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tfrasca's 142 Turbo Project

Thanks, guys. This has been really fun, and something I've wanted to figure out for a while.

The next thing will be the waste gate routing. Wondering if anyone has any input on routing two waste gates back into the down pipe. Should I try to keep them separate all the way to the down pipe, or should I join the two together, then into the down pipe?

If I do join the 2 1.5" tubes together, what size should the "collector" tube be?
 
Good work dude. Can highly recommend getting a purge setup going. Obviously a dual flow meter regulator is nice but It doesn't have to be that complicated or expensive. In a pinch I've gotten by with sticking a tee fitting in the hose from the regulator to the welder and regulating the purge flow with a ball valve.

I don't think the wastegate plumbing is super critical, you just want to make sure the tubes have approximately the same number of bends and total bend angle so the pressure drop across the tubes is about equal. A good guideline is to dump the wastegate gasses back into the exhaust as far away from the turbo as packaging allows for. This will minimize the impact you have on flow out of the turbine housing. If you do combine the outlets my gut check says 2" tubing should be more than adequate.
 
Nice job man, that thing looks great and stout too. Most of the weld el manifolds I've seen were a bit...lacking in the aesthetics department. Great effort for a first TIG project!

I don't see any glaring reason not to join the wastegate outlet tubes together prior to merging with the downpipe, especially if that's easier for packaging and/or fabrication. Wastegate flow should be as unrestrictive as possible both pre- and post-valve, to make the best use of the valve size you've got and to avoid boost creep.

Flow area of a 1.5" tube is 1.77 square inches, x2 = 3.53 in^2. Solving for the diameter you'd need a 2.12" tube to match the flow area of 2x 1.5" tubes, not accounting for losses due to bends or dynamic effects. If you can fit a 2.25" or 2.5" tube you should be ok, as long as bends aren't too tight, like 1D or bigger.
 
Jinx on the reply, Alex.

A good guideline is to dump the wastegate gasses back into the exhaust as far away from the turbo as packaging allows for. This will minimize the impact you have on flow out of the turbine housing.

Also this ^. I can see that we have taught you well.

The effect of dumping wastegate outflow too close to the turbine wheel exducer (as in an old-school internally wastegated housing with a common open discharge section) is effectively a restriction on flow through the turbine stage, which gets accounted for during boost control but will inevitably increase your pre-turbo exhaust backpressure. Join the wastegate back in down by the bellhousing or at the bend where the exhaust goes horizontal under the car, if you can. Use a flex section too, which hopefully goes without saying.
 
Good work dude. Can highly recommend getting a purge setup going. Obviously a dual flow meter regulator is nice but It doesn't have to be that complicated or expensive. In a pinch I've gotten by with sticking a tee fitting in the hose from the regulator to the welder and regulating the purge flow with a ball valve.

I don't think the wastegate plumbing is super critical, you just want to make sure the tubes have approximately the same number of bends and total bend angle so the pressure drop across the tubes is about equal. A good guideline is to dump the wastegate gasses back into the exhaust as far away from the turbo as packaging allows for. This will minimize the impact you have on flow out of the turbine housing. If you do combine the outlets my gut check says 2" tubing should be more than adequate.

Thanks, Alex. That's a good, cheap solution to the purge problem. Aside from not having a set up, I was also thinking that I'd be wasting a ton of gas if I purged this. To keep things from getting too hot and warping, I was welding maybe 1/2" at a time, then cooling it with compressed air. I figured I'd be losing all my purge gas for every single weld/cooling cycle. Maybe I was being too paranoid about heat build up?

Nice job man, that thing looks great and stout too. Most of the weld el manifolds I've seen were a bit...lacking in the aesthetics department. Great effort for a first TIG project!

I don't see any glaring reason not to join the wastegate outlet tubes together prior to merging with the downpipe, especially if that's easier for packaging and/or fabrication. Wastegate flow should be as unrestrictive as possible both pre- and post-valve, to make the best use of the valve size you've got and to avoid boost creep.

Flow area of a 1.5" tube is 1.77 square inches, x2 = 3.53 in^2. Solving for the diameter you'd need a 2.12" tube to match the flow area of 2x 1.5" tubes, not accounting for losses due to bends or dynamic effects. If you can fit a 2.25" or 2.5" tube you should be ok, as long as bends aren't too tight, like 1D or bigger.

Thanks! I actually wish I'd tried harder in the aesthetics department, and run the long #4 runner underneath. I like the way the manifold looks from the bottom. Oh well.

I doubt I could fit anything bigger than a 2" tube, and get far enough down the down pipe. I'm pretty sure it's going to have to go in right before the 90 degree bend at the oil pan, but maybe I can sneak a smaller tube further down.
 
Has anyone used this type of flex hose on a waste gate, or any other exhaust?

84027.jpg


I first saw it used (poorly) on a friend's BMW 535 turbo. It was just hosed clamped on, but I'm thinking if welded, it could work well. The much lower profile would be nice.
 
I've seen the swedish dudes use it a few times, but it looks really cheesy and kind of half assed.
 
Yeah, I could see it not looking great, if you made the whole run out of it. I was thinking about just welding in 2-3" of it instead normal flex bellows. I probably won't, though.
 
Yeah, I could see it not looking great, if you made the whole run out of it. I was thinking about just welding in 2-3" of it instead normal flex bellows. I probably won't, though.

It was on an Amazon I bought out of SF. It leaked like crazy and was all dented from rocks being kicked up and the PO pushing against it to get to the car. It's a POS solution.
 
Another vote for staying away from the "hose."

The type of flex bellows I like to use has stainless braided sheath over the bellows section. It should increase abrasion resistance and help tie the room together. Vibrant has some listed under the name "TurboFlex." I like to think that's what it's called when you rev up your turbo for intimidation.

https://vibrantperformance.com/catalog/index.php?cPath=1527_1064_1114&osCsid=64f3866917c0ac4ac075ffc8ffbed5c7

Edit: there's no material listed on the Vibrant parts above, but here's a different one that is listed as 304 stainless:

https://www.maperformance.com/products/2-5-304-stainless-straight-interlock-liner-flex-coupler-4-length
 
TIP: when prepping to tig those on, hose the whole thing down with acetone, and blow it off, then dunk the ends and wipe it before welding. They're usually a lap joint for the tube OD you select and the ferrule that holds the braid down is right up to the end, and sometimes there are contaminants within the braiding that shows it ugly lil face when you hit it with heat.
 
Thanks, Alex. That's a good, cheap solution to the purge problem. Aside from not having a set up, I was also thinking that I'd be wasting a ton of gas if I purged this. To keep things from getting too hot and warping, I was welding maybe 1/2" at a time, then cooling it with compressed air. I figured I'd be losing all my purge gas for every single weld/cooling cycle. Maybe I was being too paranoid about heat build up?

I usually purge a tube for 3-5 minutes at 15cfh or so, then turn the purge flow down to 5cfh, this saves quite a bit of gas. Those purge plugs you can buy are nice but I've built many headers with just aluminum foil to cap the ends. A large gas lens helps immensely as well, I use a 1" diameter cup and lens from an automation torch that I hacked together but the SPW or furick stuff is also very good.
Once you have your sweet spot for welding current just weld short sections and jump around to different joints on the tube. This will keep the interpass temps reasonable so you don't have to wait too long. You'll notice pretty quickly if things are getting too toasty. If I'm in a hurry I will purge several runners simultaneously so I can keep skipping around to different tubes while others cool down.

I've seen the swedish dudes use it a few times, but it looks really cheesy and kind of half assed.

Agreed, those spiral wound tube things both look and are ****ty.

considering the fact that these bellows crack with some frequency I can't imagine that length of corrugated tube would survive long. Not a direct complaint on the Vibrant piece, I think it's just the nature of the beast. Tate and I have both replaced them on our headers.

Unsupported bellows are finicky. They really shouldn't be flexed at all on installation to maximize life and should only be strained in one direction if possible. It looks like vibrant sells lined bellows and it's very important to make sure the liner is oriented correctly with regard to the gas flow direction. Overbraided bellows are usually more resilient to cracking since the braid effectively works as a travel limiter and a friction damper against the convolutions which makes the bellows less likely to fatigue crack.
 
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