'18 GT 10-spd auto dyno numbers: 415/397

[NUTCASE]

I am trying to pick up what you're putting down, Nutcase, and I have some questions. I thought the richer mixture was to add a safety buffer for the cylinders and to prevent cats from overheating, not to reduce NOx emissions. I think lacing fuels with ethanol, raising operating temps, adding compression, and variable valve timing, etc do more to reduce emissions than running a richer tune.

As for the Otto cycles being inefficient, are you implying Atkinson engines are better? The latter is more at home in hybrids I thought, not performance cars.

when there is more fuel available there is more carbon available. CO2 is has a lower energy level (more stable than) NOx. So when there is more carbon available the reaction trends to CO2 over NOx. Parts of oxygen vs parts of nitrogen in the air always stay the same. So by consuming more oxygen to make CO2 you reduce the amount of NOx that can be made.

by burning access hydrocarbons you also make available more hydrogen to bond with oxygen and form water which is also very stable and low energy.

this is the same idea of how ethanol works to help emissions. even though every ethanol molecule carries oxygen the balances are different.

but as you may know you can make more power and improve MPG by leaning out this mix. This is how tuners get 30 more hp and increase MPG on a stock mustang just through a tune.

atkinson being more efficient that otto has a huge "it depends" attached. regular otto cycle engine of the same displacement can be made physically smaller. atkinson cycles also have a narrow rpm range and because hot air/fuel gets pushed back into the intake manifold before modern computer controls the intake mani was literally a bomb.

when I said the otto cycle was inefficient I was referring to how efficiently it can turn potential energy into mechanical energy. The best otto cycles in a laboratory environment are only 36% thermally efficient. but inefficient does not automatically mean ineffective. liquid fuel is easy to store and transfer, the engine is internal combustion as opposed to a rocket or something, nor is it a nuclear reactor, and it produces rotational energy which is easy to translate into our wheels turning.

 

[redfirepearlgt]

So this just got posted

Might not be real though

Stock, with no weight reduction? On stock street rubber? No alteration to the tune? No mods? I'm not buying it.

 

[NUTCASE]

forgot other things you wrote.

increasing engine temp makes the engine more thermally efficient. I totally forgot how to explain this without referring to a carnot engine. It has to do with increasing heat to increase COP (coefficient of performance) and having a near infinite cold resevior (air over the radiator) than trying to increase COP by operating the engine at a colder temp and holding heat steady.

The reason why tuners like colder engines is because they can supply more spark adavance. also having less heat in the engine bay helps boosted people worrying about the density of their air. This is different from the OEM who has to worry about making the engine more efficient.

Higher compression boils down to the equation for work. but without math, if you have 8:1, that means 1 unit of volume gets expanded to 8 units to perform the mechanical work. If you have lets say 11:1 you are now using 1 unit of volume expanded to 11 units to perform work. high compression was difficult on older engines because of cast iron blocks and heads, no VCT, older controls, poorer quality available pump gas, etc.

 

[46addict]

Thanks for the detailed response. I'm gonna let this marinate for a bit.

Mazda's Skyactiv engines are interesting. 13:1 comp that can run on 87 octane. They now have compression ignition tech that bumps it to 18:1 (taken from Wikipedia so don't take this as truth and gospel) which eliminates the need for spark. This is supposed to reduce NOx levels at the expense of more CO2 like discussed before, and eliminates the need for a catalytic converter. Maybe this will be the future of "Ecoboost."

 

[skaarlaj]

The 10R80 still has a lock-up torque converter correct? Some of these newer autos have computerized clutches instead of an actual fluid couple torque converter, as an owner of 2 of these types of cars, I can say they're efficient for sure, but launching without a torque converter just isn't the same, not sure it ever will be either.

 

[Norm Peterson]

I just looked on fords site, the 10 speed is a $1200 option. Unless you are really hung up on having a clutch I think its totally worth it. This is not a typical electronically controlled auto like we have been doing since the 90's, lots of stuff going on in there.

Is there any reason to believe that a 2018 GT with the 6MT won't put up similar numbers?

(if I'm 'hung up on' anything here, it's that I don't want to give up doing the things I enjoy doing . . . not for as long as I can still do them, anyway, and I may never be ready to just slap the gear selector in 'D' and point myself down the road)


Norm

 

[Norm Peterson]

Friction losses in any given gear should be more or less proportional to the amount of power being transmitted through it.


Norm

 

[Thereaper]

I just looked on fords site, the 10 speed is a $1200 option.

That's only $5 more than a 2014 6r80.

 

[mrgtx]

Is there any reason to believe that a 2018 GT with the 6MT won't put up similar numbers?

(if I'm 'hung up on' anything here, it's that I don't want to give up doing the things I enjoy doing . . . not for as long as I can still do them, anyway, and I may never be ready to just slap the gear selector in 'D' and point myself down the road)


Norm

Friction losses in any given gear should be more or less proportional to the amount of power being transmitted through it.


Norm

Yeah. The insanely quick shifts and additional ratios apparently more than make up for frictional losses. The current gen of performance cars with modern automatics are notably quicker than their manually shifted versions. The Camaro SS, Scatpack, Hellcat being the primary examples. I have a lot of 392/auto miles under my belt and that ZF 8speed is stunningly good.

...but I TOTALLY agree with your second point. A tenth or two in the quarter mile isn't going to make the car more fun than the pleasure of shifting through the gears.

I never thought I'd say this but I think that these cars are quick enough. In addition to the power, connection to the car and driver involvement is what makes muscle cars great...and this is exactly why we're here instead of a Tesla forum where 10 second 1/4 miles are literally a push of a button away.

 

[fdjizm]

10 speed also puts more "force" into the ground, staying in the power band will do that with all those gears.

 

[NUTCASE]

I forget exactly what iteration of the 911 it was, but I remember reading an article in a magazine probably 15 or more years ago where they had a chart of what location/speed a manual vs an auto was at in a 0-60 and 0-100. The writer could not believe the auto porsche was faster. This was about the same time I was learning that once you start getting around 11s a clutch can really be a pain in ass, and that this was the point where autos were usually faster.

that being said its hard to beat some mountain road action with windows down, open exhaust, and a clutch under your left foot.

 

[NUTCASE]

Probably the biggest thing I will miss about my 06 GT is going to be the sound it made on the back roads rev match gear braking. Not even how fast it went in the 1/4 which is where I put all my work.

 

[46addict]

10 speed also puts more "force" into the ground, staying in the power band will do that with all those gears.

That is just gear reduction doing its thing. Lower gears multiply torque.
What really helps the car go down the track is the closely spaced ratios.

 

[tjm73]

That is just gear reduction doing its thing. Lower gears multiply torque.
What really helps the car go down the track is the closely spaced ratios.

That's pretty much what fdjizm said. The close ratios keep it in the "sweet spot". Result.....quicker times.

 

[46addict]

I guess I was just agreeing with him.

 

[mrgtx]

Probably the biggest thing I will miss about my 06 GT is going to be the sound it made on the back roads rev match gear braking. Not even how fast it went in the 1/4 which is where I put all my work.

For whatever it's worth, these modern/performance oriented auto transmissions still rev-match audibly as you brake and it sounds pretty damned aggressive in "sport" mode or whatever. They also do it much faster than you or I could ever dream of.

 

[Norm Peterson]

For whatever it's worth, these modern/performance oriented auto transmissions still rev-match audibly as you brake and it sounds pretty damned aggressive in "sport" mode or whatever. They also do it much faster than you or I could ever dream of.

Yep, machines can make many tasks happen faster and more consistently than us humans can.


But that's not exactly the same thing as 'better' when you look at driving in a wider sense.


Norm

 

[Pentalab]

The 2015+ auto's come with paddle shifters... which is a real treat. So u can just stuff it into D.... and lolly gog to the grocery store.... or put it into paddle shifter mode. Manual shifts are firm + quick. Cool part is.... come up to a red light in say 4th.... when it turns green.... off you go, but in 1st. So u don't have to muck about manually shifting from 4th...down to 1st, etc. The 10 speed has enough smarts to skip shift (when in D) if just cruising about, depending on mode, and load... like up hill /down hill / level grade, etc.

Typ if a PD blower is added to an auto, the software for the auto is tweaked... when in blower mode. With blower on, the shifts have to be faster..and firmer. On my sct tuner..and tune from VMP, I can tweak the individual shifts points up/down (eng rpm) in small increments from 1-2, 2-3, 3-4, 4-5. I can also tweak the firmness up / down. 32 adjustments on the 5r55s auto tranny. The 6R80 and 10R80 have even more.

The usual complaint when manually shifting an auto is... you command to upshift now... then there is a short time lag, then it actually shifts. But the actual shifts are very fast. It's the lag that drives folks nuts. Takes time to build up line pressure etc. Some of that can be alleviated in the software tune. Each new generation of auto appears to result in improved performance, and in leaps and bounds. As long as it holds together, long term reliability, etc, is another matter.

 

[Norm Peterson]

The usual complaint when manually shifting an auto is... you command to upshift now... then there is a short time lag, then it actually shifts. But the actual shifts are very fast. It's the lag that drives folks nuts. Takes time to build up line pressure etc. Some of that can be alleviated in the software tune. Each new generation of auto appears to result in improved performance, and in leaps and bounds.

Precisely. Even if hydraulic pressures could be changed instantaneously, there's still a finite amount of time involved for some friction elements to engage and others disengage in the proper sequence.

Perhaps one of the reasons I much prefer a + / - shifter gate is that hand motion is slightly slower and more deliberate than fingertip motion, making the 'lag' between the time I finish moving the lever and the time the shift is executed appear to be slightly shorter. It's a perception thing where you don't notice system lag as long as you're still doing something to make the shift happen (i.e. still moving a lever or a paddle).


Norm

 

[mrgtx]

Yep, machines can make many tasks happen faster and more consistently than us humans can.


But that's not exactly the same thing as 'better' when you look at driving in a wider sense.


Norm

I couldn't agree more. All kinds of things are automated these days and it's more apparent than ever that an easier life is not necessarily a better life.