unorthodox crank pulley
- Thread starter Pickledoe
- Start date
be careful with pulleys, they make the alternator work harder, and can limit the life of the A/C and power steering pump. Despite what the website says, pulleys are in general not the best way to performance gains. Numberwise, Expect 1-3hp gain from the underdrive main pulley, and 1-2 from the a/c water pulleys. All together a total of about 3hp.Pickledoe said:
K
Keith@FP
A word of warning - if you are planning on turbocharging your Proteg, stay away from underdrive crank pulleys. They replace the harmonic balancer on the crank with an undamped chunk of aluminum. On a turbo Miata, that means oil pump failure in 2000 miles. Normally aspirated Miatas survive fine, but the lack of a balancer is not a good thing.
I suspect much of the change in feel from an underdrive pulley comes from the lighter weight. It's like pulling weight off the flywheel.
Keith
I suspect much of the change in feel from an underdrive pulley comes from the lighter weight. It's like pulling weight off the flywheel.
Keith
7
70
Go here for dyno's and pics of the FM Protege 5:
http://www.flyinmiata.com/protege/
http://www.flyinmiata.com/protege/
Da Yellow Mp3 Man
Member
Sorry, This is probably a dumb question but, A crank pulley is the main underdrive pulley? or are these two different things??
K
Keith@FP
To underdrive your accesories, you either need a different pulley at the crank or different pulleys on the accessories. If you replace the crank one, that's when you have problems. Replacing the ones on the accessories will not be fatal to your motor, but may have an effect on the accessories themselves.
Keith
Keith
K
Keith@FP
Safe for the engine, but probably not a terribly big change in output.
Keith
Keith
our engines are internally balanced, ie no harmonic balancer.
and i've not heard of pulleys signifigantly shortening the length of your a/c or alternator. only a slight dip in electrical power at idle.
they'll also help your car rev up faster due to the reduction in rotating mass.
and i've not heard of pulleys signifigantly shortening the length of your a/c or alternator. only a slight dip in electrical power at idle.
they'll also help your car rev up faster due to the reduction in rotating mass.
herarety said:
I don't know WHERE this idea keeps coming from, but almost ALL engines are internally balanced. They also ALL have harmonic DAMPERS of some sort. THEY HAVE NOTHING TO DO WITH BALANCING AN INTERNALLY BALANCED ENGINE. They damp out the harmonics of a flexing crank (which all cranks do) to keep internal components from coming apart at their inherent critical harmonic frequency points. If you remove a damper and subsititute a plain chunk of aluminum, your engine WILL eventually break a crank or a part connected to it. It's a very simple device that must be on the engine. If you drag race and tear down your engine and throw away cranks every weekend, then you don't need one.
As for the accessory pulleys, they just make your accessories run slower. You might have a charging problem at idle or power steering that surges but no short term damage. You might go through alternators a little more frequently, but no big deal. You just aren't going to gain a lot from them though. You want a power gain? Turn off your A/C. The other accessories don't pull much power. You are talking very small gains here for enough money that it just isn't worth it.
Keith at Flying Miata tunes cars for a living. He knows what he's talking about. I've worked on cars since I was 14 and am currently working at a BMW dealership. I also try to keep up on as much stuff as I can in regards to performance mods. I've also had 2 1/2 years or training in automotive so I know what makes an engine work as do many others that say the same thing. If you want to break cranks, keep putting a light block of aluminum on the end.
You're partially right about no harmonic balancer. Our cams and underdrive are all internally (in the motor, not on the pulley) balanced, at least on the p5. However there is still (as Traveler says) some sort of harmonic dampening. We've got a part that is rotating at up to 7000rpm. Any fluctuation in that rotation (which all cars have to some degree, no machining is flawless) causes these harmonics that "vibrate" your motor to death. The dampener is a two-way shield. Remove the dampener, and all these vibrations (both from the cams and from the pulleys) are transferred from the motor to the pulley / aux system and vice versa (depending on the harmonic source). Until we invent indestructible materials that can also be flawlessly machined, there will be some need for a harmonic dampener.herarety said:
True, as technology advances and our parts become more finely machined (which no doubt our Japanese mazdas are) the life of parts without a harmonic dampener increases. However, there is still wear on the parts without a dampener. We could no doubt make it much farther than the 2k for the turbo miata with replacement pulleys, but overall engine life would be shortened.
And yes, auxiliary life IS shortened with smaller pulleys. What does a slight dip in power do (from the smaller pulleys). Your engine electronics (and for that matter all electronics in the car) are just one giant circuit. what happens if you're constantly changing functional amperage and wattage due to a not-fully functional alternator? What would happen if you did the same thing to the PC you're typing on right now? Or a pacemaker? Why do we have transformers, dampers, and meters on our power? Oldsmobile faced constant electrical problems (and I know, I've owned three) because of alternators that did not deliver sufficient power at dead idle (the same "dimming" effect that you speak of with the replacement pulleys). Shorts are (were) as common as hell as a result.
The alternator is designed to provide ample power to all systems. True, there is some leeway (e.g they are "overengineered" a bit), but not much. Ask anyone who has added a high-output stereo. Do we really think that unorthodox or other pulley companies test on every model car they provide a pulley for to test alternator limits?
There will be some measurable power gain with these pulleys (by measurable I mean only that there is some change). But is it worth the life of your car for a miniscule power advantage?
Just my .02, I dont know anywhere near everything. If I am proven wrong, and someone puts these pulleys on their p5 and goes for 100k miles, I will be the first to apologize, honestly.
Let's keep the discussion going! And listen to Traveler, he knows what he's talking about, and has even corrected me once or twice.
Have a good day, everyone!!!!!!
Brook
hehe, I love the pulley discussion.
Just to add another point that hasn't been brought up. The harmonic dampeners are made of rubber. Over time this rubber is going to dry up and crack. It's a pretty common occurrance on the older DSM's. When it cracks the pulley will seperate and has a tendency to throw the pulley and accessory belts into the timing belt. Which in turn kills the engine when the pistons smack the valves. I think it's kind of ironic that a part who's sole purpose is to protect the engine from failure, can in-fact cause significant engine damage itself.
I've never seen a REAL Documented case of an underdrive pulley killing an engine. A lot of speculation and theoretically this speculation IS correct. But, point me to one direct case of this happening?
Even though it seems like I support underdrive crank pullies I don't have one on either of my cars. I'm undecided on the issue and I do not have any information to be willing to take the chance of using them.
Just to add another point that hasn't been brought up. The harmonic dampeners are made of rubber. Over time this rubber is going to dry up and crack. It's a pretty common occurrance on the older DSM's. When it cracks the pulley will seperate and has a tendency to throw the pulley and accessory belts into the timing belt. Which in turn kills the engine when the pistons smack the valves. I think it's kind of ironic that a part who's sole purpose is to protect the engine from failure, can in-fact cause significant engine damage itself.
I've never seen a REAL Documented case of an underdrive pulley killing an engine. A lot of speculation and theoretically this speculation IS correct. But, point me to one direct case of this happening?
Even though it seems like I support underdrive crank pullies I don't have one on either of my cars. I'm undecided on the issue and I do not have any information to be willing to take the chance of using them.
Good point! But a more uncommon occurence in modern cars. And the harmonic damper is often not just "rubber," but a long life polymer or petroleum compound. But again, that's a good point.jmauld said:
I can point to hundreds, especially with F/I cars. In addition to the Miatas mentioned earlier, I've seen a chrysler, a Monte Carlo SS, a 350 small block (in a ford pinto, that was funny), a chevy celebrity, several chevy 3800 engines (otherwiser GREAT motors, one of my favs), and about 10 million civic Si's (RICERS!) lose it due to lack of harmonic damping either from changing pulleys, replacing them with another pulley (which even had it's OWN DAMPENER), or from a bad dampener (which you alluded to in the first quote). A lot of chevy tuners who work with their big and small blocks like to change out for smaller pulleys from smaller chevy engines. Those still have a dampener, just not the one designed for the motor.jmauld said:
It's not some instant spectacular thing when you remove the dampener, but it does shorten engine life, especially with F/I or all-motor tuned cars. The folks that I know who do it with their all-motors (the "Edelbrock-Heddman" crowd, as I like to call them) do so knowing that they are shortening the life of their motor, and do so just to have fun and be rednecks (but good guys).
But again, I can only speak my experience and preference.
blynzoo said:
I'm not saying you're wrong in the pullies being the failure cause, BUT I don't seen any documentation or evidence to back these claims up? Remember, it's MUCH easier to blame a part for a failure, then to take responsibility for something that was done wrong or for improper maintenance.
Forget the honda crap. I can count on one hand the number of "honda" owners, that I know, who actually take proper care of their car. In fact I know of one honda owner that put 90K miles on the car before doing the 2nd oil change. I feel sorry for the guy who bought the car from him
K
Keith@FP
If you go into the archives of the Miatapower mailing list (www.miatapower.net), you will find a very clear correlation between installation of an Unorthodox pulley and oil pump failure on a turbo Miata. There have been at least three instances. Healthy engine. Install an Unorthodox Racing pulley. 2000 miles later, oil pump failure. By the way, Miata oil pumps don't fail otherwise. Ever.
It's not speculation, I've worked on the cars with the new engines. These engines often had balanced cranks and were built to the same quality levels (or higher) than a Protege engine.
Keep in mind that normally aspirated Miatas do not have the same difficulty. I don't anticipate that Proteges would have the same problem, but I would NOT turbocharge a Protege with an underdrive pulley.
Here's an excellent writeup from Dinan: http://www.toyotacelicaonline.com/pulleys.htm
Lotus uses a solid pulley on their race engines, a balancer on their street engines. I've seen a Motorsports Elise have the balancer come apart and destroy the engine. However, 13 years of Miata motors have shown us that the harmonic balancers do eventually fail, but this shows up by a bit of slippage between the two halves. It messes up your timing marks, that's about it. I have not heard of a single Miata motor having the pulley come apart.
Here's another way to look at it - if it was so easy, why didn't Mazda do it in the first place?
Go ahead and put an underdrive pulley on your car if you want. There are solid engineering reasons not to and the gains are minimal. You have been warned.
Keith
It's not speculation, I've worked on the cars with the new engines. These engines often had balanced cranks and were built to the same quality levels (or higher) than a Protege engine.
Keep in mind that normally aspirated Miatas do not have the same difficulty. I don't anticipate that Proteges would have the same problem, but I would NOT turbocharge a Protege with an underdrive pulley.
Here's an excellent writeup from Dinan: http://www.toyotacelicaonline.com/pulleys.htm
Lotus uses a solid pulley on their race engines, a balancer on their street engines. I've seen a Motorsports Elise have the balancer come apart and destroy the engine. However, 13 years of Miata motors have shown us that the harmonic balancers do eventually fail, but this shows up by a bit of slippage between the two halves. It messes up your timing marks, that's about it. I have not heard of a single Miata motor having the pulley come apart.
Here's another way to look at it - if it was so easy, why didn't Mazda do it in the first place?
Go ahead and put an underdrive pulley on your car if you want. There are solid engineering reasons not to and the gains are minimal. You have been warned.
Keith
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Okay, You have an otherwise stock miata, with a underdrive pulley, and it runs with no problems and may run for it's normal lifetime. (I did say "may" 
) Now you turbocharge this miata and 2000 miles later the oil pump fails. Why is the pulley the problem and not the turbocharger installation? Why are there no problems with either mod seperately? It sounds to me like maybe the oil pump is poorly designed and could also be identified for the cause of the failures.
While your information is definitely a reason to NOT put an underdrive pulley on a turbo miata, (and maybe protege's since they're related) it should be noted this doesn't necessarily mean that pulleys are bad for other makes/models. I know you didn't say that, but we all know other people will infer it.
Also, I know you were just giving a word of caution that the potential is there, specifically with these cars. And I agree with you. I would not turbocharge a protege and install an underdrive pulley. It's just not worth the risk. In fact I will probably never install an underdrive pulley regardless of induction. Unless (as someone else said) it was on a throw away engine.
I think I just like arguing.
) Now you turbocharge this miata and 2000 miles later the oil pump fails. Why is the pulley the problem and not the turbocharger installation? Why are there no problems with either mod seperately? It sounds to me like maybe the oil pump is poorly designed and could also be identified for the cause of the failures. While your information is definitely a reason to NOT put an underdrive pulley on a turbo miata, (and maybe protege's since they're related) it should be noted this doesn't necessarily mean that pulleys are bad for other makes/models. I know you didn't say that, but we all know other people will infer it.
Also, I know you were just giving a word of caution that the potential is there, specifically with these cars. And I agree with you. I would not turbocharge a protege and install an underdrive pulley. It's just not worth the risk. In fact I will probably never install an underdrive pulley regardless of induction. Unless (as someone else said) it was on a throw away engine.
I think I just like arguing.
If you want more proof, go to the chevy tuner sites, the sister sites to our own protege5.com and mp3.com. There are running threads from poor folks who put underdrive pulleys in their NEW chevys (not realizing that most "cuntry" boys stick 'em in old beaters). And dont just "dismiss" honda owners as the fault for failing hondas (although I TOTALLY agree that most ricers dont take care of their cars). Hondas are actually a perfect example of why not to do it, and why pulleys cause failure more on their cars. Honda Civics rev a lot higher than our Mazdas (which rev higher or at least redline higher than most Big3 cars). The higher revs exacerbate the problem, make for higher wear. Just trust me (and Keith, and Traveler, and so on), pulleys are NOT good for the car in the long run. True, they will do the least damage in an otherwise untuned car, but who the hell is dumb enough to make their only tune something that may or may NOT add torque, and void the warranty in the process? Pulleys are an old trick of the junk tuners who dont give a lick for the longevity of their cars, but rather want every mod available.jmauld said:Okay, You have an otherwise stock miata, with a underdrive pulley, and it runs with no problems and may run for it's normal lifetime. (I did say "may"
While your information is definitely a reason to NOT put an underdrive pulley on a turbo miata, (and maybe protege's since they're related) it should be noted this doesn't necessarily mean that pulleys are bad for other makes/models. I know you didn't say that, but we all know other people will infer it.
Also, I know you were just giving a word of caution that the potential is there, specifically with these cars. And I agree with you. I would not turbocharge a protege and install an underdrive pulley. It's just not worth the risk. In fact I will probably never install an underdrive pulley regardless of induction. Unless (as someone else said) it was on a throw away engine.
I think I just like arguing.
And as for the Miata thing, look at the numbers of Turbo Miatas without pulleys who fail (which, admittedly, is quite a few, we drive 'em hard) versus those with pulleys that fail. While not a stunning number, there is a statistically significant difference when the only factor is the pulley.
If you want the same gains, just cut the A/C out of the belt (re-belt without the A/C in there). Hell, if you're doing a short run and dont need to recharge, cut the alternator out, too, rebelt with just the main pulley and pumps. (Another chevy tuner trick)
I'm pulling out of this discussion after this post, it's getting to "flamewarish."
K
Keith@FP
jmauld said:Okay, You have an otherwise stock miata, with a underdrive pulley, and it runs with no problems and may run for it's normal lifetime. (I did say "may"
Read the link I posted. The harmonic balancer is not there for rotational stresses, but to counter stresses that come from the actual combustion process. If that combustion is a whole lot stronger, those stresses are higher.
Here's the rundown.
- there are hundreds or thousands of turbo Miatas out there.
- Miatas with turbo kits on them and stock pulleys don't have oil pump failures. Ever.
- Normally aspirated Miatas with underdrive pulleys do seem to last.
- Miatas with turbo kits and underdrive pulleys have oil pump failures within 2000 miles.
So, is the problem the turbo kit? No. The problem is the combination of the underdrive pulley and the turbo kit. It's possible to claim that the problem is a badly designed oil pump, but they do work very well when they're operating as designed. Since the turbo kit will double your horsepower and the underdrive pulley might give 5, it's pretty easy to choose
Keith
