enlarged throttle body

[rob0904 0]

hi, was bored at work this week and decided to open up the golf vr6 throttle body. want to get rid of the stupid hump sittin in front of the butterfly valve. so i got to work on it and within a couple of hours of messing when the bosses had there backs turned and it was done.

one or to of the ripple vw put in to stop u doin this.

the restricted chamber, bloody hump in the way.

now the newly bored out hump, let the VR suck all the air it can!!

this will be goin into my mk2 VR which is still in bits so havent tested it out yet. think it just makes the engine more responsive off the mark but hey every little bit helps and when u can do it for free why not

rob

[lee060 3]

tidy stuff matey . get it on the rollers to confirm its made a positive difference . some times stuff like that , acts like a placebo upon your mind , making you think its faster . agree? plus im interested to see the changes it makes

Liam

[rob0904 0]

tryin to get a friend to bolt it up on his mk3 VR, could do with doin one run with his untouched TB on and one with my touched TB. at least then i can see if my handy work was worth doin or if i ws a busy fool. might see i can get it bored out for a bigger butterfly valve. cuz i think thats what AMD do to theres, is it 63mm to 66mm or something. if anyone else has done this or knows more about the bigger butterfly that really would help

thanks

rob

[gavinvr6 0]

does the tb have like a couple of ripples circling the inside that you ground out, sorry i cant see the difference in the pics, would this help? in theory i can see where your going and since im trying to do my vr to a budget thats the sort of thing i could do myself to improve things

[rob0904 0]

hi, done a little drawing, hope this makes it a bit more clear.

As u can tell there was quite alot of material to come out, also u need to weld the under side of the hump. so u will need to get hold of an ally welder just to build that up, cuz u will need break thru the orignal cast to compleltly remove the offening hump.

Im lucky enough to have a friend with a VR so we're goin to strap this to his motor and give it a blast. Lets hope it was worth the time i spent on it.

Goin to spent some time seeing if i can enlarge the butterfly valve too, as ive got a CMM which measures to 0.001 mmm or a micron not sure if the cast is thick enough for this but will have a more detailed answer to that next week. I think ive read the amd enlarged TB has a 3mm larger butterfly valve in it. anyway im gettin boring now.

thanks

rob

[Paul1982 0]

Sorry to sound thick but the butterfly wings seem to be touching the centre bore all the way around on both pics. So is the hump you took out before the wing??

[FishWick 21]

I don't like the way the engine behaves with a bored out throttle. The ramp is there to speed up gas flow for midrange torque and smooth off air turbulance. I know the guy that makes the throttles for AmD and yep the throttle plate is 3mm bigger than standard. Englarging the plate is OK, but it's nice to keep the ramp there for a smoother driver.

[rob0904 0]

hi,

To the first question, the hump is before the valve yes.

to the second, only tried this because of the 2.9 TB, as that doesnt have the hump and is a straight run throttle where as the 2.8 TB actually steps down for what ever reason that is.

I dont actually know if doin this will increase/improve anything but is worth tryin as it didnt cost me anything. actually i got paid to do it (just dont want my bosses to know that )

if anyone knows more about this please tell me what u know.

thanks for any info

rob

[FishWick 21]

The 2.9 TB uses a two stage linkage to mimic the ramp. The butterfly opens slowly for the first 10% of travel and then opens quicker. The idea of this is to speed up gas flow at low rpms and idle. The ramp in the 2.8 throttle does the same job but obviously has the ramp there all the time, where as the 2.9 one is 'straight through' on wide open throttle.

By all means try it, it won't hurt, but I bet you end up going back to the standard throttle again as it blunts bottom end torque :-)

[rob0904 0]

hi,

haha now i know, well going to see what its like this weekend so will be able to agree/disagree with u. but u sound like ive had one of these and gone back to standard TB. is there any setup where this charge would help e.g. supercharger or something like that?

thanks

rob

[jezmoz 0]

Soz for the hijack but does a proper Rado obd1 2.9 TB have benefits over the 2.8 TB? I have one but never got round to fitting? Cheers

[rob0904 0]

hi, thats a good question, should of thought about askin that myself, may of saved my self some time. haha well never mind. im sure the boffins here will answer your question.

thanks

rob

[bugsy 0]

Rob ,the best mod you could of done would of been to taper the outer edge of (air filter side) the TB, instead of the air hitting (the kerb) the lip,on it's way into the TB. Then the air hit the ramp and is directed to pass through the top part of the butterfly on part throttle to make bottom end tourqe.Once the butterfly is at 3/4 open you should be heading towards the power band of the vr6,this is were you HP comes into play .

[vr6newcomer 1]

i agree with bugzy, thats exactly what ive had done on mine, on the advice of racepower engineering down in kent, they rebuillt my head, gas flowed, port matching e.t.c, and recommended not too much carnage in the t.b to maintain good midrange responce.

[jezmoz 0]

so a rado 2.9 TB is a good mod for a 2.8 obd1?

[apd 0]

AMD modified mine(obd1).dunno wot they've done-but it works!

[rob0904 0]

hi, well this modded T.B. has been on a friends car for about 3 weeks now and he and the other driver seem to be happy with it, they said its punchier. suppose everyone wants different things from the engine/car was what might suit them doesnt mean it will suit everyone. realy only did this cuz i was bored at work haha and while im still building the mk2 vr6 up cant test it my self.

rob

[gav_113 0]

i did this on one of mine it did make a slight difference, worth doing..ive got a enlarged TB with a bigger butterfly now..

[petervr6 0]

were did you get that from gav_vr6 got the detail

[gav_113 0]

got it off clarkie cum off a 2.9 race engine i believe.

[bulk66 0]

Hi all dose the rado 2.9 tb bolt straight on then with no mods ?

[lee060 3]

to an obd1 far as i know yes ^

[rob0904 0]

hi, just an update to let u know how the testin of this got on. the throttle body has been on a friends cars for about a month now, which was driven every day. he said it feels more responsive, but not much if any extra power, but also said that when driven sensibly he was seeing a couple of extra mpg!! which i wouldnt of thought to be honest. all in all he was happy with it. no complants any way, well just one which was,in his words, "your not havin it back!!"

now alls ive got to do is get this vr6 into my mk2 and test it for my self.

thanks

rob

[crish72 0]

Did mine but i dont like the way it ticks over at low revs now...

When i start the car from cold it stalls instantly, then ticks over at about 600rpm (virtually stalling).

It's ok once i've got going.

Any ideas why?.

Cheers