Direct swap larger throttle body M20?

[rvaughnp]

What was the cost on that? And when will they be ready for market?

[digger]

velocity, one would assume.

but what function does the slight additional velocity have that far upstream? I would think velocity in the head ports, intake and exhaust manifolds would be important but the TB i am not sure especially when you go 3" past the throttle and there is a rather large plenum that slows velocity substantially. On a carb engine its importnat but EFI don't see any benefit.

[e30 sdw]

What's involved in the bypass?

if your talking about the coolant preheater hoses, Buy a new strip of hose and go from the nipple of the block to the small hose on the thermostat housing. Wam bam thank you man!:) It looks cleaner as well

[rvaughnp]

I would think velocity in the head ports, intake and exhaust manifolds would be important but the TB i am not sure especially when you go 3" past the throttle and there is a rather large plenum that slows velocity substantially. On a carb engine its importnat but EFI don't see any benefit.

+1

For me it's not so much a velocity issue as much as the ability to direct bolt a larger TB.
Assuming the cost is reasonable, this would be the easiest way to mate the two. I think boring and what not a stock M20, would be costly and difficult and one could in screw it up and have to replace it. Modifing a M30 would be slightly less difficult but you run into the vac issues. Still not having one of these in my hands... I looked at some pics of it and it looks to be the easiest solution. This is my way of filtering out all the issues anyway. Not to discount the velocity issue.. its just that the velocity issue wouldn't be one of my concerns as long as the TB worked like it is supposed to, I'm good.
I would be curious of the "science" behind the statement though.

[nando]

well ask BMW about it then, they seemed to think it was a good idea. I'd bet it has something to do with low-throttle openings.

as far as the cost of an M20 BBTB - it's really not that expensive. mine was under $200. And you won't be able to tell from the outside..

[Dagamus(NM)]

The one I got with the bored and ported manifold from bottlecape30 was about the same.

I imagine that doing it yourself would probably be easy to mess up. I was screwing around with an old tb the other day and I will tell you that BMW really secured the plate to the shaft with those two little screws. I'm sure with some pb blaster and determination they would come out but I was just messing around and really just trying to get the plastic pieces out of the spring perch things.

I like the look of this piece and it seems that things may be a little easier with this. I have 3 e30's to mess with so I like to try different things.

[digger]

well ask BMW about it then, they seemed to think it was a good idea. I'd bet it has something to do with low-throttle openings.

as far as the cost of an M20 BBTB - it's really not that expensive. mine was under $200. And you won't be able to tell from the outside..

Probably to do with structural integrity

[rvaughnp]

Nando, how much of a difference does your car run with the enlarge M20 TB compared to what is was before?
What did it cost you to get that bored TB?

[nando]

I don't know, I haven't had a chance to put into it. I'm hoping to eliminate the pressure drop I get above peak torque (and hopefully extend the torque curve).

I think it was around $150 + core?

as far as structural integrity, that doesn't make a lot of sense. they could have made it thicker on the outside if they wanted. why make it thinner at all on the ends?

[rvaughnp]

Did you supply bottlecape30 with the M20 core? Or did he supply it and do the mod?

[nando]

he had one, I haven't sent a core back to him yet.