RS4 Supercharger Argument

B6/7 S4/RS4
#21

KB isnt seen because they make their own kits and I gather dont wanna sell just blowers.

Paxton is owned by vortech (vortech was founded by old paxton employees) and makes the same stuff with the drive set up reversed iirc.

eaton is the choice because they are a huge oem supplier and a tuner can try to use some of that oemness to sell to people, as if the blower is the biggest concern. they are also low maintenance and proven to run very long in oem applications.

for twin screws autorotor would be a good choice, they have some smaller units (vs KB who starts big and gets huge)

in all seriousness, I think we should all look into GM twin lobe roots blowers though, a 6-71 would be a terrific fit…

LOK

#22

so hard to justify 10k plus for a supercharger on these cars, especially in that it’s not bundled into the original purchase price that you include in your financing…unless you are paying cash I guess

#23

well, someone will happily pay it, so it’s up to everyone. The TTS kit is $21,000. The APR kit was originally $19,000. They both had no trouble selling without proof of a damn thing (the APR proof came over a year after selling…because it took that long for a JHM tuen to get on the car in order to produce a result worth talking about).

If you look at the typical B7 RS4, the owner spends $1000-1500 on downpipes, $2000-4000 on a catback exhaust, $700 or so on a tune…and they’re typically making about 350 wheel horsepower or less, if you exclude JHM.

i.e. most common setup is Milltek downpipes, Milltek catback non res, valved, pick your tune (APR, GIAC, EPL). That is $4000+ in mods. They’re almost half way to a $10,000 supercharger kit, but they’re only making about 20-30 whp and wtq over stock.

#24

EATON’s compressor map, and comments on the TVS indicate it should max out (at warrantyable RPMs) at CFM that could provide 525 hp (crank) or about 450 whp. The RS4 can handle much more than that, so certainly it’s blower limited (now lol…beem’s point is a good one)

#25

anyone know how to convert KG/s (mass flow) to CFM (air flow) at say sea level density?

p.s. madison, if you are adding an image to this site, the tags need to be TWO words, that are each 6 letters long or more. It’s weird, I know. Let’s badger God to change that to 1 word minimum with a minimum length of 2 letters (as many tags like V8, S4 etc. would be fine…but are currently not includable)

http://i278.photobucket.com/albums/kk89/mbgt72/Car%20Pics/Forum%20Photos/RotexC38CompressorMap.jpg

I found this…

[quote]kg/m2/s is called “mass velocity”

In order to convert this to cfm (called “volumetric flow rate”) you also have to know the cross sectional area of the conduit through the material flows (cross sectional area = m2, or square meters in this example)

You also have to know the density (kg/m3, kilograms per cubic meter) of the material flowingNow, mass flow (kg/s) = Mass velocity (kg/m2/s) * cross-sectional area (m2).

Volumetric flow (m3/s) = Mass flow (kg/s) / density (kg/m3).

Volumetric flow (cu ft/min) = volumetric flow (m3/s) * 35.31 cu ft/m3 * 60 s/min
Source(s):
37 years of chemical engineering experience

Try Crane Technical Paper No. 410 “Flow of Fluids Through Valves, Fittings, and Pipe”, available at any university library.
5 years ago Report Abuse .
[/quote]

#26

1 kg/s is approximately 132 lbs/m. To convert lbs/m to cfm multiply by the air density. IIRC it is between 12 and 13 cf/lb depending on the temperature and humidity.

#27

http://www.audizine.com/forum/showthread.php/468598-MRC-Tuning-B7-RS4-(VIDEO)

The plot thickens…Santa Pod in the near future…dummmmm dum dum dummmmm!!!

#28

welcome to post 1 of this thread NY07RS4! ;D

[quote]TTS - This is a Rotrex centrifugal supercharger, tuned by MRC Tuning in the UK. Not much is known about the kit, but they’re doing plenty of advertising etc.
TUNE: MRC
COST: $21,000 USD (13,000 pounds sterling)
CLAIMED GAINS: 180 hp (crank) on the MRC dyno
ACTUAL GAINS: Huh
1/4 MILE RESULTS: none yet, although MRC is only 30 miles from Santa Pod, an IHRA dragstrip. Their first customer (DannyRS4) said he’s going to Santa Pod in a couple of weeks.
[/quote]

#29

i’m still lost

#30

from Rotrex themselves

CFM =kg/s × 1731.8

@15°C and 0.1013MPa

So…at 70%, pushing 34 PSI, at 90,000 RPMs, the C38-81 is flowing about 0.48 KG/s…and assuming the conditions shown, pretty normal, that’s 831 CFM…a.k.a. about 550 hp (assuming 100hp per 150 CFM). This is all before any losses for driving the blower which can be 10-50 hp on twin screws we’ve seen…not sure on these Cfuges.

Does that sound right? I know it doesn’t sound like 600 hp (claimed) so I’m sure there’s more to it. To get to the claimed 600 hp, you’d need to get to some 900 CFM…thus you’d need to hit 0.52 kg/s…which is 90,000 RPM at 40 PSI and around 68-69% efficiency.

http://audirevolution.net/addons/albums/images/317212600.jpg

#31

That sounds correct. They are using an are density of about 13.1 which is reasonable. Has anyone ever published numbers at the wheels for the TTS kit? I am assuming no, but it would be nice to see.

#32

[/quote]
I did read the entire post, I guess I missed that last part in your original post. My bad.

#33

update: added the MTM supercharger, the first one available for the RS4. How’d we miss that lol?

#34

http://www.motodyne.com/frames/audi_RS4.html

Bro you are slippin! You forgot yet another! Hell I might have one more up my sleeve ;D ;D

#35

LOL - Motodyne. That’s a good one!!

#36

:smiley: ;D ;D ;D^^^^^

#37

Anyone have any info to add to the original post? I left a bunch of question marks up there for things I didn’t know the answer to.

p.s. I contacted the MTM supercahrged RS4 in Rochester, the guy who got his work done at MTM’s montreal distributor. He has a Misano Red RS4 and he called it ‘the cherry bomb’.

It dyno’d around 410 whp at Horchaus (MTM Montreal), so take it with a grain of salt, but that sounds about right. Hopefully Al will pop in here to share some thoughts. We should arrange that dragstrip day in Rochester like NY07RS4 was suggesting…and try to get Al to come out. Nice guy…but he has way too many amazing cars to get excited about his RS4. It’s his winter beater lol.

#38

First world problems lol

#39

the craziest I’ve seen lately is a guy on 6speedonline with a 997 GT2…and he’s talking about getting a 60-130 time…but all the guys on 6speed want him to get times for his other cars, which include

Veyron SS, Mercedes McLaren SLR and a 997 GT2 that is faster than the Veyron, and some kind of Lambo.

Guy is from Dubai.

#40

^Sounds like a car guy to me!!