Are Harmonic Damper needed on Flat Six?
Moderator: Team
-
- Member
- Posts: 57
- Joined: Wed Mar 29, 2006 2:11 pm
- Location:
Are Harmonic Damper needed on Flat Six?
From my reading, flat six engines are balanced due to there geometric configuration of opposed cylinders.
"In the horizontally-opposed or boxer configuration, the two halves are mirror images of each other and the directly opposing pistons are moving toward each other or away from each other at the same time. The two motions cancel each other. Hence the engine is in perfect primary balance. Straight-3 engines have no secondary imbalances, so all you are left with is an intrinsic tertiary vibration caused by the fact there are only three cylinders firing per crankshaft revolution."
My question is do I need a harmonic damper on a flat six engine? I'm hesitant to just throw on a aluminum crank pulley on my engine for fear of premature wear.
Regards,
Justin
"In the horizontally-opposed or boxer configuration, the two halves are mirror images of each other and the directly opposing pistons are moving toward each other or away from each other at the same time. The two motions cancel each other. Hence the engine is in perfect primary balance. Straight-3 engines have no secondary imbalances, so all you are left with is an intrinsic tertiary vibration caused by the fact there are only three cylinders firing per crankshaft revolution."
My question is do I need a harmonic damper on a flat six engine? I'm hesitant to just throw on a aluminum crank pulley on my engine for fear of premature wear.
Regards,
Justin
Best Regards,
Justin Olson
Justin Olson
-
- Pro
- Posts: 270
- Joined: Sun Aug 27, 2006 5:01 am
- Location: Van Alstyne, Texas
There still may be harmonics at certain RPMs that you may want to dampen out, but the "harmonic balancer" will typically just be a very heavy, balanced pulley on any boxer.
If the manufacturer didn't put one on, it probably isn't needed, and may actually create issues.
IIRC the Corvair crank does have some particular RPM//harmonic that should be avoided, and I do believe they make dampers for those, but it's another "nice" thing to have and not usually required..
I once saw a T1 VW motor set up with a very lightweight flywheel ...and a 6 lb crank pulley. These aren't active dampers, just heavy pulleys... and the pulley end really only has a woodruff key to keep things straight and is prone to cracking there, no taper.
(Any hipo T1 will have a fully counterweighed crank with additional mass, so adding more to the weak snout is probably counterproductive IMHO)
Looked cool, but I'm skeptical it did more than that, and perhaps less.
They DO make V8 style dampers for T1 VW motors IIRC, but they are very seldom used, and probably even less often actually required.
I don't recall ever seeing a huge damper on a 911, the fan pulley is typically pretty small dia.
What's your application?
If the manufacturer didn't put one on, it probably isn't needed, and may actually create issues.
IIRC the Corvair crank does have some particular RPM//harmonic that should be avoided, and I do believe they make dampers for those, but it's another "nice" thing to have and not usually required..
I once saw a T1 VW motor set up with a very lightweight flywheel ...and a 6 lb crank pulley. These aren't active dampers, just heavy pulleys... and the pulley end really only has a woodruff key to keep things straight and is prone to cracking there, no taper.
(Any hipo T1 will have a fully counterweighed crank with additional mass, so adding more to the weak snout is probably counterproductive IMHO)
Looked cool, but I'm skeptical it did more than that, and perhaps less.
They DO make V8 style dampers for T1 VW motors IIRC, but they are very seldom used, and probably even less often actually required.
I don't recall ever seeing a huge damper on a 911, the fan pulley is typically pretty small dia.
What's your application?
The late Gene Berg did extensive R&D work on Type 1 Volkswagens; he was the one who developed and recommended the heavy crank pulleys. His theory was that the heavy pulley dampened the vibrations that would otherwise run back down the crankshaft and cause excessive case/bearing wear. I have no personal experience because I never run anything but stock in my VW's so never made enough power to get into that realm. Gene, on the other hand, made enough VW power to cause all sorts of mayhem.
Joe
Joe
-
- Member
- Posts: 57
- Joined: Wed Mar 29, 2006 2:11 pm
- Location:
-
- Member
- Posts: 57
- Joined: Wed Mar 29, 2006 2:11 pm
- Location:
-
- Expert
- Posts: 763
- Joined: Mon Dec 25, 2006 7:09 pm
- Location: Kansas City, MO
My partner and I are building a 12,000 rpm SB Chevy and ATI designed the balancer for this engine. I'd at least call them and get their response.
Ron
Ron
Last edited by Ron Golden on Wed Sep 09, 2009 11:45 pm, edited 1 time in total.
-
- Expert
- Posts: 571
- Joined: Fri Dec 01, 2006 5:25 pm
- Location:
-
- Member
- Posts: 57
- Joined: Wed Mar 29, 2006 2:11 pm
- Location: