HP Junkies: Torn Motronic AFM Rubber Boot...

[WydRyd]

OK, it finally happened. The rubber boot which interfaces the Air Flow Meter to the Throttle Body finally gave way after 2 years and tore. I suspect because of the high boost pressures I run (1.25bar)

As the pic below shows, it tore right at the junction where the T-Bolt clamp fastens the boot to the throttle body.

Is this a common area where these tear?

If so, is there a way to actually strengthen this area?

I'm thinking of perhaps lining the inside of a new boot with extra tough, cloth lined tape. Would that work?

Any ideas/suggestions?

[WydRyd]

Looks like I'm going to have to do this mod and go to a Nitrile connector which'll handle the sort of boost levels I'm running

[dean]

When I did my EFI conversion, I eliminated that rubber ell and used an Alu. ell instead. I heard the rubber ones failed with boost.

Dean

[david.avery]

Merv, I had my AFM machined for the pipe, and a barb lip cut in it for the boot for $95.00 USD... worth it I think.

Todd @ protomotive said that you could run the stock boot, but "there is a single place they all eventually blow out". I guess that's where it is

[beepbeep]

Hmm..I'm not a fan of having AMM on the pressure side unless it's hot-wire AMM secured with heavy-duty ruber hoses.

[WydRyd]

Originally posted by beepbeep
Hmm..I'm not a fan of having AMM on the pressure side unless it's hot-wire AMM secured with heavy-duty ruber hoses.

beepbeep, the AFM has worked very well up to 500+ HP power levels! Juan Ruiz was still running an AFM setup all the way to 600+ RWHP, until he finally decided to go aftermarket EFI with pressure sensing

BTW, what size should the barb fitting be for the Idle Speed Actuator valve hose? Is it 5/8" ID? Can someone confirm please?

[david.avery]

Hi Merv

Todd had me drill a .625 " hole and tap with a 3/8" pipe tap... hope that helps.

[WydRyd]

Thanks mate!

[WydRyd]

Originally posted by david.avery
Merv, I had my AFM machined for the pipe, and a barb lip cut in it for the boot for $95.00 USD... worth it I think.

David, I actually used a Dremel tool and hand file to fabricate a barb lip on my AFM to stop the boot from sliding off under boost. Worked out very well and never popped off after that

Just a tip for anyone else considering such a mod and wants to save some cash

[YermanCars]

Wydryd, what did you end up doing. i am having the same Problem

[WydRyd]

YermanCars, I did exactly the same mod as shown above, using a 90 degree Nitrile connector and a brass 5/8" NPT fitting tapped onto the AFM. Works great! I can't believe how much HP I was losing with that turn boot

Oh, make sure you block off the metal vacuum pipe that use to go into the OEM rubber boot. It's not needed once you go to the Nitrile connector.

[MotoSook]

Originally posted by beepbeep
Hmm..I'm not a fan of having AMM on the pressure side unless it's hot-wire AMM secured with heavy-duty ruber hoses.

The intake is being modified to draw low pressure air through it, upstream of the turbo. The AFM blew up last night when someone was being a bit heavy footed (Just kidding T)

Actually, from what was described to me the AFM may have been a rebuilt unit....

[WydRyd]

Here's a pic of the mod I performed.



I'm not overly wrapped with the kink in the Nitrile connector's bend radius. May have to remove it again and trim it up so it forms a nice consistent bend radius from AFM to Throttle Body.

For now, it works fine though and I've only tested it up to 1.1bar and am quite surprised at how much HP I was losing with that torn unit

[tsuter]

Looks like a short radius elbow or Cobra head needed.

[MotoSook]

There is a short radius 90 degree rubber (or silicone) elbow available. It's 0.25-0.375 inch wall thickness, and it fits perfectly between the AFM and the TB.

[Rot 911]

Any chance of finding some PVC pipe that would fit? Could always paint it some color other than white.

[WydRyd]

Originally posted by Souk
There is a short radius 90 degree rubber (or silicone) elbow available. It's 0.25-0.375 inch wall thickness, and it fits perfectly between the AFM and the TB.

Where can I get one of those from Souk?