I think you need to do a lot more research before you come here spouting off about things that you know nothing about. The two motors are not the same, and Mazda does know what it is talking about.I thought I would see what the MX-5 was running as it seems to be the Mazda "sports-car" and was shocked to find out it only has the 2.0L motor at 155 horsepower - not much of a sports car. Further more, after comparing all the specs to see they are the exact same - their site says for the Mazda 3 use regular unleaded, but for the same motor under MX-5 it says use premium. Seems like Mazda doesn't even know what they are talking about.
Internally, the two motors are pretty much the same. The tune on the MX5 is tweaked a bit for more throttle response and a couple other things.
The reason that the MX5 needs 91 octane is to prevent detonation. When detonation is detected, the ECU pulls timing until it stops. This means a power loss. The Skyactiv engine needs a high level of exhaust scavenging to prevent detonation using 87 octane. This is accomplished on the Mazda 3 using a tri-y header that separates the exhaust pulses and prevents them from returning spent gasses into the cylinder. Unfortunately, this header does not fit in the MX5 tunnel, so it gets a regular shorty header type exhaust. This header can't scavenge nearly as well so 91 octane is required to prevent excessive detonation. There is an aftermarket tri-way for the MX5 that makes a significant power improvement.
As for not being much of a sports car, ask the significant number of high dollar sports car drivers who have had their butts handed to them by a 155 hp car. Also, the mx5 is significantly faster then the Mazda 3.MX-5 is 1113KG, Mazda 3 Sedan is 1303KG. Are you telling me 190KG difference determines a sport car vs. sedan? Clearly you have no idea what you are talking about.
Looking for value added feedback - not a pissing contest.
Feedback? You are getting it. If you don't like what you are hearing, oh well. Get over it.
Quarter seconds? How about 10 seconds? Thats how much faster the MX5 is around The Streets of Willow vs the much vaunted 707hp Dodge Charger Hellcat. Get over the power trip and learn what a real sports car is.Again, original question was about the motor and facts. Sure Its sport looking - and likely fun to drive no doubt, and yes 410lbs of weight is a good chunk that would help. but at the end of the day it still 155hp NA sports car. It likely is a little faster than the 3, but unless your talking quarter seconds on track its not going to be a giant notice of a difference once you take the "fun" level out of it. .
You do realize that the MX5 is the single most raced car around the world?