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View Full Version : Driving Impressions: U.R. underdrive pulley...



H8PVMNT
06-04-2008, 03:27 AM
I just installed the Unorthodox Racing underdrive pulley on my '91 GT-S with the 5SFE 2.2 litre. I have a 300 mile road trip I take about once a week for work and I have been keeping track of my milage and driving experience as I try new parts and tricks. I only pay attention to results on mild days with no rain or wind just to keep my opinions as objective as possible.

Here is what I've found regarding the underdrive pulley:

Power:

Off Line- On off line acceleration I have not noticed any difference.

At Speed- I have however noticed more snort for passing while in 4th and 5th gears at highway speeds. Top speed on the same stretch of road I always use is about 2 mph faster.

Economy:

Highway- I would usualy get about 30-32 mpg on the highway if I keep it under 75. If I went 80+ my milage would drop to about 22 mpg. I have not noticed any increase in milage under normal 75 mph highway driving conditions. What I have noticed from the underdrive pulley is a huge increase in milage when I am going faster than 80 mph. I just went on a road trip cruising between 80 and 100 mph and I got 28 mpg. Thats a 6 mpg increase while hauling ass!

Around Town- I have not been able to get a good representation for around town driving, but last time I checked I was getting about 23 in town so I expect the same gains there, we'll see.

Conclusions: 1) More power for passing.
2) 6 mpg (27%) increase in milage above 80 mph.
3) 2 mph increase in top speed (no big deal)

Overall I think it was worth the money spent, esspecially if you have a fast 80+ mph commute.

Simonhla
06-04-2008, 04:08 AM
How much was it?

Denver_whiteST185
06-04-2008, 08:32 AM
undamped pulleys can cause premature main bearing failure, and in extreme cases, major crankshaft damage. just an FYI for anyone considering one, you may want to research them.

Conrad_Turbo
06-04-2008, 07:46 PM
undamped pulleys can cause premature main bearing failure, and in extreme cases, major crankshaft damage. just an FYI for anyone considering one, you may want to research them.

Resonance is a bitch! :laugh:

Lightweight pulley's are nice to look at, but the OEM does more than a fine job. It'd be interesting to see the MPG results on a rolling dyno, but running accessories slower effectively derates the alternator power output and power steering feedback.

H8PVMNT
06-05-2008, 05:57 AM
Good to know about the resonance/crakshaft damage thing...

The 22re toyota truck engine has an undamped pulley from the factory and goes like 250K easy if you keep it on the road and don't flop it on it's side all the time or drive vertical with it like me...

Maybe I'm missing some important fact about the internal ballancing of the engines, etc.
Clue me in, where's the info/research on this problem? Also are there any known engine issues with lightweight flywheels? I was planning on using one on my '94 truck for the 3RZ I'm swapping in this summer.

I too would like to see results on a rolling dyno, but I like to try stuff out just for the heck of it to see what happens on the trail so I just wanted to share what I found. No BS though, those are the real numbers on the same road with the same driving conditions. I was disapointed not to see any milage gains under 75 mph, but it is kind of interesting about the better milage above 80...
I'll drive it for 100K and let you know what happens to the crankshaft. Long term test.

The power steering is a little weak at idle, but the charging system is keeping up just fine.
The price was around $180 I think.

Here's an even better question:*Is there a proper damped, smaller diameter pulley available off a Toyota car that would underdrive the accesories on a 5SFE?

Conrad_Turbo
06-05-2008, 04:27 PM
Here's an even better question:*Is there a proper damped, smaller diameter pulley available off a Toyota car that would underdrive the accesories on a 5SFE?

Not that I know of. It's far easier to machine and anodize a block of aluminum instead. :D

Here is a blurb I spouted off in the past:


Most engines are internally balanced via the crankcase counterweights... BUT what that SALESMAN (not engineer) does not know is that by having a damper on the shaft it reduces the natural frequency of the crankshaft. This keeps any chances of harmonics from damaging the bearings due to the crank being in resonance.

What I mean by resonance is...a good example of that is when an opera singer breaks a wine glass. The reason it broke is because the frequency of the opera singer's voice is the same (or very close) to the resonant frequency of the glass.

So with a crank you have a frequency being inputted into the crank and it changes throughout the whole rpm band. So by having a rubber damper (it's encased in the pulley) it reduces the resonant frequency by dampening the shaft. This eliminates the chance of the crankshaft from going through the resonant frequency at any rpm.

Having a solid blingin' cnc machined crank pulley just increases the natural frequency of the crankshaft and will likely put the crankshaft into the same frequency band as a particular running rpm. Not good...


Here is a quote from Larry Wilmer replying to an Unorthodox Racing FAQ.


I just read the top of the article, and they're dead wrong from the get-go. Externally balanced engines have a counterweight built in to the hub of the harmonic balancer, bolted to the crank, or built in to the flywheel. The crankshaft can NOT be properly balanced without these weighted pieces attached. Internally balanced engines do not require additional weights, so their flywheels (and harmonic balancers) can be neutral balanced. All the weight necessary to balance the rotating assembly is contained in the crankshaft counterweights.

When a cylinder fires, that crankshaft journal pulses forward (yes crankshafts flex), and that journal also rebounds. Every journal on the crank goes through the same motions and the greater the engine's power, the more violent the pulsations.
Try to picture this now....the crank is rotating, but the individual journals are oscillating back and forth at the same time, meaning that there's vibration in the crankshaft. This vibration is transmitted into everything connected to the crank. Ask someone in the aircraft industry about the effects of vibration sometime.....it doesn't take much to break pieces that appear very substantial...and the same is true about the bottom end of an engine.

Despite what Unorthodox and other manufacturers of solid hubs say, it's essential that you have a vibration dampening device attached to the crankshaft to reduce vibration and resultant breakage.

In-line 4 cylinders are inherently out of balance, since all the crank journals are 180 degrees in layout, with side-by-side cylinders. V8 engines on the other hand have journals every 90 degrees (as well as cylinders separated in a "V"), so there's a hell of a lot less vibration, comparatively speaking.

Now there are some classes in motorsports where V8's run pretty damned well (all things considered), but you won't find a single instance where their engine builders use solid hubs (like Unorthodox pulleys), unless they run in a class where tear-downs occur after every race.
As mass-conscious as NASCAR engine builders, you won't find a single one who would even consider running a non-dampened crank...hell they didn't even do that on 3-4 lap specials (qualifying engines)...which are now illegal.

To sum this up from where I'm sitting....Unorthodox came up with a pretty component that was easy as hell to make...and there's nothing easier than a pulley. They advertise the crap out of them and they take advantage of this largely young and uneducated market.
Their rational is total bullsh*t. You can talk around the subject all you want, but it's a long-time proven fact that you MUST be able to dampen crankshaft vibration.
Think about it for a minute....it's a hell of a lot cheaper to manufacture solid hubs than harmonic balancers, so why in the hell would everyone in the world who races for MONEY use them?
Ask Unothodox how many (domestic) ProStock engine builders or NASCAR engine builders have asked them to make them solid hubs, or how about Indy and CART? You won't find that crap in any of those places. We ALL were forced to use solid hubs back in the late 70's when we were "exploding" stock balancers (from extreme rpm), and NOBODY could keep a crank in an engine for more than a handful of runs down the quarter mile. EVERYONE broke a crank a week, until a couple aftermarket manufacturers of real harmonic balancers saved the day.


I have a few SAE articles as well...but I think the above quotes should suffice. :D

H8PVMNT
06-05-2008, 10:59 PM
It really worked for gas milage... To bad nobody is making a harmonic balancer that would take care of the resonance issue while at the same time underdriving the accesories. That would be worth buying!

I haven't been able to find a underdrive kit for the 5S accesories instead of the crank. That would be a nice way to acomplish the same effect too, but without the issues.

My other question though: Wouldn't an aluminum flywheel kind of have a similar ill effect? I know the flywheel is undamped, but are they a certain weight for an engineering reason as well?

How about machining the crankshaft counterweights to eliminate weight and crank case wind resistance issues?

Denver_whiteST185
06-06-2008, 06:47 AM
flywheels do not dampen the resonance of the engine. they provide inertial energy so your car can stay at certain engine speeds easier. thats why you will need to provide more throttle to keep a car with a light weight flywheel at a certain engine speed. the benefit is that the car will rev quicker (less parasitic loss).

im actually surprised you got better gas mileage, but i really haven't sat down and thought through all the factors. you can get a underdriven alternator pulley and a powersteering pulley from fensport in the UK.

If conrad only had a nice CNC machine to make all of us at celicatech.net a set of underdriven alternator and powersteering pulleys (and an A/C delete pulley for those of us that ripped that monstrosity out), that would be awesome of him to do, and we would all love him...
:lolhittin

3SmeCaptain
06-06-2008, 07:12 AM
um... this sounds weird actually...

last i heard from toyota *this topic came up on several scion forums*, any engine that toyota has designed that is of straight block design such as inline 4, straight 6 and so on, are all balanced shaft designs. the need of a dampening pulley is only needed on their V type engines because their cranks aren't balanced correctly because of the V setup where as the straight designed engines don't need a dampened pulley and that the dampened pulley is used just to same on cost by using a pulley that is already made for the V type engines so that it is just a pre-ready part to use. i know several people who have been running light weight pulleys for years on straight designed engines and have yet to have any problems with their bearings. i my self have a perrin light weight pulley on my scion and it's been on there for the past 2 years and no problems have come up. i also have a buddy of mine who's running a blacktop SR20 with a light weight pulley and he's been running his for as long as he's had his 240 which to my understanding, he's had it running like that for about 7 years. only problem he's had is him using SPEC clutches and having them explode on him for no apparent reason and has reccently changed to a ACT clutch. but still, no problems. i don't care how many articles anyone can dig up, i've seen them in action for very long periods of time and have yet to hear about a single one of them causing any problems at all and they are all on straight line based engines.

EDIT: then again, i'm not trying to bark back at any given info here. i'm just sharing my experiences towards this topic is all.

Conrad_Turbo
06-06-2008, 05:05 PM
um... this sounds weird actually...

last i heard from toyota *this topic came up on several scion forums*, any engine that toyota has designed that is of straight block design such as inline 4, straight 6 and so on, are all balanced shaft designs. the need of a dampening pulley is only needed on their V type engines because their cranks aren't balanced correctly because of the V setup where as the straight designed engines don't need a dampened pulley and that the dampened pulley is used just to same on cost by using a pulley that is already made for the V type engines so that it is just a pre-ready part to use. i know several people who have been running light weight pulleys for years on straight designed engines and have yet to have any problems with their bearings. i my self have a perrin light weight pulley on my scion and it's been on there for the past 2 years and no problems have come up. i also have a buddy of mine who's running a blacktop SR20 with a light weight pulley and he's been running his for as long as he's had his 240 which to my understanding, he's had it running like that for about 7 years. only problem he's had is him using SPEC clutches and having them explode on him for no apparent reason and has reccently changed to a ACT clutch. but still, no problems. i don't care how many articles anyone can dig up, i've seen them in action for very long periods of time and have yet to hear about a single one of them causing any problems at all and they are all on straight line based engines.

EDIT: then again, i'm not trying to bark back at any given info here. i'm just sharing my experiences towards this topic is all.

3S-GTE crank pulley (http://www.turbomr2.com/MR2/HowTo/Engine_Upgrade/Rebuild/Images/ECU/Trigger_Wheel_Collar_6189.JPG)

As found from here: http://www.turbomr2.com/MR2/HowTo/Engine_Upgrade/Rebuild/Rebuilding_the_3SGTE-03.htm

Doesn't look to be a solid piece of steel...

What do you think would cost more to produce in large quantities, 1) A solid cast pulley with post machining processing...or 2) A two piece cast pulley with poured rubber/urethante isolator with post machining processing? Companies do things to save costs and eliminate unncessary costs, if a two piece, rubber damped pulley costs more why would they have done it if it was unecessary?

Denver_whiteST185, a friend of mine owned a Haas CNC mill...unfortunately he didn't use it enough and just didn't have enough CNC experience and he sold it late last year. :(

Luni
06-06-2008, 05:26 PM
This has come up before too, and while I agree with the nature of the stock pulley being a harmonic balancer, theres 2 things that I want to add.

1) most of our cars and engines have well over 100k miles on them, theyre over 15 years old, and the rubber in that balancer has degraded, and definately is not doing its job like it used to.

2) I have not seen a single cause of engine failure that has resulted from putting an UR pulley or any pulley other than stock onto a 3SGTE/5SFE/1MZ/3VZ, etc.

So, while I wouldnt run one, I dont think its near as big of a deal as people make it out to be. I too have seen people who have ran them for several years and many miles to no ill effects. I just dont buy into it. I have a hard time believing that Toyota would have engineered their engines longevitiy around one very simple, device.

Thats just my .02

H8PVMNT
06-06-2008, 05:51 PM
I'll tell you what I'm going to do...

There are ALOT of arguments all over about this mod. Very few are from personal hands on research. Both theoreys make sense. I am leaning toards the negative ballance effect myself, however, I think we need some real world facts on this.

My 5SFE has only about 110K on it right now and had a pretty easy, well maintained life from the previous and 1st owner. I don't know what the rods and mains look like, but they should still be in pretty fair shape so far. I love rebuilding engines and I want to build another 5S with a better head and some real nice pistons, higher compression etc. I put alot of miles on my celica because of my work. I will get another 5S to build and have it ready in a year or so. In the mean time I'll put a whole lot of hard miles on with that underdrive pulley installed. I think about 50K should give us a good fair test. Then I'll take it all appart and plastiguage the rods and mains, measure how far out the journals are and such and post the info on here.

Here's where you guys come in:

Then I need somebody to come up with similar info from tearing down a stock bottom end without an underdrive pulley so we can see the difference in wear and post the results on the same thread. There are alot of other factors for wear but if the pulley tears things up we should be able to see some different wear characteristics front to rear from being out of ballance.

Then we will KNOW from personal experience if these things are good or bad...

Thanks for all your info on this so far you guys are awsome! :bigthumbu

Wheel On!

Conrad_Turbo
06-06-2008, 06:26 PM
It needs to be done in a lab environment, 50k miles on one engine may equate to a lower runtime than another engine, rpms also play a factor. There are SAE documents that prove what a harmonic balancer does, or books like this: http://www.amazon.co.uk/Advanced-Engine-Technology-Heinz-Heisler/dp/0340568224

The author is the Head of Transportation Studies at the College of North West London, I'm sure he has far more first hand experience than anyone on multiple forums combined in terms of this topic.

Luni I agree the stock damper failing is not a good thing for crank dynamics, however that is a good reason to buy a new one. It's like saying the stock suspension is blown and worn out, instead of putting in aluminum blocks, putting in the OEM replacement is the best choice.

Edit: A good read: http://wps.com/AMC/Rambler-327/The%20New%20American%20Motors%20V-8%20Engine%20(SAE%20Paper%20details).htm

Luni
06-06-2008, 07:31 PM
And again I want to reiterate that Im not one for this mod, Im just saying there are more factors than people generally take into account. The primary factor is the stock pulley loses its dampening ability over time. It isnt necessarily a "balance" thing, its a vibration dampening thing.

One thing that was done by an MR2 member was he took the UR pulley, drilled holes in it and filled all the holes in with polyurethane. He said before he filled it, if he hit it with a tuning fork, it resonated ALOT, after, it just thumped and didnt resonate a note at all. Obviously that isnt a "real world test" but its an indication that what he did helped with the vibration absorbing abilities of the underdrive pulley.

I agree with replacing the stock pulley, however an OEM one is expensive as sin. Id LOVE to see someone reproduce the stock pulley in aftermarket form, while still retaining the balance, dropping some weight, and doing a 2 piece design with rubber or poly between the layers to absorb the resonances from the crank.

Maybe you should get on that Conrad :)

Conrad_Turbo
06-06-2008, 10:16 PM
And again I want to reiterate that Im not one for this mod, Im just saying there are more factors than people generally take into account. The primary factor is the stock pulley loses its dampening ability over time. It isnt necessarily a "balance" thing, its a vibration dampening thing.

One thing that was done by an MR2 member was he took the UR pulley, drilled holes in it and filled all the holes in with polyurethane. He said before he filled it, if he hit it with a tuning fork, it resonated ALOT, after, it just thumped and didnt resonate a note at all. Obviously that isnt a "real world test" but its an indication that what he did helped with the vibration absorbing abilities of the underdrive pulley.

I agree with replacing the stock pulley, however an OEM one is expensive as sin. Id LOVE to see someone reproduce the stock pulley in aftermarket form, while still retaining the balance, dropping some weight, and doing a 2 piece design with rubber or poly between the layers to absorb the resonances from the crank.

Maybe you should get on that Conrad :)

That's true, filling it with poly would reduce it's resonance frequency. The only difference between that test and what Toyota knows is that they know what the resonance frequency of the engine is, and they can specifically design a pulley to dampen those peak frequencies. I know you're not one for the mod. :D

I don't know of any company that would do what you would like...reason being the R&D and costs would make the part cost prohibitive to even begin producing, especially when there are anodized super lightweight aluminum pulley's for sale by many manufacturers.

You can put a wine glass on a concrete floor and tap it with a fork, then do the same with the wine glass on a sponge. The frequency will drop due to the isolation (spring) properties of the foam, the rubber in the pulley is the isolator which reduces the harmonics in the crank.

H8PVMNT
06-07-2008, 01:58 AM
It needs to be done in a lab environment, 50k miles on one engine may equate to a lower runtime than another engine, rpms also play a factor. There are SAE documents that prove what a harmonic balancer does, or books like this: http://www.amazon.co.uk/Advanced-Engine-Technology-Heinz-Heisler/dp/0340568224

The author is the Head of Transportation Studies at the College of North West London, I'm sure he has far more first hand experience than anyone on multiple forums combined in terms of this topic.

Luni I agree the stock damper failing is not a good thing for crank dynamics, however that is a good reason to buy a new one. It's like saying the stock suspension is blown and worn out, instead of putting in aluminum blocks, putting in the OEM replacement is the best choice.

Edit: A good read: http://wps.com/AMC/Rambler-327/The%20New%20American%20Motors%20V-8%20Engine%20(SAE%20Paper%20details).htm

Of course there are alot of other factors that you can't account for unless you had perfectly matched castings. A guy could have a blown head gasket and get coolant in his botom end and gall up the journals, or race all the time, or not change oil etc.

I have tore down a few of the 22re truck engines and they do all have similar wear characteristics to a point that you could tell what normal wear looks like compared to something weird.

From what I've read on the underdrive pulleys you see more wear on the front of the crankshaft than normal. This is the kind of wear I'm talking about looking for for comparison. Not so much how worn is it, but how did it wear? Was there something different than normal? This could be recognized outside the lab if you had enough data from measuring worn engines before rebuilds.

Surely there are enough of you guys that do your oun rebuilds to come up with enough data to figure out what normal wear is! I come from the hardcore 4WD scene and we do practically everthing on our rigs ourselves, even if it means screwing up to learn. You just don't get any respect if you take it to the shop.

I'm not trying to prove one way or the other here mind you. I just figure since I already bought the danged thing I could see what happens since nobody really has.

METDeath
06-07-2008, 03:46 AM
So here's a question, since we're sort of on the subject, if your drive pulley was bad, how could you tell? I have a nasty vibration all through my car at 500-1100 RPM, and about that it dies out, would that be an indicator of it being out?

Mafix
06-09-2008, 09:05 PM
there is a reason the 3s has a factory fluid dampener.

vip09
06-09-2008, 11:35 PM
Just about every person that put these on the 2zz had their oil pump blow up.. causing dead engines. Too much vibration.

VikingJZ
06-10-2008, 04:06 AM
Well thats a 2ZZ.



It is reasons like this that I claim my full respect for what comes on the car. There is so much he said she said about products like this (and many others) that lead me to believe its a hit or miss part. If the vast majority of postees claim a certain part is worth the money and reliable, I will consider it.

Otherwise, I just leave it alone.

H8PVMNT
06-10-2008, 05:59 AM
I don't know... You guys have me spooked. I think I'll do the polyerethane fill or maybe just put the stock one back on and get the underdrive pulleys for the accessories that were mentioned. The basic idea works, just maybe not on the crankshaft...

Luni
06-10-2008, 08:24 AM
Id honestly think the polyurethane filler would be a helluva lot better than not, HOWEVER, by doing that you negate some of the weight difference. Im sure even a poly filled aluminum UD pulley will weigh less than the stock one. Dunno man. Disucssions like this are the main reason why Id personally never buy a UD pulley.

Another thing to take into consideration is he had access to a lathe and a balance caliper tool thingy ma bob.

He was able to balance it out by using the lathe. If you cant remove the material (cause it will never be perfect without it) you shouldnt try doing that.

Conrad_Turbo
06-10-2008, 03:53 PM
there is a reason the 3s has a factory fluid dampener.

And it definately wasn't for cost savings! I wouldn't put a lightweight pulley on my car even if it was free...it'd sit on the coffee table as a conversational piece. HOWEVER I am all for lightweight smaller diameter pullies on accessories (provided they don't need to run so fast in the first place).

Mafix
06-10-2008, 08:46 PM
as am i.

caneman
06-11-2008, 02:43 AM
There was a time during the last century when troops marched to destinations. They were trained to break cadence when approaching a bridge, as their usual "Hut! Two, Three, Four!" could set up a dangerous resonance vibration that could bring the bridge down. Think about that the next time you watch the Boston Marathon crossing a bridge. They're all perfectly safe, of course, because they're running at different cadences.

Lightened flywheels, if done by experts, are perfectly safe and do offer much quicker off-the-line acceleration. I bought my 1959 Porsche 1600 Super back in 1965 from the chief mechanic of Porsche of America's racing team. It'd outrun Chevy tri-powered V8s, at least until their much greater HP took over. HP always wins out in the end...

BTW, no... I don't have that Porsche any longer, I sold it two years later for $1695 USD... Who knew? I cry every time I see a similar Porsche sold at the Barrett-Jackson Auctions. A lot.