So my dad and I have a bit of an argument. I don't know the answer, and he is convinced I'm stupid.

So when you add a supercharger reduction pulley to your car, it makes more boost, correct? How does the supercharger provide more boost to the engine without the wastegate getting in the way and allowing the added boost to dump out?

BTW, how much will adding boost reduce the life of the engine and the supercharger?

Thanks.

 

You are stupid.. Your dad is the winner.


Haha.. JK..

Plenty of people have ran the 15% pulley with no issues. But it's like everything in life. No two cars will react the same. You might go 150,000 miles with not one issue. Or you might end up needing some sort of work in 10k miles..

 

Well i'm not the best guy to ask, but I don't think the supercharger uses a wastegate. I'm pretty sure only turbos use them. The life of the SC has not been known to be a problem. They built in a good cushion for us, up until you add lets say a 19% pulley, then bad things start to happen. But i'm sure the experts will chime in soon .

 

There isn't a wastegate, but a bypass valve. It's a closed system. The valve opens under light load conditions raising efficiency, closes under heavy load conditions, and supplying positive boost to the intake manifold.
When you add a reduction pulley you are overdriving the supercharger from it's stock configuration. This will supply more boost when the bypass valve is closed.
In general terms, any time an engine makes a higher specific output of power for a given configuration, you are putting more stress on the engine and potentially shortening it's life cycle. In realistic terms, if you wanted an engine to last forever, you should look at a Mercedes diesel. I've heard stories of 1,000,000Km out of Merc taxis in Europe. If you want a reduction pulley to have more fun with your car, I don't think you are cutting a substantial percentage of it's life by adding one. As always, you experience may vary.

 

You are correct, a reduction pulley spins the supercharger faster creating more boost. Some preasure is released but the max boost is not instant, it builds as the RPMs increase. As long as you don't reduce it to much the life of the supercharger is not changed dramatically, but the more reduction, the more wear on it. Hope that helps.

 

big howe pretty much answered it. The supercharger makes more boost because it is directly driven by the crank pulley of the engine. The smaller the pulley, the faster the supercharger rotors spin.

There is a bypass valve, which is designed to reduce load on the supercharger when not needed, and thereby increase mileage and longevity of the supercharger. It is vacuum based and the bypass valve is open anytime there is very light to no load on the motor - which is not RPM based, but load based. You could run all the way to redline with no boost if you do it under light load.

Just because you are making more boost does not mean you are making more power though - there is a balance of temp and pressure to achieve the optimum density. There is a specific efficiency range for each supercharger design, and ours is well within its design limits with the smaller pulley offered by the aftermarket. Because of that, the temp increase created by making more pressure (boost) is not detrimental to the life of the blower in any significant measure. I have many customers who have over 100K on the blower since the pulley install (and I've now done over 1000 with my own hands).

Hope that helps - now you can sound brilliant to your dad!

Randy

 

....yeah, what Randy said!

Smaller pulley, goood.

 

Hey, Randy is back.

 

Thanks for the explanation!

Is it possible for the bypass valve to remain stuck open? And would there be any indication that it is stuck open besides the loss of power (because the supercharger is not functioning properly)?

Just curious.

 

Sure, a BPV with a weak spring won't allow vacuum thus showing lower boost that your system is capable of. When I replaced my OEM BPV with a Detroit Tuned BPV, I had the chance to feel how strong the spring was on the OEM, mine required very little pressure to open it, versus the DT BPV where it was significantly harder to open by hand, and it sprung closed that much better once it was opened. This meant that when I stomped on the gas, the boost gauge would give me an instant reading, and when I let off the gas, it immediately showed vacuum. Prior to the new BPV, the needle would take longer to settle down.

 

Interesting. Thanks, OG.

 

Yep. Best pulley put-er-on-er out there.

Don't know how much boost, but my grin-o-meter is up there!

 

If you can measure boost, it will show a lack of it. That is the best indication of a bad bypass valve. You would also not hear the supercharger whine as clearly, as it won't be under load. They do go bad, but most of the time the butterfly itself is the issue. They even come bad new from the factory, with just plain bad tolerances on the butterfly.

Hope that helps!
Randy

 

Thanks again.

(Being now out of warranty, I am doing my best to learn everything about all the nuts and bolts of this car so that I can do my best in diagnosis, maintenance and repair )

 

Glad to help. If you ever have any questions, I think I have seen most of the R53's tricks, and I'd be happy to give whatever advice I can. Just shoot me an email - randy@webbmotorsports.com .

Randy

 

OK, thanks!

 

Thanks for all the responses. I schooled my pops.

 

Don't forget that in stock pulley size, the supercharger is below max operating RPM specs. A 15% reduction pulley takes it to about the max operating spec RPM at redline. Note that the JCW pulley is a bit bigger, but the engine rev limit is lifted so it gets near max pulley spec at the higher redline.

 

Dual Speed Pulley

kit is high and there are many existing supercharger installations in theDevelopment of the dual speed supercharger showed the dramatic benefits a two speed drive gives to a supercharged vehicle. However the cost of developing a complete installation market.

It was therefore clear that a stand alone dual speed pulley would make available the benefits of dual speed supercharging to a much larger market.

Initial development work is underway and the product will be available from April 2008.

Initial applications are expected on applications such as the Mustang - the attached data shows what this can do for the vehicle.



Longboard

 

2 things:
With a weak spring in the by pass valve - can mean that the valve does not close tight - it's vacume that opens it. With the BPV opened, heat from the blower is reduced, HP loss is reduced, efficiency is increased & life extened.

The supercharged Mini has a purpose built blower motor.

Longboard, I like the dual speed

 

That happened to Artoo and I didn't know until one day when I downshifted to pass someone on a country road and went into limp mode. Shutting the car down and restarting brought it back to normal except the check engine light stayed on for a few restart cycles. All I had to do was accelerate hard and it shut down. Replaced the valve (it was stuck open) and all was well.

I don't really drive it hard much so I had no idea of how long that was a problem as it otherwise drove OK and gas milage didn't change much.

So, find a country road and let her rip!

Rich

 

Dual speed pulley... OMFG!!!