Bored out Throttle Body, not just ported and polished...

I've also seen conflicting posts about how big the ABF throttle body is. 65mm or 60mm.
The outside edge, ID measures 65mm. The actual throttle plate measures 60mm so, unless I'm mistaken, it's a 60mm throttle body?

 

Although mk4 2.3 v5 TB (AGZ 10valve) looks like it has same TPS plug as my 2L 8v. Anyone know the size of the v5 throttle body?

OBD2 vr6 looks like the same plug as 2.0 8v too.

 

Ok so I've got hold of the throttle body that looks the easiest to convert. It's off a Seat Toledo 2.3 V5 2000reg. Looks identical to the Golf AGZ 10v 2.3 v5, apart from the price 19.50 delivered!
70mm ID at the rear edge and 65mm at the throttle plate, so it's a 65mm TB.

 

Looks like I'll be able to slot the holes, like the ABF TB, so it will fit the standard 2.0 8v inlet

 

Thanks for the info in this thread; i'm keen to try the 10v V5 70mm throttle body on my counterflow 2.0 8v inlet manifold. It should work well with the later AGG engine, as the throttle position sensors look to be the same!

The only issue i have come across is that the coolant lines from the 8v throttle body take a sharp turn to avoid contact with the valve cover - something the V5 throttle body never had to avoid being a different way round!

Can the brass coolant connectors be prized from the throttle body? I'm considering taking the right-angled connectors from the 8v TB and pressing them into the V5 TB to make an almost-identical and fully operational 70mm 8v TB

 

^^VR5 and VR6 run on Bosch M3.8.X ECUs, run the same VDO throttle.

 

I've decided to make the V5 throttle body shown in previous pictures fit a Mk3 GTI 2.0 8v inlet manifold - the later AGG inlet. The throttle position sensors look to be the same and will plug straight in to the Mk3 GTI loom, so hopefully no teething problems with the TPS once it's all plugged in! The bore of the opening (both sides) of the V5 throttle body is 70mm, and the throttle plate itself is 65mm. This compared to a 54mm throttle plate on the original 2.0 8v throttle body means the throttle plate will increase by roughly 45% in area.

I'm gonna leave the V5 throttle body as it came from VW and not grind out any of the humps; i'm imagining the sudden increase in the size of the throttle plate will be plenty and i'd rather not potentially wreck a good throttle body by mucking around with a dremel before i've first tested it

One small difference between the Mk3 throttle body (marked '2.0') and the Mk4 throttle body ('V5') is the coolant fittings - the 2 brass coolant connectors are in exactly the same place on both throttle bodies, but the Mk3 ones are at a right-angle and the Mk4 ones are just straight out. These needed changing in the Mk4 throttle body to allow the OEM Mk3 coolant lines to be used and not clash the rocker cover - I prized the straight Mk4 ones from the V5 TB and pressed the Mk3 ones in. Luckily I had a spare Mk3 throttle body that had been previously damaged, so this made the perfect candidate to chop to bits to retrieve the brass fittings!

Shown side by side, the V5 TB and AGG TB are very similar and the TPS plugs the same. As Toyotec said above, obviously from the same 'family' of TBs!


This photo should show the Mk3 brass fittings successfully pressed into the Mk4 throttle body. One concern on inspection of the 'wheel' the cable sits in though, is that the positions of fully-closed and fully-open differs slightly between the 2 TBs - the Mk3 one is fully-closed at 8-o'clock, and fully-open at about 1-o'clock - the Mk4 one is fully-closed at 9-o'clock and fully-open at 12-o'clock. I'm not sure until trial fitting whether this difference will mean the throttle cable is too long and therefore slack? Otherwise I can't see a problem with the operation!

I did check the part numbers of the throttle cables on the Mk3 and Mk4 to see if they changed, and i only found the 'revision' letter of the cable changed (the part number was the same) - essentially the Mk4 one is just an updated Mk3 one. Hopefully this doesn't also mean they shortened it ...



The inlet manifold and V5 throttle body are currently at the engineering shop for some work - I've opted to get the holes for the 2.0 throttle body welded up and new holes drilled and tapped to fit the V5 TB. Some more material is being added to the corners of the inlet manifold face to allow for the slightly wider bolt holes!
Also will have to make a gasket, since the V5 used an O-ring on a plastic inlet manifold and not a paper item like the Mk3s.


I hope the effects of the larger throttle body will be beneficial (with it being a project on a spare manifold, i'm not fussed if it fails terribly) - hopefully the torque at the lower end of the rev range won't be sacrificed too much, but also hopefully the car will pull a little harder at the higher end of the revs due to the bottleneck of the smaller TB being removed.

The car has a MAF sensor with a much larger internal diameter than the original 54mm throttle body plate. This was obviously for a reason, for VW to have engineered a 'bottleneck' into the inlet setup, therefore hopefully the new inlet setup with a more uniform internal diameter throughout won't render the car gutless until 3,000 rpm lol

If any of you made it to the end of this reply, thanks for your time I'll report back once the parts are back from the shop - i'll grind out the bore of the inlet manifold to match the larger 70mm throttle outlet and then fit it up to the car!

Tom

 

I made it up to here, did it work and did you feel a positive difference in how the car performed?

 

Hi Beales, there are a few variables when i fitted the above inlet manifold to my AGG gti - the new inlet manifold had the larger throttle body, and i'd also largened the opening into the manifold from the throttle body and smoothed it to a shine. Also to consider was that the runners of the inlet manifold were clean, whereas the standard manifold i removed from the gti initially had oily residue in the runners (possibly a slight hinderance to performance?) also the plug for the throttle position sensor on the gti loom needed trimming to fit - the gti loom plugs in one way and the VR5 throttle body had the 'one-way-plug' the other way. Pins line up though.

In conclusion, although i cannot provide a Toyotec dyno graph and figures, i feel the larger throttle body has made a marginal improvement - throttle response (especially on downshift blips) seems sharper and faster, and mayyyybe feels a little free-er revving from 3000rpm onwards. Most noticeable improvement (depending on how childish you are) is a slight increase in the volume of induction roar lol the car sounds almost as if it's on throttle bodies, quite an angry bark now (i run a smooth ally pipe to a smoothed, 'holed' airbox with a tweaked trumpet.)

Overall cost of the work involved was about 40 in labour from a local engineering shop, for his time to weld additional metal onto the manifold and drill/tap new holes. Grab some gasket paper while you're there too! there are no off-the-shelf ones for this witchcraft. I widened the manifold opening in my own time.

This stuff paired with a panel filter, PB camshaft, Milltek cat-back exhaust and uprated engine mounts makes for quite a lively car in the wet lol

Tom