[BlueScreaM]

What is the hp numbers and tq numbers for the 4.2 F-150 and if anything will need to be replaced besides the engine dropped into and 03 v6. I will replace the cam since the engine will be out of car. The installation will not be an issue. Ive looked for a good form explaining it but cant find one.

[ESG-642T]

....

Let me google that for you

[ReverendDexter]

Quote wikipedia:


Engine Years Power Torque
4.2L V6 1997–2004 202 hp 252 lb·ft

[nukeman13]

is that rwhp or at the crank?

[ReverendDexter]

Originally Posted by nukeman13 is that rwhp or at the crank?

Always assume any power numbers you see are at the crank unless otherwise specified.

[BlueScreaM]

yeah i know that... probably should have worded that better is it worth swapping out the 3.8 for it and with a cam how much hp, preferably someone thats done it?

[236Mustang]

Originally Posted by Ahoboscheese yeah i know that... probably should have worded that better is it worth swapping out the 3.8 for it and with a cam how much hp, preferably someone thats done it?

with a cam, you could get quite a bit of HP/TQ from it

[mcqueen]

I don't know how worth it it would be. That engine is making 202hp and you're currently making 190 at the crank. Unless you have plenty of money yo throw around, I'd say just cam the 3.8. I just can't see spending all that money on a new engine for 12hp.

[ESG-642T]

Originally Posted by mcqueen I don't know how worth it it would be. That engine is making 202hp and you're currently making 190 at the crank. Unless you have plenty of money yo throw around, I'd say just cam the 3.8. I just can't see spending all that money on a new engine for 12hp.

You guys really have to stop looking at peak horsepower numbers.

[ReverendDexter]

Originally Posted by mcqueen I just can't see spending all that money on a new engine for 12hp.

It's not just 12hp, it's 12hp and 30+ lb-ft of torque at peak, and who knows how much more throughout the curve. Gotta remember that truck motors are always spec'd low on hp because their cams are set up to make torque at lower rpm, so you lose the high end where you'd see a nice fat hp number.

Look at the math - hp = tq * rpm/5250.

So, you're making 190hp @ 5500 rpm. That means, at that rpm, you're making...

190 = X * 5500/5250 == 190 = X * 1.04 == X = 190/1.04 == 181 lb-ft @ 5500 rpm (note, this is NOT your peak torque! Your peak torque would be at a lower rpm - this is the torque you're making when the engine is making the most horsepower)

Now, add that 30 lb-ft from the larger displacement, and assume a cam profile similar to the stock 3.8 cam:

X = 211 * 5500/5250 == X = 211 * 1.04 == 221 hp.

So, at a hp peak rpm more respective of the cam that would be used in a Mustang, that's not a 12 hp bump, that's a 30hp bump, and again, that's just at PEAK.

Now add in the even better aftermarket cam, and you're gonna see even more power than that.

[BlueScreaM]

thats why im thinking about getting a cam since like you said it is a truck engine built for different purpose.

[kevinski72]

Originally Posted by ReverendDexter It's not just 12hp, it's 12hp and 30+ lb-ft of torque at peak, and who knows how much more throughout the curve. Gotta remember that truck motors are always spec'd low on hp because their cams are set up to make torque at lower rpm, so you lose the high end where you'd see a nice fat hp number. Look at the math - hp = tq * rpm/5250. So, you're making 190hp @ 5500 rpm. That means, at that rpm, you're making... 190 = X * 5500/5250 == 190 = X * 1.04 == X = 190/1.04 == 181 lb-ft @ 5500 rpm (note, this is NOT your peak torque! Your peak torque would be at a lower rpm - this is the torque you're making when the engine is making the most horsepower) Now, add that 30 lb-ft from the larger displacement, and assume a cam profile similar to the stock 3.8 cam: X = 211 * 5500/5250 == X = 211 * 1.04 == 221 hp. So, at a hp peak rpm more respective of the cam that would be used in a Mustang, that's not a 12 hp bump, that's a 30hp bump, and again, that's just at PEAK. Now add in the even better aftermarket cam, and you're gonna see even more power than that.

School is in session

[mcqueen]

Originally Posted by ReverendDexter It's not just 12hp, it's 12hp and 30+ lb-ft of torque at peak, and who knows how much more throughout the curve. Gotta remember that truck motors are always spec'd low on hp because their cams are set up to make torque at lower rpm, so you lose the high end where you'd see a nice fat hp number. Look at the math - hp = tq * rpm/5250. So, you're making 190hp @ 5500 rpm. That means, at that rpm, you're making... 190 = X * 5500/5250 == 190 = X * 1.04 == X = 190/1.04 == 181 lb-ft @ 5500 rpm (note, this is NOT your peak torque! Your peak torque would be at a lower rpm - this is the torque you're making when the engine is making the most horsepower) Now, add that 30 lb-ft from the larger displacement, and assume a cam profile similar to the stock 3.8 cam: X = 211 * 5500/5250 == X = 211 * 1.04 == 221 hp. So, at a hp peak rpm more respective of the cam that would be used in a Mustang, that's not a 12 hp bump, that's a 30hp bump, and again, that's just at PEAK. Now add in the even better aftermarket cam, and you're gonna see even more power than that.

Good call Rev, I didn't even think about the torque gains on the 4.2 over the 3.8. As they say, horsepower sells cars, torque wins races.

[v6kid]

Originally Posted by ESG-642T .... Let me google that for you

That was pretty epic