specizripn

Ok, so some of you know I have made posts about modifying my 4.6 for twin turbos, and I've come to realize that it is a terrible idea! So I've decided I'd drop a 5.4 in the 4.6 bay, and maybe put some PI heads on etc etc... I know about all the problems like needing spacers, and a cowl hood to make the taller 5.4 fit, but I can't seem to find one to put in. I'd be fine with a new one or even a gently used very low miles one that can be rebuilt with new gaskets, cams, PI heads etc.

Long story short the only 5.4 DOHC crate engines I've been able to find are like $20-$30k! Does anyone know where I can find one new or gently used? Thanks in advance!

JT76

So you went from wanting 1000+ hp to wanting 300 Hp? lol

Look for one out of a navigator.

Vukov

just out of curiosity what goes into the swap? don't need like a complete breakdown i realize thats asking a lot but just a basic (need new computer? need new tranny? motor mounts? ect...) and specizripn why do you need a gently used motor if you would plan to rebuild it anyway? why not get one with more miles and with the money you saved do a FULL rebuild maybe even a custom one...my two cents

specizripn

I don't know. I'm too ADHD to realize how stupid some of my ideas are... I think I'm just going to build one from the ground up with a buddy of mine.

When I mentioned a slightly used or new one I wasn't thinking about the fact that I'm rebuilding it anyway... Also I'm still trying to get a twin turbo which lead me to my other realization: that if I were to buy a used engine I'd have to replace every single part including the block, making it pointless to buy one to begin with.

Also to answer the question about what is needed for the swap:
-if the 4.6 has 6 bolt crank you need a flex plate from the 5.4 (5.4 has 8 bolts)
-new computer or a re-calibration of the 4.6 PCM and recalibration of the MAF (no need for a new MAF)
-all electrical wiring
-New pulleys, because if you change the pulleys you can keep the original alternator, Air Conditioning compressor, water pump and power steering pump
-4.6 exhaust may not match up (due to the angle) so you may need to make small modifications (cutting/soldering) to make it fit right
-new ignition coil packs
-install the 4.6 pilot bearing and remove to flex plate to bolt up the transmission
-If you have an auto tranny you will need a new torque converter
-fuel rails
-intake manifold
-knock sensor
-fuel lines
-may need new sump and oil lines, but don't take my word for it

Hope that answers the questions, and thanks everyone, but I'm just going to build a new motor from the ground up... Thanks
I probably won't start for a few months as I gather up the right parts to handle over 1k hp. I think im going to check out mmr and get some chryo treated parts. Think I'll also get a ricardo 6speed, new rear axles, rear dif, suspension and stiffen the chasis so my car doesn't fold like a tin can. I may make a thread on my build progress and swap...

Vukov

wow i knew there would probably be a lot for the swap but put into words to read sure makes it seem like a lot lol thanks for that tho i'll probably just end up building a 281 i'm only looking for the 400-500 MAX hp range i think i can get somewhere in there with a custom rebuild...anyone think I can get there N/A? i would love to stay n/a i love naturally aspirated high compression motors

zero2005

rwhp or engine hp?

most i'd expect out of a N/A 4.6 would be 330-340 rwhp, which would be close to 400 crank, and its gunna cost you an arm and a leg to get there. thats with some extreme heads, cams, intake, high rpms... its not as simple as just bumping the CR and hoping for the best.

budget wise, toss on some spray (100 or 125 shot) and call it a day, or bolt on a supercharger.

the stock bottom end (rods are weak link) will take 400-420 rwhp as a safe limit, before it grenades HOWEVER, that is dependent on 3 things. 1. a GOOD tune, 2. how harsh you thrash it, and 3. the components used. if any one of those things exceed the threshold, it is VERY possible for it to break even at mild HP levels...

dont fear the juice or boost. its the quickest way to bolt on power...

Vukov

well that's a little bit disapointing...even to build in from the block then up (high compression pistonts, balanced crank...ect) you think it would be hard to accomplish? i mean if that's the fact then that's it superchager it is...its not that i fear them or even don't like them i love the whine/scream of a s/c when slamed at WOT don't get me wrong i just love a custom built motor n/a, kinda that the motor is giving me the power. that and i love the sound of a high reving, n/a built motor and it would be a lil bit pride in my ride and bragging rights that i had n/a pushing what some of the s/c guys are and that i built a motor and didn't just spend $$$ and bolt something on.....BUT if i'll never get my 450 horses n/a out of that specific 4.6 (maybe a newer one could???) then s/c it is cuz do love em!

zero2005

you'd be better off spending the cash on a 5.0 coyote motor... the amount of money you'd put into a 2v 4.6 would be rediculous, and getting even 400 rwhp would be i wanna say impossible. 4v might get you there, i've never seen a N/A built 4.6 4v, as the cash that could be spent on one, you might as well go big so they all go with a low compression motor for the boost and/or juice.

no reason to spend thousands of dollars for a N/A 4.6 @ 400 rwhp when you can do it for much much much less with boost or juice.

the whole point of a V8 in a "muscle" or "pony" car is the low end Torque, not the high revving... sure there are those who do it... but the torque is what is gunna get your car moving, especially with all that weight. 2v's just dont breathe enough in stock form to really push it farther than 5600 rpm's, and any higher than that in stock form your gunna be breaking all kinds of things on the top end of the motor. you could build the heads for RPM's, but your talking trick flow twisted wedge heads, plus all the accessories like springs and such... just go take a look at the prices on those heads to get an idea of what your in for...

the 4v is a bit of a different story. they do flow good, and there are 2 types, B and C heads. with the B heads (like off older 4v's like mark VIII's) you also have to deal with IMRC, so you'd also need the computer, or run a delete. the newer C heads are from like Mach-1's and newer cobra's, they flow better. you can do a basic search for more numbers/info.

you could stroke it for more displacement but, then your not talkin a 4.6 anymore really, and stroking it usually increases low end torque but decreases top end RPM's... and a 5.4 is essentially a stroked 4.6 (slightly taller block) so the RPM's are lower...

honestly, with all the money you could dump into a NA 4.6, you'd be better off just biting the bullet and goin turbo, supercharger, or nitrous. that or look for the new 5.0 coyote motor. higher compression motor, 4v, bigger displacement motor and also has variable valve timing, and from the factory "only" pushes 412 hp (factory specs, i've heard rumors its making more). if they needed all that just to push that at the crank, then imagine what it'll take to get a 4.6 there...

but your gunna do what your gunna do. i'm just giving you info. IMO, if you plan on keepin the car, boost boost boost! if you got the money to throw at it and someone who can work miracles, then by all means, please prove me wrong! lol i would love to see a 4.6 N/A make 400+ rwhp.

Vukov

a lot of awesome info here really learning a lot....beggining to realize this dream of 400 horses in a 4.6 is not too realistic. The reason for wanting a higher reving v8 is i'm wanting more of a track car then a drag car, i like dragging and fun freeway driving but i LOVE going on long drives through places with tight curves and long bends and would hope to start goin to tracks (not a whole lot localy and the closest ones are an arm and a leg). But s/c would work just fine on a track wasn't thinking that i wouldn't just had a thing for n/a motors.

zero2005

i would definately say boost then. you can account for the lower RPM's and make it up with gears. gears will make the shifts shorter. you can also throw in a T-56 which has a much better gear ratio than the T-45/T-3650, and it has a better final gear so you can maintain highway drivability with higher gear ratio's. dont fear the gear.

if you are doing a bit more track than just a fun street car, i would recommend skipping the centrifugal supercharger unless your tight on a budget and go straight for a positive displacement blower (roots/twin screw) for the instant boost. turbo is another option, but expect to pay about the same or more for a turbo setup then a kenne bell... with my cheapo chinese turbokit, i got full 8-9lbs boost around 3200-3600 RPMs (stock motor). the only problem with a turbo on a manual car, is you cant build boost as "reliably" as an auto can with a transbrake. the only thing you could do is something like a 2-step, but a transbrake will build more boost.

the biggest problem with these cars is the rear suspension. its terrible. if i had known you wanted a more "track" or "backroads" car i would suggest dumping more money into fixing that instead. there's 2 options IMO, dump the Solid axle for a cobra IRS, or, go with a 3-link setup. a Panhard bar and Torque arm setup would be ideal if you wanted to keep the solid axle. there's a reason the newer gen mustangs use the PHB setup (they dont use a torque arm, they use a shorter upper link that is centrally located) i suggest you take a peak into the suspension side of this forum and look at Jazzer the Cats sticky about suspension.