RotaryBred

i'm still puzzled as to why they are still doing the side port exhaust. you think they would've learned that more power can be harnessed with peripheral ports which would make the sale of the car more appealing to the young and old, and raise gas milage since it is much less restrictive. Old people dont want 8's because the gas mileage sucks, and young people (who care about going fast) don't want them because in order to get and real power outta them, you might as well do away with the whole engine!

hhn2002

its seems as if this engine may be better suited to boost than the original renesis.
correct me if im wrong but shorter housings mean shorter apex seals which means better resistance to breaking(less breaking points).
higher displacement generally handle boost better too i think. more surface area to cool means less chance of detonation and apex seals bouncing around.

RotaryBred

you are correct about the apex seals, but someone correct me if I'm wrong - a high compression engine is a high compression engine. once that compression hits a certain PSI, no more boost can be pushed in. That is why the renesis is impossible to see much HP gain from compared to the previous 13b models.

Paul1982

Looks Nice

RotaryBred

do you think a high compression engine (since its built to withstand higher pressures) would respond to insane amounts of boost with a water/meth injection kit and really good tune? just a thought

Jeff20B

iTrader: (13)

Does anyone know how wide these new rotors are? I have... ideas.

rotormind

there suppose to be the same width as the 12a

Black91n/a

The side exhaust is supposed to help with emissions to keep the unburnt hydrocarboms in the engine to get burnt, rather than being emitted as a pollutant. I think it was supposed to help milage too somehow. So while peripheral may be better for performance I don't think they can get it to pass smog any more.

rotormind

yah but the rx8 still didnt get good gas milage. i think they need to figure out more on the peripheral exhaust. the side exhaust is better on emissions because they r able to send the unburned carbons back into the combustion chamber. the problem is, its a waist of power

rotormind

dam, i didnt notice i just about said everything u did

Black91n/a

While it may be "bad for power" the RX-8 does have the most powerful NA rotary ever produced from the factory, so a side exhaust can't be that bad.

rotarygod

iTrader: (1)

As I've posted in other threads, there is more to power than just flow. Port timing has a huge effect. This is why the Renesis does so well. It's not because of the compression ratio or the intake manifold. The Side exhaust port timing is better suited to a street engine in terms of power, emissions, and as a match for the intake port timing. The Renesis doesn't even have port overlap and many claim this is needed for good power. It's not. There are many misconceptions about flow and timing. I actually wish Mazda would develop an all side port race engine.

rotarygod

iTrader: (1)

I've heard 2 rumors but don't know for sure. One says 70mm like the 12A, and another says 75mm.

rotarygod

iTrader: (1)

Put a 4.44:1 rear end in your car and add 400 lbs and see how good your mileage is! If you had a Renesis in your car, you'd get better gas mileage than you do now. You need to look at the entire package. The RX-8 actually gets comparable gas mileage to the much lighter and less agressively geared RX-7's.

MTheoryInc

iTrader: (3)

I think the problem with a boosted renesis engine is the lack of proper stand-alone engine management. The hot ticket among turbo rx8 owners seems to be the the GReddy e-manage which as the greddy site says it best "as close to a stand-alone management system as you can get while maintaining the best features of a "piggy-back" engine management". The first key ingredients in any reliable high HP (350+ rwhp) rotary is stand-alone engine management.

neit_jnf

iTrader: (17)

Copied this from a mazdas247 post:

from a Japanese website

10A
e=15mm
R=105mm
b=60mm
Vh=491cc

13A
e=17.5mm
R=120mm
b=60mm
Vh=655cc

12A
e=15mm
R=105mm
b=70mm
Vh=573cc


13B
e=15mm
R=105mm
b=80mm
Vh=654cc

プロトタイプ

12A'（12A量産前に検討されたエンジン）
e=16.4mm
R=112mm
b=60mm
Vh=573cc

21A
e=18.5mm
R=128mm
b=85mm
Vh=1046cc

22A
e=18.5mm
R=128mm
b=95mm
Vh=1169cc

15A
e=15mm
R=105mm
b=90mm
Vh=737cc

And their guess for 16X is

16X
e=17.5
R=122.5
b=70
Vh=797cc

cewrx7r1

iTrader: (2)

You need to redo your math.

13B = working displacement compared to a 4cycle engine = 2.6L
16X = working displacement compared to a 4cycle engine = 3.2L
20B = working displacement compared to a 4cycle engine = 3.9L

3.2/2.6 = 1.23 or 23% larger
3.9/2.6 = 1.50 or 50% larger

chiptosser

This should have better low end torque

680RWHP12A

interesting motor.. its definatly a prototype, the oil filter pedastal mount only has one hole, how do ya like that?!

Bluem

i have some SAE papers with details on the side port design if someone is interested pm me.

Developed Technologies of the New Rotary Engine (RENESIS)

by: Masaki Ohkubo, Seiji Tashima, Ritsuharu Shimizu,
Suguru Fuse and Hiroshi Ebino. Mazda Motor Corporation

baps9422

Sweet Jesus Love It

diabolical1

iTrader: (3)

they're not going back to peripheral exhaust ports. side ports are the present and future. the problem is that mainstream hasn't caught up yet. porting, especially on the exhaust appears to be a bit tricky, but the bottomline is that these side port engines do their job better than the older design. i mean think about it. stockports on these engines are making what it would take streetporting or forced induction to make on the older engines - with the same fuel. i'm sure it's just a matter of time before we all have a bag of tricks for making more power.

diabolical1

iTrader: (3)

yeah, i was curious about that, too.

exactly!

CrackHeadMel

iTrader: (2)

Maby the oil then goes to the oil cooler? all pressure is regulated pre-oil filter or post oil cooler?

rotormind

this is the second time i heard someone say that the older 13b need to be streetported to make as much power as a renesis. thats basically saying that the the ports on a renesis is the same size as a stock n/a 13b. well if u believe this, than your wrong. the port on the renesis is about 3 times bigger than the older
13b. but guess what, the rx8 is only making a little over 180rwhp. go to the rx8 forums where they show there actuall dyno numbers and u will see that most of them with mods r only making around 180 to 190rwhp. now u also have to consider that the renesis has lighter rotors with more compression, lighter
e-shaft, better intake design, less restrictive exhaust, and all new technology around it. the rx8 barely make any gains with mods. some guy were only making like 5hp off an exhaust. so why would that side exhaust be considered any with hp? older 13b's make more power on a streetport