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Just a curious question.... what would you estimate the flywheel horsepower of a 2011 completely stock GT500.....without the M122 supercharger? In other words what would be the horsepower if the 5.4L was naturally aspirated?
 

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Just a curious question.... what would you estimate the flywheel horsepower of a 2011 completely stock GT500.....without the M122 supercharger? In other words what would be the horsepower if the 5.4L was naturally aspirated?
Just a wild guess, but I’d assume somewhere in the 300s. It’s set up with lower compression.
 

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Just a curious question.... what would you estimate the flywheel horsepower of a 2011 completely stock GT500.....without the M122 supercharger? In other words what would be the horsepower if the 5.4L was naturally aspirated?
Let's do some rough estimating and see where we come out.

Stock blower pushes 9psi on a 2011, for a total input pressure of 23.7 psi (assuming 14.7 psi atmospheric (standard temperature and pressure). Since an engine is just an air pump ratios can help us.

550*14.7/23.7 = 340hp (roughly)

However, we need to add back in the power used to spin the blower. I don't know this exact number, but 50hp is a reasonable guess with the stock pulley setup.

Given all of that the stock motor, without blower would make a little under 400HP (assuming an appropriately higher flowing intake manifold is used and it is properly returned).

Another point of comparison is that the same motor was used in F150s and made over 300hp (as tuned for a truck - lower hp, more low end)
 

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It would be right around 300 hp. The trucks using the 5.4 were either 2 valve or 3 valve, the latter had VCT. It's highest offering was 320 hp. Ford made a few configurations with a 4 valve head and the closest would be the engine in the Navigator at 300 hp. The cams in the GT500 5.4 are very mild and as Tim mentioned compression ratios are low. Cam specs between the Lincoln 5.4 4v's and the 5.4 GT500 are damn near identical and it's all done by 5,000 rpm in n/a trim. So if you convert the 340 above for rpm, you get 283 (340 / 6000 x 5000). Ford upped the ponies in a similar 5.4 engine in the Cobra R by bumping the compression ratio and using a much more aggressive camshaft. It was rated it at 385 hp, which is said to be conservative.

Cam duration at .050" lobe lift in/ex and lift in/ex (for comparison)
GT 500 - 184/196 and .397"/.397"
Cobra R - 212/212 and .515"/.468"

If you compare the above to aftermarket cam specs, you'll find that most aftermarket specs provide duration at the valve, so the disparity will be significant. For example, the cams I'm running are rated at 212/216 at .050" lobe lift and 228/232 at .050" valve lift.
 

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Discussion Starter #5
So the blower adds roughly 200hp... I was close to your estimates, as I guessed around 350 +/-

Thanks for your replies...
 

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It would be right around 300 hp. The trucks using the 5.4 were either 2 valve or 3 valve, the latter had VCT. It's highest offering was 320 hp. Ford made a few configurations with a 4 valve head and the closest would be the engine in the Navigator at 300 hp. The cams in the GT500 5.4 are very mild and as Tim mentioned compression ratios are low. Cam specs between the Lincoln 5.4 4v's and the 5.4 GT500 are damn near identical and it's all done by 5,000 rpm in n/a trim. So if you convert the 340 above for rpm, you get 283 (340 / 6000 x 5000). Ford upped the ponies in a similar 5.4 engine in the Cobra R by bumping the compression ratio and using a much more aggressive camshaft. It was rated it at 385 hp, which is said to be conservative.

Cam duration at .050" lobe lift in/ex and lift in/ex (for comparison)
GT 500 - 184/196 and .397"/.397"
Cobra R - 212/212 and .515"/.468"

If you compare the above to aftermarket cam specs, you'll find that most aftermarket specs provide duration at the valve, so the disparity will be significant. For example, the cams I'm running are rated at 212/216 at .050" lobe lift and 228/232 at .050" valve lift.
Now that is some research!
 

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Just a curious question.... what would you estimate the flywheel horsepower of a 2011 completely stock GT500.....without the M122 supercharger? In other words what would be the horsepower if the 5.4L was naturally aspirated?
Wow. That’s a pretty broad question given the range of use that same 5.4L otherwise saw in everything from Expeditions and E-Series to Super Duties and Ford GT (blown). I’d average the specs of several such examples from the most recent years they were in use and maybe add 10% to account for tuning bias toward its intended use.
 
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