and has wires going into it and is screwed into the plenium ( the plastic thing with "injection" written on it)

On the photo you posted it's just to right hand side of the pipe that has the Z bend in it (just out of shot)- basically you don't really need to worry to much about it as the current car has one too so just unplug and replug.

HTH

Mac

Victor Meldrew · Post by **Victor Meldrew** » Mon Jul 17, 2006 1:05 am

mac wrote:The IACV is a round thing about 1/4 of the way along the engine and has wires going into it and is screwed into the plenium ( the plastic thing with "injection" written on it)

On the photo you posted it's just to right hand side of the pipe that has the Z bend in it (just out of shot)- basically you don't really need to worry to much about it as the current car has one too so just unplug and replug.

HTH

Mac

Oh right then.. my car has the alloy VVC manifold on it. I asume it is pretty much the same set up.

This is the same manifold I have, I take it the IACV is the thing right next to the throttle body with the wires coming out.. looks easy enough to change out, the angle of the pipe is different but I think there should be enough flex in it to fit.

Rich H · Post by **Rich H** » Mon Jul 17, 2006 9:40 am

See in the last pic, 1" black hose coming from the top of the throttle body going to a small round thing with a plug on it? That is the IACV IIRC, connect that 1" hose to the connection on your new TB and Robert is your fathers brother.

Rich

Victor Meldrew · Post by **Victor Meldrew** » Mon Jul 17, 2006 7:02 pm

RICHARDHUMBLE wrote: and Robert is your fathers brother.

Rich

Now see youve lost me there again....