bbtb specifications?

[goosiegander]

Evening all,

If i were to pass my old m20b20 throttle body on to the machine shop building my 2.8 stroker what spec would it need boring to? It is currently 52.9mm onto the inlet manifold, what should i be aiming at?

What else is entailed? I asume enlarging the butterfly gate and boring the inlet manifold to match...

Any input would be greatly appreciated.

Rgds Chris

[maggspower]

I'm pretty sure that a bbtb is 64mm.

I would start with one off a m20b25 as they are bigger, 58mm I think.

[goosiegander]

Thanks -sorry i should have been more specific, i have a spare 2 litre throttle body sitting in the work shop. I have a 2.5 attached to the b25 sitting in the car atm. If i dont get one made up before i do the swap i'll just use the 2.5 tb.

I did see a spec of 64.5 but i dont know if that would be too extreme?

[goosiegander]

also i just put the calipers against the 2 litre tb and 64.5 looks impossible -i assume now you mean the 2.5 is a larger casting?

[zimmer-320i]

so why have a 2.0 one bored when you have a 2.5 one??? im certain you wont be able to bore it to the size you need becasue of the internal jacket, just start with a 2.5 tb that way means less machining! and id say 62mm at the most

or use these people £45 on exchange!!

http://www.headtune.co.uk/index.php?mai ... ucts_id=43

not bad and good company

[maggspower]

Grab the m20b20 throttle body, walk to the corner of the room and put it in the bin

It sounds like the casting is different, you need to start with a m20b25. Even if they were the same casting there is more wok involved and therefore more ££.

With the 2.8 it will be a very worth while mod as there is an extra 300cc of air to be shifted, and bare in mind that a bbtb shows gains on a 2.5. The best bet would be get another second hand one and get it bored out, make sure you get the right one to go with what else you have, there are 2 types.

Alternitivly get one from evolve.

[goosiegander]

Yeah i think thats the way forward, there is someone else on here that does bbtb's as well -haven't heard much about evolve recently, anyone know what happened?

[maggspower]

Yeah I cant remember the someone elses name but I'm sure he made them for evolve.

Evolve are still trading but no longer linked with the zone, it was all on the hush hush, but one of the mods let slip they hadn't payed their bill

Anyway I've had a few dealings with evolve, and the have been ok, not amazing, but ok, I have always got my stuff. I think others have had problems though.

[Jhonno]

Grab the m20b20 throttle body, walk to the corner of the room and put it in the bin

It sounds like the casting is different, you need to start with a m20b25. Even if they were the same casting there is more wok involved and therefore more ££.

Well no, as you would be performing the same operation, just a little extra material removal..

[maggspower]

Grab the m20b20 throttle body, walk to the corner of the room and put it in the bin

It sounds like the casting is different, you need to start with a m20b25. Even if they were the same casting there is more wok involved and therefore more ££.

Well no, as you would be performing the same operation, just a little extra material removal..

I am a firm believer that you should have as few m20b20 parts on your car as possible

[Jhonno]

[HartgeH27]

Yeah I cant remember the someone elses name but I'm sure he made them for evolve.

Evolve are still trading but no longer linked with the zone, it was all on the hush hush, but one of the mods let slip they hadn't payed their bill

Anyway I've had a few dealings with evolve, and the have been ok, not amazing, but ok, I have always got my stuff. I think others have had problems though.

Mags, I am sure your posting is in good faith but unfortunately not factual.

One Moderator got his facts wrong with regard to Evolve and made his statement erroneously.

Evolve have traded well within the Zone and although no longer on the Zone continue to trade successfully.

The Zone had no problems with Evolve during their tenure but both sides felt a change of marketing was on the cards.

We now have the space filled by OEM (Cotswold) and Evolve have changed their marketing strategy.

Hope that helps clarify and put to bed any incorrect rumours.

[maggspower]

As I said I never had any real problems with Evolve, and I would use them again no question, as the products are good quality and a good price.

I'm pleased that evolve an the zone parted compay on good terms, but surely this should of been corrected the moment it was aired.

http://www.e30zone.net/modules.php?name ... highlight=

After reading that I'm sure you can understand my confusion!!!!

May be it would have been a good idea to publicly appologise to Evolve, and set the matter straight, then this would have been avioded

[goosiegander]

Grab the m20b20 throttle body, walk to the corner of the room and put it in the bin

It sounds like the casting is different, you need to start with a m20b25. Even if they were the same casting there is more wok involved and therefore more ££.

Well no, as you would be performing the same operation, just a little extra material removal..

So is it possible to go 64.5mm with a 2 litre tb?looks like you would be offsetting exit apature by at least 2mm

[zimmer-320i]

no 64mm with 2.5 tb!

and its not performing the same operation as the casting overal size is bigger , if you nore out the 2.0 tb to much you cut in to the jacket and the fixing for the butterfly arm section its self, leaving you with a useless tb!!

[maggspower]

I wasn't joking when I said throw the b20 thing away!!

[goosiegander]

indeed so lol

[tomson]

There will not be enough meat on a B20 TB to make it the size of a B25 TB let alone larger again!
If you put a B20 & a B25 TB together where the inlet elbow would meet them, the B20 fit's inside the B25 TB!