28 replies to this topic

[Wedge]

I know this isn't that closely F1 related but I at least got a F1 manufacturer. Has anybody heard about the V5 engine that Honda are building for the World Superbike Championship (I think)? Just wondering how the engineers managed to balance the harmonics in it and what the firing orders would be.

[Ali_G]

I believe taht there is an old thread on this. Use the search function and check it out.

Niall

[Bluehair]

The V5 that Honda are building is for the 2002 GP Bike season. I don't remember where I read it, but I believe the construction of this engine has carefully matched the weight of the first 3 pistons and connecting rods to equal the rear 2 pistons and connecting rods. That is, the size of each of the first 3 cylinders are smaller than the rear 2. Or maybe that I'm wrong, and they'll use some other means of balancing the harmonics. I do recall reading that in one particular type of tune up, it was able to produce 260hp!

[Nathan]

Honda was "suppose" to have a 2.5-Liter V-5 made for the S2000 back when the concept was first released to the public. So Im going to go out on a limb and say I wouldnt doubt this, since they have previous (granted limite) experiance with it.

[Engineguy]

Originally posted by Nathan
Honda was "suppose" to have a 2.5-Liter V-5 made for the S2000 back when the concept was first released to the public. So Im going to go out on a limb and say I wouldnt doubt this, since they have previous (granted limite) experiance with it.

There has been a trend to put balance pretty far down on the list of priorities for pure racing engines. As bore:stroke ratios have climbed to well above 2:1, and titanium rods and ever decreasing crankpin diameters have become the norm, the imbalance forces have become managable, so packaging, friction reduction, and power potential come first... i.e. build whatever configuration suits your needs and live with the (micro) shakes.

The S2000 2.5L V5, with an emissions-driven bore/stroke of 87mm/84mm is an entirely different world from the F1 bike engine, and probably requires a balance shaft due to the long stroke. The 990cc V5, with only a 38mm stroke, was probably configured only for compact packaging and nearly evenly spaced power pulses.

[Engineguy]

Judging from the intake trumpet spacing, and the spark plug boot spacing, I'd guess this engine has three crankpins... the first and last crankpins each have a rod from one front and one rear cylinder, while the middle crankpin carries only the the rod from the center front cylinder. Nice package... narrower, obviously, than an inline 4, narrower than an inline 3 (because the bores would be bigger), perhaps even as narrow as a V4 (again, because the bores would be bigger).

[desmo]

Engineguy, good work. After reading your post and looking at the pic, I think you're right about the crank arrangement.

I wonder why the FIM allows more technical innovation than F1, the supposed pinnacle of motorsport? Sad really.

[Alex]

I've heard that they will not go with full 990cc displacement, but rather keep it somewhere around 800cc.

The reasons are supposedly increased weight and that too much power would simply chew that rear tyre.

[Engineguy]

Originally posted by Alex
I've heard that they will not go with full 990cc displacement, but rather keep it somewhere around 800cc.

The reasons are supposedly increased weight and that too much power would simply chew that rear tyre.

All kinds of rumors, but that would only decrease engine width 18 mm, decrease weight very little, and lose you 20% of your top end power. There are better ways to handle tire wear without getting smoked at any track with a long straight.

[Fudman]

Would it be possible to run this configuration, V5, as a Big Bang type motor? IE fire the front 3 cylinders then the rear 2 like a V Twin. Might solve some traction problems with 260HP? on tap...

For anyone interested in motor cycles especially or most people in this forum I'm sure, I can recommend The Britten Story video about the New Zealand built Britten V Twin bike. Absolutely staggering that they built a bike in a back shed that could blow away factory Ducati Superbikes at Daytona!

[wheel]

why not just build a v8 like drysdale engineering from australia. more cyls. more speed more power.

[Engineguy]

Originally posted by wheel
why not just build a v8 like drysdale engineering from australia. more cyls. more speed more power.

More cylinders does not always mean more power. At some point, friction increases overcome the valve area increase. Note that F1 3.0L engine designers settled on V10s over V12s when they had a choice... it was a borderline decision, and when it looked like new developments tilted it toward V12s, an economic decision was made to mandate V10s. If the choice between 300cc per cyl and 250cc per cyl was borderline for them, it looks like 4 cylinders would be ideal (for the 990) if pneumatic valve closure were legal. Perhaps metal valve springs are required(?), pushing Honda to 5 cylinders to boost the valvetrain RPM limit. More cylinders always equates to more weight and usually less efficient packaging also. Some are choosing inline 4s and some are choosing a V3 for these new regs. Note also that the 5 cyl gets a 22 pound weight break over a 6 or more cyl. And the V3 gets an additional 22 pound weight break! Pretty significant.

Four-stroke GP's: The Basic Regulations

Engine Displacement
Four-strokes maximum 990cc, two-strokes maximum 500cc
Minimum weights
Four-strokes, two/three cylinders 135kg
Four-strokes, two/three cylinders (oval pistons) 145kg
Four-strokes, four/five cylinders 145kg
Four-strokes, four or more cylinders (oval pistons) 155kg
Four-strokes, six or more cylinders 155kg
Two-strokes, four cylinders 130kg
Fuel tank capacity
Four-strokes, maximum 24 liters (22 liters from 2004)
Two-stroke, maximum 32 liters
Noise limits
Pre-race limit: 115 db(A)
Post-race limit: 120 db(A)
All other technical regulations according to current terms. Detail regulations still under discussion. Final regulations will be ratified "some time before the end of 2000."

[desmo]

Engineguy wrote: "At some point, friction increases
overcome the valve area increase."

Actually counter to intuitive reasoning, an increase in cylinder multiplicity does not mean necessarily higher frictional losses. From SAE Paper 983035 "Comparison of V10 and V12 F1 Engines" by Boretti and Cantore:

"The V12 engine has a mep(f) always smaller than the mep(f) of the V10 running at the same speed. Opposite to series engines running low Rpms, where increasing the number of cylinders means increased friction, in racing engines running high Rpms, friction reduces by increasing the number of cylinders."

[Engineguy]

Originally posted by desmo
"The V12 engine has a mep(f) always smaller than the mep(f) of the V10 running at the same speed. Opposite to series engines running low Rpms, where increasing the number of cylinders means increased friction, in racing engines running high Rpms, friction reduces by increasing the number of cylinders."

Are they comparing existing or hypothetical engines? You should compare engines of identical bore/stroke ratio and indentical rod_length/stroke ratio to keep rod angularity differences from skewing the results. Also note it says "running at the same speed" which ignores the principal reason for running more cylinders; to overcome RPM limitations and run more RPMs.

I'll have to download the paper and see what their reasoning and proof is. Those names sound Italian... maybe they're partial to V12s. I'm anxious to see at what RPM the laws of physics reverse themselves!

[Halfwitt]

Originally posted by Engineguy

I'll have to download the paper and see what their reasoning and proof is. Those names sound Italian... maybe they're partial to V12s. I'm anxious to see at what RPM the laws of physics reverse themselves!

I've seen the paper. These chaps are obviously big V12 fans. As I remember it, they seem to be quite biased toward the V12 from the outset. I'm with you on this one Engineguy, running at optimal conditions, a V12 might have more power, but also with increased friction. Years ago people tried building 10 cylinder 500cc two-stroke GP bikes (1970's: 10 x ITOM 50cc cylinder on a common crankcase). It failed dismally, as frictional losses were so high

[desmo]

Engineguy- Sorry I missed your post. I'll try to provide some answers to your questions.

Are they comparing existing or hypothetical engines?

"Computations are performed here by using the WAVE code that is developed by Ricardo North America...Friction values are obtained by using a certainly less reliable empirical method. Such technique represents typical rapid methods that are often used to obtain a feel for a complex subject based on a limited amount of experimental data. Consequently, results in term of friction and brake values have to be considered very carefully."

This paper was written by engineers working on Ferrari's F1 engine development program. The caveats about the results give pause, but I wouldn't discount their observations simply because they do not meet fully scientific standards of repeatability, transparancy and peer review. The logistics of developing racing engines necessarily doesn't allow for the time or money to work to scientific standards.

You should compare engines of identical bore/stroke ratio and indentical rod_length/stroke ratio to keep rod angularity differences from skewing the results.

"We consider engines of similar design, having the same displacement, but a different number of cylinders. Engines have equal bore/stroke, connecting rod length/stroke, intake and exhaust valve diameter/bore ratios, and equal maximum power mean piston speed."

The authors acknowledge the effect of rpm on friction correctly noting that many of the friction pressures are a function of rpm squared.

My gut says that the increase in the area of the cylinder swept area, port area, bearing area etc. would likely result in a higher friction pressure for more cylinders all else being equal or as equal as is practical, but I am by no means confident enough in my intuition to challenge the findings of this paper.

Halfwitt- unless I am way off base there were no 10 cylinder GP bikes 2 or 4 stroke. Guzzi's V-8 and Honda's pseudo V-8 NR- both 4 strokes- were as close as anyone ever got. In fact I cannot recall a 2 stroke GP bike with more than 4 cylinders although perhaps they have been tried.

[Halfwitt]

It was built by those most interesting and enterprising bunch in motorcycle sport: The sidecar men. It was in the seventies, and might never have raced in anger, but I saw a picture in Motor Cycle News if I remember rightly.

I can't recall any other two-strokes with more than 4 cylinders, but I am sure someone must have tried it.

[DangerMouse]

fudman looks like it is a big bang engine....


here's a snippet from a trackside observer about the V5 after it's first run (from MCN)


"We know the engine is a water-cooled V5, with cylinders in three-forward/two-backward formation, but that's about it.
The exact capacity is still secret, as is the firing order of the engine or how Honda have balanced it, but a clue to both of those questions comes in the reported sound of the engine: despite having more than twice as many cylinders as something like a VTR1000 SP-1, observers said it sounded just like a massive V-twin.
This could mean that Honda are firing each bank of cylinders separately, with the front three in one big bang and the rear two in a smaller bang, and adding a balance shaft to the rear two-cylinder bank to balance it against the front trio."

[desmo]

Engineguy, if you PM me with your mailing address, I'd be happy to let you borrow my copy of the SAE paper Comparison of V10 and V12 F1 Engines. It'll save you 10 bucks!

[MN]

Jun/16/2001, Spain

Honda RC211V
4-stroke V5, 20 valves, 990cc, V-angle=75.5, No balancer, Engine weight=NSR500 x 110%

[Isamu]

What a beautiful looking bike

thanx for the pics MN:up:

[Wolf]

Is it just me, or are those 10% for almost twice as much displacement AND strokes, a bit too small a weight increase? I mean, for entire bike it would be OK, I guess- but for just an engine....

[desmo]

I agree Wolf. If that figure is correct, that can only mean the NSR500 engine was massively overweight. I actually read it at first as NR500, so it seemed semi-plausible.

[MN]

Originally posted by Wolf
Is it just me, or are those 10% for almost twice as much displacement AND strokes, a bit too small a weight increase? I mean, for entire bike it would be OK, I guess- but for just an engine....

Well, I'm pretty sure that they can make it even lighter if they
wish to but the minimum weight required by FIM regurations is rather heavy.

135Kg: 3 cyl or less
145Kg: 4 or 5 cyl
155Kg: 6 cyl

[Halfwitt]

Originally posted by desmo
I agree Wolf. If that figure is correct, that can only mean the NSR500 engine was massively overweight. I actually read it at first as NR500, so it seemed semi-plausible.

Might it be that the engine was made deliberately overweight to get the C of G right? When they increased bike weight from 115 to 135 kg the scope was there to do this.

[desmo]

I would think one would build every component as light as practical so that ballast could be used to fine tune the CofG placement as in F1. I know on GP bikes the engine is already pretty close to the ideal location for a concentrated mass, so perhaps. For braking/acceleration on a bike an ultra low CofG is best, but as was discovered with the experimental Elf bike with the fuel tank below the engine, if the CofG gets too far below the roll axis it can negatively affect the turn-in ability.

[nzkarit]

Originally posted by Fudman

For anyone interested in motor cycles especially or most people in this forum I'm sure, I can recommend The Britten Story video about the New Zealand built Britten V Twin bike. Absolutely staggering that they built a bike in a back shed that could blow away factory Ducati Superbikes at Daytona!

There wind tunnel was one guy sitting on the bike and another guy looking to see if it looked good.

If you want to know more about eh Brittens have a look at http://www.britten.co.nz/

[MN]

Aug 7~8, RC211V first test at Suzuka.

[nivas]

Here it is, the new wonder from Honda, listen to the sound of it, sounds really cool. (RealPlayer needed)

http://www.tochigine...A/wgp/rc211v.rm