2.1 and 1.9 AFM interchangeability

[wbx]

Hello everyone,

Just idle curiosity here - are the 2.1 and 1.9 AFMs electrically and mechanically interchangeable? I'm 99% sure electrically, yes, but not so sure about the mechanicals.

A samba search yielded the following conflicting statements:

[hdenter]

My take is that you can use the 2.1 AFM with the 2.1 Thottle body on a 2.1 phlenum with digijet on an 1.9. They all bolt together. There is a mod needed to mount the later plenum on a 1.9 case and you will need to mod the switch wires for the 2.1 throttle body.
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'79 triple white convertible bug
'84 sunroof vanagon
'85 weekender

[tencentlife]

All correct, but to add that the AFM has to stay with its air filter box. The rectangular mounting dimensions are in fact different, but you could get past that. The problem is the position and angle of the AFM changes, and the AFM's are different lengths as well. Basically, if you want to go to late intake system, the most practical way is to do the whole thing, or at least make everything 2.1 from the plenum back to the airbox. There's no real penalty in staying with 1.9 runners for a 2.1 or 2.2, in fact they probably improve the midrange torque a bit, being slightly smaller.

The plenum mounting tabs differ because the crankcases changed, you can weld on suitable adapting tabs or do like some I've seen, bend the tabs up and let the runners carry the plenum, it's pretty damn rigid that way I gotta say.

But I just remembered, here's the rub: if you want to go late intake on early cooling, and you have to use the late airbox to use the late AFM and so on, the air box pushes hard up against the main radiator coolant hoses where they run vertically down to the right of the bellhousing. I took a 2.1 airbox and heated it up to form it around the hoses, it's doable but I chose not to do it because it was for a customer. There would be rubbing contact of hoses and airbox at that place, there's only so far you can deform the airbox and still fit the stock filter element in it.
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[wbx]

Cool, thanks for the replies, guys. That pretty much says it all (or at least enough):
AFMs fit only their version of air box, and there is an interference problem with a 2.1 air box with the 1.9 cooling...

My only added bit is that after the S bend boot (which pretty much has to match the AFM), parts are interchangeable. My air intake is 1.9 until the TB, and from the TB on it is all 2.1....
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[hdenter]

Not so fast WBX, I don't think the S boot is interchangeable. I think the 2.1 components are are all a little larger in diameter. Thats why you need the 2.1 plenum and throttle body with the AFM and airbox. The S boot is a little larger, too. I think you need to change all the complonents to have everything fit well.

If you are doing what you discribe, then one end of your S boot is possibly not fitting well depending on which one you are using (1.9 or 2.1)

hans
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'79 triple white convertible bug
'84 sunroof vanagon
'85 weekender

[hdenter]

Just checked Van-Cafe's website and there are different part #'s for the intake boots. I suspect that the using the 2.1 AFM would also mean the possible need for the 2.1 "vanagon syndrom" patch on the harness. for some reason my '85 digijet has the patch. Tencent and others commented that the patch doesn't hurt even if it is not needed and I never took it off.

Hans
_________________
'79 triple white convertible bug
'84 sunroof vanagon
'85 weekender

[wbx]