UR Pulley and Fidanza flywheel on SR

[om3ga]

I keep hearing people say that you shouldnt run lighter weight pulleys or flywheels on the sr? Why is this? Im going to be buying both things and installing them soon but now im afraid that something is going to get destroyed haha.

[slider2828]

Crank Pulley which is also called a harmonic dampner is perfectly balanced for the crank as well as has weight to help keep the engine rotating same with the flywheel. Remove these weights and the crank will have lack of centrifugal force and momentum to keep it spinning in rotation. Without this momentum, the crank will twist because the pistons and rods cause a little counter rotation because guess what, combustion happens before top dead center. I won't get into why before top dead center, but this causes a counter rotation on the crank and ends up twisting the crank.

[Gorilla Unit 33]

is this just on the SR? because of the dampner?

[om3ga]

So it is bad then? Its better to keep the stock crank pulley and flywheel? I need real proof i mean what your saying makes sense but it cant be that bad why would they sell this stuff? I mean i see if the flywheel or crank pulley is off balanced then yeah that would cause a problem but in this case they are high quality items id imagine them working fine without damaging anything.

[fliprayzin240sx]

Just the crank pulley, lighter flywheel wouldnt mess with the balance. If you're decided on a main pulley, this is the only one thats recommended out there. (http://www.phase2motortrend.com/atisudampusr.html)

[zenki.life]

lighter pullys dont hurt anything. supposedly my kade gets +12 hp will the full UR belt set

[HYPNOTIK]

I def recommend a lighter flywheel, you'll notice a huge difference in throttle response. I need to get off my lazy ass and put mine back in, I can't stand the stock heavy ass flywheel.

[2jzs14]

I def recommend a lighter flywheel, you'll notice a huge difference in throttle response. I need to get off my lazy ass and put mine back in, I can't stand the stock heavy ass flywheel.
I agree i noticed a huge difference when i put a lighter flywheel in my car. although it makes a hell of alot of rattling sound. but then again my car is stock as shit otherwise and i dont have any loud ass exhaust to cover it up

[slider2828]

One or the other, I wouldn't recommend both.... Lighter flywheels also makes it a little harder to drive as when clutching in on a hill, the rpm dips under normal 800 rpm usually because of rotating mass as well...

Most bs crank pulleys aren't balanced, hence suggesting the ATI dampner

[chris300zr]

i thought the SR20DET was internally balanced from the factory?

[om3ga]

i thought the SR20DET was internally balanced from the factory?

Me too but i do understand that if the pulley is a POS then it could definitely hurt something especially at high rpms. If the pulley is not balanced correctly then id imagine it damaging something but Unorthodox Racing has been around for awhile and they really only specialize in pulleys...

[Def]

It has nothing to do with balancing(the engine is internally balanced), but the stock crank pulley absorbs or "damps" vibrations. Hence why the ATI is actually a sophisticated damper, not just a solid piece of aluminum.

I don't think the import crowd will ever learn this.... well maybe the RB guys as they learned what harmonic vibrations do to an engine(eat oil pumps).

[chris300zr]

It has nothing to do with balancing(the engine is internally balanced), but the stock crank pulley absorbs or "damps" vibrations. Hence why the ATI is actually a sophisticated damper, not just a solid piece of aluminum.

I don't think the import crowd will ever learn this.... well maybe the RB guys as they learned what harmonic vibrations do to an engine(eat oil pumps).

do you have a link with more information on this? only one i found was this:
Dinan BMW - The Dangers of Power Pulleys and Understanding the Harmonic Damper (http://www.dinancars.com/bmw/technial-info/the-dangers-of-power-pulleys-and-understanding-the-harmonic-damper)

[Def]

On RB26's eating oil pumps? It's all over the place. They generally accept the ATI damper posted above as the only thing better than the factory crank at keeping the torsional vibrations properly damped.

[om3ga]

So will it also damage the oil pump on the SR? I have just never heard of an engine failing from using light weight crank pulleys or flyhwheels.

[gsxr141]

well, what about lighter flywheels? can the vibration i'm feeling at 2400rpm hurt anything? btw, it's a soch with an 11lb flywheel.

[Def]

So will it also damage the oil pump on the SR? I have just never heard of an engine failing from using light weight crank pulleys or flyhwheels.

It can, but typically inline 4 engines have a short enough crank that the natural frequency is higher than they typically rev(just like a shorter tuning fork gives a higher frequency when you hit it on something). Not saying your engine will asplode 10 miles down the road after you toss a solid crank pulley on it, but it's typically hard on the bearings and can damage things running off the crank like oil pumps.

The vibration you're feeling at 2400 RPMs is likely on decel with the clutch engaged and mostly in 4th gear right? It's due to the springs in the clutch disk being the incorrect stiffness and letting the differential pinion and ring gears resonant at their natural frequency(the compression strokes on decel at 2400 PRM happen to be right around this frequency, and 4th being a 1:1 transmits this most readily). I had the same problem on my car, and tossed in a stock SR clutch disk with EVERYTHING else the same on my car and the vibration went away. I have a 10.5 lb TODA flywheel and ACT HD pressure plate.

[om3ga]

Do you know anywhere that you can buy New OEM crank pulleys for the SR? I havent been able to find a place. I either need a NEW OEM one or im getting the Unorthodox racing one.

[Def]

Call some shops and see. Not sure why it has to be "NEW," it's not like they wear out usually.

[gsxr141]

it does it in every gear in my car. the trans shop said not to worry about it. they said it would be annoying, but not a problem.

[om3ga]

Is my crank pulley a harmonic/torsional/vibration damper or a harmonic balancer?

People are getting their crank pulleys confused with the harmonic dampers found on some domestic V6 & V8 engines. "Harmonic Balancer" is a term used loosely in the automotive industry. Technically, this type of device does not exist. The "balancer" part comes from engines that are externally balanced and have a counterweight cast into the damper. None of the applications we offer use a counterweight as part of the pulley, as these engines are all internally balanced.
The pulleys on most of the new import and smaller domestic engines have an elastomer (rubber ring) incorporated into the pulley making them look similar to a harmonic damper. The elastomer in the OEM pulley serves as an isolator, which is there to suppress noise from the engine accessories; the A/C compressor, P/S pump, and alternator. This is what the manufacturers call NVH (Noise Vibration & Harshness) when referring to noticeable noise and vibration in the passenger compartment. It is important to realize in these applications, the elastomer is inadequate in size and durability to act as an effective torsional damper. If you look at the pulleys on some imports there is no rubber to be found at all. We have samples of these, mostly from Acura/Honda B & D Series engines, Nissan Altima, 1.8L Eclipse, 2.3L Fords, Chrysler 2.2L's, and 1.8L VW's just to mention a few. Most owners who have installed our pulleys notice the engine actually feels smoother. This is result of replacing the heavy crank pulley with our crank pulley. NVH is variable and unique to every car. NVH will increase with the installation of an aftermarket intake and/or exhaust, for example. Think of OEM intake systems in newer cars, they use baffles and resonators in the intake to quiet all the intake noise. Aftermarket intakes eliminate these resonators and create dramatic increases in engine noise from the throttle opening and closing. So to most tuners, certain types of NVH can make the driving experience more enjoyable.
The purpose of a traditional harmonic damper is to protect against crank failure from torsional movement and frequencies of high amplitude. This is not necessary in most modern engines because of the many advances in engine design and materials. Factors such as shorter stroke length, smaller displacement, piston dwell time, piston pin off-set, power output, etc., do determine when and how these harmonics and torsional movements occur. More importantly the actual tune of the engine, espcially with modified vheciles, is the biggest factor in potential engine damage. Poor tuning leads to detonation which is an engine killer that no damper can stop.
Again, there is a lot of internet hearsay about solid crank pulleys. When engine problems occur, too often people are quick to blame the pulley first, rather than taking the time to look logically into why there was a problem.

[Def]

Where did you copy and paste that from? They obviously don't have any sort of background in dynamics or materials engineering.

*ALL* materials have a spring constant(they bend when a stress is applied), even if the "small strip of rubber" doesn't look very big, it is the thickness it is to give the proper stiffness in relation to the inertia of the outer ring to give an exact natural frequency.

I don't really want to give the college level mechanical engineering background in this post to really understand this issue, but suffice it to say, the above post was probably written by some Honda "tuner" who doesn't know anything about what he's saying besides something he read on the internet. The internet, where the only failure mode possible on an engine is bad tuning leading to detonation and engine destruction... Ugh... Like I said, I don't think import guys will ever understand this...

[om3ga]

Yeah it was from some site online. Well i think the reason that tuner guys argue it is because they hear that all american engines rely on the harmonic balancer since they are not internally balanced. However on the "Tuner" import engines they are internally balanced and ive heard the crank sees nothing from it besides less rotational mass. I wish there was some PROVEN TRUTH out there for the import engines showing why a solid pulley is bad.

[Matej]

(PROOF) That NA KA can make 200CHP on $1000 - S-Chassis.com (http://www.club240.com/forums/showthread.php?s=&threadid=30440)

Does an aluminum pulley affect dampening? The answer is NO. KAE and DE do not come with a dampener ( they are low RPM rev engines and useless for having such a large non harmonic half weighted crank). So pulleys are fine.
An SR is the same way, I would assume.

[ATLspeed]

Has anyone actually thought about how WORN out their stock crank pulley is? How much is it helping if the rubber in the pulley is worn/cracked like a bushing? I never hear of anyone saying: "I got new oem timing chaing, oem water pump...and oh yea new oem crank pulley!"

Just go put the UR pulley on and be done with it. You may need shorter belts also

[zenki.life]

Has anyone actually thought about how WORN out their stock crank pulley is? How much is it helping if the rubber in the pulley is worn/cracked like a bushing? I never hear of anyone saying: "I got new oem timing chaing, oem water pump...and oh yea new oem crank pulley!"

Just go put the UR pulley on and be done with it. You may need shorter belts also

i know for my ka24 you DO need shorter belt. who knows about the SR.

[Matej]

There are pdf's on UR's website that list the belt part numbers.

[ixfxi]

god hasnt this fucking topic been beaten to death already? i thought weve debunked this years and years ago..........

even in the super fruitcake miata community, this is known and understood:

Flyin' Miata : Engine/Drivetrain : Internals : ATI Damper pulley kit (http://www.flyinmiata.com/index.php?deptid=4530&parentid=0&stocknumber=04-95570%20%201994-95)

"We`ve found that really high horsepower Miatas - over 280 hp - have been overwhelming the stock harmonic damper. This can crack the gears on the oil pump as well as damage the bearings from the hammering. We worked with ATI to develop this replacement damper to solve the problem. You can read more about what harmonic dampers do here.

This unit replaces the stock damper with what is essentially two in one. The result is not only a safer engine, but one that runs more smoothly all the time thanks to the improved vibration absorption. This is exactly the opposite of billet "underdrive pulleys" that remove the stock damper. We`ve seen those destroy a typical turbo Miata engine in a couple of thousand miles."

ahem. carry on your useless non-engineering level of existence. class dismissed.

[Matej]

Sounds like a plug to sell ATI pulleys. They should also know better than to call the stock Miata pulley a harmonic damper.

I still believe a pulley is a safer mod than any turbo, or a lot of other common mods for that matter. Never have I seen evidence of a pulley destroying an SR/KA.

[om3ga]

Yeah this is the type of discussing that makes me wonder haha someone always brings up a random fact from some other cars engine about harmonic dampeners/crank pulleys. The only thing i can think of that would make me not buy the UR one is if i saw actual proof of it hurting a KA/SR. Another thing i thought about is, If the UR pulley is a great idea for the SR why the hell dosn't any other aftermarket company make one? I mean there is such a huge market out there for the SR that you would think some japanese tuner company would make one as well such as hks/nismo/tomei etc... I just want someone that owns one and has been running it for years to come in here and tell me about it then id buy it haha.

[Matej]

Of course, if you want to go all out...

http://www.naprec.co.jp/contents/img/parts_img/parts_b301.jpg

[om3ga]

Whose motor is that? And what pulley setup is that? That is sexy hot.

[burnsauto]

god hasnt this fucking topic been beaten to death already? i thought weve debunked this years and years ago..........

even in the super fruitcake miata community, this is known and understood:

Flyin' Miata : Engine/Drivetrain : Internals : ATI Damper pulley kit (http://www.flyinmiata.com/index.php?deptid=4530&parentid=0&stocknumber=04-95570%20%201994-95)

"We`ve found that really high horsepower Miatas - over 280 hp - have been overwhelming the stock harmonic damper. This can crack the gears on the oil pump as well as damage the bearings from the hammering. We worked with ATI to develop this replacement damper to solve the problem. You can read more about what harmonic dampers do here.

This unit replaces the stock damper with what is essentially two in one. The result is not only a safer engine, but one that runs more smoothly all the time thanks to the improved vibration absorption. This is exactly the opposite of billet "underdrive pulleys" that remove the stock damper. We`ve seen those destroy a typical turbo Miata engine in a couple of thousand miles."

ahem. carry on your useless non-engineering level of existence. class dismissed.

lol, i love you mike.



..Also, those yellow pulley's above are made my NAPREC of Japan, its a $1500.00 set.

Be a baller.
http://www.rhdjapan.com/jdm/NAPREC-ATI-Damper-Pulley-Kit-S14-S15-Silvia-SR20DET-52349

[om3ga]

Says for s14-s15 SR only.

[kuelee]

will just the crank pulley do anything..as of freeing hp? or do we have to use all the pulleys together?

[silviatunersr20]

I had the ur lite weight pulley and fidanza flywheel on my sr and I never had a problem. It made a big difference in revs. I loved it.

[om3ga]

I had the ur lite weight pulley and fidanza flywheel on my sr and I never had a problem. It made a big difference in revs. I loved it.


How long did you run it for? Also did you have an oil pressure gauge? If so what was your pressure before and after running the pulley for awhile? What happened to your SR that is making you sell the pulley?

[silviatunersr20]

How long did you run it for? Also did you have an oil pressure gauge? If so what was your pressure before and after running the pulley for awhile? What happened to your SR that is making you sell the pulley?

I ran it like that for over a year with no problems. Yes I had a gauge but I have forgot what the oil pressure was since its been months since I have drove the car. I sold the sr to fund my ls2 swap. I WANT TQ!

[ixfxi]

Whose motor is that? And what pulley setup is that? That is sexy hot.

its called an sr20det



cant believe youre still listening to hear-say about engine vibration/harmonics