Shortblock for ~550 rwhp, 302 or 351 based?

281pony · Jan 23, 2011

im at 440 rwhp on a stock 302 bottom end. it might last a year, a week, who knows. i want to build something i have faith in. i've been looking into a 302 based block all along, at 550 rwhp it leaves the typical 4 bolt blocks.

all these blocks in a 331 variety are atleast 3k for just a shortblock, used. 5k+ if i buy it all new. so i started thinking, since i would already be getting a new oil pan, camshaft, and some other like items. would it be more efficient for me to just do a 351 swap?

from what i understand, a roller 351 block is good for around 700 hp, is this correct? even if i converted a older 351 block to roller, i think i still come out ahead in the end.

what do you guys think? 351 is heavier, but so is a dart block. i need to do some conversion parts with a 351, but if my shortblock costs me 2000 less, i can do it all easily and complete a long block instead of just the shortblock.

robo · Jan 23, 2011

i've been considering the same thing.

build a 408 and be done with it.

of course, a dart block with a 9.5 deck height would be even better.

281pony · Jan 23, 2011

robo said:
i've been considering the same thing.

build a 408 and be done with it.

of course, a dart block with a 9.5 deck height would be even better.

there is definately positives and negatives to both. i initially wanted a high revving 331 with some boost. i might just stick to that. vortech bracket requires some modifications for a 351.

gah i can't decide. i was trying to be in the process of this, or done with it before my stock block went boom. maybe i should just pick up another stock shortblock for a rainy day when it breaks.

this is a money thing more then anything. i wanted to be at or under 4k to do everything.

2000xp8 · Jan 23, 2011

The price on the 351 swap parts adds up.
Also, you sure you can get a 351 with a good rotating assembly done for 2 grand?
Certainly won't be a 408 for that money.

Let's not forget either that they extra cubes may just mean less boost, not more power, you can only spin an S trim so fast.
You will be moving towards a T trim, and unless you purposely purchased a Heavy Duty S, that means at least a new head unit.

My opinion, get yourself a boss block, start building it into a good 347, then when it's done you can just do a block swap, then worry about getting a t trim afterwards.

I like the 351 based engines when going for max power NA.

281pony · Jan 23, 2011

2000xp8 said:
The price on the 351 swap parts adds up.
Also, you sure you can get a 351 with a good rotating assembly done for 2 grand?
Certainly won't be a 408 for that money.

Let's not forget either that they extra cubes may just mean less boost, not more power, you can only spin an S trim so fast.
You will be moving towards a T trim, and unless you purposely purchased a Heavy Duty S, that means at least a new head unit.

My opinion, get yourself a boss block, start building it into a good 347, then when it's done you can just do a block swap, then worry about getting a t trim afterwards.

I like the 351 based engines when going for max power NA.

good info, thanks. i planned on just keeping it a 351 with a simple rebuild. i am sorta leaning towards staying 302 though, just for the fact of not dealing with the swap bs on top of it.

i didn't get my vortech on purpose really, i kinda fell into a deal. however, my s-trim is nearly a t-trim already. it's an si trim, i believe it is rated for 50 hp less then a t-trim. it should work good for me. i'm not trying to push a ton of boost on either application. like 12-14 pounds should get me where i want to be.

that has been my biggest drawback, finding a block to start with for a decent price.

SMOKEDYA · Jan 23, 2011

If your comparing cost to strength,i say 351.peace

john

FastDriver · Jan 24, 2011

At 550rwhp you're much better off with a 351. You can do the 302 thing, and at 440rwhp you're fine as long as you keep your tune safe. Going up to 550 will be pushing a 302. They are cheap and plentiful, but for that matter, so are 351s.

giddyup306 · Jan 24, 2011

281pony said:
what do you guys think? 351 is heavier, but so is a dart block. i need to do some conversion parts with a 351, but if my shortblock costs me 2000 less, i can do it all easily and complete a long block instead of just the shortblock.

For me I'd rather be lighter. I have a 69-70 BOSS 302 block. I've heard of 880 RWHP, two cases of 1500, and another of 1600. It's pretty cool when your stroker blows your buddies car out of the watter with less cubes than his had stock.

Gen414 · Jan 26, 2011

OK, first of all...trying to find an original Boss block...good luck with that. And ten when you DO find one..gonna pay same or more then say a Dart block. Unless doing a numbers matching resto, the Dart (or teh like) block becomes a no brainer.
As far as a stock Boss block holding over 1500HP? Hmmmm, would be a first.

So now on to OP...
Ive done both, 302 based and 351. 302 stock block will become questionable once you hit 500+.
351 block is good for 700+. I was throwing close to 800 at mine when a ROD took a dump, and wiped out block. And then I made teh swap over to Gen III/IV power (for you Ford guys, that would be Chevy )

I personally would just build teh 351 and call it aday. use stock block (and stock 2 bolt mains) use stock crank, pick up a set of rods and pistons and will have one tough, affordable shortblock.

Oh, and cubes is free horsepower...so even if you are adding some weight to nose, the extra power/durability will MORE thanmake up for it. You can find 351 shortblocks and longblocks in junkyards for $200-$500 all day long...

Gen414 · Jan 26, 2011

Not sure if I am allowed to post links to ebay, but quick peak @ there for 351 turned up @ 200 items, and here is a bare block for buy it now $225

http://cgi.ebay.com/ebaymotors/FORD...r_Truck_Parts_Accessories&hash=item588c0e2674

If Im not allowed to post links to ebay, I apologize and mod can delete it, or let me know, and i will delete it.

But just browsing ebay for 351 in parts section...found a 385 HP crate motor from Ford for $450.

Found a 408" brand new, assembled, never ran shortblock for $2200, and it goes on...

2000xp8 · Jan 26, 2011

Gen414 said:
OK, first of all...trying to find an original Boss block...good luck with that. And ten when you DO find one..gonna pay same or more then say a Dart block.

Gen,
Ford brought back the boss block, most of their new crate engines are based on them.
While not exactly the same as the original, both the new and old block can be used as race blocks and support more power than anyone reading stangnet could throw at them.

S&B · Jan 26, 2011

I will start with answering your question, building up a block be it A4, dart, Boss ... is going to add up at the end of the day your going to have 7-10K in the setup, probably why 2000xp just decided to pony up all at once and but his 03 setup

At the end of the day you cant tell 450 rwhp to 600 rwhp it just all feels fast and spinning tires.

FastDriver · Jan 27, 2011

S&B said:
At the end of the day you cant tell 450 rwhp to 600 rwhp it just all feels fast and spinning tires.

I beg to differ on that one, bro. You can definitely tell a difference. I've gotten 760rwhp to hook a couple of times on the street in 4th gear and let me tell you, it was quite a difference. Scary as ****! It's like being on a rocket ship. Rocketing from 80-140 in a couple of seconds is amazing. I remember when 450rwhp used to be scary. 760 is ridiculous.

Gen414 · Jan 27, 2011

2000xp8 said:
Gen,
Ford brought back the boss block, most of their new crate engines are based on them.
While not exactly the same as the original, both the new and old block can be used as race blocks and support more power than anyone reading stangnet could throw at them.

No kidding? Cool...didn't know that. been away from teh Ford camp now for a number of years...guess would say going on 10, maybe 12 years now??

Use to run Ford Ford Weekend...started back in 1992, and ran all the way up until 1998? 1999?? Started in Street Stock, then Street 5.0, then Street Outlaw. Shoot, back then, they wouldn't allow Powerglides in Street Outlaw!! HAHAHA!!! Had to run C4, or C6, HAHAHA!!!
Also back then, Outlaw was limited to 360 CI!! Whew, time really has flown by...

S&B · Jan 27, 2011

FastDriver said:
I beg to differ on that one, bro. You can definitely tell a difference. I've gotten 760rwhp to hook a couple of times on the street in 4th gear and let me tell you, it was quite a difference. Scary as ****! It's like being on a rocket ship. Rocketing from 80-140 in a couple of seconds is amazing. I remember when 450rwhp used to be scary. 760 is ridiculous.

the older you get the less you do this, I guess for me, I wish i would have saved the some of the crazy money i put into the car after i made 450hp and I think wow I could have just baught another car with that money. and still had tons of fun. My 1992 vert that was bone stock down to the clutch was more enjoyable for me to drive I turned the key and never worried about one thing.

thats why factory swaps apeal to me its the "within the limits" power that is perfected for everyday use. I think i might just part my motor and blower setup out and go buy cobra deal

Noobz347 · Jan 27, 2011

Choose your poison.... pick all, some, or none of the available options to meet your HP goal. There's lots of ways to do it but one just one thing seems to remain conastant:

Fast
Cheap
Reliable

Pick two of the above and base your build from it because you can't have all three.

FastDriver · Jan 27, 2011

Oh man, you are speaking the words that I have pondered all the time. I had so much fun with a simple H/C/I combo that made 320 and was a struggle to get into the 11s. The twin-turbo setup was different and fun too, but more expensive and problematic. The single turbo setup now was exponentially more expensive and so far has been exponentially less fun, in all honesty. I could have built my C5 with a simple H/C/I combo and I think it would have been more fun... I'm stubborn and still feel I have a long way to go on the mustang, though. I'll see it through, because I'm so close. I'm afraid of starting another project for fear of overdoing it, though. ... maybe one day I'll just go back to the basics.

FastDriver · Jan 27, 2011

All that said, S&B, refer to the first quote in my sig

2000xp8 · Jan 27, 2011

S&B said:
the older you get the less you do this, I guess for me, I wish i would have saved the some of the crazy money i put into the car after i made 450hp and I think wow I could have just baught another car with that money. and still had tons of fun. My 1992 vert that was bone stock down to the clutch was more enjoyable for me to drive I turned the key and never worried about one thing.

thats why factory swaps apeal to me its the "within the limits" power that is perfected for everyday use. I think i might just part my motor and blower setup out and go buy cobra deal

I feel the same way, that's why i did it.
A/C works, starts right up, decent gas mileage, no cooling issues, and most importantly no blown head gaskets when you beat on it.
And if 500rwhp aint enough, you can go ported blower to 525, and if that doesn't cut it, a used whipple at less than 2 grand will take you to 600rwhp.
None of which changes any of the thing i mentioned above.

Turbos are cool and all, but they just don't seem to do well for street use.
For a street mustang with pushrods, from what i've seen, cap it at a T trim and enjoy.

GroverDill · Jan 27, 2011

Said it more than once, if I could go back and start over....

408 on a roller 351 block
tko500
stockish fuel system

Done.

Shortblock for ~550 rwhp, 302 or 351 based?

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