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    #31
    A lot of it has to do with the ****ty fuel we have here so the compr number was dropped slightly. this engine doesnt run at this steady compression number due to the changes in valve timing. intake cam is electronically controlled and the exhaust cam timing is now controlled hyudraulically just like it use to be on the older motor on the intake side. why they didnt go electronically on the exhaust side is beyond me. I had a two day skyactive training course at mazda canada. interesting motors thats for sure. smaller oil galleries, new piston design, small skirt, very light, large dome with center cavity to optimize combustion. new fuel system and injector design (6 different spray patterns all designed to hit certain spots in the chamber and piston). High pressure fuel pump now pumps higher psi then the older motor as well. believe it was 1700psi now to 2300psi. oil pressure is also controlled hydraulicly to reduce resistance in the motor. eg: 15psi pressureat idle and 2000rpm, 4000rpm and pressure instantly jumps to 60 psi. no egr. on start up the intake cam gets retarded to about 60 degrees. sounds funny for about 20 -30 sec. if you do a compression test on this motor the first pump gives you a reading of 25 psi and your final reading is around 80 psi. yes you read it right. this on a new motor. a vacuum pump is now used because this motor produced little vac, this was needed because if you just start the car and take off you would have no power assist to your brakes. this pump is bolted to the back of the high pressure fuel pump and both are driven by the exhaust cam. 6 speed manuel is very compact and light. really it is still rated at a weak 200ft lbs torque. the diesel is a little beefier and rated at 300 ft lbs. everything about this motor and transmissions (manuel and auto) are very different from previous generations. Auto now have the inhibitor switch, tcm, reverse light switch all built into one unit and this is inside the transmission and bolted to the top of the valve body. any issues with this and i believe the whole unit has to be replaced. Torque converter is now pretty much locked all the time to give it a more solid feel (like a manuel) slip happens very slightly at take off and at cruise when you briefly take your foot off the gas. sorry for the novel. there is tons more to the skyactive drivetrain. very interesting and i do believe mazda has a winner here. maybe will post more info as i get it
    Last edited by progt91; 10-14-2011, 09:17 PM.
    91 protege gt. dropzone mx3 springs, mx3 crossmember, ractive front and rear strut braces, rear lower mx3 brace, 4 wheel disc brakes, corksport ss brake and clutch lines,kvr front pads, ractive cai,ram air hood scoop, modified front bumper, shaved ant and rear trunk lock, fubu ant, short shifter, corksport bronzeoil shifter bushings,92 glass sunroof and tail lights, mx3 center console, autometer gauges (volt and oil pressure) cluster needles painted to match, sound system, 17 inch eagle alloy 193 with 205 40 17 rubber. klze is ALIVE BABY!! . http://www.cardomain.com/ride/2394656http://www.toprotege.com/forums/show...hlight=project[url]

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      #32
      progt91, nice write-up, very informative. Thanks for the information.

      Happy Motoring!
      02 DX Millenium Red - The Penultimate Driving Machine
      MP3 Strut Tower Bar kit; Cusco Front Lower Arm Tie Bar
      MSP Springs, Struts, Stabilizer Bars, Trailing Links, #3 Engine Mount
      Kartboy Stabilizer Bar Bushings; Nyloil Shifter Bushings; Red Line MT-90 Gear Oil
      MP3 Shifter, Knob and Aluminum Pedal Set
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      Comment


        #33
        Nice write-up for sure, but didn't exactly answer my question. I know we get a lower compression than the rest of the world to make sure the engine can run on 87 octane. Everything I've read and heard, besides in this thread and one of Motor Trend's articles, said we were getting 13:1. So is 12:1 the official ratio? And when did that change happen?

        Sent from my HTC Incredible using Tapatalk.

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          #34
          ^^^
          I don't know when the change was made but according to Mazda USA the CR is 12:1.

          Speculation:
          If 14:1 requires 91 octane, then perhaps 13:1 requires 89 octane, and the mandated USA 87 octane may require 12:1.

          Happy Motoring!
          02 DX Millenium Red - The Penultimate Driving Machine
          MP3 Strut Tower Bar kit; Cusco Front Lower Arm Tie Bar
          MSP Springs, Struts, Stabilizer Bars, Trailing Links, #3 Engine Mount
          Kartboy Stabilizer Bar Bushings; Nyloil Shifter Bushings; Red Line MT-90 Gear Oil
          MP3 Shifter, Knob and Aluminum Pedal Set
          Suvlights HD Wiring Harness; Osram Night Breaker H4 Bulbs; Exide Edge AGM Battery
          Summer: 5Zigen FN01R-C 16 x 7" Wheels; Yoko S.drive 205/45-16s
          Winter: Enkei OR52 16 x 7" Wheels; Falken Ziex ZE-912 205/45-16s
          Modified OEM Air Intake; Racing Beat Exhaust System; Techna-Fit SS Clutch Line
          Denso SKJ16CR-L11 Extended Tip Spark Plugs; Magnecor Wires
          Power Slot Front Brake Rotors; Techna-Fit SS Brake Lines; Hawk HPS Pads
          Red Line Synthetic Engine Oil; C/S Aluminum Oil Cap
          Cyberdyne Digital Gauges: Tach; Ambient Air Temp; Voltmeter

          Comment


            #35
            The official number i have in my book is 12.0:1 displacement 1.997 bore and stroke 83.5 x 91.2
            91 protege gt. dropzone mx3 springs, mx3 crossmember, ractive front and rear strut braces, rear lower mx3 brace, 4 wheel disc brakes, corksport ss brake and clutch lines,kvr front pads, ractive cai,ram air hood scoop, modified front bumper, shaved ant and rear trunk lock, fubu ant, short shifter, corksport bronzeoil shifter bushings,92 glass sunroof and tail lights, mx3 center console, autometer gauges (volt and oil pressure) cluster needles painted to match, sound system, 17 inch eagle alloy 193 with 205 40 17 rubber. klze is ALIVE BABY!! . http://www.cardomain.com/ride/2394656http://www.toprotege.com/forums/show...hlight=project[url]

            Comment


              #36
              Connecting rods distance between small and big ends 155.2 mm thickness is 22mm weight is 461 g forged cracked rods. The weight of the old rods is 524g 21.8 thickness 160.3 DISTANCE BETWEEN ENDS
              91 protege gt. dropzone mx3 springs, mx3 crossmember, ractive front and rear strut braces, rear lower mx3 brace, 4 wheel disc brakes, corksport ss brake and clutch lines,kvr front pads, ractive cai,ram air hood scoop, modified front bumper, shaved ant and rear trunk lock, fubu ant, short shifter, corksport bronzeoil shifter bushings,92 glass sunroof and tail lights, mx3 center console, autometer gauges (volt and oil pressure) cluster needles painted to match, sound system, 17 inch eagle alloy 193 with 205 40 17 rubber. klze is ALIVE BABY!! . http://www.cardomain.com/ride/2394656http://www.toprotege.com/forums/show...hlight=project[url]

              Comment


                #37
                I think I figured out where my compression confusion came from. Motor Trend recently took the 2012 Mazda3 with the SkyActiv-G engine for a "First Drive" and posted the article to their Android mobile app. The article states that the 2012 3 uses a 12:1 compression while the 2013 CX-5 will use 13:1. The reason? The fancy 4-2-1 exhaust header won't fit in the Mazda3 engine bay without firewall modifications.

                That same article also states that the fuel pressure is at 2900psi, where as progt91 reported 2300. Not sure which is correct. Maybe Motor Trend was talking about the 13:1, CX-5 engine when they noted the fuel pressure.
                Last edited by irishkev90; 10-24-2011, 11:30 AM.

                Comment


                  #38
                  Originally posted by FE3-323 View Post
                  thank god ford's influence is gone........... thats all i have to say
                  We probably would have bought a new Mazda 3 if it weren't for the gas mileage, front end "styling", and smaller cargo area. The new Duratec 2.0 GDI makes 160hp and gets up to 40mpgs. It's good that Mazda is catching up though ;-)
                  _________________________________
                  '12 Focus SE hatch
                  '04 Eddie Bauer V8 4X4 Explorer
                  '05 Saab 9-3 turbo (sold)
                  '90 Mazda 323 GT (sold)
                  '04 Mazda Tribute (sold)
                  '92 Mazda Protege LX (sold)
                  '91 Mazda Protege LX (blown engine)
                  '91 Honda Prelude (totalled)
                  '91 Honda CRX SI (sold)

                  Comment


                    #39
                    More on Compression Ratios

                    According to an article in the February 2012 Road&Track magazine (Drives: 2012 Mazda3, page 32), the SkyActiv-G engine for the European Domestic Market will have a 14:1 CR which of course requires premium fuel. According to the article, "Mazda felt that a premium fuel requirement wouldn't fit North Americans' perception of value." Since the use of 87 octane fuel in NA limits the CR to no higher than 12:1, that's what were stuck with.

                    IMO, this is a very short-sighted decision perhaps influenced more by political considerations than technological benefits. Due to the rather substantial increase in TE of the European version, not only would there be an increased power output but additionally a marked decrease in fuel consumption that could even end up offsetting the higher cost of 91 octane. Even at equal cost, using less fuel is still a beneficial outcome. This is only speculation on my part and I could be wrong but I somehow doubt that, given the competition, Mazda would turn their econobox into an unaffordable gas-guzzler in a land where typical gas prices trump ours by a large margin. As I see it, this is just another example of a widely-held but incorrect perception obscuring the actual reality of a situation - gasoline is bad so premium gasoline is badder still - something we human beings seem to be good at doing.

                    At this point I still believe that the JDM SkyActiv-G engine utilizes a 13:1 CR and requires 89 octane but if anyone has more recent information please post a correction.

                    As always, in the interest of science and for humanity.

                    Happy Motoring!
                    02 DX Millenium Red - The Penultimate Driving Machine
                    MP3 Strut Tower Bar kit; Cusco Front Lower Arm Tie Bar
                    MSP Springs, Struts, Stabilizer Bars, Trailing Links, #3 Engine Mount
                    Kartboy Stabilizer Bar Bushings; Nyloil Shifter Bushings; Red Line MT-90 Gear Oil
                    MP3 Shifter, Knob and Aluminum Pedal Set
                    Suvlights HD Wiring Harness; Osram Night Breaker H4 Bulbs; Exide Edge AGM Battery
                    Summer: 5Zigen FN01R-C 16 x 7" Wheels; Yoko S.drive 205/45-16s
                    Winter: Enkei OR52 16 x 7" Wheels; Falken Ziex ZE-912 205/45-16s
                    Modified OEM Air Intake; Racing Beat Exhaust System; Techna-Fit SS Clutch Line
                    Denso SKJ16CR-L11 Extended Tip Spark Plugs; Magnecor Wires
                    Power Slot Front Brake Rotors; Techna-Fit SS Brake Lines; Hawk HPS Pads
                    Red Line Synthetic Engine Oil; C/S Aluminum Oil Cap
                    Cyberdyne Digital Gauges: Tach; Ambient Air Temp; Voltmeter

                    Comment


                      #40
                      I want Mazda to give me the option of ordering the car with the higher compression. If someone is willing to pay the extra money for the gas, why would Mazda hold hem back from getting what they wanted?


                      I'll have more to add when I get on break.

                      Comment


                        #41
                        I don't know if it's Mazda holding us back from getting what we want or rather that they are unwilling to buck the prevailing political climate here.


                        Happy Motoring!
                        02 DX Millenium Red - The Penultimate Driving Machine
                        MP3 Strut Tower Bar kit; Cusco Front Lower Arm Tie Bar
                        MSP Springs, Struts, Stabilizer Bars, Trailing Links, #3 Engine Mount
                        Kartboy Stabilizer Bar Bushings; Nyloil Shifter Bushings; Red Line MT-90 Gear Oil
                        MP3 Shifter, Knob and Aluminum Pedal Set
                        Suvlights HD Wiring Harness; Osram Night Breaker H4 Bulbs; Exide Edge AGM Battery
                        Summer: 5Zigen FN01R-C 16 x 7" Wheels; Yoko S.drive 205/45-16s
                        Winter: Enkei OR52 16 x 7" Wheels; Falken Ziex ZE-912 205/45-16s
                        Modified OEM Air Intake; Racing Beat Exhaust System; Techna-Fit SS Clutch Line
                        Denso SKJ16CR-L11 Extended Tip Spark Plugs; Magnecor Wires
                        Power Slot Front Brake Rotors; Techna-Fit SS Brake Lines; Hawk HPS Pads
                        Red Line Synthetic Engine Oil; C/S Aluminum Oil Cap
                        Cyberdyne Digital Gauges: Tach; Ambient Air Temp; Voltmeter

                        Comment


                          #42
                          I'm not saying they are holding us back. Just another "the world gets something we don't" kind of feeling.

                          Their decision to allow the engine to use lower octane gas, through lower compression, is made from a financial standpoint. A small, niche company like Mazda can't afford to have their best selling car requiring more expensive gasoline. Yes, the fuel saved will offset to added cost, but for Americans (in general) want upfront costs to be cheap, like 87 octane compared to 93.

                          A larger company, like Toyota or Honda, can afford to have one of their cars require higher octane because the number of models they sell can offset the cost of selling fewer, higher-octane cars. Same story with hybrids. Mercedes-Benz can add a hybrid system to their cars for pocket change, relatively speaking. That same, $3,000 system would put most buyers off if it was in a $18,000 compact sedan.

                          (To be continued next break)

                          Comment


                            #43
                            i vote political power.... since the politics are the ones controlling our MPG ceiling.....
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                            1992- project FE3..... 313 WHP @ 9.3psi




                            I pet my dash when I get into the car..."good car"
                            he actually has a mazda tree, parts grow on it

                            Comment


                              #44
                              Additional Data from Car and Driver Magazine

                              The April 2012 issue of Car and Driver magazine includes a road test of the Mazda 3i Touring model with the SkyActiv-G engine. Mention is made that there is a 30% reduction in internal engine friction versus the normal 2.0 L engine. In the future (time unspecified) the present 12:1 CR will be raised to 13:1 and a 4-2-1 exhaust header will be incorporated into the design to further increase combustion efficiency. This will of course result in an additional increase in fuel efficiency and power output.

                              For more details on the road test, go to:


                              Happy Motoring!
                              Last edited by goldstar; 03-06-2012, 01:58 PM.
                              02 DX Millenium Red - The Penultimate Driving Machine
                              MP3 Strut Tower Bar kit; Cusco Front Lower Arm Tie Bar
                              MSP Springs, Struts, Stabilizer Bars, Trailing Links, #3 Engine Mount
                              Kartboy Stabilizer Bar Bushings; Nyloil Shifter Bushings; Red Line MT-90 Gear Oil
                              MP3 Shifter, Knob and Aluminum Pedal Set
                              Suvlights HD Wiring Harness; Osram Night Breaker H4 Bulbs; Exide Edge AGM Battery
                              Summer: 5Zigen FN01R-C 16 x 7" Wheels; Yoko S.drive 205/45-16s
                              Winter: Enkei OR52 16 x 7" Wheels; Falken Ziex ZE-912 205/45-16s
                              Modified OEM Air Intake; Racing Beat Exhaust System; Techna-Fit SS Clutch Line
                              Denso SKJ16CR-L11 Extended Tip Spark Plugs; Magnecor Wires
                              Power Slot Front Brake Rotors; Techna-Fit SS Brake Lines; Hawk HPS Pads
                              Red Line Synthetic Engine Oil; C/S Aluminum Oil Cap
                              Cyberdyne Digital Gauges: Tach; Ambient Air Temp; Voltmeter

                              Comment


                                #45
                                I never continued my rant and now I don't know where I was going, haha.

                                Sounds like the new SkyActiv-3 is pretty promising. Still wish we could get the full 14:1 compression version, though

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