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Do aftermarket pulleys add any power?

56K views 39 replies 33 participants last post by  Mr Ree NZ 
#1 ·
Do they? Does anybody have a dyno sheet to prove it? I have read not to use the crank pulley, so does that affect power gains in any way? Any insight will be appreciated!
Thanks,
Jason
 
#5 · (Edited)
Correction,

Aftermarket "LIGHTENED" pulleys will recover lost horsepower due less rotational mass. Basically every pound of rotation mass is equvilent to 10 pounds dry mass. This will require less output being taken from the crank to run these accessories. Underdrive pulleys are usually made of aluminum versus the default steel type of pulleys. Unless the O.E. pulley weighs less, you will make more HP. Also, a simple example of this has to do with why people are generally worried about how much their wheels weigh in regards to racing / dynoing. Lighter wheels will make your car faster for sure.

Also, never install an underdrive crank pulley on a 2JZ-GTE engine. You will no longer have a harmonic balancer unless you go with the Boostlogic or Titan dampener. However, both of these units are not underdrive.
 
#6 ·
Most of the power recovery is from the lightweight and underdriven crank pulley though. With just accessories done I wouldn't expect much.

For the power I wouldn't risk an undampened crank pulley like most aftermarket units are.
 
#7 ·
So, pretty much pulley's on a Supra are a useless waste of money? I think I will just take the money and put it toward a stall/built tranny.

Off topic, but if I have a set of Bogarts that weigh 8lbs against the stock polished that weigh ~24lbs, I will save 16lbs which equals 160lbs dry mass? So, that would be roughly .16 in thoery off of my ET right? Since for every 100lbs you remove, you gain 1/10th in ET.

Thanks,
Jason
 
#9 ·
The Unorthodox is NOT an under drive crank pulley like most other aftermarket cranks are. It is also lighter than the stock pulley.

Most people go for the Boostlogic or Titan crank because they are SFI approved and fully dampened, yet keeping the stock size. This is the best route to go.


To get more HP from replacing pulleys, weight is key. Less weight = more HP.


Simple as that really.
 
#10 ·
Sorry to resurrect this thread, but I was just wondering if anyone has ever documented (dynoed) gains with these lightened and/or overdrive accessory pulleys (power steering, alternator, waterpump). I know the N/A Supra guys claim gains of 5-8rwhp, so logic would conclude that the pulleys should gain slightly more on TT models. Does anyone have any hard evidence?
 
#11 ·
I did a little bit of research and it seems that most of the aftermarket pulley sets are of the same diameter as the OEM ones so the only difference is that they are made of 6061-T6 aluminum as opposed to steel. Aluminum is approximately 1/3 as dense as steel, so assuming a similar mass and the fact that the aftermarket pulleys weigh about 1 lb, that would mean that the stock pulleys weigh about 3 lbs.

The weights listed here are in line with my estimates:
http://www.moreboost.org/weights.htm

0.50 pulley - alternator
1.34 pulley - power steering
1.00 pulley - waterpump

0.20 pulley - Unorthodox alternator
0.80 pulley - Unorthodox power steering
0.50 pulley - Unorthodox waterpump

So in other words we have about 2 lbs savings in rotational weight.
I believe rotational weight is worth about 2x-3x static weight, so let's be generous and say 3x, netting a 3x 2 lbs = 6lbs advantage or about a 0.5 hp gain.

I think I'll pass.



Also, I found this quite amusing:
http://www.unorthodoxracing.com/install/Ultra_SS/04060120_.pdf
"The maximum HP gains will occur in 5-7 days of installation, once the computer recalibrates to take advantage of the engines lighter rotational weight."
 
#12 ·
WhiteBlazze said:
The Unorthodox is NOT an under drive crank pulley like most other aftermarket cranks are. It is also lighter than the stock pulley.

Most people go for the Boostlogic or Titan crank because they are SFI approved and fully dampened, yet keeping the stock size. This is the best route to go.


To get more HP from replacing pulleys, weight is key. Less weight = more HP.


Simple as that really.
The boostlogic is stock size, but I believe the Titan is actually larger, overdriving the accessories. I'm really surprised no one makes underdrive accessory pulleys for these cars, I know with every car I've ever put pulleys on it's made a difference.
 
#14 ·
I bought pullies that are the same size as stock but lighter and they are polished. I bought them because my stock pullies look terrible, the paint is flaking on them and i wanted to avoid a crack in the future. I also figured if it made any performance gain, then thats only a bonus. By the way, they were $59 shipped and nice quality. I was referred to them by another member here. Use stock size belt as well.
 
#19 ·
I agree. I speak bad english too, so I can relate. Sticker Printing? Are you an authrozied vendor?! Heh.

Anyway, I just picked up a set of UR Pulleys not too long ago from MVP. Hopefully, I'll have them installed soon. It's minus the crank pulley, though.
 
#16 ·
Wtf!!!!!!!!!!!! Bot alert
 
#20 ·
I recently upgraded my all pulleys, except the crank, for a better look under the hood. I didn't feel a difference in the car's drivability, but I was also not expecting a power gain. Pulleys won't add a substantial amount of power to the point where the driver will feel the difference. You MAY see a difference on the dyno..... but that's still a maybe.
 
#23 · (Edited)
I had UR pullies for years on my APU car,when my stock crank pulley cracked,I swapped it out with UR crank pulley ,I immediately felt the throttle being more responsive,so I'd imagine there were some power gains,BTW it's been about 2 years,still running fine,drive it everyday
 
#30 ·
Glad to hear this. There's so much speculation out there about the possible damage a UR crank pulley will do to our engines since it's not a harmonic balancer like the BL or ATI. There has been a great deal of theory, but I have yet to read about anyone actually blowing up a 2jz when running a UR crank pulley and it showing to be the cause of failure.
 
#25 ·
Ahaha, those replies make reading random threads worthwhile.

I got a driftmotion set and am in the process of installing them, once I get this stupid powersteering pump rebuilt, which would go a lot easier if the oil seal would co-operate and come out.
Weighed a couple while I was at it so might as well post kg weights since I couldn't be bothered converting the lb weights.

Stock PS pulley 6.08kg
Alloy 3.4kg

Stock water pump 4.57kg
Alloy 2.23kg

Alternator ??
Alloy 0.99kg

I had another reason for buying the driftmotion ones. Suspected a bent PS pulley, OEM is around $200NZD, $58 for a 3 piece alloy set, works well for me.
 
#26 ·
Haha, so awesome. Love digital scales. When posting those weights up I thought 6kg sounded a bit suspect for a pulley. Weighed the alloy PS one at 200 something grams using analogue scales. Yeah, maybe using the electric scales in the workshop for carbon epoxy meant the fumes went straight to its head. Ignore those weights :p

Price difference still stands, that was my reason for buying them.
 
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