Does the 4A-F underdrive pulley really exist? I have searched around on the internet and I have found some sites talking about them but they never seem to tell me where I can order one!! I have even heard someone mention it on the forum but I can't seem to find the post anymore!! Does anyone know where I can get my hands on one? Would the 4A-GE underdrive pulley work on a 4A-F? Thanks for any help!!
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Underdrive pulleys wont give you any horsepower except add more wear to your alternator and waterpump, not to mention waterpump cavitation..... Bolt on's really dont do squat
Well your alternator would have a reduced voltage output/rpm, so that would drain your battery on the long term, especially if you have a stereo system which needs power. Not to mention added stress to the alternator itself and the regulator, because its driven at a non spec speed at low rpm.
Your water pump flows less, because it was designed to run at a certain rpm speed and we all know what happens when waterflow is impaired.
These are the main cons I can think about, its your car and money, you take your pick.
Well your alternator would have a reduced voltage output/rpm, so that would drain your battery on the long term, especially if you have a stereo system which needs power. Not to mention added stress to the alternator itself and the regulator, because its driven at a non spec speed at low rpm.
Your water pump flows less, because it was designed to run at a certain rpm speed and we all know what happens when waterflow is impaired.
These are the main cons I can think about, its your car and money, you take your pick.
Heheh... ok. Whatever you wanna think... As far as the alternator goes... less stress = longer life. The alternator will still be charging the battery just fine, and everything else will work normally, even if you have a system. I had a sub and amp set up in mine... and I ran fine for the 2-3 years that I had my UD pulley. It *may* drain the battery... but that's assuming people are gonna be idling all day. As for the waterpump... again, when cars are driven, the accesories speed up with the engine speed. Even under reduction, the accesories will work just fine. There is little to no risk involved really. The only issue I would think would be crank balance... but UD pullies are typically balanced anyways...
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Sorry guys I hate to interupt, but I just want to know if any company makes one for my car and if so where can I get my hands one?! Most of the U D pulleys I have seen only underdrive by 10 or 15% and I figure as long as my cooling system is kept in good condition I should be okay and as far as draining my battery because of a system, I don't have one. (Cars aren't sound studios they are cars, but that is just my opinion!!)
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I just thought I'd revive this thread cuz I too would like to find an underdrive pulley, if they exist.
oh, and by the way flashmn- I have the utmost respect for all the experience you have with 4a-f motors but I have to straighten something out. underdrive pulleys dont MAKE extra power but they do free up some- sometimes quite a bit. And I have never heard of anyone having battery problems as a result unless they have massive sterio systems or racing alternators.
oh, and by the way flashmn- I have the utmost respect for all the experience you have with 4a-f motors but I have to straighten something out. underdrive pulleys dont MAKE extra power but they do free up some- sometimes quite a bit.
On honda motors they can destroy the oilpump, theres been some cases of oilpumps shattering. Then again, I'm running a set of NORMAL SIZED but lightweight alt and waterpump pulleys. I opted to keep the crank as is and besides I would of had to send my pulley to the guy making them, because its different than the norm, because I have aircon and the others with 99% certainty, dont.
You can trash a honda oil pump with an underdrive? Its BELT driven? Shows what I know- I am just an old chevy guy. My modified TPI 350 camaro would eat you alive though man!-lol
Seriously though kudos on the turbo project. I will definitely be keeping tabs on your progress!
Yeah, that honda forum explains much. The problem is that these guys are using an unbalanced, non dampened pulley on a high RPM motor which needs a harmonic damper, not just a simple pulley.
Whats more, I bet that motor is factory ballanced, probably externally ballanced. What this means is that like any cast or forged component, the rotating assembly (crank, rods, pistons, harmonic ballancer) will have slight irregularities in their weight and therefor their ballance when the whole thing is spun at high RPMs. Ballancing the motor is when this irregularity is measured on a special dyno and eliminated by removing a small ammount of metal from the crankshaft (internally ballanced) or the harmonic ballancer (externally ballanced) Thus the harmonic ballancer may be minutely asymetrical in order ballance out the whole rotating assembly. installing a perfectly semetrical one will unballance the crank.
Of course an unballanced crank will flex due to cintrifugal force when it is spun, more so a extreme RPMs. As we all should know, crankshaft flex is THE ENEMY!!! It robs our horsepower, blows our main seals, puts wear on our moter, and it can even bend the crank permanently.
Apparently on hondas it can also shatter the oil pump where it meshes with the crankshaft.
And, sweet irony- those guys were probably losing horsepower by adding the underdrive due to the added friction from the flexing crank.
Was that answer directed to me, if it was may I remind you that I am a motorsports techie.
Anyhow, as far as I know honda motors are all as are toyota, internally balanced. However if you take a pulley that causes some harmonic problems to the balanced crankshaft shit hits the fan. Plus alot of the pulleys out there dont have harmonic dampening and have been balanced by themself, not with the crankshaft.
An unbalanced crank wont actually flex under load, it will start to chatter, eat out the bearings and kill the oilpump, cranks flex when you dont have enough bearings on them.
Most 4 cyl engines have 5. I've seen some with 3, I've seen a 4A-GE crank broken in two.
Oh, and I just realized that even if that motor is internally ballanced, the factory pulley could have been slightly irregular and that would have been accounted for by the ballancing process. in this case, once again, adding a new pulley could theoretically throw the whole thing out of whack.(although I find it more likely that in the case of a simple pulley the motor would have been ballanced without the pulley, which could easily be manufactured to fairly close tolerances of symmetry)
At any rate, I would feel pretty comfortable putting an underdrive on any car which is internally ballanced, does not require a damper and does not regularly ascend to more than 6500 RPMs. It should free up some horsepower at high rpms that would otherwise be wasted spinning your accessories faster than they need to go anyway.
That said, I must conceed that the whole underdrive idea is not as trouble free as I originally thought- and in many cases only affordable to do it right if you are having the motor disassembled and ballanced anyway (which you should do if you swap or modify the crank, pistons or connecting rods.
(of course it just occured to me that on chevy and pontiac the pulley is separate from the ballancer and should be a hassle free change)
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it all makes sense now.
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