Evil F1 SS

It seems like I will be over spining my ATI procharger D1SC. The recomended maximum RPM for a D1SC is 62,000 rpm. My red line will be 6500 engine RPM's, at 6100 engine RPM's the Blower will be at 62,525 rpm's thats ok 6300 engine rpm's will put the blower at 64,576 rpm's and at my red line 6500 engine RPM's the blower will be spining at 66,635 RPM's thats 4625 RPM's above the rating. Its not that overspun. Will it break quick? I know I will be cutting the life of the blower, but will it hold? Are prochargers claims at 62k conservative for waranty/liability reasons?

1dirtyZ

iTrader: (1)

it's not the life or longevity of the blower that determines the max. rpm. what happens at 62000 rpm is that the blower impeller approaches the the speed of sound, when that happenes a small shockwave leads the impeller blade edge. what this does is actually diminish the efficiency of the impeller and in turn the blower looses boost.

hope i made sence with all that babbling.

Evil F1 SS

I have seend Blowers rated at 70K and above. Some turbo's are rated at over 100K? So I should be ok with the blower being over spun a little? The guys over at CamaroZ28.com said that it will break for sure. That seemed a little hard to swallow.

FASST

I'm guessing that the turbos and superchargers that you saw with ratings 70k+ were actually smaller than your D1SC. Since the impeller is smaller, the linear velocity is lower at a given rpm. Therefore, it can spin higher before it hits the speed of sound. The larger the impeller, the lower the max speed.

Black LS1 T/A

What size crank and blower pulley are you running?

KHShapiro

iTrader: (10)

you can always step up to an F1

Black LS1 T/A

Don'tthey make one bigger than that for the LS1?
F2-R?

WIKDPSI

As I stated on the Camaroz28 board you will crash the impeller into the housing if you overspin it. Take my word for it. I went through 3 D1SC from overspining it by 1000 rpm. I know what I am talking about.

Black LS1 T/A

What are your crank and blower pulley sizes?

How do you know for sure when you are overspinning the blower with all the belt slippage?

Black LS1 T/A

Unless you are running a cog assembly, I'd think it is tough to say for a certainty how much you are spinning the blower, right?

NoGo

iTrader: (2)

Negative on the 'whiping out your blower'.

Reefing on your belt tensioner enough to get it to spin to 62,000 rpm, is how you whipe out a blower.

I have never seen a D1 whiped out from overspinning. I have seen D1's whiped out from too much tension on the belt, or misalignments which plays all kind of havoc on the blower at high RPM.

Just my .02

ChrisB

I don't know about the D1, but I know plenty of vortech setup's that are regularly overspun - is it the best thing to do? Probably not, as you would benefit from a larger blower more than likely, but it should not destroy the blower unless you are having other issues (compressor surge, etc.)

Also it's worth noting that while you want to avoid going sonic at exducer, that the speed of sound will actually increase relative to atmospheric since the air is compressed - so at higher pressure ratio's you can get away with higher impeller speeds before you run into this issue.

I would also question how you are determining red line, etc. In the end you are just going to have to throw the car on a dyno and see where it makes the best sense to shift - if you really go significantly hypersonic then you will probably see a reduction in horsepower - so it will not benefit you to spin that high anyway - so you would shift lower regardless.

KHShapiro

iTrader: (10)

f2-r now thats a big daddy
i know the f1 will fit on the d1sc bracket the transmission is just a little deeper i would " assume" the f2-r would be similar