why does everyone want to spin the coyote up to 8000 plus?

LarryJM

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just smack the limiter. That's what it's for. Of course you'd need a tune to remove it...

Alternatively could paper over the tachometer!
I do not feel a falloff of torque at all as it hits the stock limiter. It pulls hard right to the cutoff of fuel.
 

stevbd

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No, all those things do matter and it's an over-simplification to think otherwise. I get that if you don't have an engineering mindset that you're going to look for "easy" rather than "rigorous", but that doesn't make "easy" as good of an approach.

All those HP to weight and 1/4 mile estimators? What they're working with in the background is some assumptions about torque in the vicinity of peak power rpm and gearing. Don't forget that power varies more with rpm than torque does until you get past peak power rpm.

Norm

Norm, I'm not trying to argue with you and for sure I'm no math whiz.

But respectfully, yes I can follow the gist of your math and going back to your post #68, when you are talking about "torque in the vicinity of peak power rpm...", or "power varies more with rpm than torque does," those are just a lot of words for "horsepower."

I'm just saying that in general terms, torque at a specific rpm is a measure of HP - and all things being equal (they never are) HP is a better overall measure than torque for determining how fast a car will accelerate. I think, lol.

I confess I didn't read all the details of your charts - they look awesome btw and I'm sure they are correct - but any time you are analyzing "power" at different rpms, you are talking about "horsepower" at different rpms. For sure, some motors have a nice flat torque curve, so the HP is nice and progressive, others have a peaky torque curve, so the HP is also peaky, but regardless, all of your excellent work analyzing "torque" or "power" at various rpms boils down to an analysis of horsepower.

@tjm73 is laughing at what a discussion he started!

Peace, cheers, and Happy New Year.
 

Norm Peterson

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I do not feel a falloff of torque at all as it hits the stock limiter. It pulls hard right to the cutoff of fuel.
It's there, and you'd be able to see it in a datalog of either acceleration directly or the flattening-out of a speed vs time plot. How much it falls off depends on the engine's state of tune (and a few other things).


Norm
 

Norm Peterson

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But respectfully, yes I can follow the gist of your math and going back to your post #68, when you are talking about "torque in the vicinity of peak power rpm...", or "power varies more with rpm than torque does," those are just a lot of words for "horsepower."
Not exactly. A HP curve (along with a little messing around with gear ratio spacing and redline) tells you where you need to run the engine for best performance, but it won't tell you what that performance is going to be.

I've been saying that all along. I can't help it if the physics behind it all involves more math than the average drag racer cares to wrestle with. It's why I ended up being an engineer and not a parts counter guy at some local speed shop.



So I went through a little dimensional analysis - seeing if the units of torque or HP can be made consistent with the units of acceleration. No numbers, no pictures.

For torque, it's as simple as it gets. ft*lbs of torque divided by ft of tire radius gives you lbs of traction. With a car weight expressed in lbs, you get acceleration in dimensionless g's.

If you want to get fancy from F=ma and use mass instead of car weight you end up with lbs of traction divided by lb*sec^2/ft, which reduces to ft/sec^2 . . . which is acceleration in its native units.


On the HP side, HP is ft*lbs/sec, HP/weight would be ft*lbs/(lbs*sec) which resolves to ft/sec which is the units of velocity rather than acceleration. You're missing one of the 'seconds' that would give you the ft/sec^2 for acceleration.

Working HP with mass isn't any better (you end up with ft^2/sec^3, which would be velocity times acceleration)


I'm just saying that in general terms, torque at a specific rpm is a measure of HP - and all things being equal (they never are) HP is a better overall measure than torque for determining how fast a car will accelerate. I think, lol.
I will give you that it's an easier way of determining the rpm range you need to use.

Perhaps the disconnect here is between understanding what acceleration is in physics terms (what it is) and understanding from observations and experience what it does. They aren't the same thing.


I confess I didn't read all the details of your charts - they look awesome btw and I'm sure they are correct - but any time you are analyzing "power" at different rpms, you are talking about "horsepower" at different rpms. For sure, some motors have a nice flat torque curve, so the HP is nice and progressive, others have a peaky torque curve, so the HP is also peaky, but regardless, all of your excellent work analyzing "torque" or "power" at various rpms boils down to an analysis of horsepower.
It's much more than that. It can run an acceleration sim for any range of speeds or distances, not just typical quarter or eighth mile runs.

It even does accelerations (sort of, in the background) where you could be using the "wrong" gear for maximum performance. 40 to 75 in 5th gear? No problem, other than I'd have to dig into the detail calcs a bit. The common HP-based dragstrip formulas
(ET=5.825*[weight/HP]^0.333 and Trap Speed = 234*[HP/weight]^0.333) would be utterly worthless for anything like that.



Peace, cheers, and Happy New Year.
Happy New Year back at ya



Norm
 
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LarryJM

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It's there, and you'd be able to see it in a datalog of either acceleration directly or the flattening-out of a speed vs time plot. How much it falls off depends on the engine's state of tune (and a few other things).


Norm
I purchased the Mustang new in Feb 2014 but the Mustang was made in Aug 2013 and I do have a Boss ECU. Right now that is all I can prove. There is no hint what so ever of any torque fall off at the cutoff point of 6850 rpm.
 

Juice

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Is there anyway to get the rev limiter to 7000 RPM vis 6850 on a stock Mustang GT without a tune? Since I removed the sound tube and have Lloyd thick carpets, it's EZ to hit the rev limiter in passing on a two lane. The Rev Limiter must cut the fuel off so it gives you no warning.

No. And even if you have a custom tune on hand held that lets you raise rev limit, that is still not enough. That 6850 rpm limit needs to be adjusted in the EOT protection section before you can tweak it with the hand held tuner.
 

Norm Peterson

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I purchased the Mustang new in Feb 2014 but the Mustang was made in Aug 2013 and I do have a Boss ECU. Right now that is all I can prove. There is no hint what so ever of any torque fall off at the cutoff point of 6850 rpm.
It may not be as perceptible to everybody as a datalog would show, but if you actually are reaching the engine's true peak power the torque has to be dropping off. Has to, since peak HP happens when the torque starts dropping off faster than the rpms are rising. Torque is already dropping off between peak torque rpm and peak HP rpm.


Norm
 

LarryJM

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It may not be as perceptible to everybody as a datalog would show, but if you actually are reaching the engine's true peak power the torque has to be dropping off. Has to, since peak HP happens when the torque starts dropping off faster than the rpms are rising. Torque is already dropping off between peak torque rpm and peak HP rpm.


Norm
Something I do not feel. Some records suggest Ford installed leftover Boss Long Blocks in very early built 2014s. I can't prove that but I can prove I have a Boss ECU by Hollander Index.
 

Juice

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Something I do not feel. Some records suggest Ford installed leftover Boss Long Blocks in very early built 2014s. I can't prove that but I can prove I have a Boss ECU by Hollander Index.
Boss ECU by part number or TearTag? It's the 4 digit TearTag that really matters.
 

LarryJM

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The part number on the ECU. I will post a picture. Then you can look it up yourself. It's listed in the Hollander Index for use with 2013 and 2014 Boss Engines.
 
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LarryJM

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ECU Picture 2014 Mustang GT made Aug 2013. I hope it clear enough. ACC ACD and ACE can be used in any Boss or Standard 2013/2014 Mustang GT.

DSC_0303.JPG
 
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Dino Dino Bambino

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A HP curve (along with a little messing around with gear ratio spacing and redline) tells you where you need to run the engine for best performance

As long as there's no mechanical limitation, you can set your redline rpm where the HP curve has dropped to 95% of its peak. For example, if your modified Coyote engine puts down a peak 460rwhp at 7000rpm, the "redline" rpm would be at the point past that where the HP curve has dropped to 437rwhp. On most engines, that'll be ~500rpm past peak HP rpm but it may be more or less depending on how quickly the HP curve drops after it peaks.
 
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Juice

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ECU Picture 2014 Mustang GT made Aug 2013. I hope it clear enough. ACC ACD and ACE can be used in any Boss or Standard 2013/2014 Mustang GT.

View attachment 75794
Pcm code is KWC3. This is for a GT coyote. I am running KWC4, which is an updated version, likely for 2014 MY.
The last 3 letters are revisions of a Ford part number. First 4 of the part number are year/vehicle, the middle numbers are the "part". So 12a650=pcm.
 
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LarryJM

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Pcm code is KWC3. This is for a GT coyote. I am running KWC4, which is an updated version, likely for 2014 MY.
The last 3 letters are revisions of a Ford part number. First 4 of the part number are year/vehicle, the middle numbers are the "part". So 12a650=pcm.
All may be true but the Hollander Index says any ACC ACD or ACE version will work in a Boss. Is this the dual path Track Key version for both 2013 and early 2014? Track Key was available to the 2014 early versions but was discontinued when it did not work for all 2014 Mustang GTs. It seems the KWC3 is for a 2013 Mustang GT Boss ACD. So all I am saying is this is a Dual Path ECU that will work on both Boss and Standard Coyotes by Hollander Index.
 
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Juice

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All may be true but the Hollander Index says any ACC ACD or ACE version will work in a Boss. Is this the dual path Track Key version for both 2013 and early 2014? Track Key was available to the 2014 early versions but was discontinued when it did not work for all 2014 Mustang GTs.
Correct, but what Hollander does not mention is the programming needed with IDS after replacement.
As for the track key option, that is stored in the instrument cluster along with the PATS stored keys. But you need the Boss software in the pcm to be able to use it.
 

LarryJM

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Correct, but what Hollander does not mention is the programming needed with IDS after replacement.
As for the track key option, that is stored in the instrument cluster along with the PATS stored keys. But you need the Boss software in the pcm to be able to use it.
What makes you think the Boss software is not already in it? So what would happen if they did use the leftover 2013 Boss long blocks sitting in the six trailers in back of the plant for some of the first builds of 2014. They would not have manifolds on them. Just the block and CNC machine heads with a slightly different cam. I may not know the exact numbers but I believe 2500 Boss Long Blocks were made and 1500 were used in the 2013 production run. Then the production manager gets a note that no more Boss production for 2014. What does he do with the rest of the engines? As far as Track Key, I have heard it's in the Cluster but I also heard it's in the ECU that will take two programs at once. I was thinking of a premium cluster using Ford Scan. No where in Ford Scan that it says there are two programs in the cluster. Then if you understand Track Key, they say it will work with the standard clusters. No matter how you look at it, there are about 1000 missing Boss Long Blocks.
 
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Juice

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What makes you think the Boss software is not already in it? So what would happen if they did use the leftover 2013 Boss long blocks sitting in the six trailers in back of the plant for some of the first builds of 2014. They would not have manifolds on them. Just the block and CNC machine heads with a slightly different cam. I may not know the exact numbers but I believe 2500 Boss Long Blocks were made and 1500 were used in the 2013 production run. Then the production manager gets a note that no more Boss production for 2014. What does he do with the rest of the engines? As far as Track Key, I have heard it's in the Cluster but I also heard it's in the ECU that will take two programs at once. I was thinking of a premium cluster using Ford Scan. No where in Ford Scan that it says there are two programs in the cluster. Then if you understand Track Key, they say it will work with the standard clusters. No matter how you look at it, there are about 1000 missing Boss Long Blocks.
Two things: KWC3 is not for a Boss.
You said the revs are limited to 6850. Boss software would let it rev higher. Boss intake and cams are also different, and that also has to be addressed in the tune.
 

LarryJM

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Two things: KWC3 is not for a Boss.
You said the revs are limited to 6850. Boss software would let it rev higher. Boss intake and cams are also different, and that also has to be addressed in the tune.
I did not say it had boss software on it. People tell me what it isn't without telling me what it is. So the proper response is, KWC3 is not for Boss but RWD4 is. People can't even agree on how many Boss engines were made between 2012 to 2013. One guess is 4016 were made for 2012 and 4273 for 2013. Now the question is, how many were made for the 2014 canceled production run? So if you tell me what can't be true, you MUST also tell me what can. Then one record does say the exhaust cam is slightly different from Boss to Standard. Everyone knows a Gen 1 Truck Coyote with a different exhaust cam runs great with a gen 1 5.0 Mustang GT software. I would think it would be the same with a Gen 1 Boss and a Gen 1 standard engine. The only reason you can't use Gen 1 software on a Gen 2 is because Gen 2 is not a full VCT engine. You could never get it to Ghost Cam. Then we are only talking about long blocks. There was a group someplace that installed a standard manifold on a Boss and they felt it made much better power in the low end with not much fall off on the top.
 
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