I'm not as mechanically inclined as the others here, but I'll vote 351W every day of the week and twice on Sundays.
I had an FFR Cobra. When I bought it, it had a mildly worked 302. The car was fast and a ton of fun. I cooked it doing an HPDE day and we dropped in a similarly mildly worked 351W. What a world of difference. Lots more low end torque and it would still rev just fine. It felt like a totally different car. Sounded much meaner too.
Apparently you can use a "big bore" aftermarket block and stroke a 351w all the way up to 454 cubes. 
For a street car I'd say a 351 makes a great engine. I went through lot's of different combo's in my old SN95 from new. By far my favorite was a late 351 roller block. GT40 cleaned up GT40 heads, mild cam, 351W GT40 lower intake (ported) and portmatched Explorer upper intake, mild cam and shorty headers. On the Dyno it only made about 260rwhp, but the RWlb/ft was something like 340/350, I can't remember exactly. It was a blast to drive. Not the fastest thing at the strip, but for on the street and exiting corners at autoX it was a blast. All the low end torque right now, with instant throttle response was far more fun and easier to tune than a supercharger.
What's this going into & what are your plans once the thing runs? If you're talking about commuting or mild street performance, either works. Normally, torque rules the street so the nod goes to the 5.7-L if it will easily fit. In some cars, it won't. An easy upgrade is a 347 from a 302 but beware. If you're looking for really high performance, a 'skilled' builder can break either size stock-block with add-ons. One of my autocross friends was having good luck with a crate 347 in a Mustang, so he changed the limiter chip from 6200 to 6800 rpms. Next week he showed up at a Club meeting CARRYING the block's rear main (with cap still torqued and the end of the crank w/ 2 rod throws) in his hands... Total mileage= 1200 from factory-new. Dart or World makes better blocks if you need the strength.
The_Jed wrote: Apparently you can use a "big bore" aftermarket block and stroke a 351w all the way up to 454 cubes.
Fords are not cursed with narrow pan rails and low camshafts the way Ch*vys are.
bosswrench wrote: What's this going into & what are your plans once the thing runs? If you're talking about commuting or mild street performance, either works. Normally, torque rules the street so the nod goes to the 5.7-L if it will easily fit.
79 Mercedes 450SEL. Just a driver with a little 'oomph'. I think both motors will fit easily. The transmissions is a different story lol.
351w, LT1, or a really cheap steal of a deal LS-based motor. This won't be happening anytime soon. Just the plan when the M117 finally poops.
Personally I'd use a big displacement motor (Ford 460, Cadillac 500, B/O/P 455, BBC, etc.)if swapping an old school american V8 into a S class, but that's just me. The 460 is of particular interest due to a lot of the smog era power loss being fixable with a timing chain set(they just retarded the pre smog cam), gets you something like 50hp.
Cams stopped being installed retarded when they put EFI on the 460.
I've played with Pontiac engines for a long time.
First time I opened a Windsor motor I wondered how the damn things even held together, they're light for a reason.
Not saying they're poor engines, just the size of things like connecting rods and rod bolts made me wonder how it held up as well as it did.
EFI small block.
Trans_Maro wrote: Not saying they're poor engines, just the size of things like connecting rods and rod bolts made me wonder how it held up as well as it did.
Correctly sized not boat anchors is why 
For this build I definitely think a 351 over a 302
80/20 rule here, the 351 is a better build candidate for a street motor. The intake is the limiting factor here. You can get monster heads that a 302 doesn't have the displacement to flow under 5000 rpm that on a 351 has great mid range potential, but then you are limited on the intake you get to use.
I would say build what fits your budget. In the end, not enough difference to make or break you, but the potential in the 351 is there.
Spend $1000 for a wrecked V8 3rd gen explorer and have a decent injected 302 and a good 4R70W auto trans. Freshen the motor and drop in an RV torque can. Drive the wheels off it.
Adrian_Thompson wrote: For a street car I'd say a 351 makes a great engine. I went through lot's of different combo's in my old SN95 from new. By far my favorite was a late 351 roller block. GT40 cleaned up GT40 heads, mild cam, 351W GT40 lower intake (ported) and portmatched Explorer upper intake, mild cam and shorty headers. On the Dyno it only made about 260rwhp, but the RWlb/ft was something like 340/350, I can't remember exactly. It was a blast to drive. Not the fastest thing at the strip, but for on the street and exiting corners at autoX it was a blast. All the low end torque right now, with instant throttle response was far more fun and easier to tune than a supercharger.
I saw a post you made somewhere about the fuel economy of said SN95 but I have been unable to find it again.
Do you any pis or a thread of the car somewhere?
What were all of the mods/upgrades?
What sort of real world MPG were you pulling down with said beastie?
Nice job resurrecting a 7 year old thread.
The m117 in that 79' 450SEL is still running strong. It has over 400k miles on it right now. No longer my car but the young woman who bought it still drives it daily.
A T5 will live longer behind a 302. The T5 part of your equation really holds back a 351. Most 351s easily exceed the max torque of commonly available T5s.
In reply to AnthonyGS (Forum Supporter) :
This thread was 7 years ago lol
In reply to yupididit :
I'm rereading and thinking, I need to fabricate more. I haven't used the term beef-metal in forever
yupididit said:In reply to AnthonyGS (Forum Supporter) :
This thread was 7 years ago lol
Ya got me. Since it was you and on the front page, I figured it was current and didn't check the dates. It wasn't the first time and probably won't be the last. I still stand behind the T5 longevity behind a 351W concerns.
AnthonyGS (Forum Supporter) said: I still stand behind the T5 longevity behind a 351W concerns.
As do we all.
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