Looking for 70mm throttle body mod

[G60Rallye]

I tried to get Aelred to get me one done ages ago, but not heard anything for a long time.

Perhaps JP can do them for us?

[terrybullwon]

otherwise even the slightest lack of perfect seal can cause problems with the idle speed

You do need a gap though other wise the car will not idle

[A80Avant]

No you dont. That is what the idle valve is there for. It does the idling

[terrybullwon]

No you dont. That is what the idle valve is there for. It does the idling

Hold a OEM one up to a light..... every one i have done has a gap very small but a gap maybe less than a tho

The idle speed problems you have must be vems. I dont have a valve and my idle is just fine

[Jamo]

it ain't vems because vems will happily idle without the valve, what's with the recent anti vems posts?

[A80Avant]

Oem ones as all can be modified to be more open or closed by the small screw. They are calibrated stock to be in the position they are but can be completely closed if you move the screw. Mine doesn't, but vems was able to compensate. Not that it makes any difference to the thread. Bottom line is that the flap should be able to be completely shut.

[mcandmar]

Generally cars are setup to idle ~750-800rpms with the valve closed, ECU then raises the idle just a bit using the ISV. Throttle bodys do not totally seal, the Audi workshop manual has a section on how to set the throttle butterfly position, it should be open a couple of degrees.

[A80Avant]

I don't know how motronic manages to control idle but I'm pretty sire that on stock TB you can close it shut if you want

[JP]

I tried to get Aelred to get me one done ages ago, but not heard anything for a long time.

Perhaps JP can do them for us?

Can do them if people want but only if there is no other source as don't wish to step on anyone's toes.


Although I wouldn't bore them to 70mm instead it'd be around 69.2mm as otherwise it leaves the wall thickness too thin preventing one from really clamping down on the boost hose when running big boost pressures. I've got a jig made up for the butterflies to make them with a nice tight but free moving clearance. I did originally look at mass producing the butterfly unfortunately it is easier to make it to the size of the bore than it is to make the bore to the size of the flap. So unfortunately they are all done as individual items.

Hth JP

[Jamo]

JP what kind of price and turnaround would you be looking at?

[A80Avant]

I had mine done on an AAN TB and due to the fact that the area to clamp is wider it works nice. It may be an option if someone finds a used AAN TB

[Jamo]

Mine is an AAN TB

[A80Avant]

it should work fine.

[Wizard-of-OD]

time machine bump.

Can do them if people want but only if there is no other source as don't wish to step on anyone's toes.


Although I wouldn't bore them to 70mm instead it'd be around 69.2mm as otherwise it leaves the wall thickness too thin preventing one from really clamping down on the boost hose when running big boost pressures. I've got a jig made up for the butterflies to make them with a nice tight but free moving clearance. I did originally look at mass producing the butterfly unfortunately it is easier to make it to the size of the bore than it is to make the bore to the size of the flap. So unfortunately they are all done as individual items.

Hth JP

for JP as always.

Was sent this thread after having a discussion with a forum member here and briefly skimmed through it. Back in 2009 I performed (with the help of Unitronic) larger throttle body testing.
Thread (need to rehost the images)

http://forums.vwvortex.com/showthread.php?4690902

The general consensus was "well an Evo runs a 60mm throttle body and those make 700+whp). The answer I gave then which I will give now (all be it 3 years too late) is that it is not about power but about response. For my goals going with 2.5L at minimum I am going to go with a 75mm unit.

After dismantling both a 3B and AAN throttle body , JP is absolutely correct. The dimensions for the OEM throttle body as follows:
- OD @ rib of boot lip = 75mm
- OD @ base of boot lip = 72mm
- ID @ mouth = 68.2mm
- OD of throttle plate = 66mm (not sure where it was posted as 65mm but I got 66mm across 2 different throttle plates?)

By opening up the throttle body to 70mm you are looking at a wall thickness of 1mm at the base . The throttle plate shaft has a slit that maximum can be is 67.5mm and with machining can be taken to 72.5mm.

Considering I need to go to 75mm , I am going to recreate the cast portion out of billet , opening up the shaft slots to 75mm end to end and maintaining everything else in the OEM configuration. This is what I came up with:



Now I just need to find a 14mm OD x 10mm ID x 10mm long needle bearing...

p.s. I am staying Motronic so a Mustang or other DBC throttle body upgrade is not in the cards.

[GazzaG60]

was gonna say just get a mustang one and go from there.

think the illusion is in the fact that the bigger throttle allows more air per given amount of pedal. shame they become ****** on juice.