Skyactiv tune and compression ratio discussion

[BrandonB]

Hey guys,
First off I just want to say that I am NOT wondering if the $49.99 chip on ebay will actually give me an extra 50hp :P

Basically I just bought myself a Mazda 3 sport Skyactiv (Which is #@%ing awesome in every way possible!!!!) and after reading this article http://www.insideline.com/mazda/3/2012/2012-mazda-3-skyactiv-g-first-drive.html as well as a few others it seems like the engine in my car is a de-tuned euro model. So what I was wondering is if am I able to have the euro tune run on my car and use premium or something along those lines. I know that we cannot flash or chip our ecu's but I didnt know how it would work with an oem euro tune.

[Kiyomi]

really dont know what to say. you bought the skyactiv for the gas mileage. any engine mods you do will probably effect the fuel consumption. if you want more power, get i/h/e first before a tune which probably wont be available for a long time.

[5_Alive]

Hey guys,
First off I just want to say that I am NOT wondering if the $49.99 chip on ebay will actually give me an extra 50hp :P

Basically I just bought myself a Mazda 3 sport Skyactiv (Which is #@%ing awesome in every way possible!!!!) and after reading this article http://www.insideline.com/mazda/3/2012/2012-mazda-3-skyactiv-g-first-drive.html as well as a few others it seems like the engine in my car is a de-tuned euro model. So what I was wondering is if am I able to have the euro tune run on my car and use premium or something along those lines. I know that we cannot flash or chip our ecu's but I didnt know how it would work with an oem euro tune.

Go to the dealership and ask for the updated tune. A few of the SkyActiv's that were first shipped had a European tune programmed.

[Aitch]

I wasn't aware that there was a different tune for an engine running the 12:1 compression ratio. The article only mentions Euro-spec engines with the 14:1 ratio, which would have a tune pretty much useless for our engines.

I'm not saying you're wrong about the details, just that I wasn't aware of another tune for 12:1/premium fuel and would like to hear more about it.

[boyracer]

I wasn't aware that there was a different tune for an engine running the 12:1 compression ratio. The article only mentions Euro-spec engines with the 14:1 ratio, which would have a tune pretty much useless for our engines.

I'm not saying you're wrong about the details, just that I wasn't aware of another tune for 12:1/premium fuel and would like to hear more about it.

I think Itch is right. What I got from the article was that until recently they have been only sampling European versions of this engine (I would assume in Europe).

[Booter22]

i think there is an updated pcm program but its not a tune by any means. i wouldnt say to change the header.. ever, unless you can find one that is way better designed, but i would think none of them out in production now would be better then what you have so i wouldnt change that at the least until a specific on is released for the sky actives. i dont know how the car would perform with the intake but it would be interesting to see/hear. couldnt go wrong with an exhaust. but i dont know what opening the intake and exhaust would do for " performance gains " it would do more for the ear candy thats for sure, less for fuel economy..:P

[Aitch]

I think Itch is right..

haha, I see what you did there..... :tomato

[ottoyu34]

Would be interesting if you could pull this off. First, have to find out if mechanically there is a difference between US-spec and Euro-spec Skyactiv 3. Afterwards, what is the differences in electronics such as ECU.

I would say for now, play around with tire pressure, maybe a high-flow drop-in filter, & drive smarter could yield better fuel economy. Exhaust mods usually hurt fuel economy for what I usually hear.

[5_Alive]

Sorry, meant to say what Jeff posted; pcm update.

I'm still used to using the term "tune" from my MS3 days.. :chuckle

[boyracer]

haha, I see what you did there..... :tomato

Damn! Sorry about that. My mistake!! How I screwed that up I do not know. (My head is down in shame)

[The Wolf]

OP, are you talking about trying to revert to 14:1 compression?

[Aitch]

Damn! Sorry about that. My mistake!! How I screwed that up I do not know. (My head is down in shame)

No worries, someone made that comment about mis-reading my signature too!

Sent from my phone using 1s, 0s, and radio waves.

[stevenma188]

... $49.99 ... ebay ... 50hp ...

The combination of those 3 things indicate to me bogus.

[TheMAN]

There's a bunch of misinformation flying across in this thread... no doubt to me attributed to a bad case of "selective reading"

first off, there is NO Euro-spec SkyActiv 3.... whether one is planned or not, I don't know... but for now there isn't one, and it seems the CX-5 will be the first Mazda there to have this engine

as that article said (but confusingly), the Mazda3's SkyActiv engine's compression ratio had to be lowered to 12:1 because of the exhaust manifold issue... the exhaust tunnel isn't large enough to fit the fancy 4-2-1 header that the CX-5 will see... do any of you honestly think that an overseas (such as JDM) Mazda3 SkyActive engine will have a higher compression ratio? That doesn't make sense at all! The "Euro spec versions" the article talks about is referring to the CX-5 prototype... and probably also the Mazda6 prototypes that the press were driving around in Vancouver earlier this year... NOTHING to do with the Mazda3 and it's bad writing which caused this to be misread

Due to the fact that Mazda couldn't fit the 4-2-1 header into the current 3, the compression ratio must be dropped because of exhaust back pressure... this raises combustion temperatures and no doubt will cause detonation issues... any of you know anything about engines will see how disastrous this can be with such a high compression engine.... so since there isn't an "Euro-spec" SkyActiv Mazda3, the only countries that will get the SkyActiv engine in the 3 will be Canada, USA, Japan, Australia, Hong Kong, and New Zealand... all have the exact same engines (which is 12:1 compression)


second, the ECU update for the early SkyActiv 3s wasn't to get rid of the "Euro-spec tune"... it's to correct a cold start idle issue that could turn on the check engine light.... nothing more

[5_Alive]

There's a bunch of misinformation flying across in this thread... no doubt to me attributed to a bad case of "selective reading"

first off, there is NO Euro-spec SkyActiv 3.... whether one is planned or not, I don't know... but for now there isn't one, and it seems the CX-5 will be the first Mazda there to have this engine

as that article said (but confusingly), the Mazda3's SkyActiv engine's compression ratio had to be lowered to 12:1 because of the exhaust manifold issue... the exhaust tunnel isn't large enough to fit the fancy 4-2-1 header that the CX-5 will see... do any of you honestly think that an overseas (such as JDM) Mazda3 SkyActive engine will have a higher compression ratio? That doesn't make sense at all! The "Euro spec versions" the article talks about is referring to the CX-5 prototype... and probably also the Mazda6 prototypes that the press were driving around in Vancouver earlier this year... NOTHING to do with the Mazda3 and it's bad writing which caused this to be misread

Due to the fact that Mazda couldn't fit the 4-2-1 header into the current 3, the compression ratio must be dropped because of exhaust back pressure... this raises combustion temperatures and no doubt will cause detonation issues... any of you know anything about engines will see how disastrous this can be with such a high compression engine.... so since there isn't an "Euro-spec" SkyActiv Mazda3, the only countries that will get the SkyActiv engine in the 3 will be Canada, USA, Japan, Australia, Hong Kong, and New Zealand... all have the exact same engines (which is 12:1 compression)


second, the ECU update for the early SkyActiv 3s wasn't to get rid of the "Euro-spec tune"... it's to correct a cold start idle issue that could turn on the check engine light.... nothing more

Well, that's great. Oops!
Only thing I'm interested in is how you know exactly what the update is? Last I checked, Mazda doesn't divulge such info. It says update xyz & doesn't say why.
I'm intrigued that the update only corrects a cold start issue, and nothing more.

Long and short to the OP, if you bought a SkyActiv to upgrade it and want to make it "go fast", not right in my books. You should have bought a MS3.

[TheMAN]

just a fix for the P0012:00 "cam timing over retarded" code

[BrandonB]

Thanks for clearing that up, I figured if it was possible why the heck not. Looks like ill have to wait for some bolt-ons to come onto the market before I start tweaking things.

[Kiyomi]

if what im reading on the sky active engine is correct, bolt-ons might be bad for a high compression engine, let alone gaining hp, mite actually lose hp/tq.

[PR3Y11]

honestly, if you're looking to mod for power gain, you definitely got the wrong car. that's like saying or i want to build a wicked track car and start with a prius

[5_Alive]

honestly, if you're looking to mod for power gain, you definitely got the wrong car. that's like saying or i want to build a wicked track car and start with a prius

:chuckle
Truth..

[strikaskofer]

the Mazda3's SkyActiv engine's compression ratio had to be lowered to 12:1 because of the exhaust manifold issue...

Hey everyone, this thread is more than a year old I realize but I'm just wondering how this reduction in compression ratio was accomplished? Was it related to the timing/something electronic or are the piston rods shorter. I don't imagine the length of the cylinder cavity is actually shorter because that would mean different castings for the engine and also because the higher compression cx-5 version at 13:1 is also a 2.0L.

Just curious to understand what is under my hood :)

Thanks,

[Aitch]

Compression ratio has to be modified mechanically, not with tuning. Unfortunately I don't know if it was the piston or rods but I'm guessing it wasn't a different head casting. I'd bet on pistons.

[Booter22]

the difference in the compression ratio from the cx5 to the 3 sky is due to the headers. this gen 3 almost got the "full" sky engine but because of limited engine room it did not get the 4-2-1 header that the cx5 has which allows for the higher compression. at least thats my understanding of the difference why the 3 is lower compression then the cx5

[Lockdown]

You're not saying that the header changed the compression, right?
Because of the header design, the comp ratio was changed.
Piston, rod or spacer/gaskets.

[Aitch]

Yeah I think that was worded poorly. The compression ratio was lowered because the proper headers wouldn't fit, and our gas sucks (I believe euro cars got the higher compression because they have the better base gas to support it even without the proper headers).

Edit - because I like to back things up when I have time :)

Motor Trend: (http://www.motortrend.com/roadtests/sedans/1110_2012_mazda3_skyactiv_g_first_test/viewall.html)


In its purest, European form, the Skyactiv-G 2.0-liter features an almost impossibly lofty 14:1 compression. ...over in fancy pants Europe you can get a Skyactiv-G that takes 91 octane. However, here in America, Mazda sees premium fuel as a barrier to sales. Therefore the Mazda3 with Skyactiv-G we get runs on 87 octane. Meaning that Mazda had to lower the compression ratio to 13:1. Er, whoops, that's not true. That's going to be true on the upcoming CX-5 with its trick 4-2-1 exhaust header. But since that header would require altering the Mazda3's firewall, engineers had to use the exhaust system that's already there and lower the compression ratio to 12:1.

Japan also has a 13:1 variant (http://www.sae.org/mags/aei/10335):


Compression ratio is increased from 10:1 to 12:1 in the U.S. and 13:1 in Japan. Both engines are compatible with regular-octane fuel. A premium-octane, 14:1 compression version is available in Europe and Japan.

A superficial Google search doesn't return what component was changed to alter the compression ratio. I'm still betting on slightly tweaked versions of the pistons, as they have the least effect on other engine parameters (slightly different rod lengths not only alters the stroke, but also the angles of the rod as the crank rotates; a different head would be a very expensive piece).

[Booter22]

yes its not that i was saying the lesser compression was because of the exhaust header. but from what i understand with how the engine was designed they could not set the sky with the higher compression like the cx5 because of the exhaust manifold. something about the 4-2-1 headers flow and so on and so forth. i dont exactly remember the just of it but i remember that was more or less the going line we got from mazda why the 3 was lower compression then the cx5 with the same motor.

[Aitch]

Yeah the long headers increase the exhaust scavenging efficiency enough that 14:1 is possible with premium gas, 13:1 with regular.

[standsideways]

Yeah I think that was worded poorly. The compression ratio was lowered because the proper headers wouldn't fit, and our gas sucks (I believe euro cars got the higher compression because they have the better base gas to support it even without the proper headers).

Edit - because I like to back things up when I have time :)

The common "european gas is better" claim is because they measure there gas different than we do.

Europe uses JUST the AKI(anti knock index)

North america uses (r+m)/2
(RON+MON)/2

So the European 100 aki super v gas and similar are acutally a 94 (r+m)/2

We all know how euros love to claim everything is better in Europe lol :)

[TheMAN]

the euro and japanese skyactiv 3 uses the same exact engine as ours.... no higher compression... that "higher compression" BS you hear applies to the CX-5 and new 6 only!

[Aitch]

Came across another thread that suggested compression ratios can also be easily altered using different head gaskets. That would seem the cheapest and most practical method....

[standsideways]

Thicker=lower compression

Not by much either, and then you need engine management also : /

More of a fully built "get every last ounce out of the motor" kinda thing

[Aitch]

No what I'm saying is that the 13:1 to 12:1 change could be accomplished by the gasket. And then of course the engine management would be programmed to match.

[standsideways]

No what I'm saying is that the 13:1 to 12:1 change could be accomplished by the gasket. And then of course the engine management would be programmed to match.

ohhhhhh right i see what you are saying.

could very well be possible that they did it like that, it sure would cut production costs down by just using a different gasket.