How are resonance and harmonics are dealt with in ICE?

[The_r1_kid]

Hello all. I love this forum and spend a lot of time here. Thanks everyone for contributing. I finally have a question.
Would anyone care to dive deeper into engine harmonics and frequencies and how they are canceled, damped, or other wise dealt with?

secondary questions:
How do you figure out how to size a balance shaft to smooth out an imbalanced engine? like the big bang moto gp
engines, the street going Yamaha R1, or a lawnmower.

How does the V angle effect the balance of the engine?

Then there is torsional forces from each combustion event. It seems as though GP engines and sportbikes don't bother with any real dampening like car engines do how do they get away with it, or do they?

If you happen to know of any papers texts articles or books that would be greatly appreciated.

[Tommy Cookers]

.... torsional forces from each combustion event. It seems as though GP engines and sportbikes don't bother with any real dampening like car engines do how do they get away with it, or do they?

How does the V angle effect the balance of the engine?

... How do you figure out how to size a balance shaft to smooth out an imbalanced engine? like the big bang moto gp
engines, the street going Yamaha R1, or a lawnmower.

a road car crankshaft has power takeoff at the end and a lot of flywheel at the end
so its natural frequency is low enough to need a damper
a GP or road bike crankshaft has central or other non-end takeoff and no flywheel
it behaves rather like 2 very short crankshafts would
so its natural frequency can be high enough not to need a damper
torsionals come from power strokes (but also from reciprocational inertial loads)
we know about the 1960s US Ford Indy 7200 rpm dohc 32 valve V8 (related to the production smallblock)
without a damper the crankshaft would have failed at around 6000 rpm (4th order peak) or 8000 rpm (3rd order peak)
fatigue becoming catastrophically quick above about +- 0.25 degree torsional deflection


a 90 degree (or nearly 90 deg) V angle is very handy (eg much F1 since the 1970s)
a 90 deg V twin (with right amount of in-crankshaft counterbalance) has no vibration at engine frequency ('primary')
so by extension cranks for 90 deg bank V4s with no primary force vibration can be with ....
(uneven) firing twice or once per rev eg Honda NR500 and race VFR or road VFR engines or the predictable even firing
uneven firing giving the stronger & smaller crankshaft


on M1/R1 and 270 deg twins and balance shafts etc there's been years of detailed 'discussion' in the 2 Stroke thread
and on so-called 'big bang' - whatever people mean by that
most of the detail in posts by manolis

[Maritimer]

I know the 4G63 in my Talon has a damper on the front end of the crank as well as a balance shaft in the block, but they're exceptionally buzzy engines.

Many road car motors will only have a damper on the crank, some engines like I4s or the Triton V10s have balance shafts as well.

[Greg Locock]

Big I4s need a balancer shaft and various ungodly V engines would benefit from one. I used to tune TV dampers and bending dampers by ear as a party piece - it was easier to get the tune roughly right on a car and then get them signed off on the dyno.

Your front pulley may be a combined TV and bending damper. There are a few engines where a bending damper is needed, but generally they are there to improve refinement. TV dampers are needed for durability.

[Zynerji]

Big I4s need a balancer shaft and various ungodly V engines would benefit from one. I used to tune TV dampers and bending dampers by ear as a party piece - it was easier to get the tune roughly right on a car and then get them signed off on the dyno.

Your front pulley may be a combined TV and bending damper. There are a few engines where a bending damper is needed, but generally they are there to improve refinement. TV dampers are needed for durability.

How do you tune dampers? I've seen video of them showing what frequencies they dampen, but I always took that as how you "ordered" custom ones... By providing frequencies that you need dampened, and it comes made for those specific ones.

Can you tune viscous dampers in the field?

[Greg Locock]

I'm talking about the rubber ones. You have to know the sound of the engine, TVs and bending are quite easy to pick, we used to call it combustion harshness, basically a rough sounding quality to the noise. I couldn't do it on an engine I hadn't spent time listening to, but did one in a day on a new engine, Isuzu piazza turbo, if anybody cares!

It's much easier with instrumentation obviously, and that's actually how I tune into the subjective problem.

[coaster]

I read somewhere the Indy Buick V6 had crankshaft damper called a 'rattle', the bob weights were loose and allowed to clunk about minutely to adapt to the different frequencies.
It is rumoured many F1 V10 camshafts had rattles at the opposite end of the driven side, this information has had limited sharing as it is of continued relevance to F1.

[Greg Locock]

Yup, untuned dampers have been used since about 1920. Other alternatives to bob weights are chambers partly filled with sand, and of course uncoupled flywheels embedded in fluid.

The advantage of these untuned systems (bit of a misnomer, they are still 'sized') is that they work on a wide range of frequencies. The disadvantage is that the maximum attenuation is limited in comparison with a tuned absorber of the same size.

[coaster]

Hey Greg, i saw a pencil sketch online of the toyota V10 dampers which looked like a hybrid of those 2 principals, the 10? cyindrical weights on a pitch circle spacing were sandwiched between large belville washers terminating on the weights centreline.
A dampered damper.

[Zynerji]

Could you, theoretically, cut a slot in the Hbeam of a connecting rod, and pop in a tuned mass damper to combat these frequencies?

[J.A.W.]

Could you, theoretically, cut a slot in the Hbeam of a connecting rod, and pop in a tuned mass damper to combat these frequencies?

Or use a hollow conrod, & 1/2 fill it with a solution-suspended matrix for damping purposes...

Member here 'manolis' has a site in which he presents his ideas to deal with this - maybe that 'big claim'
outboard motor company you've posted on another thread - is using his system?

https://pattakon.com/pattakonVRA.htm

[coaster]

Greg or Billzilla might know, those ideas sound absolutely fantastic to me, you better get it time stamped and witnessed i reckon.

[Greg Locock]

New ones on me. I think the conrod engineer would have a fit.

[palaboran]

A bit off-topic but resonance reminded me. How many kW are lost in the noise of the exhaust and how many absorbed by the turbo charger?

[Billzilla]

Greg or Billzilla might know, those ideas sound absolutely fantastic to me, you better get it time stamped and witnessed i reckon.

Definitely not me sorry - I started drawing-up a small V8 engine in CAD and when I got to the crankshaft I rapidly realised I don't know anywhere near enough to get it right first-time.