39 replies to this topic

[int2str]

Hey guys!

I know this is not F1 related, but I'd like to hear your opinion on this, since I greatly value your engine knowledge. Here we go:

As anyone who follows WSB road racing knows, the big 1000cc V-twins are dominating the smaller 750cc four cylinders, despite the 4-cylinders having a little more top-end power, and quicker and easier steering transitions, due to their lighter cranks (the V-twins have relatively huge cranks which cause a lot of gyroscopic inertia).

So, the fours have great top-end power, quicker steering, but lose out on mid-range torque due to the smaller displacement, and, perhaps more importantly, lose out on rear wheel drive and tire hookup (traction), due to the more frequent power pulses of the 4-cylinder not allowing the rear tire to hook-up as the V-twins do, with their less frequent power pulses.

The 4 cylinder fires 2 pulses at the rear tire for each revolution of the motor, while the twin only fires one pulse - this gives the tire time to gain grip again, when right on the edge of traction, much like ABS braking does when a tire loses traction during braking.

On top of the fewer power pulses, the V-twin has the added advantage of an irregular power cycle, with 2 power pulses following each other in quick succession, and then a long gap until the next cycle...this gives the tire even more time to hookup between each power cycle.
The 4 cylinder, on the other hand, has even power pulses, with no extra gap in the cycle.

This leads to the V-twin being able to REALLY capitalize on their mid-range torque, and get such great drive out of the corners, negating the top speed of the four cylinders.

So, thinking about this disadvantage of the four cylinder, I wondered if any has tried to make a "virtual V-twin" out of a four cylinder!!

This is not as difficult as it sounds, and would require a simple camshaft change, and changes to the ignition and fuel injection black box....simple and cheap mods.

What I'm wondering about is changing the ignition timing and camshaft timing so that cylinders 1 and 4, which are at TDC together in any in-line four cylinder anyway, fire SIMULTANEOUSLY, followed 180 degrees later by cylinders 2 and 3 firing simultaneously!

This would give a single virtual power stroke, followed by another single virtual power stroke 180 degrees later, followed by a nice long gap of 540 degrees....JUST like a V-twin!!!

Now...think about the fact that the 4 cylinder will continue to have the same ability to rev as it always had, with its shorter stroke and lighter pistons...and it retains all the other advantages of twice the number of valves compared to the V-twin, lighter crank, etc, etc.

So, you'd be riding a 4 cylinder that sounds exactly like a V-twin, and has the same great traction out of corners, but can also rev safely to 15-16K!!!

I'm sure that the factories must have tried this ...as they used quite successfully with the 500cc 2-strokes, and I wonder what any downfalls would be?

Sorry for the long post...but this kind of stuff intrigues me!!!

Cheers,
Andre

[Mark Beckman]

The answer is very simple Andre, they sell 4 cylinder motocycles, not twins and they dont want their 4 cylinders sounding "wrong" or having people think that they are admitting the opposition is right.

I converted a couple of Honda 4's for customers for speedcar use in the 80's thru no more than having new cams ground up, ignition systems on most Jap 4's already fire every stroke anyway.

Traction increase was superior and no reliability problems.

During the 60's when Johnny Giles was racing scrambles on Triumph 500cc twins (360 degree parallel, pistons rise and fall together), he had cams ground to run it as a single (twingle as they are named) and won first time out and said traction was fantastic and he couldnt keep the front wheel down.

Triumph promptly told him "Triumph sell twins, not singles, put it away".

Ducati's motor for next years Moto GP is an "L" 4cylinder but in fact will be running as a twin (2x twingles) so they get the best of both worlds, the swept volume of a 4 but the sound and traction of a V twin so they can keep selling bikes based on their V twin cylinder reputation.

Not to mention other factors such as their current chassis has been developed around the V twins power characteristics, smart heh !

By the way I think 180 degree twins sound lousy, V twins or Yamaha TRX vertical twin are 270 degrees.

Your thoughts are well founded but the marketing world is stronger than the engineering one and has been the killer of many great racing bikes/cars/ideas over time.

[Scoots]

Mark, I'd bet that in the top racing series' the engineers would win. Look at Honda making the RC51 when they had all that investment in I4s, or in MotoGP with 500cc 2-strokes for so long (marketers have finally got what they've wanted for years ... 4-stroke bikes that can be sold in the US).

Marketing is certainly part of it, but the marketing people know that being 1st under the checkered flag is THE most important thing to the marketing people, the engineers, and the company.

[ray b]

what happened to the BIGBANG 4's I thought that the latest race 4's fire all at the same time to give a BIGBANG or was that an other class/rules????

[int2str]

Thanks for the great reply, Mark!
So are there any reasons NOT to get your CAMs reground on an I-4 to mimick the V-2 power curve? Are there any balance issues or crankshaft stability concerns?

Cheers,
Andre

[Alaweni]

From what I gather from your idea it sounds very similiar to what Ducati is planning for their MotoGP assault next year. I can't remember the name for they coined it (Desmodromic or something), but they are taking a V-4 and having two cylinders fire at the same time or a virtual v-twin. Traction is one of major benefits.

[VAR1016]

As some of you might know I am a Lancia Fulvia fanatic.

Briefly the principle of the Fulvia engine is that laid down by Vincenzo Lancia in 1916: a narrow angle V-4 with offset crankpins, so that it fires like a straight four but is more compact.

The crankpins are offset at double the angle of the Vee. The 1300cc Fulvia has a Vee angle of 12 deg 40' and the 1600, 11 deg 20' - principally to allow for the overlap of the con-rods.

Now a friend has experimented using a 1300cc block bored out to accept the 1600cc pistons (77mm out to 82.4mm).

He used a 1300cc crankshaft which is offset to a wider V-angle, so insead of 22 deg 40' (which is where his crank should have been given the new block angle which was essential for clearance) his crankshaft had a total offset of 25 deg 20'. (We are not in the position to have cranks made from billets!!).

Now we expected awful vibrations from this hybrid 1486cc engine. We were most astonished that a) it was incredibly smooth compared with a standard 1600, and b) that it developed a great deal; of torque.

Could this be related to the uneven firing - a sort of "partial V-twin" I wonder? Or perhaps the con-rod/stroke ratio (2.2/1 ) played a part in this?

[Sadly the thickness of the cylinder walls proved to be the engine's undoing - experiments are continuing]

PdeRL

[desmo]

I had no idea it would be so easy to "twingle" an I-4 UJM engine, Mark! And gotta agree on the 180 cranked twins, they sound awful.

Marion, I think the difference between a motorcycle or car and a locomotive is all about pneumatic tire dynamics. I imagine steel on steel would work best with the relatively smooth power of electric propulsion, but I have spoken to engineers about "big bang" traction benefits and they appear real and quantifiable. As far as I know they were discovered virtually by accident as dirtrackers couldn't understand why Harley Davidson flatrackers were faster than vertical twins that showed better on the dyno. Old Brit 360 degree crank vertical twins hooked up better when "twingled."

The road racers for years thought that they knew so much more than the dirttrackers with their agricultural seeming engines, but when the concept was tried on paved road courses it worked as well! I would love to hear someone explain how it all really works. I am imaginig the tire distorting torsionally with each firing impulse, and the "big bang" impulses being better in tune with the torsional "spring rate" or frequency of the tire, but that's pure guesswork.

And this stuff isn't unrelated to F1, TC systems likely use cylinder cut outs that emulate the same effect. Picture FOs that change in response to wheel speed.

[Mark Beckman]

Originally posted by Scoots
Mark, I'd bet that in the top racing series' the engineers would win. Look at Honda making the RC51 when they had all that investment in I4s, or in MotoGP with 500cc 2-strokes for so long (marketers have finally got what they've wanted for years ... 4-stroke bikes that can be sold in the US).

Marketing is certainly part of it, but the marketing people know that being 1st under the checkered flag is THE most important thing to the marketing people, the engineers, and the company.

Well now you are talking about a different class of racing and even then I bet the Engineers were told to design (for the latest MotoGP regs) whatever would win, but errrr, make sure we can make it for production later on if it does !

Honda, Yamaha and Suzuki all tried selling production variants of there 500cc 2 stroke Grand Prix bikes and no one wanted them.

Superbikes however are a different story and all Manafacturers who compete in Superbikes all have healthy sales of their simulated models.

[Mark Beckman]

Originally posted by int2str
Thanks for the great reply, Mark!
So are there any reasons NOT to get your CAMs reground on an I-4 to mimick the V-2 power curve? Are there any balance issues or crankshaft stability concerns?

Cheers,
Andre

My biggest concern would be gearbox as you are doubling the torque on each pulse even though you are halving the amount of them.

I can tell you for fact that a 500cc single motorcycle gears are bigger than a 500cc twins which in turn are bigger than a 500cc 4 cyl.

As I said you are not mimicking a V twin, you are mimicking a 180 degree twin.

[Scoots]

M.L. I'm not going to try to supply you with your specs, but from seeing many many many races I can tell you that Honda tried mighty hard to get their I-4s to hook up like the Ducks, they couldn't so they made a twin and still couldn't ... for a while. Part of it is ability to put power to the ground earlier in a corner because the power comes on in a more manageable manner in a twin than in a high-strung I-4. I guess that may help support your point M.L.

[Mark Beckman]

Originally posted by marion5drsn
I am waiting! Yours M.L. Anderson

While your waiting go to your favorite search engines and type in Honda NSR 500 Big Bang.

[VAR1016]

Originally posted by marion5drsn
If my memory serves me correctly an engineer at Ferrari wanted to try this back in the late forties or fifties but was fired by Enzo himself. Maybe a real Tiofosi can check into this.

I think that you mean the two-cylinder 2.5 litre engine built by Aurelio Lampredi about 1954/5. This was 114mm bore x 118 mm stroke (I think) with four valves per cylinder. They got about 175bhp out of but eventually gave up.

It was intended for use on twisty circuits like Monaco.

PdeRL

[Bluehair]

NOT VOODOO SCIENCE!!!

Poor explanations? Yes. Lack of charts and graphs? Yes. But given enough time, a good explanation and supportive data will come to surface. At this point in time, the only evidence available is what we are seeing in WSB and some dirt track racing. I might point out that 4-strokes are finding their way into Moto-X and will also claim better traction than that of the 2 stroke. Again, fewer power pulses = better traction. I have had a similar theory, for some time now, that Top Fuelers and Funny Cars (as well as most any drag racing car/bike) will get better traction at lower RPM than at high RPM. Again, at lower RPM, the rear wheel is receiving fewer power pulses.

Difficult to accept? Yes. But I think the overall feedback from the drivers is more than just a psychological factor. At any rate, I support and welcome the feedback of those that express their disbelief. Without you, we are at risk of accepting all sorts of wild claims. In the meantime, I'll see if I can find some quanifiable data on the big bang theory, or as I prefer: "fewer bang theory".

[JacnGille]

I thought the difference in two-stroke and four-stroke MotoX was the four-strokes much wider power band opposed to the two-stroke's "all or nothing" power delivery.

[desmo]

That is a generalization that often holds true but there are very "peaky" 4-strokes and very "torquey" 2 strokes. For the purposes of this thread the primary difference is that 2-strokes fire every crankshaft revolution.

[H. Eckener]

Bluehair,

On the subject of drag tire traction, if you can get a hold of a copy of Chuck Hallum's SAE paper "The Magic of the Drag Tire". http://www.sae-socal...uck_hallum.html

He presents a different theory/model on how a drag can seem to sustain such a high level of traction, during the initial acceleration of the car. The theory is a combination of tire "wind-up" and tread momentum transfer from the tire to the pavement. What some people call rolling resistance in tires he calls it the "magic" behind the drag tire's traction.

He does present this just as a theory (his results show very good agreement with DAQ) and his model doesn't include any sort of sophisticated modeling of tire dynamics, so maybe cyclical variations of torque and traction get averaged out. But I remain skeptical.

[Mark Beckman]

Originally posted by Bluehair
NOT VOODOO SCIENCE!!!

I might point out that 4-strokes are finding their way into Moto-X and will also claim better traction than that of the 2 stroke. Again, fewer power pulses = better traction. I have had a similar theory, for some time

One of the reasons the Honda CR250 is quite successful in MX is that it only revs to 6000 rpm compared to some of its 2 stroke rivals which spin higher.

The 4 strokes rev around 12000 rpm making them fire the same amount of times as the 2 strokes giving no advantage.

[Mark Beckman]

Originally posted by marion5drsn
I went to the Big Bang but these engines seem to be two strokes so this would require a different approach.


Voodoo Science. The rear tire of some racing motorcycles are 17 inches = 53.407 inches or 4.45 feet or 1186.5 rev per mile.
At 8000 rpm this is 4000 bangs per minute at 60 mph or a mile a minute and 66.66 bangs a second. According to this the rubber has to take a different traction derivative (?) in every fifteen thousandths (.015) of a second. This has to be cut (divided) by the number of cylinders plus the amount of time the cylinder firers per revolution.

If the theory of tire traction holds, then all racing engines should be single cylinders and no exceptions. If my memory serves me correctly an engineer at Ferrari wanted to try this back in the late forties or fifties but was fired by Enzo himself. Maybe a real Tiofosi can check into this.
If the theory were true then shouldn’t all the manufacturers go to single cylinders? Cut total engine weight and complexity. They could also use six valves per cyl. and variable valve timing. Then they would sound like the old Norton’s. The chuff chuff sound would return. Some people loved it.
Well back to the old drawing board. Yours M.L. Anderson

A single 750cc SOS racer gets 95 hp, a 750cc 4cyl Superbike gets 185 hp that is your simple answer.

However Superbikes are a different story, equal hp, equal weight, equal tyres but one has a superior traction advantage, not voodoo, fact.

The big bang (called this because its 4 cly's fired only 70 degrees apart making it almost a single cyl engine) engine comparison needs to be done to its preceding engine, keep it relative, doesnt matter if 2 stroke or not it only matters why it was made and what it acheived.

[Mark Beckman]

Originally posted by marion5drsn
V-2 DUCATI VOODOO ENGINE.
This layout shows the two cylinders firing right after one another that is a 0 deg. and 90 deg. The other alternative is for # 1 to fire at 0 deg and # 2 to fire at 450 deg. I used the Ducati single throw crank and 90 degrees cylinder block angle.
The oddball layout would give a 450-degree “idle” period. At 7,000 rpm this is a time period of 62.5%.
7,000 rpm divided by 60 sec. = 116.7 rev. per sec.
1 revolution divided by 116. 7 =. 0085714 seconds times 62.5% = .005371 parts of a second. This is the time that the tire has to reestablish its form for the next power application. Human reaction time is usually around .3 seconds. I rest my case as the “Voodoo CASE” until someone comes up with some “Proof”. I am going to talk with the Wolf Man, Dracula and Dr. Frankenstein about all of this. Yours M.L. Anderson

http://home.earthlin...IRINGLAYOUT.JPG

Umm what has rider reaction time got to do with ?

Heres another Boris Karloff mentioning traction in regards to engine pulses, but what would he know.
http://www.americanm...cfm?NEWSID=1887

[12.9:1]

marion5drsn . Take heart,

There is another idea, witch relies on much less black magic, much more on known principals
and a pinch of fuzzy logic.

Here an article by Kevin Cameron - one who is always looking for the how behind the heahline,
and has gained my utmost respect.

Falling Torque-Curve Theory

.

[desmo]

That link has been posted before here, but I highly recommend it.

At least one F1 engineer not only believes in the 'big bang' traction theory for motorcycles, but has talked to tire engineers about it's implications for F1 as well. The phenomenon is probably real but undocumented in any scientific sense, which should fuel healthy skepticism. This falling torque curve originally developed for dirt trackers is surely rsponsible for some of the advantages attributed to 'big bang' traction.

[Ben]

An engineer from Ricardo Motorsport told me that F1 drive shafts have, in the past, been designed to twist by up to 60 degrees and effectively perform a torsional vibration damping role.

I also noticed that Peter Wright mentions the phenomenon (big bang traction improvements that is) in his book.

Ben

[Mark Beckman]

Originally posted by 12.9:1
marion5drsn . Take heart,

There is another idea, witch relies on much less black magic, much more on known principals
and a pinch of fuzzy logic.

Here an article by Kevin Cameron - one who is always looking for the how behind the heahline,
and has gained my utmost respect.

Falling Torque-Curve Theory

.

Well Kevin Cameron says....
"The answer to why WSB has turned into "Battle of the Twins" may be much simpler than that. Each of the V-Twin teams (Honda, Ducati, Aprilia) spends nearly $10 million a year in the class, which is surely far above what is spent by the remaining four-cylinder teams (Bertocchi's and Harald Eckl's Kawasaki teams, and the Batta Team Alstare Suzuki outfit). Less money spent means less of all the good things: power, acceleration, chassis setup.

Skeptics further point out that the four-cylinder bikes are still being ridden by the sort of rider traditional in WSB until recently – veterans gracefully finishing their careers, or second-level riders. The Twins-makers, on the other hand, are bidding directly against 500 GP to get top riders like Bayliss, Edwards and Corser".


Was this Guy born yesterday ? This is just bullshit, what he failed to mention is that the whole might of Honda's Factory Team was behind a 4 cylinder bike up until 3 years ago. Honda raced the RC30 and RC45 with Colin Edwards who just happens to be the same rider who is now winning the World Championship on the Twin, who complained loudly and often about the advantage of the twins, and then we have the might of Yamaha who designed a 4 cylinder bike from the ground up to win, the R7 (with a GP500 chassis no less) with Noriuki Haga riding and as they sell 4 cylinder sports bikes, not twins, they packed it in when they found they were uncompetitive against the twins and that was before Bayliss arrived too - just a small couple of oversights.

Some more reading....
http://www.v-four.fr...uk/genetics.htm

[12.9:1]

Originally posted by Mark Beckman

This is just bullshit,

[Mark Beckman]

Oh outstanding comeback 12.9:1.

[Mark Beckman]

Gee some more FACTS that kind of go against Kevin Camerons statement.

http://www.v-four.fr....uk/rc45-99.htm

http://www.f1jordan....olinedwards.asp

Andre reference in those 2 to "we race what we sell"

http://www.motorcycl...mcyam/99r7.html

http://www.just-bike...sp?item=63&ft=4

http://www.just-bike...sp?item=63&ft=4
(you may even notice this there)
........10 bhp less than the last version of the RC45, according to Honda sources. That makes it 181 bhp at 12,000 rpm, according to my records - some going for a V-twin, especially when combined with the kind of twin-cylinder rideability that allows the SP-1W to lap a second faster on almost every circuit than its 10 bhp more powerful V4 predecessor. In terms of top speed, the two are almost.......

http://www.michigani...om/RC51/sp1.htm

Thats enough for now but I am happy to keep finding FACTS against opinions if nessessary.

[Mark Beckman]

Originally posted by desmo
That link has been posted before here, but I highly recommend it.

At least one F1 engineer not only believes in the 'big bang' traction theory for motorcycles, but has talked to tire engineers about it's implications for F1 as well. The phenomenon is probably real but undocumented in any scientific sense, which should fuel healthy skepticism. This falling torque curve originally developed for dirt trackers is surely rsponsible for some of the advantages attributed to 'big bang' traction.

Well there is some sense in the following power stroke not being as strong as the on prior stroke that broke traction, not continuing that broken traction (say that 3 time fast when drunk ) and of course you keep a car/bike under control during loss of traction by moderation of the torque by way of your throttle.

I often laugh though at statements that encompass the thought that something isnt real until proven its real by science.

I notice on a current affair show on TV recently that scientists have proven that a female is more likely to have sex after drinking alcohol.

Laughable, but this is what I mean, its something in the real world that works and is well known.

Also I point out that the Harley flat trackers are part big bang engine with a 315 and 405 degree gap.

[12.9:1]

Mr. Beckman

Sadly, I find my self having to explain, not torque-curve theory, but the structure of a magazine article.

So then, the article begins with an introduction, where in Mr. Cameron presents several popular theorys, or explanations, for the winning ways of the V-twins, Versus the I-fours, despite the fours HP advantage.

Some examples
"For several seasons now, people have speculated"
"Skeptics further point out"
"Four-cylinder lobbyists also argue"

After prsenting these ideas, he begins his presentation, not just of his theory, but invites us on a journey of discovery.
Cameron does not put forth his ideas as dogma, rather as ideas - somthing to think about.

He Wraps up with a question.
"Could this be the reason why 1000cc V-Twins, even though often less powerful than 750 Fours at peak, nevertheless accelerate out of turns faster? Could it be that falling torque – natural anti-spin – has been Ducati's great strength"

.




though I dont really understand why you posted those articles, I did find several statements that seem to support Mr Cameron -


"Current regulations mean that twin cylinder machines can be up to 1000cc in capacity, while 4-cylinder bikes have a limit of 750cc. While the 750cc bike, in particular the RC45, make as much if not more peak power than the V-twins, the advantage in acceleration out of a corner more than makes up for it."

"There are negative aspects to the new bike. Because it’s a twin, it feels like it runs out of power much earlier than a four. The initial huge surge of acceleration tails off as the revs rise"

"I explored the level of grip on the damp track, It would drive from as low as 5500 rpm without a hiccup or any transmission snatch, all the way to the 12,000 rpm revlimiter (11,750 rpm on the 8-Hour bike). Don’t get the idea you’d never rev it that low in real world racing, because Colin Edwards says he’s learnt how to ride the torque curve and pull out of tight turns as low as 6000 rpm on the bike. When you do that, you can feel the rear Michelin’s level of grip almost as well as if you were sitting on the tyre"

[H. Eckener]

An engineer from Ricardo Motorsport told me that F1 drive shafts have, in the past, been designed to twist by up to 60 degrees and effectively perform a torsional vibration damping role.

I also noticed that Peter Wright mentions the phenomenon (big bang traction improvements that is) in his book.

Ben

60 degrees wow amazing I would have thought a tenth of that or so would be the maximum.

Although, I must point out torisonal damping driveshafts to me sounds like the opposite approach you would take with big bang traction in mind as a design goal.

[VAR1016]

Originally posted by H. Eckener


60 degrees wow amazing I would have thought a tenth of that or so would be the maximum.

Although, I must point out torisonal damping driveshafts to me sounds like the opposite approach you would take with big bang traction in mind as a design goal.

Yes indeed!

In fact the series 1 1600cc Lancia Fulvias used this principle, but it was solely to preserve the clutch!

PdeRL

[VAR1016]

Originally posted by marion5drsn
A quote from Ben.
An engineer from Ricardo Motorsport told me that F1 drive shafts have, in the past, been designed to twist by up to 60 degrees and effectively perform a torsional vibration-damping role


Drive shafts and torsion twist maximum. There have been some very weird drive shafts in cars and the one that is the most weird is the one in an old Pontiac that I believe was made to curve so as to clear parts under the floor pan. But as to rear engine F1 cars are you talking about the shaft from the differential or the short shaft in the gearbox? I can’t see a u-jointed shaft bending that much in such a short distance. Altho this would allow the drive shaft to bend and not break. One of the problems I believe in the final drive is the lack of constant angular velocity universal joints, as I also believe that the “Pot Joints” are not true c.a.v.u.j. If I were correct on this then it would be an advantage to have shafts that allow a lot of twist. One must remember that 60 degrees is one sixth of the total circle! The tube must be very thin to accomplish this. I am also wondering if very many people understand the properties of a
c.a.v.u.j. and its proper application to the problems of traction on race cars, this in conjunction with the “torque-dividing differential”. This is a discussion dear to my heart. Yours M.L. Anderson

The Fulvia is front-wheel drive. The inside joints i.e. those adjacent to the gearbox were sliding pot joints, whilst those on the outside were Rzeppa joints. The drive shafts were probably about 60% of the diameter of the shafts fitted to other Fulvia models (and indeed the series 2 1600s).

PdeRL

[Scoots]

It's true that a V-4 vibrates more than an I-4 ... what's your point?

[Scoots]

Okay then

[jluetjen]

There have been a number of references on this thread about "Big Bang" engines, F1 (cars?) and the potential or benefits of applying the "Big Bang" strategy to race cars. I didn't see that anyone pointed out that it had been tried.

Honda tried racing a "Big Bang" Turbo V8 in their first year in CART. The V8 which they supplied to Bobby Rahal was reportedly a "Big Bang" engine. It certainly did have a different exhaust note when I saw them race at New Hampshere International -- the car sounded much like an American V8 rather then the normal for CART "Flat Plane" V8. In addition to being heavy, the engine suffered from a lack of HP which they never seemed to remedy. Honda dropped the "Big Bang" engine the following year, but by then Bobby had dropped Honda and the rest is history.

[MiG82]

Originally posted by Bluehair
I have had a similar theory, for some time now, that Top Fuelers and Funny Cars (as well as most any drag racing car/bike) will get better traction at lower RPM than at high RPM. Again, at lower RPM, the rear wheel is receiving fewer power pulses.

Top Fuelers and funny cars only run at one speed (about 8000 RPM) throughout nearly the whole race (the revs drop a bit at the end). Right off the line they have 8000 RPM. They slip the multistage timed clutch till about 3/4 of the race distance.
So they have the same frequency of power pulses all through the race.

[Bluehair]

Perhaps I was a bit vague with that statement. Let me specify that I have often felt that nitro cars would get better traction at lower rpm such as in the days of the 2.90 ring gear (rules mandate a ratio of 3.20 or higher-numerically). It is pure speculation, but I think that if the rules allowed a gear ration of say 2.0, the cars would not only experience a slight increase in grip, but would also recover from tire spin much easier. Instead of averaging 8000 RPM, they may be working around 5500 RPM where the power pulses are a bit farther apart. Furthermore, the clutch would be allowed to lock up sooner, decreasing the time in which certain malfunctions typically occur (such as the pneumatics that operate "the canon").

[VAR1016]

Originally posted by marion5drsn
V-4 ENGINE CONFIGURATION: After working on his engine configuration and the conclusion I’ve reached is that this is the worst of all worlds in four cylinder. The reason that the motorcycle manufacturers can get by with it is the pistons and upper conrods are light in weight. Even with using four-throw cranks it is seems to me to be impossible to get rid of the Secondary Shake problem. I would say that a 4-cylinder inline or 180-degree opposed engines are far superior to this layout of 90 degrees, as this is halfway in between the two acceptable cranks layouts. If it were not for the overall length of the Inline four It would be miles ahead of the V-4! It is so bad that the V-2 in my opinion is superior. This especially is true in view of the cost of the V-2 versus the V-4. The big trouble of the V-2 is the lack of a dual throw crank.

All of this after working on it off and on for about a month.
A nd now to work on a three cylinder engine!!!
Yours M.L. Anderson

Mr Anderson, what do you think of Lancia's solution of staggering the in-line four so as to make a V-4 - with staggered crankshaft and a vee angle of about 12 degrees. The crankshaft throws are staggered at double the angle of the vee. Of course VW now uses this in some engines, I believe.

Thanks

PdeRL

[VAR1016]

Originally posted by marion5drsn
I have given this a little thought and it’s got to be better than a V-4 at 90 degrees. If the angle is low enough, which is around 22.5 degrees it‘s got to be better, I now realize better than ever the reason for the three cyl. Kawasaki’s. Even tho they were 2 strokes.
M.L. Anderson

Thank you.

The original LAncia V-4, the Lambda, had a vee angle of 22 degrees. ALl the later ones had narrower angles, the narrowest being the 1600 Fulvia at 11 degrees, 20 minutes. On some cars the vee andle was specified down to seconds!

PdeRL

[VAR1016]

Originally posted by marion5drsn
Is this the type of crank layout you are talking about"

http://home.earthlin...ANCIAV-41.5.JPG

M.L. Anderson

Yes, although the 1600 Fulvia's bore and stroke were 82 x 75mm (1584cc) The crankpin offset would be twice 11 deg 20' i.e. 22 deg 40'.

Obviously you meant to write 1-3-4-2 rather than 1-4-3-2?

A friend ran a special engine using the 1300 (25 deg 40) crank but with the block bored at 11 deg 20. 82.4 x 69.7mm = 1486cc. We expected it to vibrate like hell, but in fact it was wondrous smooth - much better than a standard engine in fact (until a bore wall cracked!)

Thanks

PdeRL