harmonic balancers

[fekbmax]

Whats preferred for a full race Fe and why ?
ATI ? TCI ? Innovators west ? Or any other dampers for a internally balanced engine. 

[Stangman]

Got shortblock done at survival and we installed a romac

[cjshaker]

The Romacs are nice pieces, but don't hold their finish very well and will rust. The ATI dampers are VERY nice and seem quite popular within race circles. Just remember that the timing marks are off and your pointer must be adjusted accordingly. I have no experience with the others.

[blykins]

ATI is up there....Romac is up there....I've even used the Powerbond SS on some higher hp stuff.  Take your pick.

[fekbmax]

I been useing ATI's but was just curious as to what you guys think.

[jayb]

I always use ATI balancers.  A heavier balancer is better for a larger stroke.

[thatdarncat]

I have an Innovators West and happy with it ( came with my current motor ). Very popular with the stock & super stock drag racers. Timing marks are in the right spot and Ford pulley bolted up. I talked to them at the PRI show, sounded like they are Ford guys at the shop.

[Stangman]

What is the reasoning with the heavier balancer for the long stroke you would almost think you would want it lighter so it would rev faster or are you looking for more power after it alredy gets goin

[jayb]

As I understand it a heavier harmonic balancer helps smooth out any tendencies towards vibration.  The longer the stroke, the more you will have that tendency, so a heavier balancer is better. 

[Autoholic]

Here is the engineering answer as to why you need a heavier harmonic balancer with a longer stroke: moment of inertia. The bigger your stoke, the larger your moment of inertia, requiring more damping in order to smooth out the power. Same goes for the flywheel.

[Stangman]

I guess I can see that I was thinking about those hit and miss motors the bigger the flywheel the more it could work or pump or whatever you were using it for that makes sense autoholic

[Autoholic]

If you want to increase the responsiveness of the engine, how quick it can rev, you need to decrease the moment of inertia. This is why a shorter stroke will rev higher. But the moment of inertia also takes into account your reciprocating mass, so making everything as light as possible helps as well, to increase the acceleration of the engine. How reliable the engine will be will take into account your valvetrain as well, making this as light as possible helps you keep revving higher, longer. At this point, your gearing will also come into play as to how quick your engine will accelerate. I should note that the moment of inertia for your drivetrain will come into play. Light weight transmission gears, differential and the rotating mass of your rims and tires. This is part of the reason why carbon fiber and magnesium rims are there, the lower weight helps make the vehicle accelerate faster due to the engine having to work less to move the rotating mass. Another reason for these rims is by having less weight on your unsprung weight, there will be less force behind suspension travel.

[blykins]

Watch about making generalities that only short stroke engines can rev....

I hear this statement frequently but it's not always the case.  A long stroke engine can turn some very high rpms and respond immediately with the right combination.   The rotating assembly weight as well as how much hp/tq the engine makes play a big role. 

There are mountain motor class engines (700-800 ci) with 5.750" strokes that can easily turn 8000 rpm and get there in an instant...

[Nightmist66]

In Autoholics defense, I believe he was just stating shorter strokes will rev "higher" than long strokes. No doubt there are some big cube motors that turn the rpm. The high revving "short stroke" is best explained by the formula and indy engines, 15-20k rpm

[Autoholic]

I never said a long stroke couldn't rev high. The fact of the matter though is that a shorter stroke will always be able to rev higher than a longer stroke, with everything else being equal. There is a good reason why you only see short stroke engines in Formula 1. No matter what you do to a long stroke engine, it will still have a higher moment of inertia and that will limit how high it can rev and how fast the engine will get there. Done properly, you could make a high revving long stroke engine but what you'll have to do to get there will end up proving the law of diminishing returns. At some point you need to question your intent for the motor. Do you want it to be high revving and make its power in the stratosphere or do you want it to be torque monster that makes its power down low? And to be clear, I would say anything at or under 8000 RPM is low as far as the spark ignition ICE goes, when you have engines in motorcycles and formula racing that rev 14,000 rpm and higher. Oh and this doesn't even touch on the topic of reliability when trying to make a long stroke engine run 8,000 rpm or how streetable such an engine would be. Not to mention how expensive it will be because you are forced to use expensive materials like titanium and high strength steels. A high revving, big stroke engine is built mainly for one purpose, drag racing and as such, it gets rebuilt regularly.