WGFV pipe nipple on compressor housing

[Keeper of The Kitten]

Hi folks,

I'm in the (long slow) process of getting my car up and running again, and one thing I want to do is fit a pipe nipple to the compressor housing of the K26/K27 turbo I have. There is a flat boss area on the housing but it is blank, it is also slightly shallower than the stock K24 boss. So it might need a shorter pipe nipple to be manufactured but that is not a big problem.

Does anyone know the machining detail of the standard compressor housing for this nipple? I will remove the nipple from the standard turbo anyway and measure the fitting and the hole it is screwed into, but any information would be appreciated. Particularly if there is anything critical about how this fitting is installed, if the hole size in the housing must be a certain size after the tapped part, that sort of thing.

Many thanks in advance

__MDC__

[Jon441cc]

Martin, we had to do this to Ross's GT3071R... i believe the thread on the
nipple from a K24 is 1/8th.

[Keeper of The Kitten]

Cheers Jon, I'll have to give you a call and discuss this in a little more detail - maybe pop over for a chat sometime as well? Been a while since we picked up all that pipe!

I'll be unscrewing the thing from my old K24 but if it's too long I'll probably just get a special made, then it can be whatever thread I like, so long as I can seal it with a Dowty or crush washer, or use a taper thread.

__MDC__

[AAH!]

Don't know whether this is helpful or not but years ago when Dialynx fitted my K26/27 Turbo they fitted a nipple into the hard plastic pressure pipe near throttle body and plumbed the WGFV into that.

Angus

[Jay]

position

The position of the nipple/waste gate take off alters the boost response... nearer the turbo outlet quicker more controlled boost... further away means less control and a bit of overboost when you plant the throttle.

As long as its tuned afterwards either can work, just depends on how near your boost threshold you will be running.

Jay

[Keeper of The Kitten]

Thanks for that guys!

Jay you'll know this turbo, seeing as it used to be yours! In the standard turbo the nipple is fitted right at the beginning of the "snail" rather than the outlet, would this be best or do you suggest that it would be better to take pressure from the outlet instead?

__MDC__

[Jay]

Me Myself and I

Me I would put it by the throttle, may be come off the alloy tude that runs along the cam cover but if you are going to push every last PSI of boost out of her and every thing is taken to the limit then tap in to the 'snail' just before the hose attaches to allow the boost to stablize and get the quickest response!

Good luck with the project... I'm embarking on a nother myself:mischeif:

Jay

[Ross]

As Jon said, 1/8" tap at the end of the scroll. Allows quick response to changes in boost pressure, and I'd agree with Jay that the pressure will have stabilised by the outside of the scroll. We just used the nipple from the K24, straight fit thanks to Jon


Ross

[Jay]

hehehe

I like the butchered fingers, the sign of a master mec' at work

jay

[Keeper of The Kitten]

Thanks again guys, and more people have agreed that this is the place to put it!

There's no boss in that area on my turbo though ...might have to do it a different way, but I like the thinking behind putting it at the end of the scroll.

Cheers! Jay I'll let you know how things are getting on as well.

__MDC__

[Jon441cc]

Martin, does the K26/27 have a boss like this ?

[Urquattro20V]

James did some thinking on this

http://www.bufkinengineering.com/pressure_tap2.htm

[Jay]

Not just that!

its not just the boost preasure but also the time delay/response of the pressure build up, right at the center of the scroll there will be almost instant response, no over shoot of boost.. at the throttle body, a long delay which means the boost over shoots before the wast gate can react specially on a normal 3B/ABY set up with long inlet track (remeber a lot of people her run front facing manifolds for this reason), this gives you an over boost (torque increase) situation, which can be useful as long as the system/engine can cope with this spike.

Also if you set your engine to run say 1 bar and take that at the center of the scroll you may only see 0.7 bar at the manifold.

It all comes down to the tuning... manufactors play safe e.g. want instant response of the waste gate so there is no over boost for their widely varying engineering margins to get the most mileage from engines and avoid warranty issues!

Jay

[Keeper of The Kitten]

Jon - there is a smaller flat rectangular boss in that area, without the wall around it, but it is a lot shallower than the boss on the K24. It would probably require the nipple to be shortened, in fact it might even be too short.

I think I'll get a boss welded to the outlet of the turbo housing anyway, so I can fit the standard type nipple. I've got a fresh one coming to me in the post.

Jay - so what you are saying is that you deliberately use the time delay to get an overboost situation?

At least if I get a boss on the outlet I will have the option to use it, or in the future it can be plugged and a different position tested.

__MDC__

[Jon441cc]

Heres a pic of my T04e ... it had the the 1/8th hole already tapped from 034