Thread: Some turbo questions I've always had..

There are quite a few things I still do not understand about a turbo system. Two of those are the external wastegate and exhaust manifold.

I'll start w/the exhaust manifold. How well does the stock DET e-manifold flow? At what point would a custom manifold be a good option?

Next up is the wastegate. I've seen people that get the stock DET e-manifold welded with a flange for an ext wastegate. How much does this cost? Also, if you run an ext wastegate you need to run an extra exhaust pipe from the ext wastegate to the downpipe, right? How much does that cost? If I got a VRS downpipe, I'd have to get it welded into the ext wastegate exhaust pipe. Would it be cheaper to just do a custom downpipe with the ext wastegate pipe??

What would be the cost for the ext wastegate flange on the stock DET e-manifold and the cost of getting a pipe from the ext wastegate to the downpipe?

How about some other options for running an ext wastegate?

A lot of questions...thanks!

-G

Custom manifold is better suited when you uprade turbos of the T3 or T4 caliber. The stock DET manifold are good for in the 400-450 whp range; where the biggest T2 flanged turbos exist (i.e. GT3071R).


Depends...maybe $50. You have to find a good welder than can weld cast iron to steel.


Yes and no. It all depends on your noise tolerance. If you want a quieter ride, merge the WG pipe back into the downpipe. If you don't mide the extra noise, you can run the WG pipe open.

Manny's Back Hehe

Thanks for the answers! I've been in the dark about this stuff for a while. Ok, so stock manifold is good unless a big turbo is used. $50 for the weld on the ext wastegate. I think there is a guy on the forum or people have recommended to get the ext WG welded, but the cost was never mentioned so I never knew how much it was.

I would want the noise to be minimal, so I would want to run the WG pipe back into the downpipe. By doing that, will the noise still be greater with an external WG over the internal WG? Also, how much do you think it would cost to get a pipe made for the ext WG and welded into the downpipe?

I'm trying to plan and price all of my options.

thanks again!

-G

the noise from the external gate wouldnt be there unless you were opening up the car and causing the gate to open, witch by that point the car is gonna be making noise anyways, i cant hear my external gate when i get on it, only time i hear it is if it is echoing off something.

It would be cheaper to make your own, if you are cutting your own pipe. If you really want to route it the gates dump pipe back in make sure you get it at least 15in away from the exhaust coming from the turbos exhaust housing. If you merge it to soon it will defeat the whole purpose, it will be the same as an internal gate IMO. The other plus to making your own DP besides cost over the VRS is you can get rid of the extra flange at/from the O2 housing. That flange might be a pain to work the dump pipe around if you are merging it back in.
If it was me I would just make a dump tube for the ext gate to keep it from melting a belt or something. It will only be open when the gate cracks or you are hitting max boost.

MMMM, I really like how this forum is going. Questions asked and answered with no crap BS! Manny got that one down really, I tell everyone I know to stick with stock DET manifolds unless they want 450 or more WHP.

External gates with external dump add HP because exhaust isn't dumped into the downpipe. It allows the exhaust to flow uninterrupted and therefore you get better flow and more power. Good stuff! External gates run larger valves and openings so they can be more accurate than internal style WG.

Brent

How much more hp would you lose by running the external WG back into the downpipe vs having it open? Also, I don't think I'd pass emissions with an open external WG

How about cost..how much would it cost for someone to make and weld the external WG pipe into the downpipe?

Well, lets remember,the waste gate ONLY open when your in Boost not Vacuum. So even if you have your car on the "Roller" type emission testing machine, your waste gate shouldn't open unless you WOT on the rollers or high revving.

Most you will get is the BOV going off and if you have the right computer that shouldn't effect you A/F at that split second to cause back fire if your BOV isn't Recirculated.

I can't answer they question fully about loosing power Via Recirculated W/G. But Trust me, if your running a decent setup I HIGHLY doubt your going to notice any difference at all. Unless your going this just for Greetz and Dyno brag reasons.
Also, Back pressure isn't that bad for turbo cars.. Just to much of it isn't good.
Nothing a 3'' D/P and Exhaust won't fix.

Excuse me for being a shmuck, but I thought that GT30 series turbines were T3 flanged? And GT40 series turbines were T4 flanged?

I'm such a noob if this isn't the case...