No I mean black in general. They dont make one yet.
2013 GT500 black upper pulley?
- Thread starter Shhhh
- Start date
No I mean black in general. They dont make one yet.
FYI your blower is spinning @ 22,604 rpms @ 7000 engine rpm. That is 2,600 rpm past it's limit for making power according to the TVS compressor map. See below.
I see the graph is dated 2008, maybe they have improved. Never planning on hitting 7k rpm anyway. But thanks for the input.
blackshelby
New Member
Weight is not the reason for the torque increase.
That is directly due to blower speed with less belt slippage.
Actually moving the weight away further from the the center of the crank will take more HP to turn . You always want the weight of a spinning object closer to the center if you are taking parasitic drag into consideration.
If you weigh the stock and a 10/15 percent OD pulley, the 10/15 percent is actually a couple ounces heavy than the stock pulley.
(Edit: The OD lower pulley is lighter than the heavy 2007 OEM pulley but heavier than the 08 -13' OEM lower pulley)
Don't they make aftermarket idlers that increase belt wrap on the snout?
Yes they do and they work pretty well, why because they are making the belt wrap around the pulley more(More work area to hold= less slippage).
There is a point to where you just can't get enough surface with the smaller pulley to carry the workload, especially when you are spinning the blower with an OD crank pulley already and using small upper. You have have a better chance of the smaller upper working if you do not run the lower crank, why less depend of the upper pulley (Blower speed)
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I buy the explanation that a lower pulley will make more power because a smaller upper may have belt slippage. But a larger diameter, heavier overdrive lower pulley will not have less parasitic drag. As explained above, heavier means more mass to get moving, mass further away from crank centerline, and anything spun by the overdrive pulley is spun faster so increased parasitic drag.
Same compressor map (same rotors being used)
Never gonna get to redline? Should have bought a Buick.
LOL
Metco is manufacturing a stock-appearing, semi-gloss-black-powdercoated 2.4" supercharger pulley for the 2013 & newer GT500.
Nicely put. :beer:
Innovators West claims both the 10% and 15% lowers are lighter than stock crank pulley assy. Thus the weight reducton of the balancer assy is the reason for the increased TQ over the upper pulley. As far as the larger diameter 10% and 15% rotating mass causing more drag due to being further from the center of the crank seems to make sense to me.
I dont think that the upper pulleys slipping has anything to do with seeing upwards of 50 rwtq(IW 10% lower 4psi) over the same upper ratio pulley matched boost increase(4 psi).
The contact info is at the top of the page for more information.
Harmonic Balancers, Dampers, Pulleys and Racing Ring Gear Services from Innovators West
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blackshelby
New Member
I just weighed all three lower pulleys.
Exact weights of the balancer's are:
The stock 07 is 21lbs, and the stock 08-12 lower is just about 10lbs, the IW 10% lower is 11lbs. I'm sure the 15% weighs even more than the 10% does.
Exact weights of the balancer's are:
The stock 07 is 21lbs, and the stock 08-12 lower is just about 10lbs, the IW 10% lower is 11lbs. I'm sure the 15% weighs even more than the 10% does.
Maybe they are saying it's lighter than the 07 only, I'm just quoting them directly but if you feel the need to you can call them and have them give out your information as a guide.
I've seen numerous accounts of weighing the balancers and the results have always been as blackshelby listed. I've never heard anyone other than IW claim that the IW pullies are lighter than the stock one.
I don't think the minimal amount of weight we're talking about is going to have a dramatic affect on power either way; I think the fact that you get more surface area for the belt to wrap onto coupled with the higher rate of acceleration from the larger lower pulley is what creates your torque increase. 3 lbs is 3 lbs, but 3 lbs faster and earlier in the RPM range means more power across the board and more importantly more torque in the lower RPM range where a roots/twinscrew blower shines.
I don't think the minimal amount of weight we're talking about is going to have a dramatic affect on power either way; I think the fact that you get more surface area for the belt to wrap onto coupled with the higher rate of acceleration from the larger lower pulley is what creates your torque increase. 3 lbs is 3 lbs, but 3 lbs faster and earlier in the RPM range means more power across the board and more importantly more torque in the lower RPM range where a roots/twinscrew blower shines.
I understand what you say about the weight of the different lowers, also what black Shelby claims as far as what he weighed his at. Today IW told me that the weight difference was what they considered the reasoning for the TQ increase also(lighter than stock). It made since to me as all accounts of O.D. lowers created more TQ. vs. upper pulley only.
Your explanation makes the most logic to me on reasoning for the TQ increase. As IW is sticking to the lighter than the stock unit claim on the 13.
blackshelby
New Member
Where did you see a dyno graph of a lower pulley making more torque than an upper pulley? (Maybe the blower speed was different on the one you seen, which would explain the torque difference)
You need to run a 2.42 upper to be close to the same as the 10 OD and as small as a 2.35 if running a 15 OD on a 13 to have similar blower speeds.
If the blower is spun at the same speed with zero slippage both will make the same power and torque.
I have seen this many times on the dyno in the past . The only thing I ever seen different between the two has been belt slippage.
I do believe the 13 balancer weighs right around the 10 pound mark too.(it is the same style as the 08-12)
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