From a driving dynamics standpoint, of course it can't be compared. The available trunk space in the Miata is pathetic. lol. I took out the spare tire to free up a little more room and it's livable. Why? You thinking about joining the dark side? (shady)
Here's a photo of the 1st gen Miata trunk from google images. Keeping in mind how skinny Miata spare tire is (it is a 115mm wide tire), you can see how small that trunk is.
This is not the reason to have high compression engine using regular fuel. Higher pressure than normal (2,900 psi vs. 1,600 psi) direct injection, six-hole injectors, volcano-top pistons, those are the elements to achieve amazing 13:1 compression ratio but still allow people to use low-octane regular gas!
This is not the reason to have high compression engine using regular fuel. Higher pressure than normal (2,900 psi vs. 1,600 psi) direct injection, six-hole injectors, volcano-top pistons, those are the elements to achieve amazing 13:1 compression ratio but still allow people to use low-octane regular gas!
I averaged around 25mpg around town and 30 on road trips in my 3100# FWD 2002 Infiniti g20 with a 4 speed slush box. It had 145bhp and 136# torque. I'd say that's very comparable given the 4 speed slushbox. Slap that motor in your cx5 and I bet it would be within 1 to 2 mpg.
This is not the reason to have high compression engine using regular fuel. Higher pressure than normal (2,900 psi vs. 1,600 psi) direct injection, six-hole injectors, volcano-top pistons, those are the elements to achieve amazing 13:1 compression ratio but still allow people to use low-octane regular gas!
Yeah I forgot to mention SkyActiv's long 4-2-1 exhaust manifold. When 2011 Mazda3 came out with the first SkyActiv Technology implemented without 4-2-1 exhaust manifold, the compression ratio increased from 10:1 to 12:1 with regular gas for US market. Once implemented fully for 2013 Mazda3 and CX-5 with 4-2-1 exhaust manifold, the compression ratio increased to 13:1 although it's 14:1 for other regions which makes SkyActiv-G having the highest compression ratio in current production engines!Mazda was able to use 13:1 compression with 87 octane gas mainly because they were the first ones to figure out how to use folded full length headers and of course direct injection. No one had been able to use full length headers because they cool off the exhaust to much for cats to work. Mazda folded the header to retain heat, and on cold start inject raw gas into the header to heat them up quickly so cats work.This is not the reason to have high compression engine using regular fuel. Higher pressure than normal (2,900 psi vs. 1,600 psi) direct injection, six-hole injectors, volcano-top pistons, those are the elements to achieve amazing 13:1 compression ratio but still allow people to use low-octane regular gas!
High compression ratio is not as easy to be accomplished by implementing smaller bore and larger stroke alnoe. Or others will follow suit instead they are off-ladling engine displacement and adding turbochargers, active aero, or other costly technologies in the name of fuel economy! I've been reading many articles and I really liked the Mazda's way with SkyActiv Technology which is based on increasing the compression ratio to improve the efficiency. But none of them mentioned smaller bore and larger stroke as the contributor to high compression ratio. As matter of fact, although Mazda old 2.0L has bore x stroke 87.5 x 83.1mm with 10:1 compression ratio and new SA 2.0L has 83.5 x 91.2mm with 13/14:1, but the old 2.5L has bore x stroke 89 x 100mm with 9.7:1 compression ratio and new SA 2.5L has the same 89 x 100mm with 13/14:1. The same bore and stroke between old and new SA 2.5L further proves smaller bore and larger stroke has nothing to do with SkyActiv's very high compression ratio. (drinks)No, having a smaller bore and larger stroke is one of the reasons Mazda was able to use a higher compression ratio. The under square engine allows for a smaller piston and longer stroke to keep the same displacement. The smaller faster moving piston allows the flame front to have less contact with the smaller piston. With the smaller piston moving faster up and down the bore, the piston has less dwell time at top dead center. Less metal and less time spent at TDC means a cooler running piston. If the piston is running cooler, than the engine can run higher compression. With all these methods mentioned above combined, Mazda was able to use a 13 to 1 compression with 87 octane fuel.This is not the reason to have high compression engine using regular fuel. Higher pressure than normal (2,900 psi vs. 1,600 psi) direct injection, six-hole injectors, volcano-top pistons, those are the elements to achieve amazing 13:1 compression ratio but still allow people to use low-octane regular gas!
Hope this clarifies it for you.
This is not just Mazda. All automakers are using all kind of technologies with expensive cost just to improve a couple of MPG's. This certainly may not impress you and many consumers. But they have the CAFE standard and many regulations to meet hence they have no other choices. SkyActiv Technology has helped Mazda to survive otherwise their cars became uncompetitive! Use US version Mazda3 as an example,
You should never compare apple to orange as you did here. Comparing a CUV, a Mazda CX-5, to a compact sedan Infiniti G20, is simply unfair! In addition to weight difference (3433 lbs 2016 CX-5 Auto FWD vs. your 2961 lbs 2002 Infiniti G20 Auto), the height and high center of gravity all make differences. Let's compare your old G20 to comparable 2015 SkyActiv Mazda3 above:
the height = frontal area...
It's been said for every point increase in compression, power goes up by approximately 3%. Increasing the compression ratio on a gasoline engine is the most basic and reliable way to gain power and fuel efficiency if you can overcome the knock issue. Mazda did it with its unique SkyActiv Technology including high compression engine and lock-up clutch oriented automatic transmission.
