Originally Posted by PhillipM (Post 2212140)

Well unfortunately that is the application we are talking about, or hadn't you noticed?

Originally Posted by PhillipM (Post 2212140)

Well unfortunately that is the application we are talking about, or hadn't you noticed?

Bit difficult to change the afr of your arm muscles, and you can still manipulate the engine function to fit the muscle scenario, if you couldn't then there would be a problem with your physics model.

Originally Posted by zoom44 (Post 2211688)

but i agree with Jeff as well- the two are only seperated by the spark event. that is the only thing that distinguishes them. either can cause the other. they are both combustion events when you dont want them which cause pressure rises when you dont want them. to me , as i said before, it puts to fine a point on it to seperate them. you could just as easily say that pre-ignition is a form of detonation.

detonation - in the context of the definitions above- can be fatal to an engine. pre-ignition is nearly always fatal. the times its not it causes more detonation and more heat leading to another pre-ignition event that is fatal.

but as with a different thread where it was tried- I agree to these definitions so we can talk about the POINT of the discussion.

Originally Posted by staticlag (Post 2212148)

So your telling me that my arm can make 250 ft/lbs of torque while only expending 1/4 of its available power? and later in the graph can only make 100ft/lbs of torque by expending 100 of its available energy?

Originally Posted by lurch519 (Post 2212150)

hp is a function of torque, not the other way around

torque is force

horsepower is work

and yes you can tune for them seperately

Originally Posted by PhillipM (Post 2212147)

The conversion factor between measurements. What does this have to do with anything?

A constant is a constant - more power at one rpm=more torque at that rpm, you can't tune for them seperately.

Originally Posted by PhillipM (Post 2212147)

The conversion factor between measurements. What does this have to do with anything?

A constant is a constant - more power at one rpm=more torque at that rpm, you can't tune for them seperately.

Originally Posted by staticlag (Post 2212157)

Lol, kind of convenient if you make up a random number that magically fits what you are trying to prove.

I can do that also,

watch

my bank account X constant

Hmm, I want a million dollars


$1 x $1,000,000

No, its not applied in all situations,

Originally Posted by MazdaManiac (Post 2212155)

I'm not talking about the constant or the calculation.
Maximum power will occur at LBT. However, we don't tune for LBT because MBT is higher and safer (and on a turbo motor we tune for RBT). The torque curve will change shape because of this. Since peak power occurs at a higher RPM than peak torque, the peak power will be a function of the instantaneous torque at that RPM, which will be somewhat less than "optimum" because of the slightly richer A/F.

[[Didn't this entire discussion already happen about a million times on this forum over the past 3 years?]]

Originally Posted by MazdaManiac (Post 2212155)

I'm not talking about the constant or the calculation.
Maximum power will occur at LBT. However, we don't tune for LBT because MBT is higher and safer (and on a turbo motor we tune for RBT). The torque curve will change shape because of this. Since peak power occurs at a higher RPM than peak torque, the peak power will be a function of the instantaneous torque at that RPM, which will be somewhat less than "optimum" because of the slightly richer A/F.

[[Didn't this entire discussion already happen about a million times on this forum over the past 3 years?]]

Originally Posted by PhillipM (Post 2212161)

Now, please explain how you'd increase one without the other?!

Originally Posted by PhillipM (Post 2212166)

Your maximum 'safe' power and torque should be the same regardless, provided your not just shifting the ignition by a set amount over the entire power band, which is never good.

Originally Posted by PhillipM (Post 2212161)

Now this is getting weird, the constant is a simple conversion rate between units, what are you smoking?
If the unit conversion were taken out of it it'd simply be

Power= Torque x RPM

Now, as we at a single RPM point when altering AFR (as per the original remark), we now get the equation

Power = Torque.

Now, please explain how you'd increase one without the other?!

Originally Posted by PhillipM (Post 2212161)

Now this is getting weird, the constant is a simple conversion rate between units, what are you smoking?
If the unit conversion were taken out of it it'd simply be

Power= Torque x RPM

Now, as we at a single RPM point when altering AFR (as per the original remark), we now get the equation

Power = Torque.

Now, please explain how you'd increase one without the other?!

Originally Posted by MazdaManiac (Post 2212169)

I think you are kinda missing the forest cause you found the biggest tree.

The A/F that will yield the highest torque peak will not be the A/F that will make the highest power peak because of the constant - time.
If the power peak occurred at the same time as the torque peak, they would be in lock step.



Your maximum power will happen at one ratio. Your maximum torque at another.
"Safe" is a side benefit. On an FI motor, the flame front is fastest at RBT.

Originally Posted by lurch519 (Post 2212179)

you drive your car around and the engine doesnt change rpm?

Originally Posted by PhillipM (Post 2212181)

Again, since maximum power is a function of torque at that rpm you have to make more torque to make more power, bit of crossed wire here as what you are refering to is the peak power and peak torque spots?
Obviously occuring at different rpm, but even then you should be able to compensate for that on a proper map by adding a little ignition advance up top to compensate for the slightly lower flame front speed.

Originally Posted by BDC (Post 2212149)

You still haven't answered my question in response to your post, Charlie. ;)

B

Originally Posted by zoom44 (Post 2211859)

thats because the octane of the fuel doesnt make a bit of difference how much power an engine can make on it as long as there is no detonation/knock/pre-ignition

Maximum Best Torque (MBT) by a given fuel is mainly determined by WHEN the ingition occurs and Flame Front speed. Flame front speed is determined by the shape of the chamber and how much turbulence is created(turbulence i.e. swirling increase flame front propagation) by that shape , and by the burn speed of the fuel.

the OCTANE of the fuel has no bearing on what the speed is. Only what is mixed in the fuel does.The specific mixture of paraffins, olefins , aromatics oxygenates are what determine the flame speed. some octane boosters may lead to lower flame speeds while others can increase it. and the pressures can effect how much the given chemical will increase or decrease the speed.

some other links in no particular order of importance

http://www.daytona-sensors.com/tech_tuning.html

http://72.14.205.104/search?q=cache:...ient=firefox-a

http://www.sacskyranch.com/deton.htm

http://72.14.205.104/search?q=cache:...ient=firefox-a

alcohol is actually a good example. high octane because of its cooling properties and high energy due to high flame speed. it works well in the injected scenario above because it is cooling AND fuel

Originally Posted by PhillipM (Post 2212233)

But ignition changes will affect A/F, especially if you tune simply to a lambda reading, which isn't advisable as they aren't infalliable.

Originally Posted by PhillipM (Post 2212233)

The extra fuel when moving away to MBT-R should raise the detonation threshold from the cooling effect at the top end,

Originally Posted by PhillipM (Post 2212233)

after all the only reason you are keeping your torque peak and dropping the power peak is because you've effective de-optimised your ignition timing at the top end as the flame front speed has more effect here, the torque peak isn't so effected because of it's position in the rpm range, but it's still changed slightly.

Originally Posted by PhillipM (Post 2212233)

If you're shifting 1 point richer and getting better torque but lower peak power then there something wrong with the map.