OK, some real world calcs from someone who actually races L bikes and is somewhat familiar with blowers in Vettes.

Chain is a 530 series (no way to run a 525/520 series with 200+ HP) w/43T driven sprocket (8.48" diameter). The strength and design limits are lower for the lower series chains.

I did the calcs based on 1/4 mile trap and on top speed (based on Texas Mile data).
at 164MPH: the chain is moving at 4714 ft/min
at 208MPH: the chain is moving at 5979 ft/min

Calcs on blower car:
at 7000RPM (based on 7" drive sprocket; eq to current shive): 12,828 ft/min

Now, the first question that rises is whether you can "sprocket down" the drive (crankshaft) to lower the chain velocity. Most blowers that guys on this board will use require an ~3:1 ratio between drive and driven (if you get into the ATI R series, they are closer to 2:1). The smallest sprocket size available for a 530 series chain is a 15T (special order 13T and 14T, but extreme wear issues ). So this means that with a 15T driven (blower), you will need a 45T drive (crank; remember 3:1 ratio requirements), which places the 45T diameter sprocket at 8.87" diameter and the velocity at 16,255 ft/min.

Now with all of that said, taking a L biker and running to 208MPH pushes the design parameters of the 530 series chain by 11.8%, but running this same chain to 7000 RPM in a blower application extends the design by 300%. This simply will not work.

I hope these calcs help in the understanding of why centrifugal blowers are not chain driven on these cars.
Aaron

 

Aaron- thank you for taking the time and effort in providing us with this information.

I agree that heat could pose to be an issue (i.e. your concern of lubrication) but air circulation would be sufficent in cooling down the chain.

Tonydee was running a chain driven blower on his BIG BLOCK c4 swap. if you chase threads that he has posted, you can get the details of the setup. I took a few hours and read through some of his posts.

He was running a relatively small crank sprocket. I also believe he was running an F1R head unit (relatively large blower with a much more aggressive transmission ratio, I believe they are in the neighborhood of 5:1 or 4.xx:1).

The vortech transmissions are something in the neighborhood of 3.xx: (typically).

I did PM Tony to see if he would chime in and get some details for us, but unfortunately he hasn't responsed. Anyone have his email address? He'd be the "only" guy (that we're aware of) that is running a chain drive, and could really aid us in the information we're after.

I'm also waiting to see the chain-driven mustang's as mentioned earlier in this thread.

 

http://www.procharger.com/racing-news/03update-mar.html

Donnie Walsh, Jr. wins the Pro 5.0 season opener at the NMRA event in Bradenton, Florida, while Doug Mangrum finishes runner-up. Both of these talented Pro 5.0 racers are running the new self-contained ProCharger F-3M (a restricted version of the F-3R) which was created specifically for NMRA competition. Both are also running the new ProCharger chain drive system with reverse-direction supercharger, in which the supercharger air inlet faces forward. This new race kit was which was debuted at the PRI trade show last December, to feed their Ford small blocks and produce 2,100+ hp.

 

http://image.musclemustangfastfords....arger_view.jpg

 

RRRR- thanks a lot for the pictures and information. I am curious to know if we can get ahold of procharger to get their thoughts on the chain-drive.

 

I would just call Pro Charger. I was reading that heat is an issue, and the auto cars were living, but not the stick cars. I found some info by just looking up chain drive supercharger

 

The larger the blower trans SUR (step-up-ratio), the less the blower will require to be "overdriven" off of the crank. This is why the Procharger larger head units become popular when trying to get max boost (as well as the increased CFM). The F1R (5.4:1 SUR) is basically the same blower that I run on my '87 street car. Most people on here with Prochargers are running P600B (3.05:1 SUR), P1/P1SC (4.10:1 SUR), or D1 (4.44:1). While most of the Vortech units run between 2.0-3.0 SUR. So the issue with the chain velocity is even worse with the Vortechs.

The F3R is 5.63:1 SUR, while the F3M is 6.24:1 SUR. If you run the much higher SUR of the F3M through my calcs, they return to the near "normal" design of a 530 series chain. That is how they are able to make this work.
Aaron

 

aaron- my point exactly. The more aggressive SUR is what is probably allowing the use of a chain. I actually think I would have preferred using the Procharger arrangement to get more power sooner (due to the SUR).

I was also pointing out that the "only" car I'd seen with a chain-drive was Tony's Big-block car that is using the F3R and a much more modest sprocket ratio...

BTW RRRR-

the automatic cars don't place as much of a "load-shock" to the drivetrain as the manual cars.... thus the reason why the automatic cars with the chain's are surviving. I'm actually not surprised to hear this information. Much like the turbo cars doing better in automatics... it sustains boost rather than cutting out like a manual car would (between shifts).

 

F3R? I don't think that was the case.... He ran an F2 (5.4:1 SUR), still chain velocity concerns when you run to 7000RPM and MIS (65K) which leads to a calculated chain speed of ~9400 ft/min (170% of design).

You should have also read about Tony's concerns with the chain and exceeding the design parameters and the long term concerns for safety when the chain fails. Not if, but when...
Aaron

 

Angular velocity is the main concern/danger.