Many thanks for the information. I looks then like effect I see must be more down to other factors, like the battery temperature as mentioned (though this too should not be a factor after warm-up, one would think), and perhpas other factors like tyre temperature, and increase drag due to denser...
Does anyone know how spark ignition ICE efficiency would be expected to vary with ambient temperature?
I have a Toyota Prius and notice the MPG suffers ~10% drop in cold weather even after warm-up. This could be due to many factors, but just wondered if the above could be one of them.
[My own...
Hmm.. I see what you mean.
Still the reputation the rotary has is that its worse than the worst of piston engines by some margin and I'm not sure that's any longer true. With further innovation it can improve further.
(Maybe the 350Z you compared with previously is a particularly good example...
Could you give some figures or a link to the press reports and extended road tests you mentioned?
I seems to to remember putting up some figures that showed an Alpha Romeo V6 to be an even bigger gas hog.
BTW, that post and quite a few others seem to have dissappeared from the board.
Any one...
Greg
"Please see FAQ731-376 for tips on how to make the best use of Eng-Tips."
I read it and asks you to remember that you are not infallible and you could be wrong.
I think your argument goes:-
you have only considered the issue "Simplistically"
... but you are right anyway,
and anyone...
Norm,
That's just the point though, where you take the power is immaterial. So in your example it's still a 4 cylinder four-stroke - that's what you're saying, isn't it? The power output is the same whichever output you choose.
So now the question is what is a Wankel engine equivalent to?
I...
Hydrae
I'm very entusiastic about rotaries, so regarding the redline, I'm only saying that if we could compare apples with apples more easily, we would be able to get a better idea of how (say) the RX8 compares with other cars in the class.
For example, currently if a journalist were to compare...
If I remember correctly, according to the book by Jan Norbye, there was a lot of debate in the early days about how one should compare engine sizes until someone called R.F.Ansdale "proved" at a Society of Automobile Engineers (?) that the Wankel was equivalent to a 2-stroke (!) of the same...
My view is that that the surface to volume thing may be out-of date dogma thats amounts to a lazy way to rubbish the Wankel concept. If you look at the fuel efficiency of the RX8 it is a huge advance on the RX7 and comparable (or better) than piston engine powered cars in the same power range...
As I appear to have been rather has on the "quasiturbine" in the last post - I should perhaps add that the points I made were only my personal opinion - I could be wrong.
Geoff
Take a look at
http://quasiturbine.promci.qc.ca/QTpasWankel.html
where they compare their engine with the Wankel. You have to hope they understand their own engine better - this is 90% gibberish.
1) They seem to think the Wankel phasing gear transmits some of the power. Obviously not true...
As far as I understand the "variable valve timing" is already a feature of the "high output" version on the rx8 Renesis engine and it does indeed have 3 inlet ports under intelligent control. I believe one of them connects to a tuned inlet tract.
I imagine its much easier to implement than with...
Isn't the probelem that unless you can find a material with very very low thermal mass, effectively you have overall higher average surface temperature. But even if you go 100C higher that won't have a huge impact on heat input to the walls when most of it surely happens in the turbulant...
Pat
Is it your feeling that (ignoring cost for the moment) that a solid ceramic topped piston, with appropriate fuelling and ignition would lead to higher efficiency?
And if so is would you say that is not possible because solid ceramic would not survive the conditions.
It seems surprising...
(This point came up in a previous thread but thought this deserved a new thread since there were no takers in the original - Mazda rx8 wankel efficiency etc)
GraviMan said:-
"Having seen carbon fibre reinforced aluminium pistons (I think they were cast in an oxygen free environment), I feel...
Thanks for all the interesting information. I noticed over the weekend that the rx8 is actually significantly better on maximum power and fuel economy than some of the supposed competition here in the UK. (I was looking particularly at an 165bhp AlphaRomeo which is apparently in direct...
Looking at the fuel consumption of the rx8 in relation to the power output, it seems to be comparable with piston engine sport cars of similar (high) performance.
Doesn't that suggest that say a single rotor version of half the output (say 110hp) but in average use having a wider open throttle...
