Paulyy

Nothing to worry about then

When the wastegate dumps exhaust back into the exhaust pipe, more exhaust will be traveling through from after it gets dumped which creates backpressure.
so the turbo needs to push out extra exhaust rather then it's own.
when the wastegate is dumped into it's own exhaust or atmosphere, there will be a decrease in backpressure and the turbo works less to get all the exhaust to escape, which equals more power.

the idea i was trying to get at with the thread was if there is much of a change in backpressure with the wastegate tied into the exhaust.

if theres somesort of gain i may just use up my 2.5" exhaust tube sitting in my back yard i used for a cat delete and make a dedicated wastegate exhaust.

Tedro951

I understand the theory, but if the wastegate is dumping, the engine doesn't want to make more power. When it wants to make more power, the gate won't be dumping. The part I am unsure about is whether a dyno (or backside) could detect any difference. My ears (and everyone else') would know if I dump.

I'm probably just looking at this too simply....

Paulyy

The turbo will notice the difference (i want to know how much hence the thread)

you're thinking about how the wastegate regulates the boost.

we're (I'm) looking at to minimize back pressure in the exhaust. the less back pressure means quicker spool, the potential of more boost from the turbo with out choking the engine with the back pressure in the Xover pipe. the less the engine chokes the more power you gain.

Crackership

I think the point that Paulyy's trying to make is that, with the WG tied in, the WG will dump, and create extra back pressure... from the stand point of "the wastegate dumps to control turbo spool" that's not an issue, but from the standpoint of "I'm going to shift quickly and bury my foot in the floor again" it means that the turbo will have to fight a moment of excessive back pressure to spool up again. Also, that extra back pressure will cause the turbo to spool down more quickly, and thus not only slow the next spool, but also make the turbo have to cover a wider range of RPM's before it's creating boost as well.

Now, I'm no turbo expert, but I would think that the advantages of dumping the WG would vary from turbo to turbo... I would think that a newer, highly efficient turbo would become notably more responsive with the WG dumped... whereas something more like a k26, maybe not so noticeable. If I'm wrong, someone please correct me, as I've been running my WG tied in since I have a k26 and didn't figure dumping it would do much... I had planned to dump it in the future when I had a better turbo.

APKhaos

Be careful with the dump to atmos setup. You need to run it clear of the underside of the car. I've seen turbo racecars with short dump under the car have problems with cooked trans and rear axles/cvs.

Paulyy

a k26/6 is a very high backpressure turbo, that's why porsche put the #8 housing on and slightly raised the boost and gained 30 hp because the engine also could breath easer.
Vic (pauer tuning) tested the back pressure differences in the xover with a to4e 50 trim #10 housing and a gt3067r .63ar and noticed a 10 psi pressure drop at 18 psi of boost. (35psi vs 24psi) and gaind 30 hp. all the spool characteristics where the same.

so say if you dumped the wastegate you might drop the 35psi to 34? 33psi? and could gain in more power maybe 5hp?

note taken

dillon410021

will there be exhaust coming out of the wastegate dump tube at idle and part throttle or just WOT/ decent boost?

TurboTommy

So, it's not clear; which of those two turbos gave the 10 psi less pressure drop?
Also, at what RPM? That's of huge significance.

By the way, one can easily drop 5 psi back pressure on the engine when having separate wastegate exhaust. (Although with me, my orginal tie-in was not the best it could have been.)
I have an in-car back pressure gauge installed.
None of this is theory only; it tranlates into real power you can feel (not just dyno #s), and also gives additional detonation safety.
Yes, it's louder. With a mini-muffler it tones it down a bit. But at full throttle it can still have a little bit of a nascar roar. Part throttle with the wastegate only a little bit open, at low boost, it's not a big deal at all.

Paulyy

Sorry the gt3076 .63 had the 10psi drop

i didnt get told at what rpm, my guess would be at the highest point of pressure.

Paulyy

just when theres boost. depending how much boost you run when it opens.

if you run a dualport wastegate it will open 3-4 psi before full boost so you wont hear it untill your pretty much full boost. on city driving you wont hear it at all.

Crackership

well, that's good to know, maybe I'll dump it sooner than I thought. I really wish I could have fit a better turbo into my budget for my current project, but there were just too many little bits that really needed to be addressed... That, and I really couldn't decide on what turbo I'd like to go with... I mean, the GT30 seems like pretty much exactly what I'd want to do, but I'm really not interested in the necessary mods to the oil drain/pedestal. A buddy does have a GT42R sitting in storage that I probably could have talked him out of, but I'm not sure it would quite fit

Here's a pic of a GT42 compared to a TD04, which is just a tiny bit bigger than a k27

Paulyy

the range for that turbo is 2L to 8L so it might just work

Theres alot of turbos to choose from that bolt on to our cars or theres alot more that need fabbing like the gt30r
the only reason i didn't like the bolt on options is that they all use kkk housing which make alot of back pressure, thats why people put huge exhausts and wastegate dumps to eliminate some backpressure.

Paulyy

I want to open this discussion again. Anyone found any evidence why one is better then the other?

boerge

I know the sound is fun for 1 day, then you hate it.

Zeff

hopefully this posts


My WG dump is a little different, the guy that fabbed my exhaust cut up the stock tie in and used that to extend the dump so it isn't right after the WG. It is much quieter than the lindsey dump, but not as quiet as the lindsey wg muffler.

If I'm able to get the car inspected and my axle replaced this weekend I should be able to get a dyno next weekend, but it won't be as accurate of a test since I had a fabspeed dp and 2.5" test pipe previously and now I have the fabspeed dp and a 3-3.5" setup.