MerkXRTurbo
New Member
I've seen a lot of debate on the value of switching to 3.0 cams when swapping to a 3.2. Some say that it has little to no value, other say that is not the case, so I decided to do some calculations and here is what I came up with. Before we start, I would like everyone to understand some things, just so that we are on the same page:
-Torque = actual measurable power output. Most people refer to torque and mean power in the low RPM range, but this is not true. On the contrary, it is entirely possible that an engine could produce HUGE torque, but not until 10,000 RPM.
-Horsepower = work done over time. Calculated via the following formula: HP=TQxRPM/5252. Using this formula you can see why a diesel truck that puts out huge torque but only turns 3000RPM puts out low HP, and why other vehicles (such as the Honda S2000) put out lame amounts of torque but are still able to put out high HP numbers at 8500 RPM.
-For this, I am assuming that the 3.2's peak torque increase has only to do with the displacement increase, and not involving the different intake cams. This may or may not be the fact, and only a dyno using different cam combinations can verify this. However, I do not believe that the lower lift cams will result in a higher TQ number. This assumption leaves us with only the intake cams being the variable.
-According to Ford's numbers, the 3.0 produces 220hp @ 6200RPM and 200tq @ 4800 rpm. The 3.2 produces the same 220hp @ 6000RPM and 215tq @ 4000 RPM.
Using our HP formula we can find a few things. Let's start by calculating HP output @ peak torque:
3.0: 200x4800/5252= 182.79hp @ peak torque
3.2: 215x4000/5252= 163.74hp @ peak torque (the lower number is due to the lower RPM)
3.2 tq w/3.0 power band (this will simulate 3.0 cams in a 3.2 - remember, I'm assuming that the torque increase is purely displacement related):
215x4800/5252= 196.50hp @ peak torque
Lets rearrange that formula to find TQ output @ peak HP:
3.0: 220x5252/6200= 186.36 tq @ peak HP
3.2: 220x5252/6000= 192.57 tq @ peak HP
Now that we have these numbers we can calculate what peak HP would be using the 3.0 power band and the 3.2 torque output:
192.57x6200/5252= 227.32 hp
So using these calculations and assumptions it is reasonable to conclude that the 3.0 cams in a 3.2 will increase the overall power output by approximately 7hp.
Now, there is one factor that I have not mentioned up until this point, and that's the width of the power band. The 3.2 cams provide a MUCH wider power band, with a much lower peak torque! Generally speaking, a car's power band is the area in between the peak TQ and peak HP. With 3.0 cams you only get 1200RPM between these two points, while 3.2 cams give you 2000RPM! Now lets look at average HP across the power band:
3.2 w/ 3.0 cams: 227.32 (peak hp) + 196.50 (hp@peak tq) /2 = 211.91hp average across that 1200 RPM span.
3.2 stock: 220 (peak hp) + 163.74 (hp@peak tq) /2 = 191.87hp average across the 2000 RPM span.
That's a pretty significant average HP difference, but it's also a very significant difference in power band width! This has actually not given us much help on which is better, but it certainly educates us on the pros and cons of each setup. In my opinion the significantly wider power band is probably more desirable for a street driven car, for drivability reasons as well as the fact that fuel economy would probably be better with the 3.2 cams, being that they put cruising RPM closer to peak torque. FWIW, I plugged the above numbers into a software based simulator I use and according to it the 3.0 cams have a slight performance advantage (less than .1 second faster from 0-60) over the 3.2 cams in an otherwise stock MTX SHO with a 3.2, but most understand that better performance doesn't necessarily equal better streetability.
I hope that my thought process hasn't been too hard to follow and that this will help somebody make a better educated choice when choosing cams for their 3.2 swap. I'm getting ready to do an MTX conversion in my '94 ATX, and I was pretty set on using 3.0 cams but I am now seriously leaning toward leaving it be.
Your thoughts are welcome.
-Torque = actual measurable power output. Most people refer to torque and mean power in the low RPM range, but this is not true. On the contrary, it is entirely possible that an engine could produce HUGE torque, but not until 10,000 RPM.
-Horsepower = work done over time. Calculated via the following formula: HP=TQxRPM/5252. Using this formula you can see why a diesel truck that puts out huge torque but only turns 3000RPM puts out low HP, and why other vehicles (such as the Honda S2000) put out lame amounts of torque but are still able to put out high HP numbers at 8500 RPM.
-For this, I am assuming that the 3.2's peak torque increase has only to do with the displacement increase, and not involving the different intake cams. This may or may not be the fact, and only a dyno using different cam combinations can verify this. However, I do not believe that the lower lift cams will result in a higher TQ number. This assumption leaves us with only the intake cams being the variable.
-According to Ford's numbers, the 3.0 produces 220hp @ 6200RPM and 200tq @ 4800 rpm. The 3.2 produces the same 220hp @ 6000RPM and 215tq @ 4000 RPM.
Using our HP formula we can find a few things. Let's start by calculating HP output @ peak torque:
3.0: 200x4800/5252= 182.79hp @ peak torque
3.2: 215x4000/5252= 163.74hp @ peak torque (the lower number is due to the lower RPM)
3.2 tq w/3.0 power band (this will simulate 3.0 cams in a 3.2 - remember, I'm assuming that the torque increase is purely displacement related):
215x4800/5252= 196.50hp @ peak torque
Lets rearrange that formula to find TQ output @ peak HP:
3.0: 220x5252/6200= 186.36 tq @ peak HP
3.2: 220x5252/6000= 192.57 tq @ peak HP
Now that we have these numbers we can calculate what peak HP would be using the 3.0 power band and the 3.2 torque output:
192.57x6200/5252= 227.32 hp
So using these calculations and assumptions it is reasonable to conclude that the 3.0 cams in a 3.2 will increase the overall power output by approximately 7hp.
Now, there is one factor that I have not mentioned up until this point, and that's the width of the power band. The 3.2 cams provide a MUCH wider power band, with a much lower peak torque! Generally speaking, a car's power band is the area in between the peak TQ and peak HP. With 3.0 cams you only get 1200RPM between these two points, while 3.2 cams give you 2000RPM! Now lets look at average HP across the power band:
3.2 w/ 3.0 cams: 227.32 (peak hp) + 196.50 (hp@peak tq) /2 = 211.91hp average across that 1200 RPM span.
3.2 stock: 220 (peak hp) + 163.74 (hp@peak tq) /2 = 191.87hp average across the 2000 RPM span.
That's a pretty significant average HP difference, but it's also a very significant difference in power band width! This has actually not given us much help on which is better, but it certainly educates us on the pros and cons of each setup. In my opinion the significantly wider power band is probably more desirable for a street driven car, for drivability reasons as well as the fact that fuel economy would probably be better with the 3.2 cams, being that they put cruising RPM closer to peak torque. FWIW, I plugged the above numbers into a software based simulator I use and according to it the 3.0 cams have a slight performance advantage (less than .1 second faster from 0-60) over the 3.2 cams in an otherwise stock MTX SHO with a 3.2, but most understand that better performance doesn't necessarily equal better streetability.
I hope that my thought process hasn't been too hard to follow and that this will help somebody make a better educated choice when choosing cams for their 3.2 swap. I'm getting ready to do an MTX conversion in my '94 ATX, and I was pretty set on using 3.0 cams but I am now seriously leaning toward leaving it be.
Your thoughts are welcome.
