I said 15HP
CX-9 Skyactiv 2.5L turbo engine
- Thread starter CC58
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I said 15HP
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- RDX Aspec Adv.
So you did. I'm tired. Demanding day in the gym.
Sorry, I just dont want it to be twisted against me. Happens a lot here.
few things,
The computer can and does pull timing before the knock sensor hears it, that is the secondary (actually primary) knock sensing system these cars use. It's called an Ion Ignition system. They will pull timing during extremely low levels of knock before the sensor hears it. Exactly why we proved you want to use OEM plugs only. We showed, on the dyno, swapping spark plugs caused an immediate loss of 10 HP because it messed up the Ion System. We documented this on the Miata forum, and were first to discover it.
You don't hear knock. Everyone seems to think you can hear detonation, you can't. If you actually HEAR it, that means the detonation is pretty bad. You wont hear low levels of knock retard (a few degrees of ignition drop worth). If you hear it with your ears, it's pretty nasty detonation. 99% of the time knock occurs and you will never hear it with your ears.
All these "experts" who interject with their factless opinions is really really starting to get old and annoying.
Colorado is beautiful for just that, and where we are located, so we know quite a bit about high altitude tuning. The air is less dense here, less pressure. That equals less cylinder pressure, which equals less heat, which equals no knock
Mazda absolutely did a fantastic job.
Thanks for the info! You know your stuff. Like I said, reverse engineering guys like yourself really get to know the ins and outs and the guts of what makes these engines run and how they work.
So with me running 91 octane, I should see peak factory HP/Torque levels at all times or will it still pull timing in certain occasions? (We don't have 93 octane here)
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I bet it still pulls timing. I know on the LS1 cars, they were very aggressive at pulling timing, no-matter what fuel you ran. I am betting the CX-5 is no different, maybe even worse.
NelsonLewis
Banned
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- 16.5 CX-5 GT AWD w/Tech BRMica
Oh it definitely still gonna pull timing...
That is true. My LS1 would pull timing even with 93 octane. Especially on hot days and when under heavy loads.
I will keep using 91 octane in my CX5. It's only a few cents more and I drive a lot of grades so I need the HP.
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Dunno where you live, but I have lots of grades here, too. I tried 91, and did not get any better mileage, or notice any more seat of the pants power. I did notice I paid about $5 more to fuel up, though. The engine management will pull timing so damage does not occur, on 87, and I noticed no gains of any sort on 91, so unless I was taking it to the strip out of curiosity, I found zero benefit to the 91, except for the theoretical/intellectual like we are having, now. Hence...87 goes in mine.
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No, but I think what everyone is saying is that 91 octane allows you to get more of that 184bhp out of it, more of the time.
My 90 5.0 Mustang's stock ECU was incredibly flexible. You could upgrade injectors, heads, rockers, cam, headers, throttle bodies, and it would adjust fuel correctly, and maintain a good idle. The CX-5 ECU has to have some flexibility to deal with variations of altitude, heat, load, and varying grades of gas. If it detects it can run more timing on 91 octane, why wouldn't it do so?
They are very flexible when it comes to variables like temp / elevation / humidity / etc.
They are not that flexible with timing. The ECU does not detect the gasoline octane rating. There are several ignition maps in the ECU for various controls. like use this map if ignition is load is lower than this and VVT is this, or use this ignition map if high load, vvt this, etc etc.
your 90 5.0 mustang ECU (probably a EEC ford ECU) was not "incredibly flexible". It was incredibly "dull," compared to todays ecu. you could get away with so much more because there were so much less controls, so much less data.
why wouldn't it do so
Because it was not programmed to do that.
Do you want to see the Skyactiv ECU disassembled? I am looking at it right now:
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Yep, I put an A9L in my 88 GT and it adapted to:
10.5:1 compression
1.6RR's
Cam with .542 lift
headers
etc. etc. etc.
However, I did eventually pull it and install a carburetor. I should have left it alone, to be honest. The carburetor never did turn out as well as the A9L did, even after dyno-runs with wide-band A/F to confirm A/F was on par at WOT. The A9L was a smart cookie!
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They are very flexible when it comes to variables like temp / elevation / humidity / etc.
They are not that flexible with timing. The ECU does not detect the gasoline octane rating. There are several ignition maps in the ECU for various controls. like use this map if ignition is load is lower than this and VVT is this, or use this ignition map if high load, vvt this, etc etc.
your 90 5.0 mustang ECU (probably a EEC ford ECU) was not "incredibly flexible". It was incredibly "dull," compared to todays ecu. you could get away with so much more because there were so much less controls, so much less data.
why wouldn't it do so
Because it was not programmed to do that.
Do you want to see the Skyactiv ECU disassembled? I am looking at it right now:
I disagree strongly. The ECU in those vehicles was awesome. My car ran pretty darn well with NO tune, and a TON of changes ranging from bumping compression by 1 point, to a HUGE change in cam profile. What modern vehicle's ECU would take advantage of those mods, power-wise, while not blowing the motor up in some way, without a tune? Those A9L's only gave up about 10whp or so vs. a secondary tuned unit, even with all the mods I had. They were darn amazing. Simpler? yes. but brutally effective.
This is why such mods were doable. The ECUs were so simple they did not recognize such differences. Fuel trims can manage to add or remove a LOT of fuel and if your 02 sensors are working properly it will do it's job and the car will run.
The ECU in those vehicles, in simple terms.. .was a "caveman." It really did not know the difference.
For example, the skyactiv BIN is 2MB. the Diesel BIN is almost 4MB.
Those 90 ford ECUs BIN is probably like 25kb.
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It may have been stupid, but it recognized what it needed to do, and got it done, whether it UNDERSTOOD, or not. Can ran great, and put down even, solid power, no-matter what mods you did, unless you put a 347ci stroker in it, at which point, a tune was in order. Short of that, a FPR set sensibly was all the "tune" you needed with that thing.
OK? so what is your point?.....
I dont know why I even post here anymore. This is like saying my paper airplane can fly in the wind so why can't I launch it into space.
Is a paper airplane as complex as a space shuttle?........
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My point is that Ford got it right, there. It gave up about 10whp to a balls-out tune on a HEAVILY modded vehicle.
Mazda has a tune with a 2MB file, and even on a STOCK car gives up about twice that.
Props to 1980's Ford for being WAY ahead of their time.
You can say the Ford ECU was "stupid"...but I was always taught that if something works, it's not stupid.
Well then I recommend swap a 5.0 ECU into your CX5.
Did I say it was stupid? I said it was simple, dull, caveman, compared to the Skyactiv ECU.
Well this was fun. But I really think it is time to stop posting here. I can only take so much stupid. MikeM has gone silent so surely someone is ready to jump in his place....
Like I said a long time ago, folks like you guys are why so little development gets done for your chassis. You're ruining it for everyone who actually wants something. Might be better to just be silent rather than fight the companies trying to do new things with the vehicle you own. Don't like what the company is offering? Great! who cares. Not the people who are interested.
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Well, if you're going for the martyr complex/image, you're doing it slightly wrong. It's coming off a lot more "millennial safe-space-ish".
