Underdrive pulleys

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#1
I was thinking of adding a set of rogue pulleys. Any of you guys used underdrive pulleys? They set does not include the crank pulley, which I would not do anyway. For the fact that the crank pulley also serves as the harmonic balance. For those who have a crank pulley please read this article from Dinan: http://dinancars.com/whitepapersFile.asp?ID=5 The kit also does not include the alternator pulley. Which is fine because I did not want to underdrive the alternator and lower the output. The kit includes the waterpump and power steering pulleys.

http://www.rogueengineering.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=RE&Category_Code=PP

These are my current mods:
1. Jim C CAI
2. M50 Manifold conversion
3. Bav Jet Hot tuned headers
4. AA tuning track pipe
5. B&B Twin Tri-flow exhaust
6. AA tuning custom software
7. 10lbs lightweight flywheel
8. Sachs power clutch
9. UUC Evo 3 Shifter
 

epj3

Senior Member
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#2
I'm not sure many experienced people reccomend pulleys, especially if you use the car for a lot of street driving. It can be bad - The steering system is designed to operate at a specific pressure which is only achieved under higher RPM's such as when you're on a track. Same with the waterpump. The engine in your car is a fairly intolerant engine (as you probably know). If the cooling system is lacking that could be a problem...but for tracking the car, its not bad becuase your engine would be at higher RPM's much more often.
 

epj3

Senior Member
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#4

Well, I dont think I'd question the pumps lasting... but I'd question the lack of the pumps doing enough work when idling around in traffic. Underdrive pulleys are built for track use, and thats pretty much it.

Another mod people do is remove the mechanical fan, and set the electric fan to turn on at specific temperature.
 

VANCE

Active Member
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ATLANTA, GA
#6
from the link i posted......................


Here's Shawn (owner of URI) in response to Dinan's white paper (sorry about the length):

To get the other side of the story, read what the owner of URI says on the subject:

We just want to make sure everybody read this.
Before making judgments with such wide implications it is important to recognize the fact that long-term real world use outweighs theoretical assumptions. Simply stated we have two years of pre-production testing under our belt and an additional four years of real world data (over 300 million miles). Not once in this period have we ever had even the slightest problems in regard to engine longevity, not one claim or call. The fact is that if there were a problem with our product we could never have kept it from the public because of the Internet Unfortunately we have taken the brunt of many rumors flying around the Internet about our products, like this article. Now we spoke with Mr. Dinan and he apologized for any undue problems this article may have caused us as he never directed it towards Unorthodox Racing Inc. That aside we have tried to take the time to educate our owners and potential owners of our products about the facts. It always seems to be that someone's cousin whose girlfriend's brother has a friend that had a problem with our product. Needless to say we never get a phone call, which we would think would be the first thing an owner would do if they have a problem with our product or any product they use that causes a failure. We wish that everybody would try to learn and think for themselves like the old adage "Believe non of what you hear and only half of what you see."

First mistake is that the majority of our gains do not come from underdriving. The majority of the gain from our product comes from weight loss, removal of rotational mass from the rotational assembly. We also do not cause problems with accessory output either, as each model we manufacture is tested to maintain factory acceptable parameters accessory output. So each vehicles underdrive is tailored to what the specs call for and never exceeds 20%. This is also concurrent with information we have received for CARB (California Air Research Board) stating that as long as we do not push beyond 20% underdrive we will remain within acceptable parameters set by the factories. They also mentioned that products exceeding 25% underdrive would not pass emissions requirements because all late model cars would run in a limp mode because of reduced voltage. So Steve Dinan theory one is wrong when applied to Unorthodox Racing products. Secondly the gains are not small, we have seen on BMW E36's 5-9 HP regularly and from 13-18 HP maximum. The stock crank pulley/damper is what is called an audible harmonic damper, in laymen's terms that means control of harmonics you would hear in the occupant compartment. Similar example is the factory use of baffles and resonators in the intake manifold. These methods are used because of the factories fanaticism about quiet in the occupant compartment. They have nothing to do with engine longevity. The flywheel has dramatically greater effect on engine longevity.

We have our own engineering and design team but we have also had direct contact with many of the OE manufacturers on this subject. We have worked with engine builders, many of who have been in the industry since the mid fifties. We also have worked with many Speedvision racecar teams with a number of different vehicle models. One was Last Minute Racings E36, driven by Alain Chebeir. Last Minute Racing ran our 4-piece pulley kit including the crank pulley for the entire 1999 season. Not once did he ever encounter a problem with our product. We also worked with The Wheel Source/Hikari Supra, driven by David Schart. That engine is very similar in many of its characteristics when compared to the BMW straight 6. They ran our 4-piece pulley kit for the entire season, and their motor as turbocharged, making considerably more power than stock, 500-550 HP compared to 320 HP stock. They never had any problems with the use of our product. We also worked with Trac Racings two VW cars, running the VR6 engine. They have run our pulleys for two seasons now with no problems. We also worked with High Speed Racings two VW's and they have had no problem whatsoever. All of these teams have disassembled their engines at various times throughout their race seasons and have found no abnormal wear or crankshaft cranking. Now those were just the road course teams. We also work with many drag racers and one Pikes Peak car (Rod Millens Supra) and none of these teams have ever had problems. Not only these facts but the fact that we have had over 100+ sets in the field on street and street/strip BMW's including some turbo models without ever having any problems leaves you to believe that Steve did not intend to include Unorthodox Racing. All of our pulleys for other vehicles have never once caused any problems, in fact aside from the examples stated above, we have over 250+ million owner driven miles out there with our product.

Steve's association of the stock crank pulley being the primary damper is incorrect, it is the dual mass flywheel that accomplishes this task. But even replacing this dual mass damper with an aluminum flywheel would not cause long-term damage as long as the flywheel were properly balanced. To give an example lets look at the Turner Motorsports Speedvision cars. Those vehicles were running underdrive pulleys from another source. To regress slightly for historical value, we had originally engineered two designs for the BMW crank pulley section, but both kits were four pieces in total. One crank pulley design was a six-bolt pulley section replacement like the way the factory designed theirs. The other design was a complete one-piece replacement of pulley sections and the hub that mounts to the crank snout. We had sent some pulleys up to Mr. Turner for evaluation. The prototype design sent to him replaced the pulley section and the steel hub section with one unit that attaches directly to the crank, as described previously. This once piece design help eliminate the weight from the heavy steel hub. Unfortunately we could not use this design for production because the aluminum would crack shortly after installation due to the high torque specification for the bolt that attached that hub to the crank snout. Now Mr. Turner instead of working with us decided he would not tell us this, which we found out at about the same time from another local owner that worked with us. Mysteriously the following race season, with other pulleys on his car they began to have crank cracking problems. Multiple motors were broken, all at the main journal before the last rear cylinder from what we understand. It was also amazing to find out that they were also using an undampened solid aluminum flywheel. It seems amazingly odd now that the breakage occurred at the rear of the crankshaft closest to the lack of damping component. But as stated before if a properly balanced flywheel would have been used the failures would not have occurred. This is supported by the fact that all the Speedvision teams, described above, we have worked with use aluminum flywheels and have had no problems whatsoever.

We have seen a few of these products and they would not even pass inspection for factory fitment even if they had the rubber isolator. The machining quality is frightening and the products are also unbalanced. These companies cut the factory timing ring off the stock pulley and remount it, for 95 or older model year BMW's, this assumes the balance of the ring once it is removed. We laser cut our timing ring and check balance during machining and after assembly. Our tolerances are held to .001" in critical areas, where we have seen regular tolerances of .005" or more from these other manufacturers. As stated before we have tried to address these issues at various times over the years through education to our dealers to FAQ's on our web page. It unfortunately comes down to the old adage that you get what you pay for when it comes to quality. There are offshore and on-shore copies of our other pulley models out there. All of these pieces are sub-standard and would not even meet factory specifications. So why do owners keep buying them, unfortunately its lack or education/understanding and plain old dollars and cents. The same problem occurs with cam sprockets with tolerances of other products, even at supposed 0 degree factory settings, not being up to even OE specifications. Meanwhile our own sprockets are held to again .001" tolerances and have timing marks that are down to the minute (60 being in a degree). Its price that drives the consumer, so unawares they are buying product that they cannot properly adjust or product that comes loose. Our pulleys are 60-70% more expensive than the offshore and onshore copies and other underdrive only products offered. Our top of the line sprockets are 60-70% more expensive than these others. We have even introduced an entry-level sprocket, which is 15% more expensive in order to be more price competitive while offering the functional quality of our top of the line without some of the additional lightening machining and extra hardware.

One other important issue is the rather random attack on a specific performance adder without looking at power adders in general. If we wish to get technical about this type of issue then all power adders must be looked at under a more rigid standard. Based on factory testing and design even changing the oil to a non-factory used oil puts the power plant or driveline into a completely different set of parameter results. Lets use intakes systems as the first example. By increasing the intake airflow response parameters are changed to some completely different set of parameters from what the factory tested or designed too. Now this does not even take into account the change in intake resonance frequencies, which again creates deviations from the factory design. This does not even take into account that the engine may make more power from this modification, which again leaves us with a deviation from parameters the factory designed the vehicle to be within. Now to be fair lets look at supercharging or forced induction for normally aspirated cars, which dramatically affects every aspect of engine function. More boost of course means more power, which in turn means more engine and drivetrain stress. This is a product that the factory never designed the vehicle to be used in conjunction with. The drive of the supercharger puts more stress on the front of the crankshaft. Turbos put more stress on the exhaust valves from backpressure and heat. Turbos are also less dependable as far as control goes, tending to spike which causes severe engine strain. Turbos also require additional expensive products like boost controllers and turbo timer. This additional stress was encompassed into the factory design of the crankshaft or the pulley system. If the factory pulley were a damper in the traditional sense the additional stress from any modifications would eliminate any special function that the factory pulley may have had because it was never designed for the additional flex of the crankshaft nor the faster spool up of the engine. Looking at other engine systems the fuel pump was never designed to deliver the amount of fuel needed based on the new demands the supercharger puts on that system. Flow might be adequate as a function of output but is the pump up to the day-to-day stress. Another parameter the factory never designed into that system. We can go on and on with how non-factory parts, even regular service parts which are non-factory can effect a vehicle. The fact is that owners that want more power assume the risks of their desire. All the products they desire to achieve these improvements where never entered into the design equation of the factory designers.

Respectfully,
Shawn Baumgartner
President
URI
 
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#7
I was just sharing the information that I found on the Dinan wedsite. I just wanted some feedback on the subject. I did mean to come across saying that the statement for Dinan
was a fact, it's just their opinion.
 


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