Crank Dampner needed or not?

[Eber]

I amin the middle of a full rebuild of both the top and bottom end and was wondering due to the addition of a crank collar if it would be wise to replace the crank damper with an ATI in order to balance both harmonics and intertia that may occur. This car will be running over 600hp and I know that the original pully dampner wears and should be replaced at intervals. I am getting the crank and flywheel balanced when the install occurs but was wondering about the necessity of an ATI damper for this build. I dont know if harmonics will play a greater role with the boring of the cylinders to 87mm or adding the crank extension. Any info would be appreciated

[Zulu]

was wondering due to the addition of a crank collar if it would be wise to replace the crank dampner with an ATI in order to balance both harmonics and intertia that may occur.

The answer to this question is NO you do not have to get an ATI damper for this reason soley. Once your Crank collar is installed you should have your crank balanced no doubt about that.

ATI dampner

Its Damper just for your information.

I dont know if harmonics will play a greater role with the boring of the cylinders to 87mm or adding the crank extension.

Once again no it will not play a larger role. If you are buying quality products and your machine shop does great work then you do not need a damper for this reason.


Would I build a motor and NOT run a new damper.

My answer - You would be foolish and crazy not to run a new damper. Let's say you have spent $10,000 on a rebuild. Crank dampers are about $600.00

So to prevent any risk of imbalance do you think it is worth $600.00 ? I would say so. Keep in mind your oil pump is gear driven right off of your crank right near your crank pulley\damper. Motors do not like imbalances.

As for which damper.

Run a ATI Race damper part # 917752


While you are putting on a new damper DO NOT reuse your crank bolt or washer. Once again cheap insurance to get new ones.

Crank pulley bolt 12309-05U00 Retail cost should be $6.29
Crank pulley washer 12308-05U00 Retail cost should be 9.95

DO NOT use an impact gun to tighten the crank pulley bolt as it causes great shock and vibration to the crank/oil pump gear. Use a torque wrench.

For that matter NOTHING on an engine build should be tightened with a impact gun.

[kelaog]

Even with a strengthened wider crank drive you can still fracture the pump. If you plan on revving above 8000rpms then I suggest yes. If this is going to be driven daily I suggest no.

[Zulu]

If you plan on revving above 8000rpms then I suggest yes. If this is going to be driven daily I suggest no.

If you value your car, reliability, wallet and most importantly piece of mind then like I said you would seriously be foolish not to run a crank damper.

[kelaog]

If you value your car, reliability, wallet and most importantly piece of mind then like I said you would seriously be foolish not to run a crank damper.

A well balanced crank would be a better solution yes? Any chance you know first hand how much engine balancing costs?

[Zulu]

A well balanced crank would be a better solution yes?

A well balanced crank is always a must does not matter if you run a crank pulley or damper.

Understand this.... connected to your crank is your

pressure plate/clutch/flywheel.
connecting rods
pistons
oil pump
etc etc etc

Now these will not always work together in perfect harmony.

You have many bearings for the crank and rods. There is a certain clearance that needs to be maintained for proper operation. Do you understand where I am going with this ? You have too many variables to be taking risks.

Crank balancing should cost you in the ballpark of about 100$

Many times you get what you pay for. Do your research and use a shop that deals with race motors or high end cars.

[mcfly]

The oil pump breaks because of the rev limiter, the block cracks because of the poor damper.

As discussed time and time again there is a real knarly harmonic that appears up near redline. You stay there too long of visit it to frequently you will end up with a cracked rb26 block just like the one sitting out in my garage right now.

You Rev your rb26 to 8300 or what ever fuel cut is and you can say good by to your oil drive in a short time.


I personally revved the said engine(stock everything) with the cracked block to 9000 rpm. The oil pump was fine, std r32 crank drive and I even reused the oem oil pump during the rebuild. The engine didn't last long past the rebuild due to the increase in my rev limit, (pre rebuild 8k/post 9k). The block was perfect when it went together, 1 month later it was cracked all over the place and visibly from the deck.
Balancing the crank won't get rid of the harmonics, the engine is a damn tuning fork when put together, you reach specific rpm's and you can really tell when you have met a resonance frequency. Doesn't matter if the engine has a 2.8L step 3 or a 2.7 JUN kit, they all do it.


Now you don't need an ati, but how much did your engine cost(labour/parts etc), do you wish to have the car down again when the coolant starts filling with oil? You make the call, My large ATI was 540 shipped with the water pully, I wouldn't want to build one without it.

[Dragon Humper]

Hey McFly, sorry about peeing on your feet a little in that other thread, are you running the American ATI or the J-Spec ATI? I thought I read somewhere on here (canT find it now) that there was an issue with the American piece.

Truth or BS?


Jon.

[mcfly]

:-? ATI is an American company...

BS anyways, I have yet to know of anyone having any sort of problem with them and i tend to get around.
Kismetcaptain did have an issue with an oil pump cracking, but we think that was due to his using a hammer at some point assembling. I don't remember the story as all the blame was placed on the hammer.

[VortXxe]

A well balanced crank would be a better solution yes? Any chance you know first hand how much engine balancing costs?

You can only balance a for 1 RPM. For example my crank is balanced for 4000rpm.

Also, on an internally balanced engine the damper is a damper, not a balancer and is zero balance.

The function of the harmonic damper is to reduce harmonic vibrations and dampen crank twist. ATI's website has some good information on the subject.

[kelaog]

Best explained to me was spinning around in a circle with two hammers, when you hit the two together it wuold send a shock through your body. Now when you replaced the hammers with rubber mallets there was a lot less shock when the hammers touched.

The damper just absorbs vibrations better, and takes them away from the block. The only thing I worry about is the airconditioning overdrive.

Anyway you can get around this? I'm still debating whether or not to put one in my build.

[Bruizer]

don't put it in then, simple. Spend the $1000 getting engine balancing and whatnot

[Rain]

AS said its just silly NOT to use one if you are doing a rebuild, there are a few who make them (all from ATI but all different specs build wise). Just finished doing a 32 build and no brainier to use one, used an RH9 damper kit.

Just do it, theres no harm in doing it, think about it as mental and financial insurance

[VortXxe]

don't put it in then, simple. Spend the $1000 getting engine balancing and whatnot

Havn't you been reading

engine balancing does NOT mean you DON'T need a harmonic damper.

The best balanced engine in the world needs one just as much as a out of balance nightmare of death when it comes to crank twist and harmonics.

On an internally balanced engine your damper doesn't also have to act as a balancer (ie: many domestic motors rely on the damper to also balance the engine, its weight isnt centered, instead its got weight shaved off one side to balance the whole thing)... thats the only difference.

[Bruizer]

I'm just talking for fun. I've got a ATI super damper in my basement for my build.
Because it makes 80hp for me .