Date: 19-Jul-99 10:40 PM
Author: Primodreams
Subject: would a little piece crackedoff crank pulley cause vibrabtion under accc?? help~

I have AEM underdrive pulleys, I like them.. I have a friend that also has the unorthodox pulleys and they are just as nice... neither of us have had any problems.. I have had mine close to 2 months.. anyone else here about the problem with the oil pump...

With all the people I know that use underdrive pulleys, the only problem I have heard of is that if you have a really high power stereo, you may not be making enough charge with the UD pulleys to push the system really hard since the alternator is spinning slower also. Some companies have gotten around this by making pulleys that reduce drag on everything else, but keep the alternator spinning at the proper speed, I don't know of any import companies that have done this yet though. As to the oil pump exploding, it sounds like a fat load of crap.

RX

As the oil pump on a Honda is driven by the crankshaft (and there are NO belts involved), how could you blow the oil pump? Underdrive pulleys will slow down the alternator, A/C, and power steering pump which may produce a touch more power at the flywheel / wheels, but the speed of the oil pump is not changed any at all. The pump is internal and it's rpm is entirely governed by the crankshaft rpm so there's no way that you can change it with external mounted belt drives. Now, if any of you are running external dry sump oil pumps, the pulley ratios could have a BIG effect on the pumps ability to provide necessary oil flow. I doubt that there are many guys running external belt driven pumps, especially since a good system will cost as much as building the entire engine.

i heard that honda crank pulleys' are counterbalanced or something where if removed... the rotating assembly will have vibrations and thats what caused oil pumps to blow out...ie.. comptech racings' type R.. blue out and oil pump with a UD racing pulley. .. i was just wondering...

Bad Vibrations

I'll post a more complete rendition of this on the too site shortly, but let me begin by saying that it's good to be back and I'm only here to expressly address some questions that need some "good" answers. I am not here to provide schedules or any information regarding the blower program. The topic is that of aftermarket crank pulleys. Let me begin by saying that we have always called the pulley on the accessory drive end on the Honda cranks Harmonic Balancers. People never seemed to understand what we were talking about and so the word "pulley" was frequently used to avoid confusion. If you look carefully at a Honda "pulley", you'll find that it's not a single piece of metal. Typically, there's a nodular iron or steel hub and another "ring" of iron or steel surrounding it containing the belt grooves. The two parts are joined by a rubber layer, which is highly compressed and sandwiched between them. Why rubber? If you notice, many four cylinder engines over the years have used counter rotating shafts to help make the engine "feel" smoother. Reciprocating internal combustion engines and especially in-line four cylinder versions, all produce shock pulses, which are very apparent to the occupants of the car. Every engine produces a shock pulse each time an individual cylinder fires. So, in the case of the four cylinder variety, there are four large individual pulses for each 720 degrees of crank rotation. Each time there's a pulse, it causes the internal components to do a rapid acceleration-deceleration event. When you consider the mass of all the internal components and visualize all these parts stopping and starting during their reciprocating and rotating motions, the additional stress "spikes" tend to make it all the more reason for one to wonder how any of it can work for any length of time. The harmonic balancer is made with the rubber coupling so that, when the individual "spikes" occur, the inner portion may move with the crank, but the rubber connected outer ring's mass helps prevent the hub and crank from going as far or as fast during the spikes or pulses. Remember that the outer part had considerable mass, so it tends to want to stay in motion at the speed that it's traveling and that's why it can prevent excessive harsh motion by the crank and other internal parts. To put it simply, the harmonic balancer is a shock absorber for the engine and thus prevents the individual pulses from destroying everything in the engine. A quick bit of history; Back in the late '70's, all the Pro Stock engines had been reduced in displacement to allow the cars to weigh less. At that time the vehicle weight was based on engine "type" and total displacement. Typically, the engines were in the 330 cubic inch range and running 10,000 to 11,000 rpm was normal, especially in high gear at the traps. There began to be a lot of engines that were "exploding" their harmonic balancers on the big end. Aside from cutting the steering in half and blowing the front tires, large hunks were also finding their way into the grandstands and there were numerous injuries, many of which ended in death. NHRA immediately mandated that solid "balancers" were to be used from that point on. Keep in mind that a balancer can't be solid and function properly, but the rules were the rules. Moroso and a couple other companies who were tight with NHRA began making aluminum billet "balancers" immediately and everyone bought them so they'd be legal to race. All of a sudden, racers were getting only 10 passes from their crankshafts, which had previously lasted an entire season. Initially, most people thought the cranks were "bad", but after destroying engine after engine, a few knowledgeable engine people figured out where the problem actually was coming from and several companies that were capable of making functioning harmonic balancers sprang up over night. They are all still in the business to this day and their units are actually much better than the factory units of years before, as they are made from premium materials and optimized for high rpm applications. With this short bit of history finished, I'll begin to wind it up by stating what we do with the Honda engines. If the balancer has more belt grooves than the application needs, i.e. the power steering pulley, we machine it off. When it comes to the the pulleys that are actually a part of the outer portion of the balancer, we leave them intact. This procedure will not lighten the unbalanced hub substantialy, but the outer balancer ring will keep all its mass and function correctly. I also need to say that a large driven mass such as a blower or alternator, can have a slight dampening effect, but to actually work properly, the belt connecting the components to the crank would need to be 4" to 5" wide and the belt tension would be so great that it would wear out the number 1 main bearing as well as the bearings of the the driven parts in short order. It's especially important to keep the balancer "as is", if you're running an aluminum flywheel. The reduction in flywheel mass can also increase the pulsation shock strength and a higher level of vibration will immediately be observable. So if you lighten the flywheel,it's absolutely more necessary than ever to maintain the mass or the harmonic balancer. I realize that there's a lot of hype out there where manufacturers are promising this and that. The oversize crank pulleys can drive other geared or belted components faster due to the diameter ratio increase, but if you're deleting the balancer in the process, the short and long term side effects are going to hinge on your decisions. Larger diameter pulleys for the alternator, power steering and any other belt driven accessory are good ways to slow the speeds and drag of the those components, but when doing a large diameter crank pulley, the larger pulleys should actually be designed to fit "over" the stock balancer. Perhaps, someone will begin to make some good quality "functional" balancers some day, but until they do, you need to proceed carefully, as some good looks and minimal power gains can be off set by a ruined engine. I'm sure that there will be some fall out regarding what I'm saying here and to that effect I need to remind everyone that we do not manufacture hubs, big pulleys, or harmonic balancers for Hondas and none of what I've said is the least bit politically motivated.

And yes, any engine with a non-functional hub or balancer can ruin the crank driven oil pump and a whole lot more.

………………………….T.O.O. ………………………

Since it is now stated that we need some kind of harmonic balancer to keep everything together, would it be possible to use whatever size pulley (solid undampened unit) and attach something like a Fluidamper to that pulley? Would that allow you to run whatever you wanted without fear of unnecessary wear? Or do I have the fluidamper concept wrong, is it just like the stock unit, with the belt riding on it, only with a different dampening system?

RacerX

The Fluidamper is an excellent product that's used by quite a number of first class engine builders. In order to work correctly, it needs to be keyed and bolted to your crank, just as the stocker. We frequently drive pumps, and alternators from pulleys that bolt to the inner hub attached to the crank, but I'd think that sticking a lot of mass out beyond the crank snout could be a recipe for trouble, due to the increased distance to the #1 main bearing. We have made some larger diameter pulleys for Hondas that slip over the originals and are held in place with several allen set screws. Perhaps this revalation will "affect" some aftermarket manufacturers to make some this way. It's really simple to do. ........T.O.O. ..............