Wastegate options/positions, need your thoughts

[Draven]

ok, but camera is broked - be prepared for phone pix.

Seriously, if you don't get a little chubby then you don't care about welding

[Casey-G]

ok, but camera is broked - be prepared for phone pix.

Seriously, if you don't get a little chubby then you don't care about welding

Keen to see the pics to mate!

[Cuts]

I made a manifold for a ta63 celica when i owned it, this is the collector i made, design is based on the 6boost ones (but no where near as good as his obviously). Yours would be different because its not split pulse like the ct26 flange.


not hard to do, cut the pipe on an angle, weld pipe togther, weld to plate, job done. you'l just have to cut yours another time so 4 pipes merge to 1 hole insted of 2 pipes to 1 hole like mine was.

also how do you plan on welding around the back of the runners where its obstructed by another runner etc? When i made mine i tacked it all togther, then one runner at a time cut them off (and the collector and the head flange) and fully welded it, then tacked it back on etc. Worked wonders.

As far as the gate goes, If your new turbo is likely to be a different flange patturn to the one your making the manifold now your shagged and might have to make 2. But if not weld gate port on now and save yourself the hasstle later.

[Casey-G]

also how do you plan on welding around the back of the runners where its obstructed by another runner etc? When i made mine i tacked it all togther, then one runner at a time cut them off (and the collector and the head flange) and fully welded it, then tacked it back on etc. Worked wonders.

Yeah i was planning on doing the same as there isn't many other ways to do so.

Cheers for the pictures man its definitely getting thoughts flowing.

[Casey-G]

So, just to blow the dust off this topic..


I have a t3 externally gated turbo coming, I was considering doing the gate on the rear housing but im not to impressed by it..

Im curious to know if i can make entire manifold, fully welded ect.. then take a holesaw to the collector and weld in another bend/straight length to then attach my waste gate to?

..if that makes sense?

[mr1jz]

Or you can just buy a premade collector from Will Tobin and specify where you wold like the gate exit to be. $110 for a 4cyl collector is cheap i think.

http://expressparts.com.au/mergecollectors.asp

In saying that, i just bought a 6Boost manifold and that collector design is porn.

[Casey-G]

Dislike buying premade stuff i can fab myself, I already have a moderate sized piece of 12mm plate, a dozen long radius buttweld fittings and the desire to make it myself, also i dont quite see how one can weld right around the inlets onto the premade collectors? looks to me like its quite a tight angle? maybe its just me..

[JP]

yes, that will work fine. Sometimes the boost control is better with the gate mounted off the exhaust housing if you've got a really nice collector and a smallish gate. Try and get the gate merge coming off the collector at an angle so the exhaust gas doesn't have to change it's path too much to get out the gate. There are example pictures in the turbosmart wastegate installation manuals you can download from their site.

[mr1jz]

You won't be able to complete the welds if you design all the runners first. You need to work in the opposite direction.

You should start with the collector.
Once this is completed, tack on two rods to the flange plate where you would like the turbo to sit and create your runners from there.

Check this thread. It's a pretty good writeup.

[JP]

^^^ What he said. I also get both flanges tacked in place with rod/scrap first, add the collector to the turbo flange and then work back towards the head flange. Once every runner is tacked together (4 tacks around the circumference of each join) I break the tacks at the head flange and the tacks holding the collector together and weld each runner individually. Once cooled they're all placed back between the two flanges, the head flange bolted to an old head as a heatsink, and the exhaust ports and collector are fully welded. Once that has cooled the flanges are faced in a mill and it's ready to go.

Depending on your runner placement, it may be difficult to get to the middle of the collector. On some manifolds I've used a lot of stick-out on the TIG and dropped a bunch of small 5mm lengths of 2.4mm filler into the center of the merge. With the filler already in the center of the merge it's easier to get it all sealed up, as if you try and feed the filler rod in normally while running a lot of stick-out you're likely to get the filler stuck to the tungsten.

[Casey-G]

You won't be able to complete the welds if you design all the runners first. You need to work in the opposite direction.

You should start with the collector.
Once this is completed, tack on two rods to the flange plate where you would like the turbo to sit and create your runners from there.

Check this thread. It's a pretty good writeup.

^^^ What he said. I also get both flanges tacked in place with rod/scrap first, add the collector to the turbo flange and then work back towards the head flange. Once every runner is tacked together (4 tacks around the circumference of each join) I break the tacks at the head flange and the tacks holding the collector together and weld each runner individually. Once cooled they're all placed back between the two flanges, the head flange bolted to an old head as a heatsink, and the exhaust ports and collector are fully welded. Once that has cooled the flanges are faced in a mill and it's ready to go.

Depending on your runner placement, it may be difficult to get to the middle of the collector. On some manifolds I've used a lot of stick-out on the TIG and dropped a bunch of small 5mm lengths of 2.4mm filler into the center of the merge. With the filler already in the center of the merge it's easier to get it all sealed up, as if you try and feed the filler rod in normally while running a lot of stick-out you're likely to get the filler stuck to the tungsten.

Cheers to the both of you.

Im buying a waste gate next week, I have a .48 rear housing, so i guess my next Q is what will the ideal waste gate size be, i would be inclined to go 44mm but a vband 38mm seems adequate in my books as it wont need to vent a hole lot high up in the rev range.

thoughts please.


As for the position, im thinking i might not come off the turbo housing, instead just have another runner coming off the collector/merge and run it out to a screamer.



cheers guys

[RT40Corona4AGTE]

I agree with mr1jz and JP on the manifold construction method

38mm V-band gate should be adaquate IMO.

FWIW I am going to be using a Tial 38mm gate.

[Bazda]

1x 38mm wastegate will be ok. But a little harder to control boost over a 44mm.

[mr1jz]

Without knowing what engine, turbocharger or intended boost level, i would say go the 44mm.

The rear housing is quite small and the wastegate possibly won't be able to remove all the gas that it needs to especially with a 38mm. It is always better to over engineer it a little.

It you run big boost all the time then the 38mm should be fine. If you want to run lower boost for the street or whatever, you will end up with boost spike and boost creep.

Boost spike = Ramp onto boost and boost will spike over the desired boost level and then come back.

Boost creep = Wastegate isn't big enough to discharge the spent gasses and in turn the boost climbs with RPM.

Hope this helps, Brendan.

[Casey-G]

Engine is a 1.6l 4agte, turbo is a t58 .48 rear .7 front, I intend to run 18-30psi



I guess a 44mm is on the cards then, anyone got a half decent one going cheapish second hand?