Smity42

fo shizzle my nizzle unless of course my shocks don't actually turn up tomorrow, then i'll be kinda snookered

wOOt, my shocks are being smuggled out of mehico today, hopefully i will get them tomorrow so I can get them back in on the weekend touge anyone?

good stuff Tas

displacement/capacity however is a characteristic of an engine that should be independant of how the engine works. I'm willing to accept gary's defintion, and call it a 3.9L, on the caveat that you multiply it by ~2/3 to compare with a 4 stroke, in the same way you multiple a 2 stroke by ~2 to compare it to a 4 stroke. But, is that a correct definition of displacement? I think it is, but am not certain.

I guess I just wasn't taking into account the 'elliptical' motion of the the rotors and the way the pistons motions are smoothed out by other components. Guess I woulda just loved to see a 13B reving to 18,000

Thanks, very informative. Much the same as we can make a smaller piston engine rev faster than a bigger one in that way. P.S. Can anyone find a good definition of 'displacement' or 'capacity' of an engine, that doesnt in any way mention pistons, so we can settle that particular aspect of the debate once and for all. I have tried but cannot find one. I am quite certain it won't equate to 1.3L though

I could go on for hours why this is both incorrect and confusing. A 4 stroke engine does a 4 stroke cycle. If you replace 'stroke' with 'cycle' you get a 4 cycle engine doing a 4 cycle cycle. A 2-stroke engine is DEFINED as an engine requiring 2 strokes of the piston to complete its thermodynamic cycle A 4-stroke engine is DEFINED as an engine requiring 4 strokes of the piston to complete its thermodynamic cycle I guess you could class a wankel as a 1-revolution engine as it requires one revolution of the rotor to complete its thermodynamic cycle. It is in no way a '2-stroke' engine. But this is not what DEFINES a 2 stroke engine. It's a characteristic of one sure, but not what defines it. Its a characteristic shared by a rotory, but if you read my post again, you'll see it shares some charactaristics of a 2 stroke and some of a 4 stroke, which is why it can not be classified as either. It is it's own type of engine (for arguments sake, lets call it a wankel ), that shares charactarestics of both a 2 stroke and a 4 stroke engine, with some of it's own thrown in. I disagree. You are, as always, entitled to your opinion. I agree with you on the characteristics it shares with a 2 stroke engine. It also shares some with a 4 stroke engine. However it fits the definition of neither, so it is neither. I'm sure that was just to simplify the demonstration of the process. I'm also sure it is fairly obvious to most that the process is repeated on each face of the rotor, 120 degrees out of phase. No one in here is trying to ignore the fact that all faces of the rotor are working at once.

I disagree with you on the stroke = cycle sydneykid the piston does 2 strokes (up and down) in one 'cycle' as you call it, therefore a 2 stroke piston motor you could call a 1 cycle motor i spose, and a 4 stroke is a 2 cycle. But cycle has a fairly blurred meaning as well. You seem to be refering to the cycle of the crank, or just the complete cycle of the pistons motion. I am not sure. There is also the combustion cycle/ thermodynamic cycle that the engine runs on, and this is what defines an engine. A 4 stroke motor is a motor that takes 4 strokes of the piston to complete its combustion cycle. This is a 4 stage cycle (intake, compression, combustion, and exhaust - the otto cycle), which happens to take 4 strokes of the piston, or 2 'cycles' of the piston/crank. In the case of a 2-stroke, this cycle is a little more blurred, but it is completed in 2 strokes, or 1 'cycle', of the piston. The rotory does a classic 4 stage otto cycle, and completes it for each face of the rotor in 1 revolution of the rotor. So I guess you could call it a 1-revolution motor, which is similar (but not the same) as a 2 stroke piston motor. It is similar to a 2 stroke in that it completes its combustion cycle in one 'cycle' of the rotor, and in that it uses ports, and that in a single rotor is performing multiple stages of the combustion cycle at once on it's different faces. However, it is similar to a 4 stroke in that it does do the classic 4 stage otto combustion cycle on each face of the rotor as it spins. Not thate in a 2 stroke, the 'top' of the piston only performs 1 half of the combustion process and the 'bottom' of the piston performs the other half. In a rotory, each face of the rotor does the entire combustion process (like the 'top' of the piston in a 4 stroke). So, as has been said before, It is NEITHER a 2 stroke or a 4 stroke, it is a rotory cycle, different from both, and similar to both , in different respects. EDIT: Good gif above, demonstrating the 4 stage otto cycle in progress as the rotor spins

oh buenos dias! I am sure that joke (Rob schneider the stapler) is from south park, robot chicken, or something else along those lines. I've def seen it before.

yep i'm sure that qualifies as parking up No doubt you were planning 400km/h+ runs up the M1 or something

Thats not a really a 3:1 ratio. Its just a method of turning an up-down motion into a round-and-round motion. You can make the lobes as long or as short as you like (within reason obviously), and the crank is still going to turn 1 time for every 1 up-down motion of the piston, although of course you will be indirectly affecting the maximum speed of the engine due to the physics involved, but this is not the same as directly stepping it up or down with a gear ratio. I spose you could argue that its a 2:1 ratio if you consider each stroke of the piston seperately) or even 1:2 if you consider the entire 4 stroke cycle, however this blurrs the line in comparison to a rotory even more . It's all irrellevant really, the only valid point of comparison for RMP is the crank vs the eccentric shaft, so 9000 it is . A valid point... though the "revolutions per minute" is a technicality. I spose we could compare RPM of the engines and say rotorys generally rev a little higher, then compare 'strokes per minute' of the pistons with the rpm of the rotors and say the pistons 'stroke' faster than the rotors rotate. Everyone be happy with that? My question is: If pistons can go up and down at 6000+ times per minute, involving a complete change of direction twice each time, why can't the actual rotors in a rotory, which just keep spinning the same direction, match or even beat that? Why don't we see wankels with rotors spinning at 6000+ rpm for an engine speed of 18000+ rpm? PS: +1 to great tits

Yeah my car got f**king covered even sitting in the garage :'( Can't car wash it tomorrow either still waiting on shocks

True lol, what I meant is we should double their actual measured capacity, ie call a 1.3L 2 stroke a 2.6L 2 stroke, since really each piston has 2 combustion chambers not one. +1 to president vote

Well, that definitely gives you 3.9L then. 6 combustion chambers * .652L (i think?) per chamber = 3.9L. But since a rotory takes 1080 degrees compared to 720 degrees of a 4 stroke, that would make it ROUGHLY the equivalent of 2.6L 4 stroke (3.9 * 720/1080), which I think we are starting to come to an agreement in this thread on? However, by this logic, shouldn't we double the capacity of a 2 stroke? If you treat the rotor as a single combustion chamber, you get 2 combustion chambers * capacity of entire chamber (~1.3L) = 2.6L. No matter what way you swing it, you can't get 1.3L I'm going to stick with calling it 3.9L, roughly equivalent to a 2.4L 4-stroke or 1.3L 2-stroke

well then, is each individual rotor one combustion chamber or 3?

agreed 100%, but you can see why it creates a bit of grey area with the built-in 1:3 ratio of the wankels

track and drift two totally different things though... Plus if i had the money to replace/repair her, I'd happily drift my 31

@GT-R32, that is difficult when trying to calculate the capacity/displacement, as basically every definition i can find on these two terms is based on pistons. @180Roman, I am reasonably certain that any multiple of 3 would work. I am no expert however, so may be wrong

NOTHING is too pretty for the track Oh Sh!t! I hope not hey!

I spose much depends on if you consider the rotor the equivalent of a single piston, or of 3 pistons. Either are probably valid arguments...

Agreed, mostly. However, it is slightly relevant in that the physical difficulty of getting a piston engine to rev is predominantly that the pistons have to change direction so fast. (There are of course many other factors involved) If a car manufacturer sold me a car telling me it had a 4 stroke piston engine that reved to 24,000 RPM, I would marvel at the feat of engineering at getting pistons to move so fast. However if i found it was just a plain old 6,000 RPM engine with a built-in 4:1 (or 1:4, depending which way you look at it) gear inside the engine, I would feel cheated. However I would agree with you, it is still a 24,000 RPM engine.

I'd love one as a dedicated track car or weekender. Not a daily though

Exedy/Daikin OEM clutches are terrific and do a fantastic job at what they are designed for. Their performance range however is a little sub par IMO. You are of course entitled to yours. And just because a lot of people use something, that does not mean it is good, it just means people are sheep/stupid. I have found in my experience a great many people are both

Yeah I'll let you know. Probably not keen so early. I hate getting up that early on days I don't have to If this is that proposed morning touge, I didn't get one , but still possibly keen...

I'm also running a Jim Berry clutch, and I have no qualms about doing it. The man knows what he is doing, and builds damn fine clutches. They sh*t all over the likes of some 'reputable' brands such as exedy. Good jap brands such as OS Giken, etc, sure, also great clutches, but my Jim Berry was far cheaper, more suitable for what I use it for, and drives like a stock clutch. And speeking of rotaries, it looks like a super fast one might have decided to play for the Road 8 sprint championship . But even if he wins the last 2 rounds I should have him, as long as i get a half decent result in both.