Golf Mk3 Throttle body on MPI?

[Chris Coates]

Been looking at the existing throttle body on the mpi whilst having the head apart over the weekend and it definitely looks like that's where a major bottleneck is for airflow....

So. I've been looking at polo mods that use the same throttle body parts - Of which it seems a popular mod is to take the throttle body from the golf mk3 as it's a wider bore...

But if it is interchangable with the original throttle body... Then it's just effectively a bolt-on swap, right? I mean barring a vag-com adjust of course.

Anyone considered/done it or could confirm whether the mounts are the same? Looks very close....

If I can find a piccy as a comparison i'll post it up.

Edit:

Found one (shamelessly lifted)

Edited 23 August, 2011 by Chris Coates

[jrw]

The 1.4MPI is the same on the MK3 as the Polo. I got a Polo one off a scrapper to replace my faulty one when i had my MK3. Think that the 1.3 and 1.4 are the same. Sounds good with an induction kit lol!

[Chris Coates]

I'm just going on the pic there... The mounting bolts are the same - the plugs should be the same... And as it's bolt-on it should just need throttle adjust via vagcom... But the bore is much bigger!

[jrw]

Is one off a 1.3 and the other off a 1.4?

My induction kit went over the collar so they must have been the same bore and it was definately off a Polo that i got it.......(unless they reduced the bore on the newer models!) Mine was a R Reg so a pretty early MPI.

[Chris Coates]

Well, the one on the right looks more like the one on my mpi - I could be wrong however...

Whereas the one on the left looks massive in comparison.

If I really REALLY wanted I guess I could do some nifty conversion to work out the real-life sizes of the body internal diameter against the pic, I guess I could do that later if nobody knows either way.

[Tech1e]

Won't work, mk3 golf as per picture uses a throttle cable, Fabias are all drive by wire.

[Chris Coates]

And the Mark IV throttle body from the golf? Which by all accounts is DBW and has pretty much the same mounting bolts?

[Tech1e]

Not all are dbw, but for the 1.4 you might get something that would work, but that would be the same as a 1.4 Fabia anyhow.

[Chris Coates]

There does seem to be some possibilities - and i'm pretty certain that the internal diameter of the golf throttle bodys is indeed larger than the fabias with the same mountings....

I'll keep you posted if I get anything concrete.

[Chris Coates]

Right.

I've confirmed it - Seems my Fabia MPI has a throttle body, 047 133 062 G, which is extremely restrictive - a 47MM internal diameter. Rubbish.

However 06F 133 062 G is much larger and is a DBW plug-in part albeit without the hose attachments, which then begs the question what the hoses actually do...

One is from the crankcase so can't be much more than possibly a vent-back, maybe pressurised - The other hose i'm not sure about yet. Thoughts anyone?

[Chris Coates]

Anybody got any thoughts?

Hoses attached to the expansion tank... One of those hoses goes to the throttle body.

I'll be cracking on with having the throttle body off tonight anyways to get a proper look at it provided the weather is good (it might be time to get myself a nice big gazebo hahaha) but it would be good to work out what the hoses going where are responsible for.

To be fair one going from the crankcase just looks like it's gonna be pressurised - probably to pressurise the map - It's the other i'm unsure about, and i've not read the haynes manual yet to work it out - thought someone might know heh.

[Jabbasport]

Just leave the pipes, some throttle bodies have coolant running through them, just blank them off and run it as you would with the standard throttle body..

Kev

[Chris Coates]

Cheers Kev, i'll let you know how I get on later on.

[anewman]

I'll bet you could suck up quite alot through a 47mm straw I am sure when Skoda designed it they didn't think "hey let's cripple this engine with a tiny throttle body". Would be interested in seeing if there are any benefits in terms of intake noise/mpg/acceleration though.

[TriggerFish]

I'll bet you could suck up quite alot through a 47mm straw

Even more with a 47.1mm one though!

Go the whole way and ITB it!

[fsa]

Which VW is the wider throttle body from?

So get rid of the OEM black plastic housing + tubing between the airbox & throttle body and replace with duct tubing of appropriate width?

[Chris Coates]

Once i've got all the details together i'll put a how-to together for it. I'm just tinkering and working out everything first.

Suffice to say, you'll need to replace the current throttle body and its cover.

[fsa]

Once i've got all the details together i'll put a how-to together for it. I'm just tinkering and working out everything first.

Suffice to say, you'll need to replace the current throttle body and its cover.

Thanks, Chris...you are epicly epic!!

[sepulchrave]

Will you be replacing the inlet plenum as well, because I would imagine that there'll be a big step down to 47mm where this larger TB bolts to it.

What leads you to believe that the standard TB is in any way restricting the airflow on your engine?

Generally speaking the manufacturer will always size the TB to suit an engines net gasflow requirements with some overhead and you need to substantially improve the engines pumping efficiency before you start to run into problems.

If you're planning on enlarging the capacity, fitting a big valve head and hairier cam then you'll need to open up the throat of the plenum along with all these other modifications. Nothing can be considered in isolation.

Sorry to be a party pooper but it won't make a blind bit of difference, there is no spiteful OEM component conspiring to conceal the real power lurking in your car, you're deluding yourselves. On a bog standard naturally aspirated engine the one component which is usually not optimally designed is the camshaft, and changing this will usually only give you 5-10% tops.

[Chris Coates]

The inlet manifold is already wider than the throttle body...

...Which is why I expect that matching it with an equal size throttle body will result in improvements.

And soon enough, i'll find out

Edited 11 September, 2011 by Chris Coates

[sepulchrave]

The inlet manifold is already wider than the throttle body...

...Which is why I expect that matching it with an equal size throttle body will result in improvements.

And soon enough, i'll find out

Good, that's the spirit, don't follow the herd.

[sausage roll]

Keep up the good work Chris and let us know the results!

[Chris Coates]

Ok - Update...

I've found 2 part numbers that would work. One with no bodging, one that might require a little fab.

Coming across them might be more tricky however...

So far (for reference):

Part number : 06A 133 062 C

Bosch number: 0 280 750 036

Is a direct bolt-on part. Increasing the diameter from 47mm to 60mm, a 27% increase.

Seen some on the bay for ~£100 - but it's a bit much just to allow all the hoses to connect...

There is a seperate part, 06F 133 062 G - Same internal diameter but no hose attachment. I'll have to have my existing TB off to work out if I can drill out a hole in the new TB in a strategic place to attach the hoses to. I'll keep you posted.

Edit 2: 06F 133 062 also can be found with the correct hose attachments:

ebay - 06F 133 062 w/hose attachments

This would be a bolt-on part also, but to be fair I think you could probably pick up a norman 06F 133 062 and drill in your own barbs to mount hoses on.

Edited 13 September, 2011 by Chris Coates

[sepulchrave]

Is a direct bolt-on part. Increasing the diameter from 47mm to 60mm, a 27% increase.

In terms of gasflow it is actually a 63% increase in cross-sectional area, don't sell yourself short!

[anewman]

The hole for the hoses in the TB is a tapered hole at the end and is very smoothly finished, and I believe the brass bit is interference fit. Might be worth looking for a way to drill a hole, then tap a thread into it which you could screw some sort of hose fixing into it. Some threadlock of some sort and you should be able to create a gas tight seal.