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Comparing Motors: 347 stroker vs. 351W swap

16K views 38 replies 18 participants last post by  Nordic  
#1 ·
So far I've received some great information on this site regarding upgrades to the differentials in my 1994 5.0L XL. Along with upgrading the diffs in the truck (4.10's all around with front and rear limited slip), I will be doing a motor for it later on in 2007 sometime. I already have a set of Edelbrock Performer heads (2.02 intake valves) that are mildly ported and polished. My goals are to increase the power and torque from the motor without going overly crazy. I'd like to gain power while not substantially hurting fuel economy and driveability.

My plan for induction and exhaust is as follows: Larger MAF & ghettofab intake piping, ExtrudeHoned factory upper & lower intake manifolds, the Edelbrock heads I mentioned coupled with 1.7 roller rockers. I already installed a true dual exhaust last week, but I will be replacing the factory exhaust manifolds with shorty headers that just came in. At some point a basic Powerdyne or Kenne Bell kit might be in the works, but not for a year or two (at least).

Given all of the above, I'll now cut to the chase: I have read about 351W swaps, and frankly they don't seem very difficult. I am trying to decide between doing a stroked 5.0L (331 - 347) or swapping in a 351W. Assuming that money is not as much of a consideration as long-term reliability, power output, and ease of installation, I'd like to get some feedback from folks who are knowledgable on this subject.

Thanks in advance for the insights, guys.

BN
 
#2 ·
to put it simply, there's no replacement for displacement. while a 347 would be a cool motor to have, something as simple as a 357 windsor with the parts you mentioned would blow the doors off a 347. with the 351 you'll have a bit more room for boring if you so desire and a stronger block. especially if you find one of the old E9 ( derek help me out) blocks. its not that hard of a swap at all, and if money isnt a consideration, DEFINITELY go with the 351
 
#5 ·
Nope The substitute for cubic inches is the blower! I stroked my 302 knowing I wanted the stronger crank, forged pistons, and stronger better connecting rods to hold up to the blower. Had I stroked a 351 and then installed the blower it would be too much power for the drive train to handle and would have involved upgrading the fuel and exhaust systems as well. Saved the 50 lbs over the 351 and can still get better mileage if you keep your foot out of it! This applies if you know you will blow!
 
#23 ·
I agree 100%.

If nothing else a 351w bored a little over is gonna be cheaper and make more power than a 347
 
#7 ·
As long as you have the $$$ for the headers and upper & lower intake manifolds, I'd say go 351, too. I wouldn't even bother with Extrude Hone; just get an Edelbrock or Trick Flow manifold and be done. If you're looking for ultimate driveability and you're halfway decent with electronics, a MAF conversion might be an idea (again, it's $$$) since you'd be adding around 50 cubic inches and who-knows what cam. There's no substitute for displacement's effect on low-end torque, given properly selected cam, intake, and heads. Waiting for a blower to spool up on a heavy truck wouldn't be MY idea of fun, but to each his own. :shrug

Oh, and 3-inch mains are bitchin'!!! :goodfinge
 
#10 ·
Waiting for a blower to spool up on a heavy truck wouldn't be MY idea of fun, but to each his own. :shrug

No spool-up! You thinkin' turbo lag? They have gotten much better. The centrifical blowers don't produce boost well at low RPM. I am running Kenny Bell which produces boost at low rpm.
 
#8 ·
ii am building a 408 stroker for my mustang, it will be a drag only car, and built to race only. but i had the same decision to make, and when it comes right down to it, i will kill any 302 based motor with this one i am building. its in the planning stages now, but when it is finished this spring, it should produce 680~700 crank hp, and it will also have a 300hp nitrous deual stage plate system on it.
 
#9 ·
thats a C9 block your thinking of... anyway 351w would be better off the bat...do some research regarding 347 motors... many people have problems with oil burning because of the very shallow piston they have to use. The oil rings sit within and 1/8 of an inch of the rod pins... makign a very weak area.. much more machine work and block work is required for a 347 so money is sky high for them...i would not run a 347... the 302 block just can't do it... a 331 would be my highest...the 347 is just not reliable...unless you dont mind a rebuild every 20k
351w: a simple .30 gets you a 357w... im not sure if i would go as far as 408...but a 393w would be pretty cool. Prices go up the higher you go... i would stick with a stock 351w...If your buying a used block and need machine work done a simple .030 over with new pistons will do wonders...now if the block you pic up needs a whole roatating assembly then by all means, stroke it. But a 351w with all the performance stuff you mention can be capable of alot of power...
i dont know what your budget is like but dont forget everything else...you dont just have a motor to build...big injector...a proper tune... fuel pump..fuel lines.. all that stuff to support the near 500ft/lb motor your building...and dont foget the 351w block is a 2 bolt main...so before you go shooting at 800+hp...remember what is holding it together

go 351w...unless ur rich then aftermarket block 393w turbocharged:rockon

dc
 
#11 ·
I agree with your statements about going 351, but I think your opinions on 347s are about 10 years out dated. You might want to check your "facts" on them. They're fine in a DD application. Go over to a mustang site, where they run them all day, every day, and spout off about your concerns with them. You'll change your mind.
I would venture to say it's the most popular stroker for a 302. I dont think it would be, if it had all the problems you just described.
 
#12 ·
if your gonna build a motor ,definitely go 351,the swap wont cost much more if you gotta get headers and intake anyway,also you can do the 392 stoker cheap,302 pistons,351 rods and a cast crank for like 200 bucks........also driving around with a low compression 8.5:1? motor for 2 year waiting for the blower may suck
 
#16 ·
Thanks for the opinions, guys. Piston and ring designs have made the 347 stroker just about as reliable as a factory 302 if tuned properly and not nitroused at every stoplight. I've got plenty of Mustang buddies who run them in daily drivers with boost. The only guys who grenade these motors are the guys who don't tune properly.

If I do the 351W swap I don't see any real reason to not do a 393 stroker and probably forget the blower. For either a built 302/347 or a 351W, what are most people doing for intake manifolds? Are most people just doing away with the factory truck manifold and setting it up like a Mustang (bigger TB, mass air meter, etc.)? If so, GREAT! I already have a few aftermarket manifolds lying around, though I'd need to get a lower manifold for the 351W. I took a look at my truck's manifold and it seemed pretty decent with a much bigger cross-sectional area in the runners than a factory HO Mustang; so that's why I considered a simple ExtrudeHone. I wouldn't mind tossing on a Mustang-type setup (Trick Flow, Edelbrock, what have you), even while I finish off the high-mileage factory 302.

If I could get a clean 330hp/350tq (rear wheel) setup that idles smoothly and is not finicky, I'd be totally happy. Seems like a stroked 351W might be the way to go.

BN
 
#18 ·
i dont see why people spend money on a 347, anywhere a 5.0L is, a 351w will fit...well exploders might be cramped. Plus if you have a 5.0L and can find a 351w that doesnt need to be bored you can put the 5.0L pistons on the 351w rods and put a 3.85" stroker crank in for 387cid stroker. The cranks are anywhere from $300-$1000 depending on quality
 
#19 ·
347 just aint enough for good power on those heavy vehicles, and you will be pushing that tiny engines limits already.
Put your money in a 351W, a 408W stroker will keep your smiling a little longer..
Ditch the 1.7 rockers, get some good 1.6 rollers, you will need another cam anyway and you can pick one with good ramps rigth where it should be instead.

Then, in a year; add a NOVI or vortech or a turbo or ... , your engine is up to it :)
 
#20 ·
NORDIC

Looking at your rig makes me seriously consider a big-inch Windsor. Sweet setup, man!

BN
 
#22 ·
Looking at your rig makes me seriously consider a big-inch Windsor. Sweet setup, man!

BN
thats good to, but be prepared to upgrade everything else . any of these guys with big inch windsors can tell you that the power will destroy every weak link in the drive train. damn i shouldnt of come in here i was already wanting another mustang. :banghead with another big windsor .:banghead
 
#21 ·
ive had both in mustangs. 347 and 351 well 408 . my 408 on hp alone would kill my 347 that had a blower with 14lbs of boost. both had TFS cylinder heads . but we arent talking about drag racing . your putting this in your bronco. after building so many projects i suggest you put a 351w in it with a fresh .30 over bore. use some of the parts you listed above and a good cam.
my 408 in my mustang ran 1/8th mile on motor , no gas , no slicks just street slicks with 3:73 gears at mid 6's 6.50 to 6.60 consistently with a c4 trans.on the gas with slicks it ran 5.90 to 6.10 depending on 60ft.
my 347 mustang with slicks and 14lbs of boost would run 6.90 to 7.00 all day long. but it had a 5spd tremec and a small crappy cam.
 
#25 ·
A reasonably healthy E4OD or C6 is good for a 408" (~450Ib/ft) provided enough cooling, filtering and sound attention to gearing and heat generation, don't get to high a stall or you _will_ cook it.
(E4OD was behind the diesels in much larger/heavier vehicles than the Bronco afterall)
That said, I probably have over 6k in my 4R100/TC setup (excluding the transmission controller)..

Did I mention enough cooling ?

What probably grenades first is your factory 8.8 rear axle(most any part of it will break..), driveshafts, ujoints, axleshafts etc. If you restrict yourself from making donuts, wheelhopping/burnouts and other stupid(fun..) stuff yours might survive longer than mine :)
 
#28 ·
I am simply trying to compensate for my small penis. :duh

Have you had yours on a real dyno? I find the Desktop numbers to be high by about 15% and you could take another 10% to get RWHP and Torque.
My little 349 pulls fine without the blower.
 
#27 ·
Gacknar, you have a nice little engine there, but you really really must double everything to close up on a little less than just enough :toothless
 
#31 ·
Actually from my understanding, the more information you put into desktop dyno, the more accurate its results are. I've heard it being generous and greedy. I think if you put in accurate information, include the correct cam specs, flow data for the heads, right compression, etc. it can be pretty accurate. Of course the only way to Know is to put it on a dyno.

Im curious about No ridic's 460w?? Thats not from a stock block is it? i want info....
 
#32 ·
It's not stock. It's buildt from a World manowar shortblock.

The World Manowar complete engine puts out 600hp/575 Ib/ft
with smaller heads/cam and without any boost.
I dont know what power mine will produce in the end, but target is 750hp,
and desktop dyno show app 800hp now. Below 6000rpm that is.
http://www.worldcastings.com/prods_pages/102075.htm

The engine is more or less ready, I lack some brackets and awaits my next supply of arp bolts from summit. Couple of months I guess before it is on the road again.

It will be a nice relief from that slow 408" I've been driving the last three years ;).
 
#33 ·
i understand the 347 issues are "out-dated" but i have heard some horror storys over the last 2 years about people having issues still...especially from the cheaper brands...
notching the block was the only other machine work i was referring to...
400 hp is fine...the o nly issue is once you start pushing past the 500 hp mark, the little 2 bolt main FSB(thats Ford small block not full size bronco) starts falling apart..
you need to decide on what you really need and remember the rest of the costs... exactly what kind of power are you looking for and what are u gonna do with it...

dc
 
#36 ·
my 302's block split down the rear center. the 347 did the same thing. thats when i sold off everything put the car 89 back stock and sold it. then built an 86 gt with a carb. 408 / c4 transbrake /reverse manual valve body. 8" 4500 stall /tfs heads/ 1&7/8 long tubes with 3" exh. big 620 custom ground solid lift cam and victor jr intake manifold port matched to the ported cast iron hi port heads with big valves. big sump pan with windage tray and a built ford 9"
and lots and lots of other mods .
 
#37 ·
One day im gonna build me a Clevor. Until then my little tired 5.0 will do.

I am kind of partial to the 302 for some reason. I just dont see the big difference between the 2 when it comes to power output. I have owned both 302 and 351W and while the 351W did have more bottom end, it fell on its face in the mid range and upper RPM's. After i Bbusted the piston and cylinder wall in the 351W i put i a Roller 302 H.O. with a mild cam and had just as much low end and lots of Mid-range power. I also see alot more Durability out of my 302's that the 351W's for some reason. But i know this argument may not apply to this thread cause these were all stock or mildly built engines and you guys are talking stroked gassed and blown.