big bore throttle body

Post Fri Dec 07, 2012 5:02 pm

as some of you guys know im getting my e30 engine work started soon, with schrick cams, btb 6branch, and was wondering whats peoples views on BIG BORE THROTTLE BODY

and where can i get one from??

and info would be great

Post Fri Dec 07, 2012 5:21 pm

Hi Faz,

I had one once, on a 1989 325i Sport, and it seemed pretty good. See the Zone Wiki:

http://www.e30zone.net/e30zonewiki/inde ... tle_Bodies

HTH,

Post Fri Dec 07, 2012 7:22 pm

Varied views I would guess. Well I've spoken to two seasoned zoners (one my cousin) and both had polar views (rubbish/great)

Post Sat Dec 08, 2012 2:47 am

Just remove your TB and take it down any engineering place and they should be able to make one for you.

Post Sun Dec 09, 2012 10:29 am

Green- i will try a few engineers down my area

Thought it would be easier just to buy 1. Less headache.

I like simple things. Lol

Post Sun Dec 09, 2012 11:35 am

Green wrote:Just remove your TB and take it down any engineering place and they should be able to make one for you.

That's the cheap part!

Difficult/expensive bit is getting a butterfly made up to suit....

Post Sun Dec 09, 2012 11:43 am

Given the tiny amount of metal you can bore out, got to be a waste of time?

Post Sun Dec 09, 2012 11:45 am

I have had one on my standard 2.5 and i now have one on the full spec'd up m20 2,8 cant really tell a difference.

Post Sun Dec 09, 2012 11:52 am

from what i understand (& i could be wrong) they only really work when combined with other induction mod's to the head, i;e MAF, head work (port, polish & gas flowed), higher lift long duration cams & a free flow exhaust (including 6 branch), & a remap. like i said i could be wrong though.

also from what i've read on here over the time i've been here the bigger TB should also have a 15% bigger CSA which in turn allowas X amount of extra in into the combustion chambers,

Post Sun Dec 09, 2012 12:32 pm

i wasnt going to get a bbtb but as i was doing my engine rebuild, with cams, 6 branch and remap, thought at the same time do that aswell.

but im getting alot of mixed views on it. some good and some bad, bad as in. doesnt make much difference.

Post Sun Dec 09, 2012 12:58 pm

There is a bit of a restriction from the throttle body, more so on the bigger capacity m20s than the 2.0. Fwiw the 2.8 i am building will need a 70mm throttle like the 330i one to feed it correctly.

The stock throttle will only bore out about 2-3mm so there is not much there, i think most of the gain is from the shape improvement of the body as the mod tends to be combined with smoothing of the shape towards a venturi.

A more worthwhile endeavor may be ti get down the scrap yard and find a throttle that is common to another car, bigger and easy to fit to the m20. Stock factory parts ftw.

Post Sun Dec 09, 2012 1:03 pm

@hairyscreech, if/when you come to sorting the 70mm TB for your 2.8 then please post up any/all info you have about it as i'm sure the folk on here who building/looking at building a naughty spec 2.8 wouls be very interested in your finding's

Post Sun Dec 09, 2012 4:16 pm

I'm working on it, I need to take some time to go scrap yard raiding for something easily adapted, otherwise I'm going to make a simple fly by wire kit to use the 330i one i have (remember I am on an M54 manifold mission), I will go m20 throttle hunting, probably when I go to get the prop for the m3 compact I'm in the middle of for a customer.

I expect what ever I find will need a conversion plate due to the difficulty of getting a large hole to the intake plenum, but the easier the better.

If anyone wants to go looking in the meantime then feel free.