JAX04

iTrader: (17)

see this is where i am confused, i dont understand how restricting the air flow to the head unit will actually allow you to make more boost sooner. i can understand how it will only allow you to make 10 psi if its pullied for say 13, but how does this allow you to make boost sooner?

i read that thread from the mustang forum and from the corvette forum and really got lost in the vette one. there were valid points from both threads. but still didnt break down how a restrictor plate can actually make the max boost sooner in the rpm range.

Aster

iTrader: (9)

The way it works is you can pulley down the supercharger so it spins faster, thus making more boost earlier in the engine's RPM band. The restrictor limits the maximum airflow to the blower preventing it from drawing in more air than your motor can handle thus limiting your maximum boost.

It would be handy to be able to know what size restrictor plate you need for different desired airflow though. I don't like the idea of guessing as it can get expensive to make several plates before you find the right size for your setup.

For instance I'm making ~13psi of boost with a 3.85" pulley on the D1SC. If I pulley down to a 3.4" pulley what size restrictor would I need to keep me from exceeding say 14psi max?

JAX04

iTrader: (17)

i see what your saying, ok, let me take a stab at it now.

A restrictor will restrict the MAX airflow the supercharger will "inhale" but it makes more boost by pullying down to boost faster. this works cuz the engine requires less CFM to make X boost at lower RPM. So the restrictor is only big enough to restrict the super from makeing X cfm on the top end. Doesnt really effect it down low. Thus allowing you to pulley down and make boost sooner. Got it. my verbage may be alittle off, but i get it now.

Now to answer your question, i did read of someone making a throttle plate type deal that would swing up and down or side to side, with a set screw that would make it adjustable like a throttle body. so you could just move the blade open or closed to obtain your desired MAX boost. i think.....

chriswtx

iTrader: (5)

yep thats correct

bluebird71

iTrader: (54)

What about welding an electric cutout valve to the intake pipe? You could open and close it a little bit at a time and watch the effects on the boost gauge. It would be like an adjustable restricter plate. Though I wouldn't normally recommend the QTP cutouts, they do make a device that will allow you to open and close the valve at set percentages. 100% open, 90% open, etc. You could calculate the difference in boost pressure per percentage of the cutout being open and have some set preferences. 100%=16 psi. for the track, 75%=12 psi for the street, etc. Would this work out like I'm thinking?

chriswtx

iTrader: (5)

problem with that is you would be bleeding boost all the time. you would loose the low end punch. a wastegate doesnt bleed boost until a given pressure is reached, so the boost ramp up on the low end is much better...

bluebird71

iTrader: (54)

Guess I'm not the first one to think of this though. Dallas Performance makes and adjustable restrictor plate valve that restricts at different levels depending on what gear your in.

http://www.youtube.com/watch?v=nAG1enBPwso

Avengeance

iTrader: (4)

Thats pretty sick.

However... having a car with a big stall and a cetri SC is kiiiiiiinda like a turbo car... or roots style. Once ya nail it and the converter flashes your in boost all the time.

JAX04

iTrader: (17)

yeah, but not full boost unless you do one of these cool tricks.

SnowTech.4

My thoughts exactly. You could have a centrifugal with the response of a positive displacement without loosing the efficiency at all.

In fact, depending on how it was done, you could easaly gain efficiency.

Combine that with the boost by gear nature of whats being discussed in here and you suddenly have the exact boost you want at all times

JAX04

iTrader: (17)

Only problem, that technology would easily double the cost of a procharger or any supercharger application.

JAX04

iTrader: (17)

so, im going to try this resrictor idea on a friends 3v rustang. any thoughts on where to start, its currently pullied for 10 psi on a p1sc1 setup. where to go from here?

Chris'stransam

iTrader: (7)

If u are using a boost controller why cant u use a E boost and u could pick the boost level u want and the gear u want it . JUst asking I want to do my ysi that way

SnowTech.4

I wonder if the guts of a snow mobile trans would work. My guess is that its very possible

JAX04

iTrader: (17)

im no genius, and dont claim know much of anything, but exactly how big is a snow mobile transmission. could it fit in the area behind a procharger, in most cases there is only INCHES to spare.

SnowTech.4

Oh, the super would likely have to be reloctaed to make something like that work, but snow mobiles tend to use a CVT transmission that lets them stay right at peak TQ all the time. I think Nissan did one in the Maxima too.

But on a snow mobile, I would not be too surprised if the components for that particular function were about the foot print of a shoe box. So big, but not impossible. Just incredibly difficult and not really worth it

T-Bones Goat

iTrader: (3)

Been talking with another member who is building a badass car. He turned me on to the idea of the wastegate. Chriswtx, do you still have yours? Any regrets?

chriswtx

iTrader: (5)

Still have mine, no regrets, works like a charm...

T-Bones Goat

iTrader: (3)

Thanks alot. Do you happen to have any part numbers for this? Any info would be much appreciated!

chriswtx

iTrader: (5)

The only parts you need is the boost controller of your choice and the right size/pressure wastegate.. I used a Greedy profec B controller and a 7psi wastegate, got the largest mm size wastgate I could fit..