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Gates green stripe blower belt
- Thread starter Detroitboy
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Why?
Otherwise the Blackbird tensioner is an excellent product. Better than the stock tensioner, better than the Litens design, and better than the ARS option.
My only concern is their pulley alignment and bearing selection. Plus their pulley is not as light as it could be.
I have a TBA pulley I'm going to try to make fit on their tensioner bracket with a shim to make it line up perfectly. The TBA pulley has nearly only half the weight.
SC grooved pulley weights:
262g TBA billet alum. (Metco is probably close to the TBA, similar design, also aluminum)
432g Blackbird billet steel
482g Litens billet steel
746g stock pulley (Dayco)
And for some napkin math:
HP needed to spin a 3" diameter 746g pulley up to 18k RPM in 0.5s is 2.5HP.
Thus with 3 stock pulleys it costs 7.5HP to spin up to WOT.
HP needed to spin a 3" diameter 262g pulley up to 18k RPM in 0.5s is 0.94HP.
Thus with 3 TBA pulleys it costs 2.8HP to spin up to WOT.
These calculations are ideal mass only, they don't account for bearing friction (full contact seals vs non-contact seals).
While a 5HP difference is in the noise when you're over 700 already, still it's certainly not nothing.
Otherwise the Blackbird tensioner is an excellent product. Better than the stock tensioner, better than the Litens design, and better than the ARS option.
My only concern is their pulley alignment and bearing selection. Plus their pulley is not as light as it could be.
I have a TBA pulley I'm going to try to make fit on their tensioner bracket with a shim to make it line up perfectly. The TBA pulley has nearly only half the weight.
SC grooved pulley weights:
262g TBA billet alum. (Metco is probably close to the TBA, similar design, also aluminum)
432g Blackbird billet steel
482g Litens billet steel
746g stock pulley (Dayco)
And for some napkin math:
HP needed to spin a 3" diameter 746g pulley up to 18k RPM in 0.5s is 2.5HP.
Thus with 3 stock pulleys it costs 7.5HP to spin up to WOT.
HP needed to spin a 3" diameter 262g pulley up to 18k RPM in 0.5s is 0.94HP.
Thus with 3 TBA pulleys it costs 2.8HP to spin up to WOT.
These calculations are ideal mass only, they don't account for bearing friction (full contact seals vs non-contact seals).
While a 5HP difference is in the noise when you're over 700 already, still it's certainly not nothing.
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There are two different parts:
- the bracket which mounts to the timing cover
- the tensioner that mounts to the bracket
The stock bracket only allows a single orientation of the tensioner.
Both HHP and Blackbird Performance offer a bracket that allows clocking the tensioner to multiple different positions.
HHP's bracket offers 5 positions.
Blackbird's bracket offers 7 I think, plus is modified such that more of them can be used. With HHPs, depending on which tensioner you have not all the positions will work due to clearance issues.
As for tensioners there exist these options:
- 3 different versions of the stock part number (the original version was by Dayco, dunno about the two newer, cheaper ones)
- ARS (which has no dampening)
- Litens
- Blackbird Perfomance
As for extra adjustable idlers there's a lot of options, I've not cataloged them.
Call up Geoff at Blackbird Performance--he's super knowledgeable. They did a /ton/ of testing when designing their tensioner.
The actual tension amount has little to do with the equation--more is not better--that just wears the belts and bearings faster.
Yes, belt wrap does matter.
However, most important is how well the spring and dampening tuning actually keep the belt in tension throughout all the possible RPM changes. Belt wrap can't help you if the bounce in the tensioner allows the belt to go slack on the pulley...
Eg, the ARS tensioner has no dampening at all--thus it can't possibly not be bouncing around and allowing the belt to go taught-slack-taught-slack as it settles...
- the bracket which mounts to the timing cover
- the tensioner that mounts to the bracket
The stock bracket only allows a single orientation of the tensioner.
Both HHP and Blackbird Performance offer a bracket that allows clocking the tensioner to multiple different positions.
HHP's bracket offers 5 positions.
Blackbird's bracket offers 7 I think, plus is modified such that more of them can be used. With HHPs, depending on which tensioner you have not all the positions will work due to clearance issues.
As for tensioners there exist these options:
- 3 different versions of the stock part number (the original version was by Dayco, dunno about the two newer, cheaper ones)
- ARS (which has no dampening)
- Litens
- Blackbird Perfomance
As for extra adjustable idlers there's a lot of options, I've not cataloged them.
Call up Geoff at Blackbird Performance--he's super knowledgeable. They did a /ton/ of testing when designing their tensioner.
The actual tension amount has little to do with the equation--more is not better--that just wears the belts and bearings faster.
Yes, belt wrap does matter.
However, most important is how well the spring and dampening tuning actually keep the belt in tension throughout all the possible RPM changes. Belt wrap can't help you if the bounce in the tensioner allows the belt to go slack on the pulley...
Eg, the ARS tensioner has no dampening at all--thus it can't possibly not be bouncing around and allowing the belt to go taught-slack-taught-slack as it settles...
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I couldn’t barely go above 3000 rpm on my car with a 2.69 upper only. AAD idler fixed that, it would literally just slip. My idler is a bit maxed out right now, but that’s due to my belt size. My belt only has 1 k miles on it, maybe less and looks pretty worn. But zero slip or issues at track, dozens of passes
