Which harmonic damper diameter?
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SPARTAN
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Which harmonic damper diameter?
"Standard" diameter for the damper is 8", correct?
Team Owner
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From: Lakeland, FL
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St. Jude Donor '03, '06, '17
Why don't you go with a small, lightweight unit. That'll give you extra HP compared to the heavy 8" balancers... Less rotating mass = more HP! There are 6 lbs aluminum balancers available... That's about 6 - 10 lbs less at the crank would make some difference!
Safety Car
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From: San Antonio TX
Lightweight dampers don't make more horsepower than heavy ones. They allow the engine to accellerate faster but unless you're running a competitive event where you're looking for even the tiny gains, it's better to run a heavier damper. The reason the factory put bigger, heavier dampers on the high performance and heavy duty (like big trucks) engines is that they do a much better job of absorbing crankshaft harmonics. There's more mass in the inertia ring.
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From: Lakeland, FL
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St. Jude Donor '03, '06, '17
Hmmm... You mean that 10 lbs more rotating mass will not increase HP?? I'd like to see physical or mathematical proof of that.. That doesn't make sense.. More weight = more resistence = less HP. I'm not claiming any specific gains, but more weight definetely means more resistence... Try putting a 50 lbs balancer on the engine and do a dyno test. Then do a dyno test with a 6 lbs aluminum one and I'd bet $$ that the dyno run with the lighter balancer will produce more HP...
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Safety Car
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From: San Antonio TX
You can put an engine on a dyno and put whatever rotating weight (either on the crank snout as a damper or on the end as a flywheel) you want to on it and it will only show up as an acceleration rate. Engine dynos measure steady-state power by increments and break the engine at each measure point.
Now an inertial chassis dyno theoretically would see and measure this as a difference in horsepower since they measure horsepower strictly through the acceleration rate. But the difference is statistically insignificant and well within the dyno's margin of error. A drag race is also a measure of the acceleration rate. So in that regard you are right.
But, and this is a big but, the difference is still insignificant unless you are running on the index for the class.
For a car driven on the street, you want to absorb the crank harmonics as best as you can. Your crank bearings will thank you for it.
Now an inertial chassis dyno theoretically would see and measure this as a difference in horsepower since they measure horsepower strictly through the acceleration rate. But the difference is statistically insignificant and well within the dyno's margin of error. A drag race is also a measure of the acceleration rate. So in that regard you are right.
But, and this is a big but, the difference is still insignificant unless you are running on the index for the class.
For a car driven on the street, you want to absorb the crank harmonics as best as you can. Your crank bearings will thank you for it.
Burning Brakes
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From: Des Allemands LA
And also if you're not worried about stock appearance of the engine at the dampner there are several aftermarket lightweight dampner's that outperform stock by a wide margin. I just installed a TCI Rattler on mine, the other advantage is there is no "ring" to wear out with this type. I had almost squeezed the entire rubber ring out of the stock one. Something about shifting @7000rpm's those stock balancers don't like.
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Originally Posted by GrandSportC3
Why don't you go with a small, lightweight unit.
Main reason: $$$
Secondary reason: $$
Melting Slicks
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From: New Cumberland PA
I don't think there would be any difference in hp. It may take a split second longer to get the rpms up to the highest hp. For accelerating and decelerating I would go with a lighter damper, but for steady driving the heavy one has a certain advantage that was previously mentioned.
Safety Car
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From: San Antonio TX
Well, there actually can't be a difference in the engine's horsepower simply due to the way engine horsepower is calculated.
HP = torque x rpm over a constant 5252.
There are only two ways to increase the horsepower of the engine: 1)increase VE to make more torque, or; 2) raise the rpm at which the torque curve occurs.
Rotating mass doesn't affect either one of those. Acceleration rate, yes, but engine horsepower, no. This would show up on a drag strip as a lower e.t., but the trap speed would be the same.
HP = torque x rpm over a constant 5252.
There are only two ways to increase the horsepower of the engine: 1)increase VE to make more torque, or; 2) raise the rpm at which the torque curve occurs.
Rotating mass doesn't affect either one of those. Acceleration rate, yes, but engine horsepower, no. This would show up on a drag strip as a lower e.t., but the trap speed would be the same.
Racer
Joined: May 2000
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From: Niedernhausen, Germany
Balancer
I have just recently bought a 8" balancer normally used on ZZ4 crate engines on ebay for 40$. Seems to work just fine. Just paint it orange, add on of these Felpro-repair sleeves (to avoid wear of the seal surface) and go.
Regards,
Thomas
Regards,
Thomas
C6 the C5 of tomorrow
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From: Twin Cities Minnesota
But the problem is how do you accurately measure torque...
But really what matters is how fast the car is on the street / strip. That is determined by how fast it can rev up to redline. if it takes forever the car will be slow.
Keeping the drive train light makes the car faster in real life. It's been said that removing 1 lb of rotating mass is like removing 10 lbs of normal mass. While thats a simplifacation, it's that kind of magnitude.
Races are not won one the Dyno
But really what matters is how fast the car is on the street / strip. That is determined by how fast it can rev up to redline. if it takes forever the car will be slow.
Keeping the drive train light makes the car faster in real life. It's been said that removing 1 lb of rotating mass is like removing 10 lbs of normal mass. While thats a simplifacation, it's that kind of magnitude.
Races are not won one the Dyno
Team Owner
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Different Vette motors had different weight and diameter dampers. The higher HP performance motors came with the larger 8 inch.
GS - Dampner weight only has additional friction losses and they are much harder on bearings and the crank shaft. Just think about a 10 pound damper spinning 7000 rpm and you shift gears in nearly an instant with auto trannies and now your spinning 4500 rpm. That is allot of twist on the crank shaft.
That is why you and i run lightweight 6 ish diameter dampers. My drag bike did not even have a flywheel per say or a damper.
GS - Dampner weight only has additional friction losses and they are much harder on bearings and the crank shaft. Just think about a 10 pound damper spinning 7000 rpm and you shift gears in nearly an instant with auto trannies and now your spinning 4500 rpm. That is allot of twist on the crank shaft.
That is why you and i run lightweight 6 ish diameter dampers. My drag bike did not even have a flywheel per say or a damper.
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From: Lakeland, FL
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St. Jude Donor '03, '06, '17
I don't know specifics about how engine dynos work, but I've seen noticable gains on chassis dynos when going with aluminum flywheel, carbon fiber lightweight shafts etc...