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No replacement for displacement!

Started by WALKEN, February 16, 2016, 03:35:05 PM

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Stout Johnson

February 17, 2016, 08:49:39 AM #15 Last Edit: February 17, 2016, 08:59:59 AM by Stout Johnson
Quote from: HornetMaX on February 17, 2016, 08:03:09 AM
People always seem to think that displacement is all that matters. Saying things like "990cc 2 stroke vs a 990cc 4 stroke would be comical" is just equivalent to say things like (in a F1 context) "a 1.500cc atmospherical vs 1.500cc turbo charged would be comical". It would be comical all right, just as "500cc 2 stroke vs 500cc nuclear would be comical". As a bonus, nobody will even think to create a 990 2 stroke (no more than people are thinking about creating a 1980cc 4 stroke). I'm not even sure a 750cc 2 stroke is needed: 500cc could still be the sweet spot.

But what about 500cc 2 stroke vs 990cc 4 stroke (which technically is what one could call a fair comparison) ? Or, if you dispute the fairness of that, what about whichever displacement for 2 and 4 strokes, but with limited fuel (because in the end, no matter the displacement, the energy that goes in depends on how much fuel you burn) ? Would that still be "comical" ?
Completely agree with that! Could not have said it better. I won't dispute anyone's opinion on whether they prefer the 2 stroke era. That is just a matter of personal taste (and propably the pyschological effect of romanticization of the olden days). But trying to derive some sort of superiority of 2-strokes by saying "990cc 2 stroke vs a 990cc 4 stroke would be comical" is just not a very well founded statement - because that comparison does not make much sense technically.
    -----------   WarStout Kawasaki Team   -----------

Hawk

Actually the 2 stroke 500cc bike should go well at the TT because it should have an advantage on the more twisty sections of the course... The only question is, has it the speed on the fastest sections to keep up with the big 4 strokes? If it has and they get the right rider then there is no reason at all it shouldn't blow away the 4 strokes.  Let us pray for this. Lol. :P  ;D

Hawk.

Napalm Nick

Maybe getting up the hills will be the hardest bit for the torque-less 2 stroke. Speed should be fine I reckon its just them damn hilly bits hehe! 
"The post you are writing has been written at least ten times already in the last 15ish years. Its already been reported, suggested, discussed, ignored or archived (but mostly ignored). Why are you doing it again?"

h106frp

Wonder what its like to have a '2 stroke seize up' at 200mph on the TT course

Napalm Nick

I think your ass would be watertight until the clutch gets pulled  ;D lol
"The post you are writing has been written at least ten times already in the last 15ish years. Its already been reported, suggested, discussed, ignored or archived (but mostly ignored). Why are you doing it again?"

Hawk

Quote from: h106frp on February 17, 2016, 01:07:00 PM
Wonder what its like to have a '2 stroke seize up' at 200mph on the TT course

Quote from: Napalm Nick on February 17, 2016, 01:18:03 PM
I think your ass would be watertight until the clutch gets pulled  ;D lol

Lol!  ;D

Yeah an oversize nappy would come in handy too. Hehe!  ;D

Hawk.

WALKEN

Why is it so difficult?

I'm not delusional and to old to understand technology.

https://en.wikipedia.org/wiki/Yamaha_YZ250

https://en.wikipedia.org/wiki/Yamaha_YZ250F

Math- the YZ is putting out 48.8 HP with 32 ft torque.  YZF is putting out 43 HP with 21 ft torque- so much for torque concerning the 4 stroke.

To match or exceed the YZ250, Yamaha put out the YZF450 4 stroke which is 250 pounds oppose to 212 pounds and the HP rating I believe is about 50hp.

Granted if you put two experienced riders on these 2 bikes you would find each bike has its weakness. But in the end both are different hence riding them differently.

The problem is the numbers! Displacement!

Believe what you want to believe but in reality it takes double displacement of a 4 stroke to match a 2 stroke, its simple math. And please stop with the smoke crap as I have owned 2 strokes that are running properly that don't smoke.

It will come back around one day and everyone who wants to conform to emissions propaganda will be eating their helmets in record numbers.

HP+torque+weight.       


Help me, help you!

Vini

Yeah, I don't know where this misconception came from but two strokes will always have more torque than a four stroke with the same power output.

Also, 500cc 2T vs 990cc 4T is only a fair comparison when both engines have the same bore/stroke ratio.

I disagree on the fuel idea, Max, because when your bike is a lot lighter with the same power, you can carry more fuel and still have a big advantage.


Quote from: WALKENIt will come back around one day and everyone who wants to conform to emissions propaganda will be eating their helmets in record numbers.
Can't wait to see what the Ryger engine will be able to do.

h106frp

I thought the big advantage was torque and power 'spread' with rpm - you do not need to stay in the power band so a 4s is 'easier' to ride.

Napalm Nick

A 2 stroke will lose its torque rapidly up a hill where, for the same rev loss, a 4 stroke won't. So if you run out of revs (or gears) on your stroker you will see the 4 stroker disappearing.  Its easier to think of a 2 stroke having less torque on a hill than the actual maths of 'engineers' and the reverse truth, so that's why there is a misconception amongst the peasants.

And, frankly, if your 2 stroke never smoked you didn't add enough oil, did they Hawky?  ;D

Right on H !
"The post you are writing has been written at least ten times already in the last 15ish years. Its already been reported, suggested, discussed, ignored or archived (but mostly ignored). Why are you doing it again?"

Hawk

Riding a 2 stroke is different to riding a 4 stroke in that to get the best out of a 2 stroke you do indeed have to keep the revs inside the powerband, and that's part of the excitement of riding 2 strokes. Plus I'd say because of that it takes a lot more skill to ride a 2 stroke well than a 4 stroke(as everyone says, a 4 stroke is an easy ride as Nick points out above).

As far as a 2 stroke being smokey? Well like most engines when cold they do smoke badly, but for sure when a 2 stroke is up to temp they don't smoke anymore than a 4 stroke in my opinion..... That is of course unless we have Nick mixing the fuel with cooking oil for visual effects. Hehe.  ;D

But yeah... If you sit on the grid giving it some with throttle on and off then of course they will smoke but normal throttle use doesn't produce anymore smoke than any other bike as far as I can tell..... But give me that good old school 2 stroke Castrol 'R' smell any day of the year!  ;D 8)

But to be honest, if emissions was the problem and reason they changed from 2 stroke to 4 stroke then why haven't we banned 2 stroke lawn mowers or chain saws or jet ski's??? They were and still are chucking out way more emissions than any motorcycle GP season ever has, and as far as the motorcycle market was concerned, motorcycles have never chucked out anywhere near as much emissions as cars and lorries have, especially now that majority of cars are diesel..... So who was the fool who promoted a change to diesel fuelled cars, eh?  Whoever it was I'll almost guarantee he was a conservative politician with their fingers in the pie of a company that would benefit from diesel car sales. Lol.
So you see the smokey or emissions argument doesn't hold true; In my opinion the change from 2 stroke to 4 stroke was purely down to politics and Honda who've always wanted to get 4 strokes into GP racing over the 2 stroke bikes, and only gave up trying to do that honestly when they failed to build a 4 stroke that could compete with the 2 stroke 500cc bikes.  :P

The quicker they bring the 2 strokes back into GP racing(looks like it's a start with the Seuter!  ;D :-* ), the quicker motorcycle GP racing will get it's soul back.  :P  8)

The younger guys here don't realise what they've been missing all these years. Lol


Hawk.


HornetMaX

Quote from: WALKEN on February 17, 2016, 04:52:19 PM
Why is it so difficult?

I'm not delusional and to old to understand technology.

https://en.wikipedia.org/wiki/Yamaha_YZ250

https://en.wikipedia.org/wiki/Yamaha_YZ250F

Math- the YZ is putting out 48.8 HP with 32 ft torque.  YZF is putting out 43 HP with 21 ft torque- so much for torque concerning the 4 stroke.
That's peak torque. Now go check mid-range torque and let me know.
And as a side note: you're showing cross bikes. It has already been stated clearly that for *some* applications, 2s do have advantages.
But it's not because you can build a better cross 2s that you can have a better motogp 2s. Not the same ballpark in terms of plenty of things (power, torque, revs, thermals, ...).

Quote from: WALKEN on February 17, 2016, 04:52:19 PM
The problem is the numbers! Displacement!

Believe what you want to believe but in reality it takes double displacement of a 4 stroke to match a 2 stroke, its simple math.
But I do agree with that. That's why it is *fair* to compare 500cc 2s vs 990cc 4s. It's you who's doing the silly thing (990cc 2s vs 990cc 4s).
The reason is trivial, once one know how a 2s and a 4s cycle works. I'm bored to try to explain why it is so. It's not even difficult to understand.

Quote from: WALKEN on February 17, 2016, 04:52:19 PM
It will come back around one day and everyone who wants to conform to emissions propaganda will be eating their helmets in record numbers.
OK, keep waiting then.
Anyway, if  they do come back (unlikely, but who knows), they will be a far cry from the 2s you all love.

Quote from: vin97 on February 17, 2016, 05:12:31 PM
Yeah, I don't know where this misconception came from but two strokes will always have more torque than a four stroke with the same power output.
More mid-range torque, better power curve. Granted, on race bikes it is a bit less important, but still.

Quote from: vin97 on February 17, 2016, 05:12:31 PM
Also, 500cc 2T vs 990cc 4T is only a fair comparison when both engines have the same bore/stroke ratio.
And why that ?
My understanding is that in motogp (and F1, if I recall correctly) they have limited the bore because that's what limits what the engine can do.
But that's valid when comparing across engines of the same type, like 5cyl vs 4cyl both 4s. I'm not sure it makes sense between 2 and 4 strokes.

Quote from: vin97 on February 17, 2016, 05:12:31 PM
I disagree on the fuel idea, Max, because when your bike is a lot lighter with the same power, you can carry more fuel and still have a big advantage.
No man. The "same fuel comparison" measures how efficient an engine is. It's not a matter of overall weight.
If a 4s is heavier (which is the case), it will waste more fuel when accelerating, but that's it.

Quote from: vin97 on February 17, 2016, 05:12:31 PM
Can't wait to see what the Ryger engine will be able to do.
Actually you can wait, as we all have been doing since a while. Wasn't it supposed to smash records somewhere at the end of 2015 ? (I can be wrong on that date, honestly I don't follow closely all the news about the super-secret Ryger engine).

doubledragoncc

It would seem you all have forgotten one major point about the difference between 2 and 4 strokes.....................Reliability!!!

When I was on the pit crew for Robert Mott who rode for Yamaha in MotoX. I had to rebuild the motor a LOT!!! 2 strokes eat the top end in a heart beat while in a racing scenario. 4 strokes are not so aggressive on the parts and mean they have less chance of failure!!!.............................I wonder if that may have been the reason for the change rather than just emissions?
And add to that the cost of the parts!!! Why do you think there is no Trabants in professional auto racing lol.

As a technician I will have to stick up for the 4 strokes, but as an out and out speed junkie, well give me an old Kwaka H2 baby.

DD
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Vini

Quote from: HornetMaX on February 17, 2016, 08:16:40 PMThat's peak torque. Now go check mid-range torque and let me know.
That range is not relevant on a race bike.
That's why bikes have gearboxes.

Quote from: HornetMaX on February 17, 2016, 08:16:40 PM
Quote from: vin97 on February 17, 2016, 05:12:31 PM
Also, 500cc 2T vs 990cc 4T is only a fair comparison when both engines have the same bore/stroke ratio.
And why that ?
Because the ratio defines how high the engine can rev.
Doesn't really make sense to compare engines that produce their peak hp at very different revs.

Quote from: HornetMaX on February 17, 2016, 08:16:40 PM
Quote from: vin97 on February 17, 2016, 05:12:31 PM
I disagree on the fuel idea, Max, because when your bike is a lot lighter with the same power, you can carry more fuel and still have a big advantage.
No man. The "same fuel comparison" measures how efficient an engine is. It's not a matter of overall weight.
If a 4s is heavier (which is the case), it will waste more fuel when accelerating, but that's it.
The 4 stroke engine is more fuel-efficient (at the moment) but a four stroke bike will still be less weight-efficient, even if you take into account that the engine needs less fuel.
If you compare a two stroke race bike against a four stroke one with the same max. power, the two stroke will always win.


If we want to go into the rideability discussion, then always remember that the most advanced electronics the 500s had was none, so it doesn't even make sense to compare them against modern superbikes with traction control and anti-wheelie (let alone MotoGP bikes).

doubledragoncc

Vin, I mean the actual physical reliability, nothing to do with electronics bro. A 4 stroke motor will outlast a 2 stroke any day and in racing it is important to have a motor that dont wear out so quickly. Work in the pits building race motors and you will understand what I mean.

DD
GPBOC Live Streams: https://www.youtube.com/c/IASystemsComputerControls; i7 12700K 5.1GHz Z690 ASUS Strix Z690-A Mobo 32GB 3600MHz DDR4 RAM ASUS Strix RTX3080 OC 10GB DDR6X ASUS Ryujin 360 AOI Cooler ROG Thor 1200w PSU in ROG Helios Tower Case.