Sup /o/
Just started reading up on the rotaries (just started getting into cars in general I guess)
They're pretty interesting, but one thing I haven't found answered is the lack of torque in a rotary engine. Apparently any semblance of torque and (to a lesser extent) power is towards the upper RPM range.
Why?
I was reading about it in context of the RX-7 FD so I may have misinterpreted it and it may be purely because of the FD's sequential turbo setup, but it seemed to imply that it was a trait inherent in all Wankel rotaries.
Why is that?
>>14143558
Because they're spinny rather than pushy
>tfw want to buy old RX7 just because rotaries are cool
TELL ME NOT TO
http://www.rx8club.com/series-i-tech-garage-22/cause-low-torque-18417/
>>14143565
That actually makes sense
the 13b rew was NOT well designed.
undersized cooling system
rats nest of vacuum lines. truly horrible.
a lack of any MAF sensor on a turbo car...
a really really badly designed downpipe.
and it was plagued with dozens of TSB's too.
honestly they messed up. it could have been better.
>>14143593
I've heard the previous 2nd gen turbo II's were actually better designed than the FD's.
Apparently they sort of dropped the ball on the 3rd gen.
>Apparently any semblance of torque and (to a lesser extent) power is towards the upper RPM range
seems like you didnt do any research. rotaries are known for making most of their torque early on.
if you want to know why a 240hp rotary that revs to 9k doesnt make as much torque as a 240hp v8 thats revs to 5k... lol
>>14143584
Got it, thanks
Would it be as simple as using a heavier rotor and crank for more torque, or what would be the simplest way to achieve more torque in a rotary?
>>14143581
thats new
usually they're bought because of the looks then they get real engines put in them
>>14143654
nice b8 dude
>>14143649
A larger eccentricity would, but you kill the good feature of wankels, their tendency to rev high becuase its less balanced.
The whole purpose of Wankels is to have a wide powerband and to stay in that powerband when driving/racing, Wankels are not drag racing engines that's what V8's are for.
>>14143649
>Would it be as simple as using a heavier rotor and crank for more torque
I'm not a mechanical engineer but I wouldn't have thought it would be quite that simple. I think that would more likely damage the propensity to be able to rev high, while gaining some minor amount of torque.
One of the posts in that thread mentioned "increasing eccentricity" - that is to say, design the engine so that more lateral, side to side, or up and down movement of the moving assembly is achieved. That should in theory assist with creating more force acting directly upon the e-shaft to make more torque.
Horse power is force x distance.
Go and take a lug nut off a tire, with a screwdriver. That was fucking hard, because all the force is being applied to the axis. Now take another one off with a 2 foot breaker bar. Fuck that was easy hey? Too bad you had to push that bar 2 feet to make it turn less than a quarter of the way around.
And that's why rotaries make no torque. The force being generated is very close to the axis of rotation.
>>14143743
No HP is (Torque x RPM)/5252
Torque is Force x distance.
>>14143790
They're both force times distance, Rpm being the distance that the force travels.
But yes I forgot about the 5252 lol
>>14143558
FDs actually have a great torque curve. This graph is of an FD vs. the FC S5 Turbo 2.
because torque a shit
high rpm is better
>>14143624
You might be the only person who thinks that they dropped the ball on the 3rd gen.
>>14143668
it probably wasnt b8
he is probably american, so he actually belives that
>>14143935
He could also be talking about 2JZs and RB20s
(LS is not the only engine that gets swapped into RX7s)
Why don't supercars run Wankel engines? It would make sense because they won't be taken out often so apex wear and oil changes aren't needed constantly and they're pretty high performance for their weight
>>14144053
A lot of super car owners also care about Sound so they like their V8s V10s and V12s and would probably prefer that over the sound the Wankel makes.
(can't really imagine a very high-pitched buzz-saw sounding Ferrari or Lamborghini)
>>14143588
intuitively, you may think it does, but he really did not accurately answer your question at all.
>>14143992
non-americans arent stupid enough to think a boat anchor iron block inline six or disgusting lolnorevs pushrod v8 should go into an rx7
>>14144053
Why would the spend a fuckton of money literally reinventing the engine or buying a fuckton of shit from mazda when they can throw in another V12 like they always have?
>>14144067
>>14144116
And there we have it.
Rotary: -1
Every other configuration: 9001
>>14143919
Is 7500 or where the redline telly considered high cause My stealth revs to 7200. Do I have a super cool high revving v6 or is that just average?
>>14145184
turbo only makes power at certain rpm
N/A rotaries rev higher
>>14144113
You joke about this. I live in South Africa, and an FD RX-7 became available a few months ago. After a blown engine, this guy went full "racecar muh v8" and threw an LS into it, now charges R400k, which is around $25k
>>14145414
is south africa also cucked by import laws?
do people obey them at all, here in mexico people just dont give a fuck and import whatever they want
>>14145446
Yep, import laws fuck shit up. Between strict classic/vintage/racecar laws and local manufacturer protection, most cars are illegal to import without going through so much shit.
People obey the laws because it's almost impossible to bring shit in without the government knowing, and the only time they're competent is when they can take our fucking money.
>>14143593
>he thinks a MAF is better than a MAP
kek
Less shit is spinning, therefore less rotational inertia, therefore less torque for a given rpm
>>14143565
>>14143588
how much money do i need to throw at an fd rx7 to do a road trip in it
>>14148071
That building in the background has some outstanding brickwork.
>>14149857
http://lmgtfy.com/?q=Road+trip+cost+calculator+
http://lmgtfy.com/?q=Fd+rx7+fuel+consumption+
Dont be useless
>>14149871
>fuel consumption even coming into the equation
>>14149879
Rethink what youve just said
>>14150072
>guy obviously asks how to make an fd reliable enough to do a road trip
>autistic with no reading comprehension comes in to talk about fuel
did you forget your tripcode?
>>14150086
>>14149879
fuel consumption is the only thing you need to 'throw money at' unless you plan to buy some shit box with blown seals on one rotor and drive it home
>>14143558
The 20B in the Eunos Cosmo makes over 400nm down low
>>14143919
Literally looks just like an ls1 torque curve. But it revs higher and makes less power
Basically rotaries make great torque all throughout their powerband. Like a proper na v8 can
RX8 Torque curve is more a gentle hill. It makes torque basically everywhere.
It has about 4 different intake valves changing the configuration of air intake manifolds to keep the engine in good tune throughout the entire rev-range.
Below 3750 rpm, the engine runs on 2-ports only, and injectors.
The SSV which controls the outer ports which open at 3750rpm or so, running the engine on 4-ports and injectors.
The VFAD in the airbox which opens at 5500rpm, shortening the intake runner.
The APV which opens at something like 6000rpm and activates two extra intake ports and all six injectors. (Mmmm, fuel)
Finally, the VDI valve opens at 7500 and shortens the intake runner to give the top-end power.
It means you can crawl around at 2000rpm in top and it won't be gutless.
It's really not a lack of torque - it's that there's no surge in torque at any point like with a turbo boosting or a diesel. It doesn't ever 'come on' to the cam.
>>14151199
Actually, it is pretty gutless at 2k (even lugs the engine a bit if you put your foot down in high gear), but about 3k and up is fine. And because of the gearing, you'd hardly be that low anyway unless you're just going at a slow cruise trying to get decent fuel economy (but where's the fun in that?)
Agreed on everything else.
>>14143935
You probably ride a donkey and live in a monarchy you grey skinned yurp tard.
>>14144067
What the actual fuck
A ported 13B sounds amazing.
20B and 26B sound god tier. You're a genuine autist if you think otherwise.
bumpu
>>14153303
>tfw reading speed is ~1200wpm
RX7 is top fuel dragster fast?
>>14153759
Le yes.
>>14143649
>heavier rotor
Increasing mass will do nothing to increase torque, just make it take longer to rev into its powerband.
I'm assuming combustion chamber design, timing of events and the path the dorito takes as it spins is what dictates power characteristics.
Adding mass is the worst thing you can do.
>>14155118
Forgot about intake design. Other anon said it, I should go to bed.
