Harmonic Dampers

[lamchop77]

Hi all

Got a question concerning harmonic dampers. Only picked up on this from Bobs quote in the compufire thread that the 2.4 motors need to use the original pulley with this built in.

I have 1.9/2.0 motors withoutbthe damper on, just a pressed steel pulley. Some of the 2.0's have them, all the 2.2/2.4's i have, have them fitted.

Why is it so important on the 2.4?

Done some reading on this with info from BHJ Dynamics Inc which i get BUT with the mods that we do to the motors we take the crank away from std which the damper is tuned to. Aren't we then aggrevating the problem?

In the case of crankshaft bending vibration BHJ quote that "In general heavy pulley/damper packages just aggrevate the motion and do nothing to control it", they also say that the rubber dampers are currently fitted more for noise reduction rather than crank reliability.

The reason i'm raising this is that i have had a lightweight (465g) alloy front pulley made with a triggerwheel built in. This weighs less than the std steel pressed pulley and has a reduced belt drive to slow down the water pump/alternator at 7500-8000 rpm. Am i going to run into problems with vibration at these levels with this pulley fitted to the 2.5 or the 2.3 long stoke motors i'm building?

Hiro - What pulleys have you been using?

Bob - With your 2.4 stroker mods what pulley did you use? Are there any dampers in the US that are a recommended aftermarket fit?

Any help would be great

Thanks

Chris

[Hiro]

Originally Posted by lamchop77 Hi all Got a question concerning harmonic dampers. Only picked up on this from Bobs quote in the compufire thread that the 2.4 motors need to use the original pulley with this built in. I have 1.9/2.0 motors withoutbthe damper on, just a pressed steel pulley. Some of the 2.0's have them, all the 2.2/2.4's i have, have them fitted. Why is it so important on the 2.4? Done some reading on this with info from BHJ Dynamics Inc which i get BUT with the mods that we do to the motors we take the crank away from std which the damper is tuned to. Aren't we then aggrevating the problem? In the case of crankshaft bending vibration BHJ quote that "In general heavy pulley/damper packages just aggrevate the motion and do nothing to control it", they also say that the rubber dampers are currently fitted more for noise reduction rather than crank reliability. The reason i'm raising this is that i have had a lightweight (465g) alloy front pulley made with a triggerwheel built in. This weighs less than the std steel pressed pulley and has a reduced belt drive to slow down the water pump/alternator at 7500-8000 rpm. Am i going to run into problems with vibration at these levels with this pulley fitted to the 2.5 or the 2.3 long stoke motors i'm building? Hiro - What pulleys have you been using? Bob - With your 2.4 stroker mods what pulley did you use? Are there any dampers in the US that are a recommended aftermarket fit? Any help would be great Thanks Chris

I'm using the Krause Renntechnik ally pulley,
about 300g & underdrive setup,
I'm not much worried about undamped vibration on my race 2.5 CIH,
lot more to worry about the bad rod ratio anyway!
Hiro

[wrench459]

From my prospective on balancing a four cylinder.
Weight match the pistons and rods(bigend,smallend and total) to under a tenth of a gram.
Get the crank as close as possible to 0 grams. I've ran the cranks out as much as 3 grams without any problems. These's guys are neutral balanced unlike the V engines that require special stuff on the flywheel or front pulley.
Then again what do I know.

[lamchop77]

Thanks guys

Pistons and rods are already done, plus rods/crank are being shotpeened for a bit of extra strength. Better get building hadn't I!!!!!

Chris

[RallyBob]

Originally Posted by lamchop77 Bob - With your 2.4 stroker mods what pulley did you use? Are there any dampers in the US that are a recommended aftermarket fit?

Billet steel or aluminium (custom made). Usually 3.5" diameter for racing use, or 4" diameter for road use, in conjunction with a 6" water pump pulley. For racing I'll also use a 4" alternator pulley. Example.

Bob

[lamchop77]

Cheers Bob thanks for that....my mind is more at ease now!!!

Chris

[neuropel]

Does anyone have a source for getting a custom pulley with an integrated "toothed" trigger wheel? I'd like to switch over to a Ford EDIS type setup using Megasquirt (I have a functioning megasquirt already up and functional with a megastim, so I've been playing with software). I just haven't come across a trigger wheel setup that I like yet. My installation would be on a 2.2 crank, and it'd be nice to have it all integrated in with the pulley. I think the requirement would be a 36-1 trigger.

Todd

[RallyBob]

Originally Posted by neuropel Does anyone have a source for getting a custom pulley with an integrated "toothed" trigger wheel? I'd like to switch over to a Ford EDIS type setup using Megasquirt (I have a functioning megasquirt already up and functional with a megastim, so I've been playing with software). I just haven't come across a trigger wheel setup that I like yet. My installation would be on a 2.2 crank, and it'd be nice to have it all integrated in with the pulley. I think the requirement would be a 30-1 trigger. Todd

My next time around having pulleys made, I'm just going to get them with a stepped flange, and buy a 36-1 toothed wheel that can be pressed on and/or tack-welded in place. I'd rather have the toothed wheel separate, so if it gets damaged you don't have to trash the entire pulley. This company in the UK makes generic toothed wheels that are compatible.

[neuropel]

That'd be perfect. I should have clarified - I haven't found a trigger wheel setup that I like USING THE STOCK PULLEY. It'd be great to have a pulley better suited to accomodate the existing trigger wheel products.

[ghcoe]

Originally Posted by neuropel That'd be perfect. I should have clarified - I haven't found a trigger wheel setup that I like USING THE STOCK PULLEY. It'd be great to have a pulley better suited to accomodate the existing trigger wheel products.

Another source here:

Trigger Wheels - DIYAutoTune.com

And their how to page. It is hard to find so figured I would just link to it too:

How to use DIYAutotune.Com's crank triggers

They also sell the megasquirt units and accessories. I think he has posted here before for a group buy on the systems. George

[RallyBob]

Originally Posted by neuropel That'd be perfect. I should have clarified - I haven't found a trigger wheel setup that I like USING THE STOCK PULLEY. It'd be great to have a pulley better suited to accomodate the existing trigger wheel products.

I wouldn't want to attach a trigger wheel to a stock stamped steel pulley, even if it were a simple and viable solution. They bend if you look at them funny. Last thing you need is a wobbly ignition trigger! You really need something more stable, and IMO a billet pulley is the solution.

[lamchop77]

I had a billet alloy pulley made here in the uk which has a smaller diameter v groove to underdrive the waterpump/alternator and a removable trigger wheel. The trigger i have is based on the std 2.4 but i'm pretty sure that i could get the guy who did it to change it to a different setup for the same sort of money.

Price was about £70 including the dreaded vat.

If any one is interested i could ask the question. Weight of mine is 465grams so shipping would be cheap!!!!!

Chris

[jeff denton]

I think I'll want MY trigger wheel attached to the forward side of the flywheel. Or on the clutch pressure plate housing? Somewhere well protected and um, HIDDEN.

[wrench459]

Originally Posted by jeff denton I think I'll want MY trigger wheel attached to the forward side of the flywheel. Or on the clutch pressure plate housing? Somewhere well protected and um, HIDDEN.

dang Jeff
Your thinking outside of the box. But why not place the 36-1 tone ring on the flywheel. For that matter the ring gear should give an accurate measurement of piston placement(with all them teeth ) Now how do we sync them together...yep I'm thinking two sensors on the flywheel ..well hidden of course. Dang gumit Jeff why did you even bring this up?

[tevo]

what is the purpose for a small diamitor and lighter damper ?

[wrench459]

Originally Posted by tevo what is the purpose for a small diamitor and lighter damper ?

It depends on the rotating mass of the crank. There's times when you can't remove what's not there...so enters an damper to even things out and/or a weighted flywheel.
There's other methods to bring the crank back inline..like drill big holes/or adding heavy metal in the counter's to rock it back into balance.
HTH

[GTJIM]

Originally Posted by tevo what is the purpose for a small diameter and lighter damper ?

Mainly used on higher reving 'racing' engines to slow down the speed of the water pump and alternator at the higher revs where the motor operates.

Turn a water pump too fast and it stops pumping water - the impeller just spins in a 'hole' in the water! Also it takes LOTS more power to spin both water pumps and alternators faster - smaller pulley less power loss to them ... and a bit more power to feed back to the wheels!

Lighter because it is smaller and usually made from alloy. This also helps the engine 'rev' more quickly as there is less weight to be made spin faster.

As always - more to it than at first look!