Bosch air flow meter question

[Meatball]

Hi
Ive just had a bunch of mods fitted cam, heads,inlet manifold, trumpets, plenum etc and a re chip....my question is im thinking of fitting one of those bosch afm that act sell...are they just plug and play or would i need a another re chip to make the bosch afm compatible with the lucus set up?

[GreenV8S]

You'll need another chip because the Bosch AFM is calibrated differently to the Lucas one.

[Meatball]

GreenV8S said:

You'll need another chip because the Bosch AFM is calibrated differently to the Lucas one.

Cheers Pete

.............................................

Does anyone know if theres any alternative AFM units that are compatible with the lucus set up to allow more air volume without re chipping?

Or could the 5am unit be improved/modified?....(clutching at straws) would removing the grill make any difference?

[trackcar]

removing the grille does improve things, but if you had any filtration probs you'd possibly damage the AFM anyway so not recommended. You can bore the AFM out or fit a by-pass hose to divert some air around it .. then becuase you've pretty much increased / bypassed a fixed % you could potentially just up the fuel pressure and the scaling of the whole map would shift .. not elegant but might get you somewhere close. Keeping the 5AM over no AFM is costing you 20hp / 20lb.ft though on car of your spec (which should be over 300 hp)

[Ballistic Banana]

Jools would removing the grill and puting a small one over the wires in the grove improve things much?

BB

[trackcar]

nah you're only talking a couple of hp from taking it off completely.

[Ballistic Banana]

Getting Rid of The Bloody Thing is the best bet then along with a number of other tempermental items

[spend]

Wanna borrow my chainsaw Simon?

Dave

[Ballistic Banana]

spend said:

Wanna borrow my chainsaw Simon?

Dave

No its Ok I have one myself along with one of these if its a bit stubburn



BB

[GreenV8S]

I've been told that the mesh doesn't produce a significant pressure drop and helps to stabilise the air flow over the element so the AFM reads more consistently. I don't have any evidence to back this up, but the man who told me is somebody who knows what he's talking about.

[2Munkys]

I'm also led to believe by the knowledgeable that what GreenV8S says is correct; Pete's contributions are always well founded.

I have the large Bosch AFM and have removed the screen and guides. The screen I removed because I have a decent airfilter upstream. The guides I removed because they do appear to reduce the throat somewhat; though possibly to a lesser extent than the 'hot-wire' and it's supporting gubbins. Most AFM's are to be found in more than one application. Some of those will be in an induction line with a torturous route and therefore requiring the airflow to be guided over the hotwire. In the Griff, my belief is that the 2 foot of straight induction tube (rigid silicone in my case) will serve better.

Time will tell; I've not put it to the test yet as I'm awaiting a motor to connect it to.

[GreenV8S]

2Munkys said:

In the Griff, my belief is that the 2 foot of straight induction tube (rigid silicone in my case) will serve better.

How thick is the boundary layer after 2' of straight pipe, and will this affect the AFM reading?

[2Munkys]

GreenV8S said:

2Munkys said:

In the Griff, my belief is that the 2 foot of straight induction tube (rigid silicone in my case) will serve better.

How thick is the boundary layer after 2' of straight pipe, and will this affect the AFM reading?

Two feet is a guestimate (and probably more than it actually measures; it's an ACT item). Time will tell; I can always put the guide back in place. I'm just experimenting with my thoughts on the matter and it's probable that Mark Adams will spot any adversity when I get around to having the re-map.

I've no idea about the consequences of the boundary layer but I'm sure it compares favourably with the old convoluted length of hose. There were no problems with the old motor breathing through it; all I've done is take the guide out. . . . for now.

[Johno]

Ballistic Banana said:

Getting Rid of The Bloody Thing is the best bet then along with a number of other tempermental items

I know which temperimental items you refer, and my winter project is to get rid of all of them . . . . particularly the troublesome and restrictive AFM.

[Meatball]

Am i correct in thinking by losing the afm i would need a programable ecu which would be in the region of £800+.....?

What about boring the AFM out is there any potential problems in doing this?...