[nileppezdel77!]

I understand that ideally, one would make incredible torque at incredible rpms, but that isn't reasonable because at a certain point the amount of torque needed to rotate the mass in the engine becomes greater than the amount of power being produced. So, to avoid that, either we need to lessen the load on the engine (DOHC, which is a fact not contested here) or increase the torque the engine can output earlier, before the RPMs become so high as to prevent the engine from making more power. In the case of the 5.4, the fact that the stroke is so long increases the torque and as a consequence, early in the powerband, increases the power. The amount of rpm doesn't matter as long as torque is increased enough before the maximum rpm.

My question is why it is preferable to have power up top rather than a little lower? If the 5.4 makes peak hp 250 rpm lower than a comparable 4.6, why not just shift there? It's not like the extra rpms themselves are going to increase the power because the 4.6 is losing torque exponentially faster as the rpms climb due to the load on the SOHC heads.

I hope I'm making sense.

[Bullitt5339]

You're getting yourself all twisted around, to be honest.........lol

It's all simple math, to be honest.

Power = Work/Time = Force * Distance/Time

So basically horsepower is torque/time. We use torque * rpm/5252 = horsepower as an easy figure for horsepower.

So if you're OK at math, you can sit and see how rpm effects your performance. Basically you need torque to get moving, but you need horsepower to achieve a given speed. If you can't make the RPM, you'll never achieve the horsepower needed to achieve those speeds. Simply by the math, you can't increase torque as quickly as RPMs, which means that turning RPMS is an easier way of making horsepower rather than increasing torque.

[Bullitt5339]

BTW:

I love discussions like this, as long as it doesn't turn into insults or name calling because people run out of things to debate, so they resort to insults instead of making their points clear and concise.

[Modded_droptop]

Not sayin one is better than the other, but I found a good read in 5.0 Mag. They changed JUST the block and used adaptor plates for the intake in a 2000 GT and dynoed it before and after. On the last page are the numbers. After a tune the 5.4 made more HP and alot more TQ throughout the powerband until 5,500rpms. Here's the link.

Mustang Engine Swap - Installing a 5.4L Motor in a New Edge - 5.0 Mustang & Super Fords Magazine

[nileppezdel77!]

I understand how the math of it works, but the application is where I'm confusing things I believe, because I still don't see how, if one can have more torque in a given section of the powerband, why they wouldn't see that as a plus. For instance, in a 4.6, the torque peaks at 250 at 3750, but in the 5.4 at 3750 it's making 297. The 5.4 makes more torque until 5750, which is the redline of the 4.6 as well. It's not like if you revved the 4.6 higher it would make more power, because the torque is decreasing exponentially towards 0 due to the increasing load of the mass of the rotating system.

If one were to modify the 4.6 to make more power in higher rev ranges, couldn't the same be done with the 5.4? It would never rotate as fast as the 4.6 due to the increased stroke length, true, but it can and would make more torque in those lower ranges, effectively making more power throughout the band until the last 250 rpms above which it can't go. It doesn't just make better torque at the 3k level, it just makes the most down there. The 5.4 makes more torque everywhere but the very top, and because of that, makes more horsepower everywhere but the very top.

Of course, FI corrects that in spades in the higher cubic inch motor.

[nileppezdel77!]

Like I mentioned, I'm still on the fence about big bore or 5.4, so this discussion is helping me feel out the pros and cons as well as get an understanding of the technical side of things.

The unfortunate part about all this though is that I won't know how it all feels unless I drive one or the other, but I can only pick one. This is all just numbers and theory, the true test is how the "seat of the pants" feeling is affected, in my opinion. The bigger bore will rev higher and feel more intense, but the 5.4 will burn rubber in every gear at 2500 rpms...

[Bullitt5339]

Originally Posted by Modded_droptop Not sayin one is better than the other, but I found a good read in 5.0 Mag. They changed JUST the block and used adaptor plates for the intake in a 2000 GT and dynoed it before and after. On the last page are the numbers. After a tune the 5.4 made more HP and alot more TQ throughout the powerband until 5,500rpms. Here's the link. Mustang Engine Swap - Installing a 5.4L Motor in a New Edge - 5.0 Mustang & Super Fords Magazine

If you open up the Excel file, you can clearly see that pre-tune, the 4.6 outperformed the 5.4 from 5000 and up in horsepower and torque. They never tuned the 4.6, so using the tuned 5.4 numbers really aren't compareable.

[Modded_droptop]

They tuned the 5.4 because it runs out of fuel at 4,000 rpms with the stock tune.

[DickH]

What kind of budget do you have for a new motor?

[nileppezdel77!]

I'm looking to spend up to 8 or 9k on the longblock and then I'd have 1-2k for miscellaneous expenses like dyno tuning and intake/ headers. I've been putting money away into a savings account dedicated to that for a while and I think by the summer I should be able to close the account and start my project. I'm just trying to figure out what route to take first and then price everything out in its entirety.

I've been leaning more towards the 5.4 the more I read about the swap, and the fact that the Boss block isn't discussed often means I don't have other's projects to live vicariously from to make a good decision about.

[86er]

the red FTP mustang video, lol, that car never ran at the track with the 5.4, he sold it to help with med school. On motor with an auto the car went 13.0000000 on nitrous it went 11.8x or so.

4.6 was rock stock with the K&N intake long tubes, plenum/tb and 3800 convertor, best sixty foot was 1.8xx.

The 5.4 had TEA stage 3 heads, custom nitrous cams and then parted out and sold

[eddy21x]

What about the 5.4 4v with a 3800 stall 4 56 gears!!!!!!!

[DickH]

I would go with 3.73 or 4.10s, 4.56 is just too much gear. If you plan on building up a proper NA 4v 5.4, don't be surprised if you close in on that 8-9k pretty quickly. I say do some more reading and don't shy away from the boss 5.0 block, you cant go wrong with that. If I didn't get my intake for my 5.4 so cheaply I had planned on going with a big bore setup with an fr500 intake. I was eyeballing the fr500 intake but picked up a boss290 manifold for half the price and then my mind was set on the 5.4

[sharkbait]

Please dont use my track times to prove any points

I ran it at the track ONE time. Just to get an idea. It was by no means the best i could do.
A N/A 5.4 will beat a N/A 4.6 mod for mod.

A little bit of weight reduction and the 5.4 will shine even more.

Also the only thing making a 5.4 not rev is the cams. There the same cams that are in the 4.6 and they starve the 4.6. So what do you think happens to the 5.4?

Put a nasty set of cams in and youll see FAR more horespower then you do in a 4.6.

[sharkbait]

Also i want to say that if i remember correctly theres a forum which keeps a record for N/A power with mod motors. Its a list of everyone over like 325 rwhp. 5.4s are putting down way more power then a 4.6.

While most h/c/i 4.6s push like 330 rwhp, 5.4s are pushing 350+ with like 400 torque

[Bullitt5339]

We don't race dynos, let's talk about track performance.

I conceded already that the 5.4 2V's would put better numbers out on the dyno, but none of them have outperformed a similarly prepared 4.6 on the dragstrip, and especially not at Autocross or Road Racing.

For reference: Show me a 100% stock longblock, stock intake, stock exhaust manifolds 5.4 car that has run in the 12's...... There's a few 4.6's that have done that right here on this website. I happen to own one of them. I'm confident that I can run mid-12's easily with my 100% stock longblock from oilpan to the stock throttle body this year.

[sharkbait]

Not really possible

one thing you need to take into account before you say that is that a HPS intake manifold and shortie headers are almost required during the swap to make it fit. But shortie headers really dont do shit, so dont get all worried and think there adding power in some way.

Second does your car have other work done to it? Is there weight reduction? Its not a fair comparison if your car has weight reduction done and the car your comparing it to dosnt.

Most people who drop 5.4s into there mustangs arnt trying to run a 100% stock longblock because...well why would you do that? Most put cams in right off the bat seeing as the cams are the issue. Also most people throw nitrous or boost on them right off the bat as well because when it comes down to it, the 5.4 will make more power then the 4.6 on boost.

Your trying to compare it in the wrong way. Trying to compare motors 100% stock is pointless when no one leaves it that way.

When i ran my car in that form with that mod list i only ran it down the track maybe 4 times. Not quite enough to "brag" about my times and use them as a comparison when debating about the swap. With a decent set of gears it would have easily been a mid 13 second car or even better with some decent driving.

I was just running it to see how much id gain with the blower right off the bat. Like a before and after