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I wonder how much horsepower it takes to turn my V-1, S-Trim unit 50,000 rpm making 10 pounds of boost.
I've looked al over the Internet using Google and can't find any information about that.
Anybody have a clue?
I'm turning it with a 6-rib serpentine belt. I also wonder just how much horsepower you could put through one of those.
Anybody ever hear those numbers?
Any information will be appreciated.
A-Trim was around 40hp at 45k rpm when I tested the unit around 20 years ago. Not much has changed in design or bearings since then. I would say with the impeller design and size you could figure 8hp per psi.
Wow.... thanks for the information!
That's a lot more than I figured, given the (perceived/imagined) physical limitations of a 6-rib belt. That's what I am running, anyway; a 6-rib Dayco Polycog with about 200 degrees of wrap on the top pulley and a lot of tension from a static idler.
I witnessed a steady 10-pounds of boost until the engine neared 5,000 rpm in top gear, and the boost slowly dropped down to about 6-7 pounds as the tach needle swung up to about 5,400. Weird....
Is that belt slippage?
This engine was pulling REALLY hard at that point, and I didn't notice the power falling off, but I'm sure it did.
What are your thoughts on that phenomenon?
Blow-By and Belt Slippage causes your PSI to drop in the higher rpms. Others watching did they mention about smoke out the tail pipe on WOT shifts? Check around your pulley and you should see a dusting of rubber from the belt slipping. You can keep it from happening also by cutting groves across the pulley to allow the air to escape from under the belt.
I was running open headers, so nobody was able to see anthing of the exhaust to tell me about it.
I looked for belt dust and there doesn't appear to be any significant amout.
How close together do the grooves need to be on the pulley to prevent air from being trapped in there, and how deep do they need to be; all the way to the bottom of the groove??
Thanks again for all the good info....
I always went 1/3rd of the depth and marked a even '+' on the side and just cut it 4 times. Not only does the belt hold better the belt sound on the pulley is much quieter.
I'll do that. Can I ask what you used to cut the pulley with; a bandsaw, maybe?
And I don't understand this part: "marked a even '+' on the side "
What was that for?
I used a cutting wheel on my hobby tool(Dremel). You can use a hand saw. I was just saying that I made 4 cuts and to get them even so I did not hear a belt howling at different frequency I made a "+" sign on the face of the pulley to get a equal distance so no matter what size pulley I was cutting the distance between cuts was the same.
Okay; now I understand!
I'll do that; sounds like a really good idea.
Wow great info!!! Thx!!