Unorthodox Pulley weight

The stock pulley is 1.985kg with rubber 1.515kg without.The UR pulley is .755kg

Jared 90 S13 - [email protected]

pulleys.jpg (8332 bytes)

I always wanted pulleys for my 240sx. Unorthodox racing has the only pulleys for 240sx. They are great. The stock pulley is about 8lb It is heavy. Trust me, I held it. Shawn who is the president of the company offered my acr to be the prototype for the pulleys. I agreed. After the initial measurements were taken and diagrams drawn. It took a 7 working days for the creation of the pulleys.  My car is pretty quick. I have raced my friends 98 Maxima and I beat him up to 70 mph by a car length. His auto passes me at that time.  After much waiting I finally had the pulley maid for my car. It is made out of aluminum and weights about 1 lb. extremely light. After the installation. I took the car for a ride. The initial pull is amazing! And as the rev. built up you feel no lag in the engine. The drag is almost gone. Every gear pulls like it were a gear lower. Anyone who is reading this, get this pulley you will love it. You will feel the power right away--real power you can feel in your seat. It is like intake + exhaust combined. My engine noise is lower at 65 mph. when I start the car the idle is a little low however it goes back to normal as soon as you drive. It will be the best 159 $ you will spend in your life! I cannot believe how fast the 3rd gear pulls now.

If you open your hood you will find that your engine has these small wheel type things attached to it which are connected to your water pump, alternator etc. Basically your engine drives these other accessories like AC , alternator , water pump. These accessories draws power from your engine. Pulleys are the small wheels which are connected to your engine and accessories which make this possible through belts.  The stock pulleys which is connected to your engine which is the main one is very heavy/cheap to make for the manufact. Unorthodox racing pulleys reduce the weight of the pulleys by making there own out of aluminum and by reducing the diameter of the pulleys which puts less stress on your car therefore free about 10 horse of real power you can feel. Think of it as the best investment in your car this year.

I rate this install around a 6.0 to 6.5 on a scale of 10 in difficulty. Probably the biggest pain in the ass, was fitting the different sized belts on. I ordered 2 sizes down on all 3 of my belts, and still had problems fitting them on.


  1. Pully
  2. Belts
  3. New front oil seal (Part # 13510-53J11 on a 95 - $7.24)
  4. Jack
  5. Jack Stands, (2 is fine)
  6. 10 mm socket
  7. 14 mm socket
  8. 14mm wrench
  9. 10mm wrench
  10. various extensions
  11. wobbly's or universals
  12. 3/8" ratchet
  13. 27 mm socket (this one is for the crank pulley) or a 1-1/16" unit will work too
  14. torque wrench
  15. 4"minimum 2 finger gear pulley
  16. Crescent wrench, or assortment of wrenches
  17. friend, girlfriend, wifey etc.

The Belts


Component Stock(Dayco #'s) U/R Needed Belt(Dayco #'s)
Alternator 5040305 5040285
A/C 5040355 5040340
Power Steering 5040990 5030385

My car is a 1991 SE with Hicas and A/C, so they may only pertain to this model. They also work with a 95 KA24DE

NOTE ** the stock powersteering belt on my car was a 4 rib design. I don't know if this is due to the Hicas running off the same belt, but the Unorthodox pulley comes machined with 3 grooves only. So, make sure you get the 503038 belt, which is a 3 groove belt. (this is one of the problems I ran into during my install.)

The Install

Jack car up in front, stick on jack stands. Remove the lower pan with 10mm socket. Remove the fan clutch and fan assembly from underneath with 10mm wrench. Pull fan out from below.

Loosen all 3 belts. The Alternator belt has a 14mm lock bolt on the tensioner, and the tensionor bolt needs a 14mm socket. It's kinda hidden underneath the upper rad hose, so a helper here is useful. The Powersteering tensionor also has a lock nut (14mm), AND I found out that on the Hicas models, you have to loosen a bolt BEHIND the Powersteering pulley so that the belt can be loosened. Take the 27mm socket, and crank the motor clockwise(facing the motor from the front) until you can fit the 14mm socket into one of the 2 holes to loosen the jam nut. The lower A/C tensionor is the easiest to access. 

Stick car in 5th gear, and have helper stomp on brake pedal hard, as you crack off the crank pulley bolt. 27mm and a good breaker bar/torque wrench should do it. (side note... my bolt popped off well under the 135-150 ft/lbs it was SUPPOSED to be torqued to.......leading me to reinforce my thoughts on vibrations on this motor. This bolt will definately be checked more often on my turbo motor)

Take gear puller, and work the gear off. Don't try to pry it off, or you'll break the pulley... it's not that strong. Pop gear off, and do 40 reps with this bad boy..... it's heavy.

Change the Front Oil Seal now - take a flathead screwdriver and pry it out. (To pop it back in, scroll down a little bit)

I weighed the stock pulley at 6-3/4 pounds. The Unorthodox was 1 lb, 9 oz

Lubricate the Unorthodox pulley with some neverseeze, and work it back on. Have friend or wifey stomp on brake pedal again in 5th. (or she can  continue to keep stomping on it if you forgot to tell her to take a break after you removed the bolt...... but by this time she's probably all cramped up, and cranky, and stuffed your brake pedal through your floorboards, and smoked your master cylinder....... fun huh ?!)

Torque the pulley bolt to around 135-150 ft lbs.

Reattach all the belts in reverse order, don't forget to tighten the powersteering inner bolt behind the p/s pulley.


O.K., we had done an install on a V-Tec Acura a couple of weeks ago, along with cam gears, and the owner really noticed a big difference, so I thought, well it should help.

Warm up car, and blast off for a couple of runs around the block.

First impression...........what a waste of $340 (Canadian), plus 3 belts and my time. Honestly, I don't know if it's me being spoiled with mega hp RX7's, race cars, or turbo cars.... but it didn't light my fuse on fire. The guys opened up my shop bay door, looked at me, and could tell immediately I wasn't impressed.


O.K., I drove it home last night, and to work this morning, and opened it up in 3rd and 4th gear. Yes it does SEEM to pull harder, especially above 4000 rpm, but it wasn't like it made 10 hp. I have a tuff time believing you can feel 3-5 hp at the motor. Sure it may have made 5-8 hp, but it didn't make me hard.

Is it worth it ?.... well as we all know, our cars are hard to make large leaps and bounds in, especially in the hp department, but I think it works. It's like adding the air filter, or headers,.....every little bit helps, and adds up. Is it worth the $200 you'll spend ? Well you're better off spending that cash on shocks if you don't have them. Will it hurt the car ? Time will tell. I'm on my last few months of running this motor, so I   didn't care. I'll stick it on my turbo motor, but the pulley will make insignificant difference on that puppy.

Maybe the numbers don't lie. I don't do before and after test with the "G-Spot" meter, or Verichom. I go by my big butt. I have a tuff time about members ranting and raving about how excellent this thing is. Idunno, like I said, it didn't make me hard. But then again, as they say, as you get older.......?! haha

back at

His Second Responce

O.K., had a week or just under to muck around with my car since I've installed the Unorthodox pulley.. .. o.k., I admit, I'm a little more impressed with it now, since I've driven 1/2 a tank in the city with it.

It does seem to pull more right up to redline. Especially in 3rd and 4th gear.....hard to say what hp figures it may translate to....but I'd figure 8-10hp at the crank (I know, it's not making hp, but reducing rotating

Overall....... well I will sheepishly admit it get's the thumbs up from me.......if that means anything to you guys/girls. I know, Mohamad, I owe you a public apology for originally doubting it. (watch...... my motor will blow up tonight !! haha) I have no idea how much it will affect the engine's longivity. I don't care, cuz I'm in the process of my turbo motor.

I doubt headers, or exhaust would make this much difference at that price.


I immediately had a leak under my car after I installed the sucker, and thought possibly I had a developed a weird crack in my front cover, or something. For the $5 for the seal (you can get aftermarket ones, or go to Nissan), on an older motor (mine has 150,000 km), you might as well stick a fresh seal in, cuz you'll be peaved if you have to remove it all IF your car develops a leak. Seals always dry up over time, so while you have access to it, you might as well change it.

two thumbs up from PDM
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O.K. Shawn and gang........I think I figured out the leaky oil seal problem with the U/R Underdrive Pulley.

In my rush to install the pulley, I never actually mic'd the pulley to check it's exact replacement of the stock pulley, and after several more weeks of a leaky oil puddle underneath my car....I finally purchased and installed a Genuine Nissan crank seal. Upon pulling the 3 week old seal out of the cover, I found that it was rubbed on and worn through by the pulley. After cleaning up the oily pulley, and making a closer inspection, sure enough, the o.d. surface of the pulley had a score mark around it, from the metal in the seal.

Seems to be, that the Unorthodox Pulley has a slight radius on it, which the stock pulley does not have. When I replaced the stock original seal which leaked after I put the U/R pulley on, I replaced it flush with the aluminum chain cover....thinking this was the proper position from the factory. (I still think it I never thought twice about how deep I seated the seal.)

Well, of course, having that slightly larger diameter/radius, the U/R pulley would rub the seal through, until a hole or tear was formed, thus the leak in the seal.

So......... my hint to you that haven't yet installed the pulley, OR those that have developed a leak....I think that you need to further tap the stock seal further into it's seat....say another 1/8" to 3/16" deep. That way it should clear the incorrectly designed and machined replacement U/R pulley.

I still think an OEM aftermarket Non-Nissan seal should be it's sealing is not what leaked on actually rubbed through like the stock original seal did.

So, this being the 3rd time around...... I'm still a little pissed at this problem.....afterall, what if someone who had zero mechanical skills had the exact same problem I had.....I timed myself last night....and by the time I jack the car up, clean up the oil, remove the belts and pulley, and replace the was over 1.5 hours of my time........I could just imagine that in a regular shop time !

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A cheap easy way to also get a little more response from your engine is to switch to an electric fan. It doesn't free up any significant power, but it improves the responsiveness of the engine a little bit. It may not seem like much, but once you get the fan thermostat off, you'll find that it has some very significant weight. With universal kits available in auto parts stores, you'll spend a little over $100 and can take little less than 2 hours to install it. The greatest benefit about doing this will be for drag racers. You can install a switch in the fan circuit to disable the fan while you are making you're run. I suppose this can be done along with a lighter pulley. And it should return superb results.

Another benefit is for anyone who's doing some custom turbo/supercharging on your 240. An electric fan is much thinner and it will fit right against your radiator. It also eliminates the obstructive fan shroud and allows you to run intake pipes without having to come up with some very creative piping.

The only drawback to this has been when the fan kicks in. I have set up my fan on an adjustable electronic thermostat. Tha initial power up of the fan will cause the engine to bog for a second in idle, but there is no noticable draw in power while driving. I feel that anything to make this (very heavy) engine lighter will help response and allow much easier heel-toe downshifts.

In case you are wondering if the cooling effects of my radiator have been reduced, I have driven the car through just about all kinds of weather and roads. I have driven through desert uphill roads in  100degree weather without a twitch in the temperature needle. I would say that any effects would be minimal.

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Another Point Of View

Howdy gang, o.k., only cuz I had one on order for another client, and he backed out of it, I obligated to the shop in town to pick up the Unorthodox underdrive pulley that everyone is raving about. As many of you know, my initial thoughts on this lightweight pulley was somewhat skeptical, and here's my story on the purchase, install, and performance.

After visiting the local speed shop with one of the only Dynojets in town, the owner was raving about an install of the Unorthodox underdrive pulley in a 300ZX twin turbo.... he made over 30 hp at the rear wheels. Hard to believe, as I thought Nissan did a fairly good job from the factory on our cars, however he talked me into ordering one up for one of our 240s.

Nice unit, mine was anodized red in colour, and it's fit and finish was A1. I've heard others saying they paid around $170-$180 US, which is about in line. (due to my discounts, I paid around $140 US for mine.


The Sept issue of Turbo mag (pg 67)gave the PULLEY a two-thumbs up. They slapped it on an eclipse and got a 10.5HP gain (Dyno confirmed) and I quote "...this makes the Unorthodox Racing underdrive pulley a killer horse power per dollar value."



What are the long term effects of pulleys.


My car was the first one to get the crank pulley from unorthodox racing. It has been ten months and my car has been running great. It revs up faster and I can feel the difference of at least 10 hp. My 300watt amp and my ac work great. I am getting better gas milage and the car is quieter. Once you get it you will love it. :)

Name: Mohammed
Email: [email protected]

More UR Pully Info

Well, I finally installed the pulley last week, and here is my story  and I'm sticking to it). Whatever sins I've committed in my lifetime must have been forgiven, cause the job went smoother than any before, and I suspect after also. I jacked up the front of the car, removed a wimpy 2" strip of plastic off the lower fan shroud, removed the big pulley bolt, wiggled and pulled the OEM pulley off with these Arnold Schwartzenegger hands (I had pulled the pulley off 6 months earlier to replace a seal), and installed the new aluminum pulley. No fan shroud or fan  had to be removed and it took all of 35 minutes to perform. Here issome info to help you guys out. The OEM pulley diameters are (from front to back on all the following references) 140mm, 153mm, & 141mm. The new UR pulley is 120mm, 120mm, & 111mm. This gives a reduction of 14% for the power steering, 22% for the alternator, and 21% for the A/C. The belt sizes (I was told by the NAPA man who sold me these belts) for these type of grooved belts are sporadic in the sizes in that they are built for application, rather than gradual size increases that the traditional v-belts used to come in. Because of this, the next available smaller belt may be 1.5" shorter, but the 2nd next smaller size may only be 1.75" shorter. This made it hard to figure out which belts to go with, so I emptied the bank on belts (but returned them the next day). The original size belts I had were 3PK990, 4PK775, & 4PK900. After all is said and done, I used the following belts (again, front to back). I used the same 3PK990 belt on the front. It was on the small side of the adjustment slot anyway to begin with, and the next size smaller would not go on. Next, I used a 040285(this is a NAPA number but I think it is a common reference) for the middle (2nd smaller size from stock), and lastly a 040340 for the rear (again, the 2nd smaller size  from stock). With these belts on, I have about 16mm of adjustment left on all three belts for retightening. I have found that these belts do not need to be as tight as the original ones were. I guess this is because of the lower drag on the ancillary components. Driving impressions: The car pulls slightly better with the A/C on full blast than the car did with the old pulley when the A/C was turned off. Another comparison would be to say the increase in power felt, was very similar to the increase in power from stock air cleaner to the Stillen K&N filter conversion. The annoying buzz at 3100 rpm disappeared too. I noticed slightly better shifts too because the engine comes down in rpm faster, letting the tranny sync in faster. Overall, I am very pleased with the part. I like it, I love it, I want some more of it. 

Terry '92 plain Jane fastback.

How do u take that damn crank pulley off?

Sometimes taking the crank pulley off is difficult even sometimes impossible especially if u have an automatic tranny. Of course one needs a 27mm socket and wrench but the problem is keeping the pulley still to apply torque on it. With 5 speeds, one can put in 5th gear but sometimes even that may not be enough (automatics, oh well). Well I have found this tool call a "strap tool" that  goes around the pulley to keep it still. It is basically a section of belt with a metal part of a wrench to go on. It is sort of like the pipe wrenches u see plumbers use. Except that instead of a chain that goes around , it is a grooved belt. I found this tool very useful in light of the fact that 140ft/lb of torque must be applied to the crank pulley.

Email: [email protected]

Harmonic Dampers

From what I have picked up over the past few months talking to various people about underdrive pulleys is that the UR eliminates the stock harmonic balancer. According to the last few posts about the ASP pulley, apparently it makes use of a harmonic balancer. From my understanding, the harmonic balancer is needed for the KA. If anyone else can add...please do, because I wouldn't mind finding out some more about them!

Here's an article from 'National Dragster, Racing Technology' about harmonic dampers:

Good Vibes
Contrary to what you might think, a crankshaft really isn't a solid, immovable object. The crank twists and bends relative to the loads placed on
it by the respective pistons and rods on each throw. General Motors' tests have shown that the crankshaft in a 350-cid small-block prepared for racing can deflect considerably at 8,000 rpm. A crankshaft also has natural frequencies. Coupled with the frequency of the torque inputs and resonance, severe crankshaft vibrations can result. The result is outright crankshaft failure if a damper of some sort isn't used to still these vibrations. Not that long ago, it was common to use an aluminum hub on the nose of a drag race engine. Bad idea. The end result was often a two-piece (or more) crank.

The Baddest Vibes
There's more here than outright crankshaft carnage. When harmful crank vibrations aren't kept in check, valve timing can be disturbed (often dramatically), oil pump driveshafts can break, wet-sump oil-pump gears can shatter, timing chains can stretch and break, and shifting gears in a stick-shift combination can become impossible, or, at least, difficult. Main-bearing wear is common when the vibes aren't controlled. Often the thrust surface of the main bearing shows signs of major degradation. Evidence of main-cap-to-block fretting, chafing, or galling is common. Rod bolts can continually loosen. Ditto for little things like valve-cover bolts. Rod bearings can blacken (the same applies to the back side of the connecting rod crank-pin hole). Valve spring life can become dismal. Flywheel and converter bolts can loosen. Flywheels can physically break. The torque converter pilot or hub to gear surface can fret or chafe.

All of the above are signs of unchecked crankshaft harmonic vibration in a race engine. Usually, the symptoms go hand in hand with a non-functioning
damper on the nose of the crank or when a simple aluminum hub is installed in place of a damper.  Also consider that the damper hung on the nose of your engine is not a balancer. In reality, it balances nothing. The main purpose of that big hunk of metal out front is to absorb harmonics. Harmonics and balance are two decidedly different things.

The Range of Motion
The operating range of an engine along with the speed at which an engine accelerates can have a profound effect on the damper requirements. Some dampers are "tuned" to operate at a specific rpm level. That's fine for an engine that runs at a constant or relatively constant speed (a good example is a diesel highway tractor with a dozen or more forward gears), but if the engine is accelerating and decelerating over a wide rpm range (as in a drag race application), then frequency tuning  becomes troublesome. Case in point is a widely publicized test run by Katech for General Motors. Four aftermarket dampers were tested on a 427-cid small-block (4.125" bore x 4.00" stroke). From 3,112 rpm to approximately 6,500 rpm, none of the dampers twisted the crankshaft more than 0.6 degrees. But after 6,500 rpm, the test proved that crankshaft twist increased by a considerable margin in three of the dampers. At 7,893 rpm, one damper showed 2.0 degrees of crank twist, another showed 1.7 degrees, and another showed approximately 1.25 degrees. The last damper, an ATI model similar to the assembly pictured, showed 0.28 degrees of crankshaft twist. From my perspective, outlining this isn't to compare dampers but to show that crankshafts definitely do migrate. They're not immovable objects, and they do twist.

George Rogozin
Email: [email protected]