Twin Charging?

B8 S4
#1

Hi guys. I’m new to the forum. I’ve posted on “vendorzine” a bit, but honestly I’m more hack-and-crack kind of modder than off-the-shelf kind of guy; that being said I think this community fits me a little better. Previous projects of mine have been 3 Z Cars, IS300, Corvette Grand Sport, Evo X, Mazdaspeed 3. Thus far, I have to say, the S4 doesn’t fail to impress, even compared to a 'Vette this thing is pretty quick off the line.

I’ve been following the “Stage 3” development, or more accurately teasers, from APR. A new larger blower does seem the most elegant solution to more ultimate power; however, have any of you given any serious thought to twin charging. I am fairly new to supercharging (I’ve dealt almost exclusively with turbo, but a linear power band is just more fun to me), but, as I understand it, positive displacement superchargers work on pressure differential. So, my theory is that a smallish centrifugal supercharger could be a much cheaper solution to our MORE BOOST desires. Any thoughts? Would weight considerations and space constraints ultimately kill such a project, or could you cram a small v3 or rotrex unit somewhere under the hood?

#2

I’m not well versed in this stuff. I do know that space is a bit tight under the hood, it may be possible but it would be tricky. That said I think the biggest hang up our platform has for stuff like this is custom tuning. AFAIK there is no reliable source for a custom tune. So something like this may be built but good luck getting it tuned.

#3

Welcome… more out of the box thinking…great list of past cars…

Twin turbo and twin supercharging is going to be two different experences…

Superchargers are gear driven so putting pressure at the inlet is not going to help… superchargers are more pumps then compressors…a turbo has lag due to not enough power on the exhaust wheel to push it… superchargers dont have that issue due to them being gear driven…you wsnt more down low jist chage the gear or pulley.the restrictions are what your fighting with superchargers make sure the intake track is free of any restriction…

#4

well, guess everyone is in luck. Check out the coming soon…isnt this the J-FLO PR Agent…

http://sillyrabbitmotorsport.com/aftermarket-audi-turbo-engine-upgrades/audi-s4-b8-supercharged

#5

It’s called compound boost. It’s damn near impossible to tune, and it has absolutely zero advantages. Anyone who does a compound boost setup does it for bragging rights.

The guy who tuned my cobra, Bob Kurgan said that you can’t predict or calculate a lot of the variables making it hard to tune.

#6

You can make a ton of power with a well designed twin screw or TVS setup such as the APR kits. Given the choices of superchargers on the market like the TVS or even a twin screw like a whipple, you will never run out of blower. There will always be one big enough to cram air down the throat of that little 3.0. But then again a centris are awesome and you can generally push a motor further with a centri than a roots/TVS/TS.

#7

just to note all compressor operate on a pressure differential between outlet and inlet.

the main advantage of multistage compressing is the ability to exceed the pratical limit for pressure ratio (varies by compressor). For instance the plant I work at has a 2 stage 100psig twin screw compressor and a few 4 stage 4500psig compressors.

Obviously a gas motor doesn’t need that kind of inlet pressure, so typically you only see multistage compressing done well on diesels where they can handle 200+ psig and need three turbos to reach that.

not to discount your idea though, I like it. I just think, like joe elaborated on, a bigger blower may be a better solution (6-71? lol).

#8

Silly rabbit = seller of rs6 hybrid knockoffs?

#9

I do realize the many draw backs of such a system. The main one being the heat generated. However, it could theoretically be far cheaper then any TVS setup. In practice I doubt if we will ever see such a system. The first compressor would have to be a centri, it would need to flow sufficient CFM to feed the TVS, but if it could do so at even a mere 3 PSI the total manifold pressure would approach 30. At that point you’d probably have to pull so much timing that it would negate any gain.

The whole thing is more of a thought experiment than anything.