Products Debate: Should I get a crank underpulley (ad says makes 5-8 whp)?
What’s out there on the web?
quote:
From www.inlinefour.com
“The FC Vector 1 Harmonic Damper is revolutionary piece of equipment. CNC constructed from billet aluminum. Designed for todays high revving engines, the FC Vector 1 damper reduces torsinal vibration, thus increasing power and efficiency. Each time a cylinder fires the resulting combustion creates a tremendous amount of pressure, which becomes the force applied to the
crankshaft. Imagine the crank as a tuning fork. Once hit, it will ring at a certain frequency. A crank will act just like a tuning fork. But, harmonics become destructive to a crank as it reaches its natural frequency. The longer the crank remains at this critical point the more severe the damage can be. So you can see why a high revving engine needs a good damper.”
quote:
from www.inlinefour.com
CTR N1 Harmonic Crank Pulley
This very rare piece is the crank pulley that Honda uses on the N1 Civic Type-R’s.
This crank pulley is pre-balanced from the factory and weighs a mere 1.8 pounds.
Perfect if you do not have any A/C or powersteering and are looking for the ultimate
crank pulley. Also, unlike many aftermarket crank pulleys, this pulley features all
three timing marks…just like your factory pulley! Genuine Honda, so you know this
fits perfectly and is made to last. Constructed out of chromoly steel, this is one
awesome part. Will fit any B-series engine. "
From Dan Ponze
our colleague at honda tech. com
on Unorthodox Crank Pulleys
quote:
"I love them, some people cling to the old wive’s tales of harmonic balancers (which Hondas don’t have). They go for just under $200. I gained 6 whp on my GSR and 3-4 on my Type R. This is on the dyno and gains are across the board. Also they are over 75% lighter than the stock one…I use UR pulleys on all my cars as well. 9500 RPM safe and you won’t never have any problems at all. It’s a LOT lighter than that CTR pulley which although technically I offer, I hate selling to anyone. What a waste. Just for reference the UR crank pulley weighs in at around 500 grams…I fail to see what the crank pulley has to do with the oil pump. "
from Greg Sumaroo (aka Frog Honda seen in Superstreet Magazine) at Honda Tech.com
quote:
“actually the unorthodox pulley works fine on cars that run to 8500, maybe 9500rpm … for the abusive drivers who run it constanly at high rpm over and over with that anodized material … it’ll warp … plus it starts to “play” near the key which then gets loose around the crank and then vibrates which puts a lot more vibration on the oil pump. I’ll take the honda
material … personally I just chop off the a/c and p/s layers from the stock pulley then rebalance.”
From Unorthodox Racing
http://www.unorthodoxracing.com/
quote:
"A number of rumors have been floating around about Honda oil pumps failing due to the use of an Unorthodox Racing Lightened Underdrive pulley. The fact is these pumps have been failing with AND WITHOUT the use of our pulleys, even before our product was available on the market. There are a number of reasons for these failures, and we will explain them here.
Most of the pump failures have been in Acura/Honda 1.6/1.8L applications. The Mazda 1.6/1.8L applications have seen a few failures, as well as the new Ford Focus ZETEC in race vehicles. Again, note that on all these applications the oil pump failures have occurred on engines not using our pulley, using the stock crank pulley.
These pump failures are linked to 4 specific issues that vary from vehicle to vehicle. These issues act individually or combine to cause the failures.
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The gears used in these pumps are of a powdered metal composition. Powdered metal is quite brittle and fragile and has a specific stress tolerance or breakage point that the factories (Honda, Mazda, etc.) build into the design. Upon severe engine acceleration the gears begin to warp under the load causing metal to metal contact between the gears themselves and the oil pump housing which causes the gears to explode.
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Honda D and B series engines have an oil pump design that utilizes a very thin cast aluminum backing plate. This backing plate is prone to flex under extreme loads like those seen in modified engines using a combination of numerous bolt-on components, some with large nitrous shots and/or forced induction kits (turbo or supercharger). These D and B series pumps do not make use of the extra screw that the H series oil pumps use. This extra screw, located in a key pressure/flex point of the backing plate, alleviates the flex problem but puts all the stress on the weak powdered metal gear as described above. On acceleration the backing plate buckles, which allows the oil pump gear to walk on the crankshaft snout and as soon as the gear moves it binds with the oil pump housing and explodes.
The H22 engine as noted above has the extra screw in the pressure point of the oil pump backing plate. The problem is that the gears of the H22 oil pump are thin in the pressure point of the gear and under extreme acceleration (major mods: High compression, forced induction, nitrous, etc) the gears fracture. This is caused by extreme pressure and the additional facts outlined in section 3 below. The H22 was also never meant to be revved past 7500 RPM, which is something that seems to be occurring with some regularity and also dramatically effects gear life.
- The inner portion of the oil pump gear, which sits on the crankshaft snout, does not fit tightly. This loose tolerance causes the crankshaft snout to slap the trailing side of the gear upon lifting of the throttle, during up-shifts, and then slap the leading side of the gear once the accelerator pedal is hit again. This constant back and forth slapping causes cracking in the gear due to its weak powdered metal design. In time the gear breaks apart…
We hope this information has helped explain the problems with the Honda oil pumps (as well as the Miata and Focus). Another factor that can cause extra stress on the pumps is the use of oil heavier than the factory specified weight. Tolerances in the pumps and engines take into consideration oil weight.
Currently we are looking into solutions for these problems, including possible replacement gears (and/or pumps) and heavy-duty backing plates for the pumps. These solutions will be applicable to all Street/Strip Honda owners using, or not using our pulleys. For those who run dedicated/extreme race vehicles you should be using an external wet or dry sump oiling system. These systems are designed for the heavy abuse a race rengine receives on the track. Remember, the stock oiling systems were designed for factory horsepower levels and can only handle a certain amount of power increase."
