I just purchased SAE Tech Paper 2004-01-1790 (see www.sae.org ) presented by Mazda at the SAE 2004 World Congress. It contains very interesting informations on the RENESIS, including the Mazda engineering power and torque figures :

High Power :
Max Torque : 216 N.m @ 5500 rpm
Max Power : 177 kW @ 8500 rpm - 241 ps / 237 hp

Std Power :
Max Torque : 222 N.m @ 5000 rpm
Max Power : 147 kW @ 7200 rpm - 200 ps / 197 hp


It partially confirms what I though about the NA vs EU vs JA descrepencies in advertised power and torque figures, as explained in this document :
http://www.enginepsd.com/techpages/tp0301_en.doc

Another interesting point is the fact that the torque curve of the Std Power is (slightly) higher than the curve of the High Power everywhere up to 5500 rpm!.

 

Check by yourself : *




* also a good opportunity to 'bump' the thread...

 

Nice to see another SAE member submit a accurate technical thread. Some of these so called experts don't have any real engineering understanding.

 

I'm actually not an SAE member. I'm just a professional engine engineer who occasionally buy interesting tech papers and books from them.

Actually, this particular tech paper was a bit disappointing as it gives little more technical info than Yagamushi's book about the RX8.

Thanks,

IKN

 

There is actually a very simple explanation as to why the 4 port engine (standard power) has more power than the 6 port engine (high power) up to 5500 rpm. The biggest reason is that the 4 port engine has longer intake runners which tune to a lower rpm. The even the rotating sleeve which retunes the intake for higher power tuning opens at a lower rpm. The intake itself is different. There is no VFAD (variable fresh air duct) on this car which retunes the power for higher up. There is only one long intake duct but even this one is longer than the long one of the 6 port engine. this too tunes the power for lower in the powerband. The ports of the engine are physically different as well. Besides the obvious fact that there are 2 less ports in the lower power engine, they are timed different as well. The intake ports The primary intake ports have less timing than those of the 6 port engine and the exhaust ports also have less total timing. Besides being timed for lower rpm use, their smaller size also means they are incapable of higher flow amounts. The smaller ports flow better which is an advantage for making power at a lower rpm. All of these things combine to give us an engine that has more power up to a point than the high power engine does. This was intentional as this engine doesn't rev near as high as the high power engine. It is through different timing and higher rpms that the 6 port engine gets the advantage.

 

I like this quote which is the last sentance of that SAE paper. "Comparison between EU and NA advertised engine performance figures should be avoided at all costs."

What I do find interesting is that according to this paper, Europe gets a 9.6:1 compression ratio while the U.S. gets a 9.9:1 compression ratio. I have only seen 10.0:1 advertised or mentioned everywhere else.

I also thought that the RON rating for gasoline yieleded much higher numbers than octane ratings. I had always thought that 102 RON was roughly equivalent to 93 octane. The test shows that 91 and 95 RON were used. This would be some low octane fuel. Even lower than 87 octane. This puzzles me.

I know it is an SAE paper but I am a little sceptical as to what some of it says. I wish there was someone available who could definitively answer the discrepancy issues of this paper vs what everyone knows about the engine. Unfortunately this is only Mazda or the actual person who wrote the paper.

 

that graph you posted above looks nearly the same that was provided by mazda soon after the launch. i am reposting the original one below. this one makes it look like the T of the high power is HIGHER after 5500 rpm which is the point where they normally give the T figure. i haven't ever gotten an answer to my question about this : why give the "peak" number at 5500 rpm if the peak is actually a little higher (220 by the looks of the graph) at higher rpm. is it just poor graphing or an true number? if it's a true number why quote the lower T/lower rpm number?

 

All the graphs I've seen so far that were used in advertising or press packs displayed some kind of discrepency. I would stay away from them.

 

Ehr, that paper about advertised power and torque was actually written by myself. It refers to the Ford Escape/Mazda Tribute 2.0L. It's not at all related to the Mazda Renesis paper mentionned above.

The base engine (NAAO Zetec 2.0L) actually has the same program compression ration (CR) but a higher CR engine was used for US power certification.

91 RON is the program fuel for the US version and 95 RON for Europe. These are supposedly the fuel rating commonly used for this kind of vehicle. Most cars in Europe run on 95 RON (called EuroSuper). Some, like Porsches, allgedly need 98 RON fuel (SuperPlus) which is actually not easily available in some European countries (e.g. Italy). Not that the European market average (average of real RON measurements, 95 being the allowed minimum) for 95 RON fuel is actually 96.5 RON