Wastegate On Intake
 

There has been a few discussions around adding a wastegate to the intake tubing.

Supercharger...

The idea here is that you overspin the supercharger to say 16psi when you only want 12psi. You put a 12psi spring in the intake wastegate. It opens at 12psi and vents off the additional boost. This in turn will push the boost curve to the left so instead of having 3psi at 3000rpms, you would have something like 5psi at 3K and full boost before redline. This would obviously have its benefits.

Now for you turbo guys (namely mid-mount)...

Say you wanted 10psi in the manifold. Here you would have your actual exhaust wastegates set to say 15psi through a boost controller. Then you would have a 10psi spring in the intake wastegate hooked directly to the manifold. The benefit of this is that the turbo will be spinning much faster through a run and when you let off the pedal it will not lag when grabbing the next gear. So a larger turbo will not slow down enough and you would have 10psi on tap. It also helps spool times as the exhaust wastegate would stay completely clsoed then pop open instead of slowly opening to reach the 10psi.

Who has any experience with this?

On the turbo side - the potential turbo-RPM benefit could be a thing but would depend heavily on the momentum of the rotating assembly and I am a little skeptical how much could carry over... but I'm no expert so maybe?

The spool part is not really a thing, as the boost controller handles this duty for you. In the simplest form, a ball/spring manual boost controller does exactly what you are describing (holds the gate shut then pop open).

For the supercharger side, certainly does sound interesting!

On my sc wastegate, we're going to install an 8lb spring and then control boost dump with a Greddy Profec.

Sounds like a nifty idea. Curious if it'll work though.

Have you considered the wastegates don't really bleed much in the grand scheme of things? The majority of exhaust gas coming out of the engine is flowing through the Turbo and that little bit of excess flow is being diverted to keep the Turbo from hitting half a billion RPM and self destructing. Even between gears or on decel, when TBs shut and engine exhaust flow drops dramatically, that's even less air the wastegates are dealing with.

Where as in an SC application on the intake side, you'd be exposing that crazy amount of flow directly to the wastegate and expecting it to stably bleed off that unwanted extra 4 PSI, even when letting off the throttle and RPM is still near redline, SC is still making stupid amounts of boost.

Maybe I'm just talking sh*t. I still love the idea, but that's the first thought that came to my mind. Sub'd.

I talked to Seb (Specialty Z) about your concern and as he hasn't done it on a 370z yet, he has done it on a mustang with success. He'll be doing my re-tune once my mechanic gets it installed. He's one of a few people that suggested we try it due to my 91 octane limitations.

Here's an article where it was done on another mustang.
http://www.mustangandfords.com/how-t...egate-install/

From my experience with the twin scroll, you would not be gaining anything with the intake wastegate. The shift is quick, and you are right back at full boost as soon as you are in the next gear. I logged it on my old 350z through Haltech. I'll see if I still have those logs.

The reason I'm attempting to do it is that I'm on flex fuel (91 and e85). I'm capped at 13psi right now due to the 91 octane. I'd like to be able to run higher boost on e85 and this would give me the capability of dumping the excess boost when on my 91 tune.

Yes, this is common in a centrifugal supercharger setup. But not on a turbo.

Wastegate On Intake
 

Seems like a lot of extra pneumatic plumbing. Especially on a car with two intakes.

And living in California with the crappy 91 octane doesn't help.

One intake. You definitely want to dump this charge (heat) pre intercooler. No sense in heating that thing up.

Personally I would use a cheap eBay wg since it will see relatively cool air in this sense vs. egts.

That is so freaking cool! :tup:

Curious, what's stopping someone using a EBC to control the Wastegate? At least you could get pretty nice granular control of the boost. That article the guy was controlling it all through switches.

We're going to use a Greddy Profec.

So I love this idea, but space is tight on our cars. Where will u mount to WG?