5.2 FPC - Devil's Advocate

[Rhumbline]

I have found nothing to support the idea that flat-plane crank V8 engines produce less torque because of their crank design. The only reasons for a current FPC engine to produce less torque would be from their shorter strokes and smaller displacements.

Agreed, if anything, the slightly greater volumetric efficiency of a FPC might slightly increase the torque rating over an otherwise similar XPC motor (same size, bore, stroke, heads, general tuning, etc.).

However, that FPC's are typically used in ultra hi-po applications where peak power is a bit more paramount than lower-rpm peak torque, they may well be tuned to give up a few lb/ft. down low for many more hps up high. That's not something inherent in a FPC but rather more of an incidental consequence of how they're used and tuned.

Also, the high-rpm punch of a highly tuned FPC might make it only feel like the lower rpm torque is somehow weaker in the seat of the pants, but that's only in comparison of being in the shadows of such lofty higher-rpm power.

XPCs and FPCs both have the same even firing rate at the crank -- every 90-degrees is it? -- its just the order of what particular cylinders are firing that is different. Even various XPCs have different cylinder firing orders.

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[Grimace427]

Agreed, if anything, the slightly greater volumetric efficiency of a FPC might slightly increase the torque rating over an otherwise similar XPC motor (same size, bore, stroke, heads, general tuning, etc.).

However, that FPC's are typically used in ultra hi-po applications where peak power is a bit more paramount than lower-rpm peak torque, they may well be tuned to give up a few lb/ft. down low for many more hps up high. That's not something inherent in a FPC but rather more of an incidental consequence of how they're used and tuned.

Also, the high-rpm punch of a highly tuned FPC might make it only feel like the lower rpm torque is somehow weaker in the seat of the pants, tbut that's only in comparison of being in the shadows of such lofty higher-rpm power.

XPCs and FPCs both have the same even firing rate at the crank -- every 90-degrees is it? -- its just the order of what particular cylinders are firing that is different. Even various XPCs have different cylinder firing orders.

FPC's fire at 180 degrees in an LRLRLRLR order versus a CPC which fires every 90 degrees but in an uneven LRLLRLRRLRLL order.


Back to my original point, looking at the one(albeit not perfect) image of the Voodoo engine, the intake manifold clearly doesn't appear to be for pure top-end only kind of powerband. I'm betting when the Ford guys are saying this engine has a broad powerband, they actually mean it.

 

[Firepath]

FPC's fire at 180 degrees in an LRLRLRLR order

They're firing every 90 degrees in a 90 degree V8. Each bank is firing every 180 degrees and the banks are 90 degrees out of phase.

 

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[Potrillo]

So a flat plane is like two inline 4 cylinder motors.

 

[planedoc]

OK, hold on to your hats....

In late 2005, GM brought us a 505HP, 470 lb-ft, 3200lb Z06 which debuted as a 2006 model.

Now, a DECADE F'G later, Ford brings us a 500-ish HP; 400-ish TQ 3600LB (est) Mustang and everyone is excited. Really?

OK, you say the LS7 is 7.0L and the FPC Ford is only 5.2L. Yep, who cares? I would think that the LS7 is physically smaller and lighter than the 5.2????

So, convince me. Is Ford really moving the needle forward with a bigger, heavier motor in a porky, heavier car - a DECADE after GM? Is this progress?

I'll give in on one point (so far). I think the FPC will sound better..... that's what 10-years has brought us.

A Z06 Corvette is not comparable to a Mustang.... 2 seat sports car vs 4 seat pony car. Now, where is the 3200lb Camaro? That would be a comp to bring up....

 

[planedoc]

1. Tell me how much a 2015 Z06 weighs. Hint: it's a lot more than the 2006 you are choosing to use for comparison to a 2016 vehicle. You can't just ignore a decade's worth of changes to crash safety standards, etc.

2. How can you dismiss the displacement of the engine in this comparison? Ford has created a motor that not even exotics like Ferrari have pulled off (largest displacement production FPC V8 ever). It's easy to throw displacement at a problem like Chevy traditionally has. Coaxing more HP out of less displacement is a much more impressive feat.

3. Mark my words, this 5.2L motor will make WELL above 500HP... not "500-ish"

It isn't the largest displacement production flat plane crank ever. In 1910 Curtis made the 8.2L (502c.i.) OX5 V8 with a FPC that was in production about 20 or so I believe....

 

[flaps]

Ford did exactly what you are asking, but added slighter larger diameter pistons, for greater breathing and TQ. Because converting over to a FPC, you tend to lose it. As the GT 5.0 will have more tq than the GT350.. so piston size determines burn and engine response, some alteration were needed to make it work.

Ferrari's 4.5L flat plane crank V8 makes 398 lbft of torque, which is 88lbft per liter. The Mustang's 5.0L makes 400 lbft, which is 80 lbft per liter. I know there are a lot more differences between these two engines besides the crank design, but there is no reason why an engine would make less torque just because it switched to a FPC design. If anything it would be higher in a FPC engine all else being equal because the crank is lighter and the exhaust pulses do not overlap between cylinders.

 

[ARTSBEST]

Isn't the current Shelby GT 500 5.8 really a punched out 5.4?

 

[scottpe]

It isn't the largest displacement production flat plane crank ever. In 1910 Curtis made the 8.2L (502c.i.) OX5 V8 with a FPC that was in production about 20 or so I believe....

Okay, you got me on a technicality. I'll file that under "it happened over 100 years ago and it's a fact that is not particularly relevant to this discussion of modern automobiles."

But thanks for the history lesson.

Wonder how big that sucker was?

 

[Firepath]

So a flat plane is like two inline 4 cylinder motors.

Yep as a simple way to think about how it works, this FPC V8 is like two inline 4s mounted at 90 degrees to each other.

 

[wproctor411]

Isn't the current Shelby GT 500 5.8 really a punched out 5.4?

It's got far more than boaring or stroking going but the architecture is the same, they changed just about every part.

http://www.mustangandfords.com/news/m5lp-1203-2013-ford-shelby-gt500-trinity-5-8l-v8/

 

[garagelogic]

OK, hold on to your hats....

In late 2005, GM brought us a 505HP, 470 lb-ft, 3200lb Z06 which debuted as a 2006 model.

Now, a DECADE F'G later, Ford brings us a 500-ish HP; 400-ish TQ 3600LB (est) Mustang and everyone is excited. Really?

OK, you say the LS7 is 7.0L and the FPC Ford is only 5.2L. Yep, who cares? I would think that the LS7 is physically smaller and lighter than the 5.2????

So, convince me. Is Ford really moving the needle forward with a bigger, heavier motor in a porky, heavier car - a DECADE after GM? Is this progress?

I'll give in on one point (so far). I think the FPC will sound better..... that's what 10-years has brought us.

Ford produced a track-specific Mustang in 2001, the Cobra R. It took GM 14 years to produce their own track-oriented Camaro with the z/28. :shrug:

 

[1320']

Ford produced a track-specific Mustang in 2001, the Cobra R. It took GM 14 years to produce their own track-oriented Camaro with the z/28. :shrug:

To be exact Ford produced the first race specific Mustang, IE one meant more for race than street, in 1995 with the 95 Cobra R with the 351 in it.

So it actually took GM almost 20 years.

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