3SX or other non-OEM Custom Crank Pulley vibrations vs STOCK CRANK PULLEY smooth ???

[BaadVR4]

I didn't say you edited your posts. I said "You have revised your statements regarding what you knew/advocated when." Here's how I came to that conclusion:

In post 157, you state:

"I never suggested the OP to run a solid pulley. I never advocated for or against, I simply stated that on my engine I decided to run the solid pulley."

In post 161:

After "indisputable evidence" was presented to me I did not advocate for anyone else to run the solid pulley. Not that the majority of it was new information to me, but that this thread is months & months old.


Very different. Which is it?


My original post 162 was a four page lay out of who said what when in this thread, meant to support my position regarding your posts. When Coopkill thanked me for all the info and IPD posted "TLDR", I reconsidered my post and deleted the vast majority. I am going to re-post the original because Coopkill has asked.

This is not, nor ever will be about "winning".

I did not edit a single one of my posts.

You win Milt, you win.

[BaadVR4]

Post 157

"I never suggested the OP to run a solid pulley. I never advocated for or against, I simply stated that on my engine I decided to run the solid pulley."

Post 161

"After "indisputable evidence" was presented to me I did not advocate for anyone else to run the solid pulley. Not that the majority of it was new information to me, but that this thread is months & months old."

Very different. Which is it?

Both posts I took exception to came after the four I cited.

Post 20:

i think an n/a will be fine but please be aware that harmonics are what we are talking about and although the power level is a factor, its constant unquelled harmonics that cause hairline fractures in time and also can get bolts to drop out of torque in time. Harmonics build on each other if you hit that rpm where they are a factor and if you keep the motor there, damage is occurring whether you want to believe it or not. I work in the construction industry and i have not seen a single generator NOT have a damper installed and they only hit about 2200 rpms. In fact, they all have them even though they could get some improvement in fuel consumption by leaving it a light metal ring and save money both factors are huge for the industry.

Post 33:

Quote Originally Posted by ProwlerGT View Post
On a flip note - I can't believe Mitsu (or any car maker) would just literally "glue" (or mold) rubber right onto a metal ring with no other metal fasteners of any kind, given all the power transferring from that pulley? I mean with all that power transferring to the pulleys, it would seem like you'd have a solid or again a rubber molded setup with metal fasteners.... but I'm no machinist or fabricator of metals so I wouldn't know how hard that is to balance or make to begin with.

torsional dampers work by having the hub and ring twist against each other with a softer material in them. you bolt the inner and outer together, then you lose the ability for the hub and ring to twist.


Quote Originally Posted by J. Fast View Post
Some might argue harmonics... mehh. It's balanced and I don't use cheap oil that breaks down and adds weight to rotating parts and throws them out of balance.

balance - whether it's internal or external - is centrifugal forces (X and Y if you look at the front of the crank). a torsional damper resists crank twist (Z rotation). they're two different things.

And for the record, bearings are very poor dampers for crank twist. They add friction across all frequencies, so you don't reduce the peaks - you just reduce the mean torque output. To prove it to you, I'll set up a simulation tomorrow for a v6 engine, and compare the torsional response for two oils: 0w20 and SAE 50. The difference may surprise you.

Post 79:

there is a thread where this has been discussed in dept
Destroying the dogma: lightweight crankpulleys


Quote Originally Posted by GTREVO
Originally Posted by GTREVO View Post
I have been an early user of underdrive pulleys for many years now but only learnt about the detrimental effects of harmonics in the 4G63 engine not too long ago.

Try replacing bearings every single race like I do and you will know that the problem lies more than just tolerances and balancing. Have been building 2.0 on the DSM's for years now and the inherent bearing problems but thank god I nitrided my cranks ( thus am able to save cranks even with worn out mains) and 2.3 strokers in my Evo 6 which kills absolutely every single mains running only 6 to 7 passes on a single event. And both makes over 700WHP. Both have not run harmonic balancers and without balance shafts. And yes, the engine DOES make a little more vibration without the balance shafts. Funny thing is that while the main bearings are worn out badly, the conrod bearings remain perfect, almost untouched....

Have recently completed a race on the stroker and will remove the main bearings shortly to compare previously on which I have ran no dampener and this time with the dampener. This will at least confirm some how on the effects of the dampener.

Am only relating my experiences with the harmonics that are killing the engine and I don't think Mitsubishi would be putting one on if it didn't need one...

If I recall in one of many early forums some long time ago, even Bushur runs the stock dampener and doesn't use pulleys....
Read more at Lightweight crank pulleys? - evolutionm.net

Quote Originally Posted by GTREVO
Originally Posted by GTREVO View Post
Sorry for my late reply on my findings with my motor. Took it apart yesterday and the results are indeed very interesting. After running at over 8000 rpms on this stroker 2.3 motor and at 35 psi making 750 WHP/656 ft/ib WTQ, the bearings were in good reasonable condition and take note, this motor was run WITH a brand new stock Mitsubishi harmonic damper, crank pulley. I swear what I saw was surprising on what I revved the motor to ( 8500 rpm at times on the track). To add to the topic of balance shafts, this motor was built without balance shafts at all. The motor has seen done 40 dyno pulls and 10 full on passes down the track at the drags..

On my earlier post, I mentioned that the mains were worn right down to metal at a lower power level ( 670 WHP) and at less rpms at the track. This was on a brand new rebuilt motor with only 7 passes down the track and about 30 dyno pulls.

The above findings I found was on the same motor except that I replaced a set of brand new Clevites on it and the new Mitsubishi crank pulley and I was all ready to replace it again yesterday but hey there you go guys.... there is no dispute that the damper is there for a reason and for a very good reason in fact.... no more aluminium pulleys for me...
Read more at Lightweight crank pulleys? - evolutionm.net
Quote Originally Posted by GTREVO
Originally Posted by GTREVO View Post
The engine was pulled apart and I can say that my mixture was perfect since there was ZERO detonation and the pistons and combustion chamber was in perfect condition. I was running the 37R with this and there was no tune difference except that it was maybe .2 of an A/F leaner with the C16.

It's all in the crank damper. I have been using the aluminium underdrive pulleys for the last 10 years and I never had an engine failure with it but it now explains why I have less life span in my motors especially big power and boost is concerned.

It was Carmela from Jackson's that warned me against using a pulley. I took her word and there we go...the difference is obvious especially in a 2.3 stroker.
Read more at Lightweight crank pulleys? - evolutionm.net
Quote Originally Posted by GTREVO
Originally Posted by GTREVO View Post
Apparently the aftermarket dampers work at all rpms whereas the factory piece is more ' tuned ' at a higher rpm. This is what I was told and I have recently purchased a Fluidamper for my Evo and it is an awesome looking piece, bit heavy though but what the heck, it saves my motor...

There you go guys, guess most of us found out the hard way...even myself..
Read more at Lightweight crank pulleys? - evolutionm.net
Quote Originally Posted by GTREVO
Originally Posted by GTREVO View Post
Well, after building and playing around with DSM and Evo motor for years now, hate to say this but...I am still learning something new everyday...

Hope my findings will help lots more people out there by keeping their harmonic balancers instead of pulleys...
Read more at Lightweight crank pulleys? - evolutionm.net

Post 115:

I hope the people in this thread that justify using a solid crank pulley by saying... "the engines are balanced from the factory" take or read an engine vibrations book. The crank pulley is there to damp TORSIONAL vibrations in the crankshaft... IE the twisting back and forth caused by compression and combustion events. You tune the rubber thickness and material so that you can damp the natural torsional vibration frequency. In most 6 cylinder crankshafts its in the 1800-2500 RPM range. The exact range that most of our engines spend their time operating in... UH OH. But remember... any deviation from the natural torsional frequency is good... less amplitude... less stress. Only bad part is... none of us actually know the exact RPM location of the natural torsional frequency. A permanent marker and a strobe light and a good shaker rig would tell us. The vibrations at high RPM are of little to no consequence. If anyone has seen a frequency response curve of any dynamic system, they will know what I'm talking about.

I'll see if I can call in a favor in my spare time and have one of our crank dampers tested to see the rpm that they are calibrated for.

PS... I know these tid bits of knowledge because... I used to work in an engineering office that designed crankshaft dampers. Rubber and Viscous dampers.

Forged crankshafts of today are not as sensitive to the cast iron cranks of the past. However, I bet if you shot a crank with a Cobalt 60 source to do an "X ray" of the crankshaft then you would see some micro cracking on cranks that don't use the stock damper.


Just some food for thought fellas! The world of Vibrations is a bitch and a half sometimes.

Post 124:

I'll swap back to OEM after I shatter a crank.

Post 134:

What happens when we run out of old OEM pulleys? I assume you're all going to be in line for the $1k aftermarket pulley?

Post 124 came after you had the benefit of the info in posts 20,33,79 and 115. Post 134 came after my post 126 and i3igpete's post 127. Neither post was attacking in anyway. Yours were.

I did address your highlighted areas of my post in post 159.

Coopkill is right. Time to give it a rest. You have declined my invitations to point out where I've been incorrect. You have revised your statements regarding what you knew/advocated when. At the end of the day I'm disappointed we were unable to address my concerns.