TheRadioFlyer

Can someone explain how this works with Fi setups? Sounds like a way to limit top-end boost to help extend the life of high-mileage engines.

Mike04

The restrictor basically reduces the diameter of the intake pipe in the area it is inserted. The smaller diameter area does not allow as much of a free flow of air to be pulled in by the SC. At lower intake air velocities the SC isn't affected too much. At higher velocities the SC cannot pull in air as easy as it could without the restrictor. That reduces the boost produced.

Kind of like the difference between having a clean air filter and a dirty one. Air flows easier through the clean filter due to less restriction which gives you more power....

TheRadioFlyer

So this goes upstream of the blower.

I'm confused exactly how this helps.

wilson34

It helps because you can put on a smaller pulley, which now spins up the blower earlier and harder but it limits the amount of air the blower can move at higher rpm.

Thus, you'll have more bottom end power and the ability to maintain a lower boost level.

Example you only want 7psi, which pulley A gives you.
Well pulley B has alot more bottom end but makes 13psi.
So you put a restrictor plate on the inlet, install pulley B, get your better midrange power but limit boost to 7psi.
BAM

TheRadioFlyer

okay. sounds good. How does one calculate what size restrictor plate is needed and how does it install?

nickolbag

mAydAy121

The proper way would be to do a choked flow calculation, as the blower will draw it at sonic (ignoring any supersonic effects) which can give you a mass flow rate through the restrictor. You can loosely determine mass flow rate through the engine and determine the resulting boost pressure from the difference.

Mike04

The restrictor goes between the air filter and the SC. ECS makes one and it works as advertised.

chuntington101

for referance most WRC car used (for 2010) a 34mm restrictor and that should limit them to about 300bhp. You often see these unsed in race series to limit some cars/classes.

Chris.

TheRadioFlyer

would this be calculated based on impeller speed.

Linky?

clemsondave

I was going to do this when I switched from the P1 to the D1. My tuner (http://forums.corvetteforum.com/memb...frost-com.html) suggested some simpler ideas (pull back timing, fuel and or lower limiter). I went his direction and never looked back.

TheRadioFlyer

Just talked to ECS about this. Sounds like a good idea for my car. I'm currently getting my old S-trim upgraded and rebuilt to Si-trim spec. My (stock) motor has 145K miles on it and gets a decent amount of blowby at the top of the rpm range. My car's also a street-only car so I rarely get an opportunity to go over 5000 rpm Anyway.

What I'd like to do is get about 4-5 psi boost around 3-4000 rpm and not get above 7psi on the top end. I'm currently running a 30-tooth pulley bt can drop down to a 28 if I can get this setup right. Those of you with experience using restrictor plates, I'd like to hear what sizes worked for you.

...i know...i know i should have gone with a maggie, but that' hindsight.

DOUG @ ECS

Really? I guess it's not ok when your trying to down grade the competition, but actually ok when your trying to help your customers? Very odd, but here's a recent post from Andy;





In actuality, we are the company that brought restrictor plates to mainstream use, and the benefits are fantastic for a cheap investment, without causing any damage to the supercharger. Which is also agreed by Paxton and Vortech themselves.
Sizing them correctly is something that cannot be answered very easily by someone on this board, unless they have direct experience with your kit. Different inlet ducts, head unit sizes etc, will dictate different sizes needed. Also a 1/16 of an inch off a restrictor plate can make a substantial difference, so go in small steps.
Fortunately for ECS customers, we have all the sizing taken care of, and all of this would have came with your base supercharger kit. So we would give you the info your looking for, but it is not terribly hard to start with a smaller hole restrictor and work your way out. It just may take a little bit to get to where your looking to be.

Good luck with it, hope that helps.




.

TheRadioFlyer

CORRECTION: I called ECS


.....you guys on the east cost wake up sooner than A&A out in Cali

Ideally, I'd like to install the restrictor plate on the downstream side of the air bridge before the "accordion" coupler. I'd make the prototype out of 0.125" ABS and the final version out of 0.125" aluminum.



Is there any benefit to a gradual reduction in cross-sectional area versus just a plate?

DOUG @ ECS

Well that makes more sense now.

I have only used "ring" style restrictors, so anything else would be trial and error on your end. They also need to be on the inlet side of the charger, the boosted side will just create a ventury and not make much of a difference overall.

0chris@sfcc

The way the supercharger works and the amount of pull it creates, there isn't going to be a huge difference- if it weren't being sucked in with such great force I think it'd be different but with a supercharger doing the heavy lifting it won't matter much.

Plus, the only time the blower is going to feel the restriction is on the top end when it's trying to pull that huge volume of air in and can't, which is when you want it to be restricted anyway. I'd just rock the flat plate like ECS does.

Also, put it as close to the blower as you can to avoid messing with plenum volumes on low boost situations and ensure it's mounted properly- there is going to be a lot of force on that plate when the blower spins up.

TheRadioFlyer

Noted. Looks like just upstream of the steel "elbow" just in front of the blower is going to be my best bet.

....and the waiting begins.

Z06ster

I'd be real curious to see a DYNO sheet on a centrifugal FI setup with a restrictor plate... anyone got one?