Hi guys, just wondering about this, and I know the answer is a lot, but roughly how much would a 26B e-shaft be? or indeed a shortblock triple e-shaft (not a 20B one) where would I ask for one of those to be made up?
KIWI racing in new Zealand
Carl Hayard would probably be you best bet to speak with.
i guess u r serious about it then lol
bear in mind i had 2 engines and 4 rotors at one point, need to consider if the old housings r useable else £300 a pair used, also wont all 4 rotors need to be same weight?
Green Brothers in Kiwi Land, ask Erdin about his contacts, down under is where the Pros go
Ok I will look into it, how much would I be looking at spending? £1k? I saw a 20B e-shaft on the bench, the first 2 lobes are standard and then the 3rd one just screws into the 20B only 3rd rotor lobe, I guess you can\'t screw 2 OEM 13b shafts together and support with a bearing?
1k lol and the rest probably closer to 3 to 4k, a 2 piece 13b shaft is well over 1k
I will start saving then lol why are they so much? could 2 13B E-shafts be modified to work for less then a billion pounds rather than making a bespoke shaft?
Interesting read :
http://www.rx7club.com/showthread.php?t=638177
Shaun
Im thinking a bit like this:
http://www.youtube.com/watch?v=A2nuYyMIVao
Which I guess is a bit like this with 2 V8 engines bolted together to make a v16:
http://www.youtube.com/watch?v=EO2MDBi6uYs
shaunwil - im loving that pic of the 39b build hehe
AH HA! this is what I needed to see:
(http://i93.photobucket.com/albums/l49/m1tch_2006/1223005630_af29a5a07e.jpg)
(http://i93.photobucket.com/albums/l49/m1tch_2006/1223005646_4cfd44737f.jpg)
(http://i93.photobucket.com/albums/l49/m1tch_2006/1223005652_0a53509908.jpg)
it does rather make sense as 1 end of the shaft is strong enough to plug into the drivetrain lol
Where did you find that and how much ???
oooooo I like that :) one problem with it.... well 2 realy:
1: it\'s toooooo quiet
2: where are the blowers??!!
Jono
I am looking into the possibility of doing this also and I would plan on making my own E-shaft.. I have a few ideas and also found a thread some US guy had done building one for his Oval dirt racer.. There are ways to put two shafts together.. Just a case of having the ability to design it and get it machined. Splines will probably be expensive to get done.. Could have Square, Hex, key ways etc and I am sure there are other ways to do it too.. Lots of other things to consider as well.. Like setting up the ignition/electronics for one. I see a dizzy and points system seems to be the cheat, I presume that is because the norm is to start with an early NA 13B? Anyway I am in the early days of researching it all.
Gotta finish my RB30 build first! Sorry No cursing! LOL!
Lee
Splines are quite easy, just find a company that manufactures gears and they will have the shaving and hobbing technology to produce a male and female spline. If you can get them to recommend a spline they already produce you don\'t have any tooling cost.
I would say there would need to be a lot of FMEA on the strength of the spline in relation to the predicted torque of the engine to make sure it doesn\'t shred when revved hard.
Its definitely an interesting thing to do, including oil passages. All the offset countersinks for lobe positions and the split of the shaft itself.
All questions from a machinist / Design Engineer. Probably a lot more to think about too like Heat treatment and finishing.
Shaun
I might be missing something here but the shaft that comes out of your gearbox and fits on your clutch is a spline and thats not even a particulary long engagement area. Also your drives shafts and prop.. It may benefit from heat treatment of sorts but I would think a deep enough spline will work fine without. Main thing is having a perfect match on the splines. If there was any for of slack to create a lashing effect then yes you would demolish it eventually.
Even using a gear manufacturer (which is probably not so easy to find generally?) I would imagine this to be an expensive route as it is a specialist process.. I was just visiting XTRAC yesterday actually who make gearboxes for a lot of motorsport applications.. The process is so highly toleranced it\'s unbelievable! very impressive machine shop though.
An option may be to buy or recycle a male and female spline section which you could weld to each corresponding shaft.. adding that much heat might upset the shaft in the first place though?
Lee
Quote from: leeroy_25;658957I was just visiting XTRAC yesterday actually who make gearboxes for a lot of motorsport applications.. The process is so highly toleranced it\'s unbelievable! very impressive machine shop though.
Lee
Yes It is ! I am a time served machinist who served his time machining truck components for gearboxes and diffs !
Shaun
Just one question - bit of an aside. Why set both shafts at the same angle? Why not set them up at 90 degrees, so there are four power strokes per revolution? Wouldn\'t that reduce stress on the splines too, or by setting them up inline, would you end up with less stress? Presumably, you\'d have less on the centre junction, but more on the gearbox end??
Don\'t forget the rotors only have 3 sides. For 2 rotor engines - the rotors are offset by 60 degrees, so the tip of one rotor would be in line with the centre face of the other one. I am guessing for 3 rotor engines you could have all 3 faces in line or face / apex / face.
So by extension for a 4 rotor it woul be face / apex / face / apex - so the 2 shafts would have to be setup as shown in the piccy
There is a thread on Rx7club that states all the correct angles for up to 4 rotor engines.
Its an interesting question on how to balance a 3 and 4 rotor engine. Doesn\'t a lot of it depend on the counterbalance weight too ?
Shaun
I get what you\'re saying, but if each engine is counterbalanced, why wouldn\'t you have the engines offset by 90 degrees, as presumably that would give you a powerstroke every 90 degrees? It just looks like that you would end up with rotors 1 & 3 firing at the same time, and 2 & 4 firing at the same time... Why wouldn\'t you want it firing 1,3,2,4 at 90 degree sequence?
Quote from: Archbish;659273I get what you\'re saying, but if each engine is counterbalanced, why wouldn\'t you have the engines offset by 90 degrees, as presumably that would give you a powerstroke every 90 degrees? It just looks like that you would end up with rotors 1 & 3 firing at the same time, and 2 & 4 firing at the same time... Why wouldn\'t you want it firing 1,3,2,4 at 90 degree sequence?
I like the thinking on this !! :god
But it wouldn\'t be every 90deg because the crank turns 3 times for every 1 turn of the rotor !
Would have thought the worry is is they are minutely out of sync then one would go off before the other and completely mess up one chamber ! Unless this can be fixed in ignition timing !
Shaun
Quote from: shaunwil;659328But it wouldn\'t be every 90deg because the crank turns 3 times for every 1 turn of the rotor !
Would have thought the worry is is they are minutely out of sync then one would go off before the other and completely mess up one chamber ! Unless this can be fixed in ignition timing !
Shaun
Pair up the ignition\'s ;)
animation (http://www.youtube.com/watch?v=HSSpoBqtwck)
ACTUAL TWIN 13B IN AN fd (http://www.youtube.com/watch?v=A2nuYyMIVao&feature=channel)
^^^in the animation , it\'s showing it firing 1,3,2,4 at 90 degree difference between the rotor angles.so for that, you would have to have the eccentric shaft at 90 degrees, right? And the FD does not sound like two simultaneous rotors firing...
((I WILL BE RIGHT! I WILL, I WILL, I WILL!!!!))
(http://cp_www.tripod.com/rotary/images/pg03_17b.gif)
having said all of the above, this (http://www.jascoautomotive.com/forum/viewtopic.php?t=696) is a real life example of 2 13bs plumbed together. The reason he\'s given is for the balancing, and the counterweight removal.
So if you can get a decent counterweight balancing done (ala Scoot 4 rotor, You Tube footage dude), then that is how to do it. If you can\'t (ala got a garage and 2 engines), then I guess in parallel seems reasonable.
Cool, always good to learn something new :D
Shaun
Four power strokes per revolution? Hmm, that means you would have to have square rotors, three power cycles per revolution per rotor/housing. As for the crank/e-shaft doing three revs per rotor revolution, I think not!!
*tumbleweed*
Quote from: Bob Monkhouse;659473Four power strokes per revolution? Hmm, that means you would have to have square rotors, three power cycles per revolution per rotor/housing. As for the crank/e-shaft doing three revs per rotor revolution, I think not!!
Look at the gears on the rotors and on the stationary gears...
It really does spin a lot quicker than the rotors !!
http://www.teamfc3s.org/info/articles/demystifying.html
I am going to have to read some threads on this as I was of the thinking put two shafts at 90deg to have 4 power cycles. Easier option is presumably to run them so you have two firing at the same time as that would lead for simpler ignition setup and I would guess more torque?
I noticed the setup when I saw the pic before and was going to post the same point!
Quote from: Archbish;659365having said all of the above, this (http://www.jascoautomotive.com/forum/viewtopic.php?t=696) is a real life example of 2 13bs plumbed together. The reason he\'s given is for the balancing, and the counterweight removal.
That guy also alludes to something that may be an issue if you consider the engine as a power source to propel a car, rather than an abstract concept nailed to a bench...tyres
Most of the thinking in bike developement has been concerned with de-evolving their power source, since it reached the point where making embarassing amounts of power was easy, but the means to control it and put it to the ground was occult at the least. Traction control is easier in a car where you have more space and surplus electrical supply for clever electronics, but the simple fact is that evenly spaced power pulses simply so not give tyres time to recover from a state of slip quickly enough. This problem is exaggerated by two-strokes, with their power stroke per revolution, and after all, rotaries are kinda two strokes that go roundy roundy rather than uppy downy...
What tends to happen is that the tyre loses traction, and just physics catches up and attempts to restore it again, BANG comes another power pulse to keep it slipping. Few two stroke GP bikes still ran even firing orders by the time they were made obsolete by MotoGP tech, and some of those still run staggered cranks, even with clever electrickery the two strokes could only dream of. Yamaha\'s all-conquering 2009 R1 also has a cross-plane crank to unevenly space the firing order and give the tyres a chance to catch up, so it goes BANG-BANG pause BANG-BANG with the pause allowing traction to be restored (hence the other term they are known by of "big bang" engines).
I know cars have another advantage in that they can fit ever more mahoosive tyres, but there are limits to this dictated from, for example, race series rules and the physical constraints of the vehicle to which the engine is fitted, presumably in this case some sort of RX chassis. The constant struggle for traction also has knock-on effects not just in terms of sheer diffculty controlling the vehicle, but also wear and tear to drivetrain and suspension componentry from being in a constant state of conflict between fairly large forces of moment.
There would be an argument for having the correct engine characteristics to promote maximum grip, rather than to overwhelm it and then try to backtrack to the tipping point. That old Pirelli slogan is hackneyed but never out of fashion after all.....unless you want to build a drift car, of course, in which case being able to provoke a break in traction at will would seem a definite advantage.
Or, of course, I could just be spouting abject boIIocks as usual
Humble apologies, not being a big expert on rotarys I\'m obviously wrong on the rotor/e shaftratio, a good example of commenting without thinking!! As for the four power strokes I\'m probably getting hold of the wrong end of the stick(a case of not really paying any attention to what the thread is all about)-der! As for firing orders on four strokes, Ducati ran what was called at the time a \'big bang\' v-twin where the firing order was only a matter of a few degees out on each cylinder(ie. the pistons instead of firing 180degrees apart as is usual). I\'m not sure if they still use this but it was effective a couple of years ago.Anyway, give me a two stroke any day of the week! (And before you start moaning, yes I love rotarys almost as much, its just I don\'t have enough knowledge of them yet)!!!!
Yeah, you\'re kinda right, Bob. In fact, all Ducatis since the first "proper" ones back in the days of Pantahs and such have intrinsically been "big bang" because they share a 90 degree V-twin engine layout (or L-twin as Ducati call it). Therefore, it\'s got a built-in bang-bang-pause firing order. one of the reasons for their legendary grunt out of corners and good traction, although the catering bean-tin size pistons flailing around help no end. Two strokes for the win, BTW!
I was talking to Jim Whittam the other day (ex superbike champion- I\'ve known him since he was a spotty teenager throwing mopeds down the street) and Nortons rotary came up. They are actually remaking the engine(something Carl mentioned to me a while ago) and, though they are increasing the capacity(573cc? to 7-something)the general design of the engine will remain the same. Oops. I\'d better start another paragraph before someone starts moaning!!
To me the main downfall of the Norton engine is the mains-large needle rollers(and I mean large) needing 20:1 petroil mixture. They smoke like ....! Jim Whttam was a bit surprised that the engine is being manufactured again coz there ain\'t no class to put it in, a bit like making a 500cc GP engine again(two stroke I mean) though it would .... all over any four stroke about!!!
Going back to the 4 rotor e-shaft, the only way to successfully marry two shafts together would be a keyed taper. With splines or serrations there is still chance of some backlash which might be ok on a halfshaft but not a crank-e shaft.