Here’s a bike most motorcycle folks have never heard of, the Harley Davidson V4 Nova. Bob Horn brought this up in a comment yesterday and pointed to a pretty interesting page that tells the story of a motorcycle that might have been and I thought it deserved a story of its own.
At the time the Shovelhead’s replacement was being designed (the engine that eventually became the Evolution V-Twin), another engine and motorcycle combination was in the works. The Nova project was to be a smaller displacement family of high tech water cooled engines in V-Twin, V4 and V6 configurations. The cylinder sizes of either 200cc or 250cc gave engine size options ranging from a 400cc V-Twin to a 1500cc V6, and lots of interchangeable parts. The heads were 2 valve overhead cam with the potential for 4 valves at a later time.
Although the project had advanced to where they had 30 engines and 12 running motorcycles, it was never produced, a casualty of the AMF years.
The article is fascinating and if you are interested in H-D technology it’s worth reading the whole thing. Thanks for the pointer, Bob!
Link: HD Nova Project link is dead
Frank says
A very interesting read. A few interesting FACTS from the article:
-HD “imported†performance just like the sport bike riders, like myself, that buy the Japanese and Italian sport bikes. When HD wanted to build their high performing NOVA they went over seas to England and Germany. Why didn’t they go across the street to Chevy, Mopar, or Ford? HD has the most loyal fan base of any bike maker. HD fans even tatoo themselves with the HD logo. One of their chief reasons for their loyalty to HD they say is because it is made in America. It’s ironic that HD doesn’t share their fans loyalty to America.
-The V4 engine in the NOVA was at a 60 degree angle. All of the top performing vtwin bikes out today use a 60+ degree vtwin. Ducatis and the Honda RC51 both use 90 degree vtwins. The Aprilia motorcycle uses a 75 degree vtwin. 60 degrees is the minimum angle where the firing of one cylinder doesn’t cancel the power of the other cylinder. On 45 degree vtwins, such as the ones HD uses, heavy counter weights are needed to keep the motors momentum turning and also to keep it from shaking to kingdom come. This robs horse power and makes the engine run slow. It’s no surprise the NOVA uses a 60 degree twin as HDs engineers understand the benefits and draw backs of different engine angles far better than I can. If you want high performance the air cooled 45 degree twin has huge draw backs.
-The engine in the NOVA was water cooled. I’ve read articles where water cooling allows for closer tolerances and high performance. The air cooled 45 degree twin needs to stay in the rolling sofas or in the bicycle frames from which it was born. It doesn’t belong in a sport bike. There are too many better alternatives available.
Bob Horn says
Frank,
Harley designed their engines (something which often gets mistaken) – they farmed out the development. Porsche, at the time, had the best R&D house in the world. Detroit was busy doing such technological tour de farces as the Fairmont and Citation. When Chevy wanted the Vega to go faster, they went to Cosworth. Remember the Ford V8 that was winning hundreds of F1 races in the ’70’s? It was designed and built by Cosworth, in England. Chrysler was doing its best to go out of business, only to get saved by a government loan and come out with FWD cars – based on VW engines and with some models from Mitsubishi.
Please explain the air cooled engines in Ducati, Moto Guzzi, and BMW sportbikes. Oh yes – in LOTS of water cooled engines, the tolerances are GREATER since the piston heats up faster than the water cooled cylinder can. The main reason for water cooled engines is noise management, not power or tolerances.
It is impossible for one cylinder to “cancel out the power” of another cylinder in any engine configuration as long as all the cylinders are firing. Totally and completely impossible.
kneeslider says
I’m leaving Frank’s comment in here since Bob already responded, however, as a general guide for everyone, if you make a comment on one post and want to respond on another, DO NOT just copy your first comment to the new story. Respond separately or refer to the prior comment, otherwise, one will be deleted.
Thanks
hoyt says
Is the debate about “cancelling power from one cylinder” more about the TERMS used to describe what is going on than the reality of the big picture?
If we agree that heavier counter weights need to be used in a 45 degree v-twin than a 60+ degree v-twin, then we could move forward with more of the discussion. The counter weight isn’t technically “cancelling” the power made by that cylinder is it?
I might agree that the heavier counter weight would make the engine’s OVERALL efficiency to take the power made (with each piston stroke) & put it to the rear wheel more challenging. Otherwise, what else besides valve train & head design (airflow & combustion chamber) would account for the difference in power output made by a v-twin with 60 degrees or greater as compared to a v-twin of 45 degrees?
For example, compare the beautiful billet engines from TP Engineering, Patrick Racing, etc. to some other designs. As impressive as the torque & hp ratings of the billet 45 degree twins are, I have often wondered what an equivalent-size of those engines would produce if it was a different design than the 45-degree.
We are starting to see some of those differences with engines like the X-Wedge and the Big Bore (Guzzi application). See http://www.bigbore.it/
The Big Bore is an interesting comparison. It looks like it uses the stock engine block with modified cylinders & heads (i.e. the stock block is an air-cooled design, but the cylinders are modified for some trick water cooling). This engine is 1420 cc & makes 160 hp. By comparison, the aftermarket billet 45-degree v-twins (such as Patrick Racing used on the Ecosse Heretic, which is 1966cc) makes 130 hp at the rear wheel. We’re talking about another whole motorcycle in engine-size difference!
Ok, there are differences such as water cooling & the Big Bore states it is for racing only (so does the Patrick Racing engine). Assuming the Big Bore has a restrictive exhaust & airflow adapted to it to make it street legal like the Ecosse probably had to do to some degreee, this still doesn’t make up for the difference in ratios of cc size to power generated.
So, what is holding the 45 degree design back from making more power? The smaller engines with a wider v design are making a disproporationately greater amount of power.
hoyt says
I forgot to add some other thoughts….
1. I’ve been wanting a moto publication to run an in-depth story about the differences of v-twins for 10 years. You would think it would need to take into account valve-train & head design, too.
This would make for excellent reading.
My last count of various sport/performance twin designs include:
boxer, 90, 87 (Moto Morini), 75, 72 (Voxan), 60, 45, 15. Also include parallel twins.
2. Does the Moto Czsyz design throw too much of a big wrench into this discussion? (sorry, couldn’t resist the pun)
Seriously, there could be some good parallels to pull into the discussion above with the Z4 from Czsyz. They have a very narrow v-angle but are smoothing things out with counter-rotating cranks instead of heavy counter weights. They seem to be pleased with the power, but apparently that has been a significant challenge with that design in relation to making similar power output with other designs.
todd says
I don’t care whether it is 45 or 60 degrees.
I’d like to comment on the AMF Nova. I think HArley was right on having a higgh tech engine development company such as Porsche engineer its motors. It’s too bad that AMF didn’t decide to go forward with the development despite the huge investment already made. Who knows, Harley might actually be considered a contender in modern motrcycling and not just a novelty/merchandising company.
I also think it’s interesting that the radiator was considered to be a styling blemish. I think the compromises that had to be made to accommodate the under seat radiator and side-saddle tanks is worse than a simple raiator out front. If the design had a conventional radiator and gas tank it might not have been looked at as such a risky venture. In fact, probably half of the development costs went to these unusual accommodations.
Harley is very quiet about development. Rightly so, just think of how many BMW purists were complaining about the posble loss of the boxer. Remember when Porsche was considering abandoning the 911 / air cooled configuration? Maybe, just maybe Harley continues to develop a competitive motorcycle and bikes like the V-rod and the Euro only Cafe bikes are test beds to determine public reception to alternative thinking.
Let’s hope the sleeping giant awakes.
-todd
zipidachimp says
whatever happened to the ducati apollo v-4? maybe because it was butt-ugly!
not every idea comes out a winner.
Bob Horn says
The V angle has as much to do with power as the brand name on the gas tank – nothing.
A parallel twin (with 360 degree crank) is nothing more than a zero degree angle V twin. The V angle has no bearing whatsoever on the crank mass requirements. The V angle has NO effect at all on combustion chamber shape, size, valve number, port configuration, or anything else.
A radial aircraft engine (especially a multi-row one) has the lowest V angle and the closest “firing intervals” of any engine – period. They are also the most powerful.
It is all just packaging and/or marketing gimmicks. There are LOTS of techno-placebos and design gimmicks in the motorcycle world which have far more to do with marketing than any functional merit. That applies, in my opinion, to every single motorcycle company to one degree or another. Which keeps things from getting deadly dull.
davidabl says
In this discussion I think that we ned to remember that water cooling will
be mandantory for emissions reasons in 2008 (and not just in the USA)
hoyt says
Todd – a large portion of the discussion between RH & Frank is revolving around 45 or 60, etc., especially when it pertains to HD. This also played a role in the Nova’s demise.
Bob – thanks – I realize there are much greater principles at play related to power generation than just the simple angle of the cylinders. But, considering the balance of a 90 degree & 180 degree v, boxer, etc. compared to other designs, the angle of separation does seem to enter the equation.
I’ve read about Voxan experimenting in increments of 1 degree at a time, until they arrived at the desired 72-degree v-twin. S & S stated they were interested in managing secondary vibration better by moving out to 56 degrees.
Sure, this doesn’t directly speak to “power generation”; but the overall big picture of an engine includes: reliable, rider-friendly, easily-packaged, power. This seems to speak to more than just marketing gimmicks.
There is at least primary & secondary forces at play that affect the overall performance. Whether that performance is internally affected by the engine itself or by the engine negatively impacting the rider’s performance due to insane vibration are topics that the engineers must consider.
hoyt says
b-t-w…..cheers to Willie G for taking a stance on the radiator styling.
Todd brings up good points related to the cost/benefit of alternative radiator placement. Nonetheless, if we keep trying, liquid cooled bikes could look as good and simple as air-cooled bikes some day.
Maybe a design contest for best-looking, fully functional radiator contest is in oder for Glynn Kerr’s MDA….?
OL Glover says
Just my opinion… but… Somewhere along the way HD decided that they didn’t want to or could not compete in a world of modern motorcycles. As a consequence, they gave up and became a company that sells t-shirts and ash trays. The build just enough of a motorcycle to sell the HD branded merchandise. I think it is a shame. I would never consider buying any of the tired old air cooled v-twins and I fear that as soon as their current crop of nostalgia seeking customers stop riding the company will decay back into the state it was in when AMF purchased it.
I wish the Nova had been a success. It might have morphed into something that I would want to buy today.
This may sound like I’m bashing HD. I’m not trying to. I would like to buy a motorcycle from HD, if only the build something that I wanted. Of course the price would need to be competitive. Current models are not. Give me something like the Buell Ulysses with a modern engine like the V-Rod engine. The V-Rod engine proves that HD can (at this time) do it. But they won’t. I think they would sell a lot of a bike like this. The only problem is, they probably would not sell a lot of t-shirts and ash trays to go along with it.
I fear that I may never be a Harley customer…….
aaron says
I was oing to read the article, but the headline turned me off. I’ve seen it. if anyone else wants to, go to the trev deely museum in vancouver. many deride it, but this bike struck me as being essentially a Vmax – only several years earlier. could you imagine how much greater the vmax’s legend would be if it were american made, 300cc bigger and with 2 extra cylinders?
wow – talk about a missed opportunity! especially with the huge tarrifs the US government mandated for big bore japanese bikes a few years later…
Bob Horn says
Hoyt,
I’d bet that if someone were to take the Voxan stroke/rod length/piston height – and played with the V angles on a piece of paper, that the 72 degrees does make the most power – because less than that would make the pistons crash.
If I read Kevin Cameron’s X-Wedge article right and remember correctly, the V angle was chosen partially due to the timing of the fuel injection triggering mechanism.
A 90 degree engine is the “perfect” angle for balance.
Of all the V twin angles out there right now, the 45 provides the greatest “minor” separation between firing intervals – 315 degrees/405 degrees. A 90 degree will fire every 270/450 degrees. A boxer twin with 180 crank (all Beemers) does the same thing as a parallel twin with a 360 degree crank. Some parallel twins have been built with 90 degree cranks.
V Fours have been built with 360 degree cranks and 180 degree cranks – the “merits” of which have been argued and didn’t make any real sense anyway. They do sound different.
Dodgy says
Apart from the fact that we all seem to have been distracted from the point of the original post (thanks Paul) by all approaching it from different angles (Ha Ha)… Things like making smaller capacity engines, four and six cylinder versions, and attracting ‘new’ customers with new technology (not just ‘lifestyle’), a balnce shaft to reduce vibration!? What? HD actually acknowledged that vibration was a problem, not a selling point? And fuel injection?
A couple of things do seem to limit the performance of the HD configuration, the very narrow angle makes filling the combustion chamber problematic, just getting a straight shot at both inlets is virtually impossible (basically they end up running a very inefficient right angle siamesed manifold). The knife and fork rod design keeps the cylinders inline which looks good I suppose, and makes the engine fairly unique, but must also limit the possibilities for improving intake efficiency.
The 45 degree angle should make the engine reasonably compact, but running a ‘traditional’ primary drive/gearbox setup doesn’t take advantage of this compared to the designs that are ‘possible’. The long stroke and 45 degree angle (presumably) force the cylinders to be taller than the same ratios with a wider angle. The long stroke engine cannot develop power efficiently because it cannot rev… The mean piston speeds simply limit it to much, and regardless of what tuners manage to extract from them, exactly the same amount of effort applied to a short stroke engine WILL get you MORE power.
And the winner is? Apart from having the most stupid riding position ever…
“V Rod Revolution, designed and developed by Porsche in Germany, 2002-present, 69 cubic inches (1.13 L), 60 degree V-twin, Liquid cooled.”
And “over-square 100 x 72 millimeter (3.94 x 2.83 inch) bore and stroke”
Sean says
I personally can’t believe that Harley was actually considering changing their old 45 degree V twin with a single crank pin, the engine configuration that makes the sound they’re trying to trademark (or have already, I never really got the point of that exercise), and what’s more they were trying to make it a competitive engine in a competitive configuration on a competitive bike. I’ll never own a Harley, except that italian one they did back in the 60s or something. That was a nice bike.
chris says
i don’t see how any of this matters. we’re all going to be mandated into riding electro-hydrogen-biodiesel bikes soon enough. 🙂
bob says
Several comments:
– Nowhere will water cooling be “mandantory” for emissions reasons in 2008 (or any other year). I can assure you that there will be plenty of air cooled motorcycles from all over the world still available in ’08 & beyond.
– Second order engine vibration is not cancelled in any engine configurations except inline sixes, V-12s & most V-8s. The only way to eliminate second order vibrations in other engine configurations is to add balance shafts.
– Second order engine vibration acts along the cylinder axis. This means in an inline four the second order vibrations are additive, in the plane of the cylinders. That’s why balance shafts are so common on fours. In a parallel twin (with a 180deg or 360deg crank) the forces are still additive. In a 45deg V Twin, the forces are spread out a little. In a 90deg V twin half of the secondary forces are aligned with one cylinder & the other half are aligned with the other cylinder, so half the force is “forward” (in bike space) & half is “vertical”. If S&S opened up the V angle on the X-Wedge to better manage secondary vibration, they must have been trying to separate the cylinders a little bit so the summed forces were closer to a 90deg V & less like a parallel twin.
– If anyone thinks that H-D farmed out the Nova development because they were incapable of doing the work, please go back & read the article at bikerenews.com. “Harley’s engineering resources would be severely stretched with both (the Nova & the Evo) programs”. I don’t know about you, but if someone came to me & said, “You will now have to start doing twice as much work as before because we have twice as many projects now” I would tell them they would have to find someone else, because I can’t just double my output for the wanting. The article explains that the project was farmed out because there were not enough resources (people) within H-D to support both programs. Doesn’t it make sense to keep the project you’re most familiar with inside & farm out the new technology?
davidabl says
I hope Bob is right re water cooling not becoming compulsory..I’m not sure where i read it. Air- cooled bikes certainly have more “soul’
btw, cancellation of the Nova project means that the last innovative Harley was
the Knucklehead in 1936.
buzzer says
I have no opinion on the subjct at hand but I wanted to thank you for the education i have received from reading the above posts. Cheers
Chris says
Too bad Hardly won’t build something like this. They could get the other half of the market that wants performance and technology in their machines. I bought a VAlkyrie instead. DOA Cycle
chris says
being as how this has turned into a conversation on engine tech. . . any idea how a motorcycle engine would do with direct injection? from what i understand of the technology – there should be no trouble, and a whole lot of benefits. so, anybody know anything?
Bryce says
I doubt that water cooling will become mandatory, but it will likely become more common. What I think is likely is that manufacturers will be given a target for emissions, and then market forces dictate a certain power and torque output for a given displacement. As that happens, it will be easier to meet emissions goals and hit performance targets with liquid cooling.
todd says
Water cooling helps to a much greater extent in noise suppression. It has a small affect on emmisions. Actually a hotter engine burns cleaner but the tolerances are more difficult to control. Since an air cooled cylinder’s fins are very efficient they take a while to warm up. Most people drive away before the engine is up to operating temp (rightly so). A water cooled engine allows the cooling to be moderated by a thermostat. It will keep the water from flowing until it (quickly) reaches the optimum temp. There is no easy way to do this on an air cooled motor. The greater clearances that are required to allow a motor to be driven under power before it has reached optimal temperatures and then stretch and grow until it does allow a small amount of blow-by. Fuel injection has helped by giving the appropriate mixtures at more opportune times but in a cooler-longer air cooled motor those mixtures must contain more fuel for a longer period of time.
The noise of these added clearances and how they are amplified by the cooling fins is no trivial matter. Some bikes’ styling allows the fitment of a full fairing to deflect some of the noise but for the popular “naked” bikes and cruisers there is no such opportunity. Either the engine is detuned as in the typical Harley case or is water cooled like most evey one else. Drive chains are the next noisiest next to tires, the bulk of the noise. Eventually most bikes will begin changing to belt drive or some sort of composite chain.
-todd
Sean says
But todd, then how will we get our hands hopelessly dirty every time it needs an oiling? Actually, a question for all you engine buffs. What is the ideal crank rotation and cylinder angle for greatest power and smoothest running?
Pete says
It would have been nice if Harley built that ugly thing.It would have been something if they were able to turn it into a sweet crotch rocket of some sort in order to compete in the sport rider market. I love and own a Harley, but they really need to make a sweet sprot bike that can compete at the same level as the Gixxers/Z’s/CBR’s”YZF’s and the Busa and ZX-14. Wouldnt it be something to see the bar and sheild running in the pack with these. Sure there is the Buell, but they are all about corners, I like them sure, but I still want to be able to keep up on the straight aways without redlining the damn thing. Harley should bring back their dirt bikes too. The old MX 250(I’ve read anyway) was a damn good bike in its day,if not one of the best, but had suspension dificulties or something of the sort. Then it was dumped after only two or three years before it could be improved.Patiently waiting Pete
OTTOMAN says
MY QUESTION IS WHAT ADVANTAGE WOULD A WATER COOLED {IF [POSSIBLE} EVO MOTOR HAVE
E. Rick Dunbar says
well folks
how would you like the real deal
in fact was looking for V2+2 Engineering in Portland Or. old address is 2106 N.E. Junior St.
if you have access to Iron Horse mag. has #133 printed in april 1995 issn 0195-1165 volume 18,no.4, issue 133
i have the story from the horse’s mouth 🙂
it’s only two pages + 5 pic’s
if iron horse can’t send it to you i’ll try
rick dunbar “the coyote”
149 leger dr
opelousas la 70570
p.s. the basic real story about what hd wanted to do
G. Wayne says
When the Nova was in R&D the market was totaly different than today. The name SPORTBIKE had not yet been invented. Cafe Racers were the thing. Harley had 90cc to 350 cc bikes that won a lot of races. The 1977-78 XLCR was awsome for it’s day, but they did not sell well. This was also a time when you could buy any Japnese motorcycle import upto 5 years old new for highly discounted prices. These were in wharehouses all over the US in the late 70’s and early 80’s. Harley built what sells and developed on that route. Bad as they might be in some people’s opinion what other motorcycle model has been built for over 50 years and still sells everyone made every year like the Sportster does.
Gerard says
Gentemen: Speaking about the angles of 45, 60 or 70 degrees: It is a golden rule that ALL parts of an engine, flywheels, pistons, cranks etc. which are stamping up and down, or swaying, or turning, give loss of power. It sounds a bit weird, but if they did not have weight at all, you`ll see an increase of power with 200 % or more. Theoretically of course. It`s not for nothing the jet engine is the strongest engine compared to its size, it has only one turning part. Greets, Gerard.
james says
to OTTOMAN in a two cylinder engine design the advantages of a water cooled system are very much a moot point, on one hand the function of running liquid to move the heat to a radiator allows for cooling in tight spaces that a finned heat sink would not be able to reach, however it can very easily create hot spots that deform and “burn” the metal that t was intended to cool, this is because when the liquid can and will often boil near the hot spots, destroying the metal by an two pronged attack by allowing the metal to melt and by oxidizing it, where as the air cooled single or twin will over heat if left at idle for extended periods of time, (w/out the use of a fan) the argument that one cooling style or another will allow for tighter tolerances is an argument straight out of the 70’s and early 80’s as modern metallurgy has allowed for engineers to design the metals rate of expansion. in an engine with more than two cylinders the liquid can reach areas that air cannot or that would require an extraordinary amount of space for cooling fins. in the end there is no advantage or disadvantage save those that are application specific (such as space requirements or cars) furthermore with the recent advances in both metallurgy and synthetic oils, we may soon be seeing engines that are designed to run at much higher temperatures again seeing a general preface for air cooled engines in the high performance market.