V8 versus Rotary!

[RWD Freak]

Right, I am a newbie here, but hopefully in the upcoming weekend, I will be able to pick up a certain Dragon Performance built single turbo FD3S hheheehehhe...[evil grins]

But back on topic, I\'ve owned many cars before and as far as the whole V8 vs. Rotory thing goes I have to say that both do have their good points and bad ones, first off, let me start off with the rotary, as simple as the rotary concept may seem, as there is only 2 moving parts within the whole engine, that also means that it is one of the most complicated, if something minor goes wrong within the engine, the motor will most likely need to be striped. As for the V8, it depends mainly on build quality, take for example the Yamaha V8 found in the Ford Taurus SHO, the weak point in them are the cam sprockets that can come lose over time and slip out of position causing major top to bottom work, but with the cam sprockets welded the car can take alot of punishment within reason. Another V8 would be the all mighty GM LS1/2/6/7 based engine, found in the C5/6 Corvette, 98-02 F-bodies, the current Vauxhall Monaro and a few of the aussie Holdens, the problem with the engines are the fact that GM put so much effort into developing the engine, they ran out of money to produce it, hence the weak pushrods, but as time went along, GM started to find the flaws, revisions began in 2001 when they introduced the cars with better flowing manifolds, and the LS6 intake, well let\'s just say after a while they now have the C6 Z06 which is almost perfect in all means, top notch everything, but I am still wondering when they\'ll start catching on to the point where steel shift forks are needed for the T56 gearbox.....anywhos back on track...

Rotary cars have a more efficient way to burn fuel and by far the most unique way. Also the weight of the engine and the size really helps, being pushed back against the firewall means much better weight distrubution so when it comes to like a circuit sprint I am sure the RX7 will come out on top compared to a evenly matched V8....we can\'t compare the LS1 motor to the 13B REW motor as there is a significant production date difference, hmm so back in 92, chevy still was limping around with the TPI engine....that is definetely hmmmm not quite what we\'re looking for so lets fast forward and give GM a year advantage and say let\'s compare the RX7 to the LT1 GM block say in a corvette....well I would love to see in a 20 lap race how many times the LT1 vette would get lapped say in Silverstone......yes they\'re very clumbsy and heavy engines....so I would say in that challenge the rotary wins. (I did not mention the 93\' Ford 302ci H/O engine because it was simply not worth talking about in my opinion....)

So here comes the sound test, well we all know that the V8s sound very very nice, especially something with long tube headers and a free flow exhaust humming with a lumpy cam....as for a RX7 though they might sound good on idle, lets face it, once they hit high revs they sound like a weed whacker from hell.

So like I said each to it\'s own advantages and if you are looking for performance the rotary wins considering what it\'s competition was. Hope this helps a bit!

Freak

[Martiny]

Ok freak, a good write up... BUT.
I will never agree that a Rotary is more complicated than a V8, or even a 6 or 4 cylinder for that matter!  No springs, levers and timing chains.

There are 3 moving parts by the way, 2 rotors and the eccentric shaft.

As for the sound - its the absolute best sound ever on song, very closely followed by a 2 stroke grand prix bike!!

A V8 to me just sounds big and heavy, which is EXACTLY what it is!!!

:-))

[rxv8]

;0.......................

[monkey-fd3s]

I believe the "VW" is knocking on the door of the 9\'s in street trim...

Is you\'re RX that fast?  Mine certainly isn\'t.  All cars are cool when tuned and worked well, imho the bug is cool.

It\'s bloody VW!!!! Huuuuuuuuuu! :rollin. Please don\'t mention how fast some can go! I know. But look at it!!!!!!!!!!!!!!!!!!

[monkey-fd3s]

To me the photo\'s below show cars as cool as each other, different engines... who cares... from Pro Mod to CCSE to Rotary Drag Cars they are all cool, all sound cool.  I don\'t really think it matters what engine your car has, as long as it runs the numbers.

[monkey-fd3s]

Why how much money has Richie put in his bug... do you actually know him?

I think if you did you\'d find that most of it was fab\'d up between a group of like minded guys on a Budget.  

If we\'re talking stock Rotary engines... then why are we talking about wheelies....  :xconfused

if i put "that" money into my 2,then id be running 9\'s all day with wheelies as well...getting outa perspective here fellas...we were talking stock ROTOR and stock v8....s :cool

[iaint]

One advantage the rotary has is the rev-limit.  Generally not that high on big displacement V8s so potentially less time \'in-gear\' for the pistony thing.

Certainly love the sound of some of the V8s - shame TVR moved away from them with the flawed S6 engine.  V10\'s sound even better

[MikeLMR]

One advantage the rotary has is the rev-limit.  Generally not that high on big displacement V8s so potentially less time \'in-gear\' for the pistony thing.

Certainly love the sound of some of the V8s - shame TVR moved away from them with the flawed S6 engine.  V10\'s sound even better

v8\'s are quite nicely balanced engines. make one out of modern materials and the correct dimensions and it will rev its nuts off just like any other engine config

The new generation of F1 V8\'s are already exceeding the rpm limits of the current V10\'s

[iaint]

v8\'s are quite nicely balanced engines. make one out of modern materials and the correct dimensions and it will rev its nuts off just like any other engine config

The new generation of F1 V8\'s are already exceeding the rpm limits of the current V10\'s

I don\'t disagree on modern V8s revving higher than older ones but large capacity pistons have inherant issues reving hard.  Similar to the limits applied to rotaries revving very high (i.e. weight of the rotors and the materials are as important as the balancing!).

Comparing the very short-throw F1 engines with a normal V8 vs a rotary isn\'t a great comparison either!  One major factor with the F1\'s high rev limit is the fact that the pistons only travel a small portion of the distance of a normal piston but have a large surface area IIRC - means a lot of power with relatively low torque and nothing lower down the range.

[MikeLMR]

are rotary engines really high reving though ? devide the shaft rpm by 3 to get rotor rpm and the rotary is a lazy torque monster of an engine

Out of interest what is the comparison between the average velocity of a rotor tip at the extreme maximum (say on a 6 second drag car) compared with a piston ring in a similar application ?

[iaint]

are rotary engines really high reving though ? devide the shaft rpm by 3 to get rotor rpm and the rotary is a lazy torque monster of an engine

Out of interest what is the comparison between the average velocity of a rotor tip at the extreme maximum (say on a 6 second drag car) compared with a piston ring in a similar application ?

Always thought the rotor/eccentric speed was 2/3 of the output shaft not 1/3?

From the little I\'ve read about this the problems with the eccentric deforming under high RPM can only be partially solved with clever balancing and needs to be dealt with by saving weight on the rotors and using the right materials which would make it very expensive.

I guess that the same goes with the tips and corner seals - need to withstand high g-forces at big rpms.

If I recall correctly Carl mentioned he can build a customer engine that\'d rev to 10krpm for a price...

[monkey-fd3s]

I think part of it is using a Billet Eccentric Shaft and they alone cost a shed load of money.....

I think they are around $2500 AUD  :yes

[ro284]

When i started this thread, The main reason was to compare the following=
One apex seal is 3inches long, X 6 = 18inches
V8 with 4inch pistons, circumference 12 inches for one piston ring , and they need two compression rings per piston, = 2 feet X 8 =16 foot of sealing surface to get the compression to fire the charge, with another 8 foot of oil control rings!! making a total length of sealing surface 8 YARDS!
Against a total of only 18 inches! OF APEX SEALS in a 13b!
No valves Tappets or cam belts or camshafts, or timing chains or tensioners, half the plugs! I think the rotary engine is incredible, (ok they may need a rebuild after 12 years, but for the end result, worth every penny! )equal power to a v8 but higher revving, and in a fabulous car.
Bob

[MikeLMR]

what about the side seals and oil seals on the rotary ?

[ro284]

(QUOTE)what about the side seals and oil seals on the rotary ?(UNQUOTE)

Well i don\'t know how long they would be, but allow a couple of yards of side/oil seals i guess, Still six yards short of the seals needed on a v8! to do the same thing.
Also no  con-rods,no enormous crank! big ends, small ends, much less mains bearings,Dizzy! is there a dizzy?scrap that! getting picky now! Rotary rules for me, even N/A and is the way in the future,IMHO.
Bob