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How effective are the under drive pulleys? I have the Power Enterprise turbo with a TRD lightened flywheel all controlled by the Apexi PFC.

I am considering adding the under drive pulleys for the alternator and water pump from monkey wrench racing along with a under drive crank pulley from vision motor works.

Please speak up if you have knowledge if they are effective. The 2003 motor is out of the car and will be easy to install. Thanks in advance for sharing your wisdom.
 

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It has been recommended not to use an aftermarket crank pulley unless it is dampened or it could cause the oil pump to shatter. Something to do with harmonics. I have no first hand experience with it so I cant say for sure. However I do use and like the MWR Pulleys. I noticed a cooler water temp at crusing speeds.
 

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As always the opinions on this one are splinted, most of people said that put in an aluminium underdrive pulley is a total blasphemy and will "FOR SURE" destroy your engine because is not damped and just a few said it is not always the case. I took the jump in this one and put the aluminium underdrive pulley for the crank and have run it for the last 10k miles and not bad side effect, I most use the car for daily and some races during the week. Although that the gains of one underdrive pulley is little if you sum all the pulleys it some more. I have the unorthodox underdrive crank pulley and is very light, less than a pound, the stock one is close to 5 pounds, monkeywrench have a dyno that shows the effect of the other underdrive pulleys in they webpage.
 

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i was always told not to use any underdrive pulleys when you have a turbo as the alternator and water pump cannot keep up with the extra demand and i've also had mix reactions with a underdrive crank pulley without a harmonic dampener two of my mates that done the mod one's crankshaft actually snapped clean in half the other's bearings went i get my 2 mwr pulleys tuesdayish and i'll let you know what the difference is but i'm after engine response not that extra oomf you can do both the altenator and water pump with the motor in the car i've already pulled both the altenator and water pump out already waiting for the parts
 

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My rotating assembly is balanced with the stock crank pulley to 10K, so thats what ill use. However, using underdrive pulleys on the water pump an alternator with a turbo setup is not going to hurt anything.
 

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just curious. has anyone switched the vane pump pulley to a lighter one? will that meaningfully increase performance? It shouldn't cause issues since the pulley has no function on an MR2
 

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Is anyone using the VMS Racing crank pulley?

Just 15 ounces, tempting, but not at the cost of snapping the crankshaft. LOL.

As best as I can determine, the stock pulley does incorporate a harmonic damper, so going with out could be trouble.

A Dorman harmonic oscillator weighing 3.3 lbs is available. Anyone know the weight of the stock pulley?

Thanks for any comments.

PS. My setup is NA.
 

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I will just get the MWR under drive alternator and water pump pulley. Keep the stock harmoni balancer. Take it from a guy tht have UD under drive alternator pulley and crank pulley. BTW I am in the process of replacing them soon and getting the MWR pulleys


Sent from TAPATALK (I am poor and don't have a computer to use!!!)
 

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I wouldn't get the alternator pulley, there is very little gain to be had from slowing down the alternator. An alternator gets only slightly less efficient at high speed. The things that are worth slowing down are belt driven pumps like PS, water, A/C, because those consume hundreds of times more power at high revs than at idle. We don't even have a P/S pump and A/C isn't always on, so just doing the water is the best bang for your buck.
 

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i was always told not to use any underdrive pulleys when you have a turbo as the alternator and water pump cannot keep up with the extra demand and i've also had mix reactions with a underdrive crank pulley without a harmonic dampener two of my mates that done the mod one's crankshaft actually snapped clean in half the other's bearings went i get my 2 mwr pulleys tuesdayish and i'll let you know what the difference is but i'm after engine response not that extra oomf you can do both the altenator and water pump with the motor in the car i've already pulled both the altenator and water pump out already waiting for the parts
Is anyone using the VMS Racing crank pulley?

Just 15 ounces, tempting, but not at the cost of snapping the crankshaft. LOL.
First if your gonna do any mod, try to get from the originator, Unorthodox Racing. Lying about certain aspects of your competitor's products in your description of your product to scare people into buying yours kind of leave a bad taste in my mouth (about the overheating from underdrive pulleys). I'm bias but do your own research. Also how can you make BETTER than OE BELT ALIGNMENT?!! :biggrin-new::biggrin-new:

Secondly KIWI and Frank is the main problem with lightweight crank pulleys. If your f*king crankshalf snapped clean in half and somehow came to blame it on pulleys, I'm not sure you should be modding motors. Something was seriously messed up with that motor already. Then we have Frank who perpetuates the misinformation that had no evidence other than a strangers words about his mates. Not even one question asked about this half broken crankshalf but its now almost fact it will break your crankshalf in half. :biggrin-new::biggrin-new: I digress.

Third thing is the research that has gone into each set of pulleys made for a new model. I have no clue what VMS or the other myriad of lightweight pulley makers now on ebay but the originators actually did research when they designed the specs for these pulleys. And to answer a question by oldman about possibility of underdriving too much certain important accessories, well they even took that into account. Voltages/waterpump too slow/cavitation issues were researched. Some "Sets" of pulleys (crank + 1 acc/2/etc) have even been designed where the acc. pulley size were increased from stock to maintain or only slightly underdrive. This is why you should not mix and match from different brands to make your own set. They even made special sets for popular supercharged kits cars where people could get more boost from an overdriven crank pulley. But watch out for cheap imitators on some models where the crank oil seal rides on the pulley snout. You need a steel sleeve in this section which is pressed on and the imitators don't understand this. Well maybe then you can blame it on your (imitator) pulley when all the oil leaks out cause the seal wore a grove in the aluminum and you seize your motor or snap your crankshalf clean in half.

To those thinking of just getting Acc pulleys only, because they are afraid or whatever, the main gain comes from the lost of weight on the crank pulley. Just changing acc pulleys without the crank pulley is like upgrading your air intake and thinking you'll get 25whp. Don't be naive, do your research and understand what does what.

Anyway, i've ran pulleys and I'm gonna run pulleys in my Kswap. Ive never had a problem and personally don't think I will in the future. And if I do, I'll have pics to show.
 

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To those thinking of just getting Acc pulleys only, because they are afraid or whatever, the main gain comes from the lost of weight on the crank pulley. Just changing acc pulleys without the crank pulley is like upgrading your air intake and thinking you'll get 25whp. Don't be naive, do your research and understand what does what.
That's not really true, water pump and power steering for cars that have it belt driven use a lot of power, and accessory pulleys aren't that heavy to begin with. Underdriving those pumps can get you a few horsepower for sure, because they actually consume a fair bit of power, but not because the pulleys are heavy and take power to spin up. An air intake on the other hand is mostly not going to do anything because the intake tube and filter only create like 0.2 psi vacuum, so of course you're not going to get 25hp from that, if you can reduce that number by 25% that would translate to like half a horsepower.
 

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The Unorthodox Racing underdrive crank pulley was the first mod I did to my car 6 years ago. I've put around 50k miles on my engine with that pulley and 2 years of autocross with raised redline, and it runs better than ever. I've seen 2zz engines destroyed due to crank pulleys, but never a 1zz.
 

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The talk years ago was that the un-dampened crank harmonics would cause oil pump gear failure on 2ZZs which would cause burnt bearings or snapped cranks. There have only been a couple of cases that were remotely substantiated. I've used the mwr under-drive pulleys on my 2ZZ for years with nothing but positive things to say with a super charger, turbo,and both being used with them
 

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Secondly KIWI and Frank is the main problem with lightweight crank pulleys.
I'm sorry if my question and comment were inappropriate. I hope that you accept my apology.

Clearly, I am uninformed on the subject, and seeking information.

Aloha, from Maui.
 

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Yes, what was said above.

Accessory pulleys help not matter if you are NA, Turbo, Supercharged, or hamster powered.

From what I've read (researched) about pulleys (I have MWR pulleys sitting in a box so I've read a lot) is that,
1zz with aftermarket crank pulley is OK,
2zz with aftermarket crank pulley has had problems.
 

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I'm sorry if my question and comment were inappropriate. I hope that you accept my apology.

Clearly, I am uninformed on the subject, and seeking information.

Aloha, from Maui.
No need for apologies. All your comments were valid. I quoted you because it fell in line with my argument.

Give UR a call, they actually have boxes of stock cranks on hand to refer back on and they have a list of stock and lightweight pulley weights to compare (maybe on their website too).
 
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