Lightweight Crank Pulley Check-In

[DashLaflash]

Did anyone check out the link I posted? I'm curious to hear what you guys think about the bearing wear. Its a 6 bolt that went 50k miles using an Unorthodox crank pulley and then snapped a timing belt at 98k.

 

[ramsack]

If you would have taken the time to insert the URL in the post instead of just pasting it, it may have worked and more people would have paid attention to it.

 

[Calan]

This is one of those debates that really doesn't have a good answer. They may work great for some people, or may cause problems for others. Looking at it from a design and engineering approach, everything points to the need for a dampener, so I personally would rather be conservative rather than take chances. (I can't afford to be tearing apart and rebuilding motors every 10k miles).

With that said, I believe CB has run the UP's on his DSM's for years with no issues. But then again, that's CB and his results don't apply to us mortals.

 

[DashLaflash]

If you would have taken the time to insert the URL in the post instead of just pasting it, it may have worked and more people would have paid attention to it.

Dude no need to get snippy. I tried linking it but it has the letters U and R next to each other in the title. It stands for Unorthodox racing but Dsmtuners sees it as the text version of the word your and edits it out as improper grammer. Something like this? http://www.dsmtuners.com/forums/bolt-tech/145566-main-bearings-after-50k-##-underdrive-crank-pulley.html

If you can get it to work please link it but I stated in my post you just have to replace the ## with "u" and "r" to work.

Also Calan Isn't that why everyone upgrades to the 16g for their first turbo upgrade, because many people have had great success with them. I guess you could say the same thing about Holset turbos. Some people have bad experiences with them and go through several. So does that mean they are all bad. I don't know about you guys but a lot of the people on here follow an upgrade path that has worked well for many others. Does that mean its the best path to take not neccessarily.

Anyone feel free to check out the link I posted and point out any abnormal bearing wear that you see and would have been caused by an undampened pulley.

 

[pneumo]

Dude no need to get snippy. I tried linking it but it has the letters U and R next to each other in the title. It stands for Unorthodox racing but Dsmtuners sees it as the text version of the word your and edits it out as improper grammer. Something like this? http://www.dsmtuners.com/forums/bolt-tech/145566-main-bearings-after-50k-##-underdrive-crank-pulley.html

If you can get it to work please link it but I stated in my post you just have to replace the ## with "u" and "r" to work.

Also Calan Isn't that why everyone upgrades to the 16g for their first turbo upgrade, because many people have had great success with them. I guess you could say the same thing about Holset turbos. Some people have bad experiences with them and go through several. So does that mean they are all bad. I don't know about you guys but a lot of the people on here follow an upgrade path that has worked well for many others. Does that mean its the best path to take not neccessarily.

Anyone feel free to check out the link I posted and point out any abnormal bearing wear that you see and would have been caused by an undampened pulley.

Thanks for the link, and yes the letters 'U' and 'R' need to be added to the link.
I don't see any abnormal wear from the underdrive solid crank pulley. The pics show some wear on the bearing next to the flywheel which I've seen on many cars.

 

[DashLaflash]

Ya as far as scientific proof goes it doesn't get much better than that. Of course the results have to be replicated more than once to be valid though. Import Tuner Magazine recently (September 2010 issue) did a dyno test on an NST lightweight crank pulley on a nissan cube 1.8l. It made a whopping 3.5hp and 4.7lb-ft of torque over the stock pulley. Not that great but it did increase mid-range and top-end power and torque was surprisingly increased.

 

[ramsack]

Scientific would be to get a VERY large amount of engines and run some with dampers and some without. Hmm...isn't this called R&D (what mitsubishi did before they even released the engines to the public?)

 

[Ludachris]

See I'm still not totally sold that these pullies cause catastrophic failure. I already bought an autozone crank pulley half a year ago without really researching about them it was just cheap. So if that one goes bad prematurely which it is likely to I might consider one of these. I know the gains are minimal but still. It just seems like internet myth to me that I would really like to clear up.

We still don't have people checking in and saying how many miles they have gone with these pullies. Maybe DSMers really do stay away from these .

So if you find that 5-10 people reply saying nothing happened, will that help you make your decision? The company that built my engine (JAM) strongly suggested I use a harmonic dampener over a solid pulley. They also suggested leaving the balance shafts in. Their belief is that these two solutions help prolong the life of the motors.

I think the question that you should be asking is "how many people who have installed a solid pulley now have over 100k miles on their motors?". Forget about the replies that say they now have thousands of miles with no problems - how about over 100k miles? I expect my rebuild to last at least 100k miles. Chances are, the motor with the pulley won't fail right away, but will it live as long as a motor with the dampener? I didn't care to take a chance on a new motor and went with the dampener. The small gains from a pulley weren't worth it to me if there were even a slight chance it would result in a shortened life span of the motor.

 

[pneumo]

I run a solid underdrive pulley on my daily driver, a 1990 Laser FWD turbo. This was a personal choice! I did it because swapping out bottom end bearings is no big deal to me. I'm a seasoned mechanic and replacing rod and main bearings is a lazy afternoon's worth of work. No big deal, the bearings are accessible by dropping the oil pan. I checked the bearings when they had 80k miles on them (245k on the motor total) and they were still in great shape. Of course I kept up the oil changes the whole time, and I keep everything clean when I replace bearings. Ironically, I chose to use a solid lightweight pulley because I take care of my car.

The performance benefit was nice, especially since I got the pulley for $20.

 

[98spyderboost]

An undampened crank will have more deflection due to torsional harmonics, which directly leads to increased wear on the main bearings. The effect can be more or less pronounced depending on engine geometry and power levels.

Enough cylinder pressure will break any crank if it's the weakest link; an undampened crank is just more susceptible due to the increased harmonic vibration.

I've seen cars run the same timing belt for over 200,000 miles. So is it safe to say that they only need to be changed at 200,000 miles because 1 or 10 made it that far? Or do you use some engineering and a bit of theoretical MTBF (mean time between failure) data, and recommend changing them at 60,000 miles?

Engineers spend lots and lots of hours with their heads in books for a reason. It's up to you if you want to tempt the laws of physics, or trust what the math tells us.

DING!!!!

I almost lost hope in this thread. Thanks for spittin' out some actually reasonable logic Calan!

 

[Calan]

Also Calan Isn't that why everyone upgrades to the 16g for their first turbo upgrade, because many people have had great success with them. I guess you could say the same thing about Holset turbos. Some people have bad experiences with them and go through several.

Comparing a turbo upgrade to whether a 4g63 crankshaft needs dampening is apples to oranges. The difference is that there is no engineering data saying that those turbos shouldn't work. In fact, with the right supporting mods they should work just fine and normally do. But all the engineering and factory testing says that the 4g63 crank needs to be dampened to prolong bearing life...period.

I hear what you're saying Josh, but like Chris said...it's a personal decision that has to be made based on if the small gains are worth the risk. I think you'll find that most of the people running an undampened crank "with no problems" are very good with DSMs and/or tear their motors down quite often for inspection or rebuild (like CB and pneumo for example). If you fall into that category, you may be just fine running one.

Personally I don't want to take the chance for 2-3 hp, as dropping the pan to inspect the bearings is more than a lazy afternoon for me.

 

[Ludachris]

Nice comparison of the timing belt, Craig. I think that was one of the best analogies anyone could have made in this discussion. Just because you find 10-20 people who have run the original timing belt beyond 150k miles, is that something you think you should try?

 

[turbo addict]

again, If you are going to rev your motor higher than factory and run more boost than stock you are going to shorten the life of the motor. I am running a aluminum pulley, and on my other car (race car) have a fluidampr. But I have seen too many stock pulleys take out the timing belt or other things when they let loose.

Even ludachris said that the machine shop told him to leave the balance shafts in, and how many of us do that? it follows the same principal, they are both to keep vibrations under control, If you are dismissing the balance shafts and arguing for a stock pulley you are contradicting yourself. that is like saying that it to ok to rob a bank but not a gas station. they both work toward the same job.

again I dont care either way just like to argue

 

[ramsack]

Comparing the balance shafts to the stock crank pulley is also like apple and oranges. As I stated before the actual patent name Mitsubishi applied to the balance shafts is "SILENT shaft." Purely a luxury device.

 

[Calan]

Even ludachris said that the machine shop told him to leave the balance shafts in, and how many of us do that? it follows the same principal, they are both to keep vibrations under control, If you are dismissing the balance shafts and arguing for a stock pulley you are contradicting yourself. that is like saying that it to ok to rob a bank but not a gas station. they both work toward the same job.

Different types of vibrations and different end results. Keeping the balance shafts will cut down on the vibrations felt through the motor mounts and driver's butt. Removing them "shouldn't" affect motor longevity to any great degree, but may cause other long term failures due to components in the engine bay or interior vibrating a bit more...but that's reaching IMHO.

You could argue that removing the BS actually reduces rotating mass and removes the very real possibility of the BS belt snapping and taking out the t-belt. So there are benefits to removing them that probably outweigh the negatives...but that is for another thread.

In any case, that's completely different than torsional stress causing a crankshaft to jump-rope up and down against main bearings. Again, it's apples to oranges.

EDIT: Too slow... ramsack beat me to it.

 

[turbo addict]

I know that they are called silent shafts, but most people call them balance shafts, either way they are not just for the feel, the shafts cancel out some of the vibrations with in the motor, just as the factory pulley absorbs them. either way it is the same, the pulley doesn't make the crank more balanced just attenuates the vibrations.

and removing the stock pulley saves the front timing cover and could even save the timing belt, just as the silent shafts, and it reduces the weight of the rotating mass and under drives the accessories which when reving higher saves load on the crank.

 

[Calan]

...the shafts cancel out some of the vibrations with in the motor, just as the factory pulley absorbs them. either way it is the same, the pulley doesn't make the crank more balanced just attenuates the vibrations.

No... it's NOT the same.

The crank dampener counteracts the crank's movement and twist in relation to a fixed set of bearings. Jumping crank smacks immovable bearings...bearings (and crank) no likey that after a while. The balance shafts counteract the engine moving as a whole against the flexible motor mounts, as the dynamic loads within the engine are transferred from side-to-side (err... front-to-back).

This discussion is starting to become a bit pointless now.

 

[turbo addict]

No... it's NOT the same.

This discussion is starting to become a bit pointless now.

the shafts dont just make the car feel like there is less vibration it cancels out some of them out, and they are not able to cause all of the vibration bearing problems. it IS the same just done in a different way.

the 1.6 4g61 is a more balanced motor and didnt come with the silent shafts, because it didn't need them, but the longer stroke and rod to stroke of the 4g63 did need wave cancelling harmonics of the silent shafts.

You guys are saying that you cant feel the vibrations but they are still there with the shafts, how does that make sence?? you cant feel them because theyare not there or not as stronge as they are with the shafts gone.

 

[ramsack]

OH MY GOD. They are used to not shake the car! That is their only function! The 4g61 doesn't need them because that engine's reciprocating mass is so minute compared to a 4g63 that Mitsubishi felt it was quiet enough. Also for a Dodge Colt or some other little grocery go-kart that is cheap, they didn't care about comfort. Those cars are tin cans and loud as shit on the highway because there is no insulation for sound. The vibrations that Silent Shafts cancel out are transferred right to the motor mount. There are no mechanical stressed induced on components from not having them! I guarantee you there are more people who removed balance shafts and have engines last as long as "stock" than there are people who got a solid pulley and had their engine last. A dampened pulley absorbs vibrations along the long axis running down the crank...torsion. The Silent Shafts work to lessen engine movement in more than 1 axis, and they are non-rotational axes.

 

[DashLaflash]

Comparing a turbo upgrade to whether a 4g63 crankshaft needs dampening is apples to oranges. The difference is that there is no engineering data saying that those turbos shouldn't work. In fact, with the right supporting mods they should work just fine and normally do. But all the engineering and factory testing says that the 4g63 crank needs to be dampened to prolong bearing life...period.

I hear what you're saying Josh, but like Chris said...it's a personal decision that has to be made based on if the small gains are worth the risk. I think you'll find that most of the people running an undampened crank "with no problems" are very good with DSMs and/or tear their motors down quite often for inspection or rebuild (like CB and pneumo for example). If you fall into that category, you may be just fine running one.

Personally I don't want to take the chance for 2-3 hp, as dropping the pan to inspect the bearings is more than a lazy afternoon for me.

Ya Craig I know you can't really compare the two and I appreciate your input. I was just saying that if I went on DSMtuners and read that everyone was now using undampened pulleys and having great success with them for many many miles I would go out and get one. Isn't that what this site is for so people can see what set ups to run on a dsm and also how to fix them . I know that's kinda the bandwagon mentallity but look at how many people are now running holsets. Its the new popular thing and for good reason. I definatley don't fall into the category of Curt Brown or pneumo but I do have a fresh engine and change my oil regularly on my cars.

My question to Turbo Addict is why do you run a dampened pulley in your racecar? You seem to be a strong supporter of the undampened pulley.

 

[turbo addict]

you cannot guarantee it because no one on here has had or can come up with 1 person that lost a motor to a pulley!! I have had a solid pulley on my car forever and have not had any problems, so have a few of my friends, I have had 2 or 3 friends that lost a timing belt and bent valves because it broke the timing belt. I would have to check for sure but my motor had 120,000 ish miles on it when I got it and I now have in the 175,000 range, all with a solid pulley.

For me that i all I need to know. I have never had any flakes in my oil or any other sign of problems. I also run an aluminum flywheel so my car is screwed, I guess my motor didnt get the memo that it was suppose to blow up. so please no one say anything to my car that it is over due to pop!!

;-)

 

[dsm-onster]

The balance shaft does NOT prevent the crank, a separate component, from vibrating. It only cancels that vibration as it transfers to the block, the conjoining component between the two. Hense, why we feel no vibration when they are there. Nothing changes a crank from exerting pressure on its surroundings except the crank itself. The silence shafts exert an additional force on the block to counter the force exerted by the crank. . . They are called silence shafts by the folks who designed them for their purpose. What most people call things is irrelevent.

 

[ramsack]

The race-car-only mentality is usually to sacrifice reliability for minute gains. To me this would only make sense if I had a race car that I raced in racing events for winning money.

 

[Ludachris]

Ya Craig I know you can't really compare the two and I appreciate your input. I was just saying that if I went on DSMtuners and read that everyone was now using undampened pulleys and having great success with them for many many miles I would go out and get one. Isn't that what this site is for so people can see what set ups to run on a dsm and also how to fix them . I know that's kinda the bandwagon mentallity but look at how many people are now running holsets. Its the new popular thing and for good reason. I definatley don't fall into the category of Curt Brown or pneumo but I do have a fresh engine and change my oil regularly on my cars.

My question to Turbo Addict is why do you run a dampened pulley in your racecar? You seem to be a strong supporter of the undampened pulley.

Yes, that's what this site is for. It's also to have members give suggestions to help prevent others from making mistakes that could cost them a lot of money. Everyone here is simply trying to give as much info as they can so that the original poster can make a good decision.

The solid pulley has widely been said to limit the life of the bearings due to vibrations, and in turn the life of the motor. Again, it may not happen right away, or to everyone, but most engine builders in our market tend to steer people towards keeping a dampener for a reason. Some people don't care about that risk, or they take the risk and are okay with the idea of freshening the engine sooner than they might otherwise have to. If you're okay with that risk, no big deal. But understand that it is a real risk. As others have said, the solid pulley poses a higher risk than removing balance shafts.

 

[Ludachris]

you cannot guarantee it because no one on here has had or can come up with 1 person that lost a motor to a pulley!! I have had a solid pulley on my car forever and have not had any problems, so have a few of my friends, I have had 2 or 3 friends that lost a timing belt and bent valves because it broke the timing belt. I would have to check for sure but my motor had 120,000 ish miles on it when I got it and I now have in the 175,000 range, all with a solid pulley.

For me that i all I need to know. I have never had any flakes in my oil or any other sign of problems. I also run an aluminum flywheel so my car is screwed, I guess my motor didnt get the memo that it was suppose to blow up. so please no one say anything to my car that it is over due to pop!!

;-)

And as others keep saying, it's not a guarantee that every engine with a solid pulley will fail prematurely, but it is a real risk. Would you not agree with that? Are you saying it's not possible that the added vibrations from a solid pulley absolutely cannot cause added wear?