BBC 7" Damper vs 8" Damper

[stokerboats]

What are the pro's/con's on a bbc of choosing either of the two dampers in an internally balanced 565 inch engine assy? Thanks.

[Alan Roehrich]

Use the bigger steel ATI Super Damper.

The only reason to use the small aluminum light dampers is for "class racing" where you have a lot of restrictions, and every last HP and acceleration is necessary to be competitive. We run those light balancers on Stock Eliminator and Super Stock engines, because we have to wring that last HP out of every possible area.

I'm freshening a 565 big block Chevy engine for Super Gas right now. It has the larger steel balancer on it. Because it runs for 400 passes before being freshened. It always looks brand new when it comes down for maintenance, and parts last forever. Even the valvesprings last upwards of 800 passes.

[stokerboats]

Alan, thanks for the reply, I have an sfi rated Powerbond 8" and haven't seen one bad report on this product. I do realize that most suggest the ATI but it's twice the cost of the Powebond.

[Alan Roehrich]

Alan, thanks for the reply, I have an sfi rated Powerbond 8" and haven't seen one bad report on this product. I do realize that most suggest the ATI but it's twice the cost of the Powebond.

Well, it is up to you. But considering the cost of building a quality 565, why would you cut corners on the balancer, when it effects the life of the rotating assembly and the valvetrain?

[FuelieNova]

Look on eBay, you can normally buy the ATI 8" directly from their eBay store for $199. They are cosmetic blems and only a close eye can tell. I messaged them and ask if they had a 7"sbc blem and he answered within 24 hrs and shipped right away. It has one minor spot on the black paint that had a stain. They come with a full warranty.
Tom

[stokerboats]

Alan, what is it, in your opinion that makes the ATI a better damper than a Powerbond? Being objective here I think. lol
I have always used the 8" damper over the 7" but only because since the time I became interested in racing with a bbc the factory always used the larger balancer on the shp engines which I always "assumed" was because they absorbed harmonics better than the smaller diameter, not because I actually knew anything. I realize that most with the higher end builds seem to prefer the ATI but is it because they "know why" or is it simply because most others do? Is the ATI better because it is proven to dampen better over all others or are other less expensive equally effective but not generally recognized due to a less famous name?

[MadBill]

Alan, what is it, in your opinion that makes the ATI a better damper than a Powerbond? Being objective here I think. lol
I have always used the 8" damper over the 7" but only because since the time I became interested in racing with a bbc the factory always used the larger balancer on the shp engines which I always "assumed" was because they absorbed harmonics better than the smaller diameter, not because I actually knew anything. I realize that most with the higher end builds seem to prefer the ATI but is it because they "know why" or is it simply because most others do? Is the ATI better because it is proven to dampen better over all others or are other less expensive equally effective but not generally recognized due to a less famous name?

You assumed right. Some years ago David Vizard did a series of very carefully controlled tests on an SBC for one of the major mfgrs. (I think it was ATI) with various dampers/hubs. He used I believe a 600 RPM/sec. accel rate to give the light weight items every possible advantage, but found the heaviest 8" unit made the most power (in the double digits) due to reduced crank twist and cam harmonics. Per: http://books.google.ca/books?id=kmTNubY ... st&f=false , this doesn't mean the biggest will always be best; it's dependent on RPM and other factors, but the lightest 'non-damper' is pretty well guaranteed to be worst.

[bigjoe1]

In any situation like this there will be other experiences . I did a test many years ago at the drag strip. we made two runswith, only one hundredths difference, then , I replaced the big 8 inch balancer with just to hub to plug the hole in the timing chain cover-- NO OTHER CHANGES--- It picked up a full TENTH of a second , This was on a 8 flat second e conorail dragster--- I remember this very clearly to this day-- Just the facts


JOE SHERMAN RACING

[Alan Roehrich]

Alan, what is it, in your opinion that makes the ATI a better damper than a Powerbond? Being objective here I think. lol
I have always used the 8" damper over the 7" but only because since the time I became interested in racing with a bbc the factory always used the larger balancer on the shp engines which I always "assumed" was because they absorbed harmonics better than the smaller diameter, not because I actually knew anything. I realize that most with the higher end builds seem to prefer the ATI but is it because they "know why" or is it simply because most others do? Is the ATI better because it is proven to dampen better over all others or are other less expensive equally effective but not generally recognized due to a less famous name?

It is a vastly superior product. The ATI balancer is far more effective at controlling harmonics, because of the design, which allows it to control harmonics over a far larger range. It is not merely a single elastomer single diameter damper. It has different durometer o-rings, at different diameters.

[RAS]

The smallest lightest balancer. Better yet, you should be asking the manufacturer of your crankshaft.

[stokerboats]

Alan, what is it, in your opinion that makes the ATI a better damper than a Powerbond? Being objective here I think. lol
I have always used the 8" damper over the 7" but only because since the time I became interested in racing with a bbc the factory always used the larger balancer on the shp engines which I always "assumed" was because they absorbed harmonics better than the smaller diameter, not because I actually knew anything. I realize that most with the higher end builds seem to prefer the ATI but is it because they "know why" or is it simply because most others do? Is the ATI better because it is proven to dampen better over all others or are other less expensive equally effective but not generally recognized due to a less famous name?

It is a vastly superior product. The ATI balancer is far more effective at controlling harmonics, because of the design, which allows it to control harmonics over a far larger range. It is not merely a single elastomer single diameter damper. It has different durometer o-rings, at different diameters.

I read the description of the product and as you stated there are two elastomer bands as I recall, one at four inches diameter and one at seven inches diameter but that said is there some proven factual comparison testing anywhere? Not being rude just trying to make an educated choice that is based on more than heresay. Thanls for your answer. Dan

[lorax]

I read the description of the product and as you stated there are two elastomer bands as I recall, one at four inches diameter and one at seven inches diameter but that said is there some proven factual comparison testing anywhere? Not being rude just trying to make an educated choice that is based on more than heresay. Thanls for your answer. Dan

Theres a little more to it than that.
There is a 2 OR 3 elastomer bands inside and outside the inertia ring, as well as one on the front and rear of the ring. The rings are available in different durometer, so they are near infinite tunable by using different elastomer o rings, including mixing them. Then the whole thing is contained in a shell that completely encloses the inertia ring like a scatter shield. Granted, the aluminum shell version much less so. But it sure beats having the inertia ring on the outside of the hub.

[Alan Roehrich]

I read the description of the product and as you stated there are two elastomer bands as I recall, one at four inches diameter and one at seven inches diameter but that said is there some proven factual comparison testing anywhere? Not being rude just trying to make an educated choice that is based on more than heresay. Thanls for your answer. Dan

There are at least a dozen or so tests that have been conducted and documented.

There is a reason that people who can afford to buy anything, and who get a lot of stuff given to them use ATI.

If you want, contact ATI, I'm sure they can provide you with data, probably more than you want. They travel to a lot of shops and set up tests.

Back to back, we've seen a considerable increase in the life of timing sets, valvesprings, bearings, and crankshafts. I've been selling and using them since the first ones went on sale around 28 years or so ago.

[MadBill]

Alan, what is it, in your opinion that makes the ATI a better damper than a Powerbond? Being objective here I think. lol
I have always used the 8" damper over the 7" but only because since the time I became interested in racing with a bbc the factory always used the larger balancer on the shp engines which I always "assumed" was because they absorbed harmonics better than the smaller diameter, not because I actually knew anything. I realize that most with the higher end builds seem to prefer the ATI but is it because they "know why" or is it simply because most others do? Is the ATI better because it is proven to dampen better over all others or are other less expensive equally effective but not generally recognized due to a less famous name?

It is a vastly superior product. The ATI balancer is far more effective at controlling harmonics, because of the design, which allows it to control harmonics over a far larger range. It is not merely a single elastomer single diameter damper. It has different durometer o-rings, at different diameters.

I read the description of the product and as you stated there are two elastomer bands as I recall, one at four inches diameter and one at seven inches diameter but that said is there some proven factual comparison testing anywhere? Not being rude just trying to make an educated choice that is based on more than heresay. Thanls for your answer. Dan

Here's a good comparison: http://www.atiracing.com/products/dampers/testing/

[DaveMcLain]

I still think that all of this aftermarket damper stuff is pure guesswork as to it's tuned effectiveness with a random selection of hot rod parts. You buy your damper and take your chances and for the most part it works.