using a wastegate on a centri blower?

rockthemullet

rockthemullet

Forum Member
I have an intercooled Vortech STrim on my 99 Cobra. I have a friend who frequents the 350z and g35 forums and showed me a thread on their site. The idea behind it is that you can run a much smaller pulley than you would normally, see a specified amount of boost much earlier in the powerband, and then cap it off at that boost for the rest of the rpm range. The "problem" with centrifugal superchargers is that their boost is linear, as in, the boost is constantly increasing depending on rpm, much like a turbo would without a wastegate. The roots or twin screw style, on the other hand, reaches a certain pressure low in the powerband and continues that throughout most of the powerband. Basically, the goal is to make a centrifugal ACT like a roots/twin screw but with the added efficiency of the centrifugal design.

Would this work? Where would the wastegate need to be located? Would an electronic boost controller be needed to adjust for the varying boost that the wastegate will see?

My car is currently equipped with an a/w "aftercooler" and a Vortech Race Bypass between the aftercooler and the throttle body. Would I need both in the system? I figured this would be a great place to ask this question.

~Eric
 
I had this idea a while back... decided it was a pain in the arse to even attempt. Either way here are a couple things I thought of...
You'd for sure need a blow through MAF, the other thing I thought of was in a turbo app. the waste gate is on the hot side, it's hard to say how it would act on the charge side of things. Seemed like it would cause the boost to fluctuate a lot - either not bleeding off enough air, or bleeding off so much that it would constantly open and close- until you found the perfect size unit. But yeah just a couple things that went through my mind when the same idea came into my mind a while back
 
Looks like someone already thought of it, lol

http://www.musclemustangfastfords.c...gal_supercharger_wastegate_install/index.html

The difference is that in that application, they're tuning down someone's race setup for the street so they can run pump gas, already running the smallest pulley possible without overspinning.

In my instance, I know I can't push my stock block much past 500. However, who says I should only see 500 at 6-7000rpm. If I can throw on a 16lb. pulley, it will ramp much quicker to 10lb. and I can cap it off. The area under the curve would be where all of the gain is. Instead of say 330 at 3000rpm, I would see 380 at 3000rpm and so on. Then, instead of having 500 from 6-7, I would have it from say 4000-7000. Of course, these are arbitrary numbers that I'm using to prove the point, I have no idea when the power would come on or cap off.

my8950, one reason for a boost controller would be to adjust the level of your boost cap, much like a turbo car. That way, I could run say 10lb on pump and 14lb on C16 without ever changing the pulley. The boost ramp would stay the same but would continue upward to 14.

VTRauder, it would definitely call me a blowthrough MAF. For me, that would mean converting from a/w to a/a since the ducting from the supercharger to the throttle body is almost entirely consumed by the a/w exchanger, leaving no room for the MAF.

~Eric
 
I have been talking about doing this for a while now with a few folks. I like the idea. It would certainly make getting a big blower out of the box alot easier on these limited tire cars. I bet alot of these guys are already running stuff like this as it is but alot of that stuff is hush hush top secret.

I would bet a wastegate would work fine.The trick would be figuring out how big of a bleed you would want and how much control you needed. Typically the bigger the wastegate valve gets the harder it becomes to control it in a linear manner. This might be one of those times wherin 2 small gates are better then one big one.
 
rockthemullet said:
The difference is that in that application, they're tuning down someone's race setup for the street so they can run pump gas, already running the smallest pulley possible without overspinning.
Click to expand...

Yeah I've seen/heard Sean mention this a few times over the past year or so, and the above quote is one of the main reasons why I'd want to do it. I'll admit I've been leery about it just because you don't really see it done, but I've been considering it more and more lately.
 
Sean said:
I have been talking about doing this for a while now with a few folks. I like the idea. It would certainly make getting a big blower out of the box alot easier on these limited tire cars. I bet alot of these guys are already running stuff like this as it is but alot of that stuff is hush hush top secret.

I would bet a wastegate would work fine.The trick would be figuring out how big of a bleed you would want and how much control you needed. Typically the bigger the wastegate valve gets the harder it becomes to control it in a linear manner. This might be one of those times wherin 2 small gates are better then one big one.
Click to expand...

Birdie2000 said:
Yeah I've seen/heard Sean mention this a few times over the past year or so, and the above quote is one of the main reasons why I'd want to do it. I'll admit I've been leery about it just because you don't really see it done, but I've been considering it more and more lately.
Click to expand...

Sean, I wouldn't doubt its out there, it just hasn't really trickled down to the backyard mechanics yet. I think with the relatively low pressure I plan on running, a standard 38mm should do the trick.

Alright guys, I'll play guinea pig. I'll need to sell my a/w and go a/a. Should be a good winter project, I'll keep everyone up to date on what I find.

Birdie, where in Westland are you? I'm around Cherry Hill and Hix.

~Eric
 
NMRA Drag Radial guys did this years ago. read up on Philip Clemmons and a couple other guys from around 02-04. . more info can be found on NMRADigital.com

Phil is a good guy too, he will answer all your questions.

a bunch of guys have done it.
 
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