Engine braking - empirical measurement?

There are lots of threads talking about the engine braking of a V-twin vs an IL4 and how there is "more."

How does one measure engine braking? I've never seen any metric for measuring it Personally, I never noticed a huge difference moving between the two so how could one prove that a K8 SV has more engine braking than a K8 GSXR600?

I'd also like to know how much mechanical stress engine braking puts upon an engine.

I don't use engine braking whatsoever (having a slipper clutch fitted doesn't really give you much choice! ) but don't really understand what the advantage is over the front brakes which IMO are far more effective and come with every motorcycle regardless of engine configuration!

Don't want to start a p!ssing contest - I'm genuinely curious

Engines are for go, brakes are for slow - that's what my driving instructor told me.

Personally I can't see why some people get so fixated on one type of engine configuration - like they have to ride a V-twin, or an IL4, or a triple etc. Engines are engines and no two IL4s are the same, in as much as a Bandit 650 motor has completely different characteristics to a ZX10R, and a Harley V-twin is a different kettle of worms to a TL1000 engine.

Originally Posted by lukemillar

Don't want to start a p!ssing contest - I'm genuinely curious

I'm curious too, and there does not appear to be an answer to my question (or your's!)

Originally Posted by Lozzo

Personally I can't see why some people get so fixated on one type of engine configuration - like they have to ride a V-twin, or an IL4, or a triple etc. Engines are engines and no two IL4s are the same, in as much as a Bandit 650 motor has completely different characteristics to a ZX10R, and a Harley V-twin is a different kettle of worms to a TL1000 engine.

I absolutely agree, and this is really not a pro IL4 or pro V-twin thread but I am interested in the truth of the commonly found statements on here; "you'll miss the engine braking" or "IL4's have no engine braking" and the suchlike. How do you actually compare the effects on any two bikes, regardless of configuration? (I only gave the SV/GSXR as an example)

[ophic]

One of the magazines compared a TL with some other bikes a loooong time ago. They discovered that it didn't have much more engine braking at all and said that the weight of the flywheel had greater impact, or some such. However I wasn't convinced.

Discussed it with YC a while back about what causes engine braking. I always thought it was the cylinders pulling a vacuum against a closed throttle. YC tested it by flicking off the kill switch on a long hill and opening the throttle. He reported that it made no difference at all.

I can't see it causing any stress to the engine - it's putting a lot less force through the components than moderate or hard acceleration.

[G]

I feel my 600rr has plenty of engine breaking.

However...

when following Pete, Spiers, Binky etc on twins... I quite often end up having to use my brakes when they are slowing down rapidly just on the engine braking. So there is a fair bit more, obviously.

I think it is a handy thing to have on tight down hill section of road where your on the brakes alot creating alot heat.

[dizzyblonde]

Originally Posted by ophic

I can't see it causing any stress to the engine - it's putting a lot less force through the components than moderate or hard acceleration.

Well quite or we'd have a lot of broken bikes around.

Myself and Peg have chatted about engine braking, and how we use our brakes. Even on the Raptor I use the engine rather than the brakes(more as they need a clean and I'd be over the front!). I conciously/naturally use what I have in the engine, rather than pulling on levers, Peg does the same on the ZZR, SVs or Raptor. All entirely different bikes completely opposite end of scales.
Obviously its all different if the brakes are needed to be pulled, but in controlled situations both of us use engine first.

Its all down to rider rather than bike I think.

Originally Posted by G

when following Pete, Spiers, Binky etc on twins... I quite often end up having to use my brakes when they are slowing down rapidly just on the engine braking. So there is a fair bit more, obviously.

I'm not disputing that there is more, but how much more?

When you roll off the throttle there are several forces acting on the package to slow you down. At the higher speeds there is a larger aerodynamic effect and we know that not all bikes are aerodynamically equal for instance.

[ophic]

Originally Posted by simesb

I'm not disputing that there is more, but how much more?

It must be measurable on a dyno, but whether the feature is actually available would depend on what the attached software could do.

[yorkie_chris]

Originally Posted by simesb

There are lots of threads talking about the engine braking of a V-twin vs an IL4 and how there is "more."

How does one measure engine braking? I've never seen any metric for measuring it Personally, I never noticed a huge difference moving between the two so how could one prove that a K8 SV has more engine braking than a K8 GSXR600?

You could easily test it with some sort of dyno. I'm not sure the common inertia type would be the best thing to use, but it's doable.

You'd end up with a simple curve of torque vs rpm just same as when on the power. I am guessing a v^2 shape curve.

Originally Posted by lukemillar

I'd also like to know how much mechanical stress engine braking puts upon an engine.

Next to none.
Low cylinder pressure differences, so your crank bearings are just spinning freely with no big impact loads.

About the only thing which could plausibly be affected is gears and such which have the stress on the opposite side of the teeth in engine braking, but they're strong enough* to get hammered when you open the throttle, and tend to be near as damnit symmetrical, no reason that can hurt them.

The one thing which is damned dangerous about engine braking is if you downshift too fast and over-rev it. Which will grenade anything!

Originally Posted by simesb

I absolutely agree, and this is really not a pro IL4 or pro V-twin thread but I am interested in the truth of the commonly found statements on here; "you'll miss the engine braking" or "IL4's have no engine braking" and the suchlike. How do you actually compare the effects on any two bikes, regardless of configuration? (I only gave the SV/GSXR as an example)

Truth is both bikes have enough engine braking to slip the back tyre when braking, but I find twins have more useful engine braking lower in the rev range for around town and such and certainly more in the high rpm range.

Comparing it, I'd say just the butt dyno works fine. If someone tries both and thinks the IL4 has less (or more) then that is just as valid even if the figures showed the opposite.

Same thing with power delivery, you can have a more powerful engine which feels gutless, if it makes its power more smoothly!