If I had the extra cash I would go with the 347.    What rpm does the 347 make peak HP?   The T5 won’t like shifting above 7K.

My 347 has similar (450hp/400tq), but not exact, build specifications to the 347 you are considering. I have no cooling issues, but live in coastal California. In 5th gear (.63), the engine runs fine from 60 mph (about 1750 rpm) on up. The engine is carbureted with a modified 4100 Autolite. The engine is all out of steam at about 5800 rpm, is rated at 6000 rpm, and makes for a good driver. The Ford instructions call for a 750 cfm Holley or equivalent, but over the last 16-18 years, the Autolite has been reliable. My flywheel is about 12 pounds and I use a lightweight pressure plate. Using a heavier rotating assembly will change the driving characteristics. 

The heads on my engine have exhaust ports exits raised 5/8 inch. If the Blueprint 347 heads have raised exhaust port exits, you will need to do some exhaust work. Not difficult, just another task.

My engine has a Victor Junior intake manifold and the added height can create hood clearance issues. 

 Another consideration is your driveline. My car has a Currie 9 plus with 31 spline axles and my subframe is boxed, so my shear pin is the 235/17 tires. Engine mounts are another consideration, as I am replacing them every once in a while.

The 302 is a well known commodity, and either choice should provide miles of smiles.
Good luck.

Steve69 wrote:

For my 69 Mustang with 5 speed.   I'm debating if 54 hp and 81 pounds of torque is worth a extra $1280?

My old 302 stock would of had around 220HP and it moved the car pretty well.  So I'm thinking 361 would do the trick.  Then I see the hp of the 415hp of the 347 and that would be fun too.  The 347s now come with front sump and non GM distributor and there new blocks.  

Thanks for your input!

BluePrint Engines 302CI Cruiser Crate Engine | Small Block Ford Style

BluePrint Engines 347CI Stroker Crate Engine | Small Block Ford Style







 

Too bad they do not have a dyno sheet available, maybe their tech support would provide one for each engine. To me that's what you want to see as peak #'s can sometimes be misleading. I mean you want to know *when* those numbers peak, but you also want to know how the engine performs throughout it's operating range. That allows you to evaluate you rear gears, tire sizes, trans gearing etc. and see how the car will perform and most importantly if you'll like it that way! 

Steve69 wrote:

TKOPerformance wrote:

The HP is probably meaningless.  That much of a torque difference though is well worth it.  That's seat of the pants, put you back in the seat power you will actually use and feel.

I do agree with kardad though, all things being equal my confidence level in a 331 is higher than a 347 due to a variety of factors.  Primarily the short deck of the 302/5.0 block really limits rod length and makes rod angularity severe.  There are also just displacements that seem to make better power per cube than smaller and larger versions.  The 331 is essentially a 327 with a 0.030" overbore.  The 327, anyone who ever had one can tell you, was a great engine.  RPM potential was better than a 350 (which is basically what a 347 is), and torque was better than a 302 (or 289 or 283).  Chevy had a version that made 365HP, which was only 10 less than the 396, but it weighed 200lbs less!  Keep in mind, that a SBC has almost 1" more deck height than a SBF, so the rod length and angularity issues are exacerbated on the Ford.  So to me, the 331 is the best stroker SBF due to making the fewest and best compromises.  If I wanted something larger I'd go to a 351 (5.8) based engine.  Just my $0.02.
 

     They are building these engines with their new blocks that have 4 bolt mains and good for 700HP.  They are using them in there 347 now. 
 

The new blocks are thicker in critical areas, and use 4 bolt mains to be stronger, but the dimensions of the block have not changed.  They still use the 8.2" deck height or else standard small block intakes would not fit, and for a variety of other reasons (hood clearance, exhaust, etc.) they wouldn't be a drop in replacement for a 302.  Definitely the new blocks are nice, but the new block doesn't address the short deck height of the 302, which is the root cause of the road angularity (and the power it costs), increased wear on the thrust side of the cylinders (as well as increased drag and the power it costs), and the issue with being very limited on rod length (meaning a less than ideal rod/stroke ratio and an engine that doesn't rev as quickly as you might think it should). 

Now, what's the actual difference here to the end user?  Like Mike said: depends on the end user.  If you don't ever see yourself putting 100k miles on the engine in your lifetime, and don't care about every last HP, etc. then it probably means nothing and I'd say just buy the 347.  I built a 331 for my '89 GT because it was a clean sheet build starting from a bare block, and I wanted as few compromises as possible.  If the car already had a 347 in it I certainly wouldn't have bothered to swap the engine to a 331.  I'm just saying, if cost wasn't an issue and both were available I would take a 331 over a 347. 

I would look at torque output…

https://blueprintengines.com/collections/408-cubic-inch-engines-br-up-to-425-hp

How’s that sayin’ go?

GO BIG OR GO HOME 😁

You have plenty of space in your engine compartment.
Definitely some nice choices with a warranty.

Last edited by Nos681 (3/29/2023 3:52 PM)

I am waiting on my 347 to be built from BluePrint Engines. They promised me the new cast block. They supposedly design and use their own brand of parts to build the engines. I believe almost everything will have their name or initials stamped on it. Will wait to see what it looks like when I get it. And if a part fails they will have nobody else to blame! 

TKOPerformance wrote:

6sally6 wrote:

By swapping the rods from the left bank to the right bank would help with the angularity problem and pick up some free HP. (one of my 'pet-suggestions')
jus say'in
6s6

They tried this on Engine Masters and it made no difference. 
 

Well they're ly'in then !!!    J/K

'According' to the late/great Joe Sherman (master engine builder) he said 5% increase.
Either way.........ya can't 'feel' 5% on the butt-o-meter.
6sal6
 

Thanks everyone for your input!   I’ll sleep on it…lol.

lowercasesteve wrote:

TKOPerformance wrote:

6sally6 wrote:

By swapping the rods from the left bank to the right bank would help with the angularity problem and pick up some free HP. (one of my 'pet-suggestions')
jus say'in
6s6

They tried this on Engine Masters and it made no difference.  Plus aftermarket pistons typically don't have the pin offset.  Now, if the pistons were offset and if the 347 used those pistons might it make a difference?  Can't say for 100% sure, as that's not exactly what they tested, but...
 

Yeah... I saw that show.  It was a big surprise to me, but the numbers don't lie..or do they?  Sounds like a good subject for these august halls.
 

So I read up on it and what I've noticed is that other than the article in Hod Rod and/or Car Craft (which I'm sure was the same article just reprinted) there is absolutely zero hard evidence that this does anything.  You have Joe Sherman claiming it works, and that obviously carries a lot of weight, but there are no dyno graphs showing power one way and then the other with that being the ONLY thing changed.  On Engine Masters. by comparison, they ran the engine both ways with that being the only change.  I'm a BIG stickler for isolating variables.  So in the end, we've got hard scientific testing vs. conjecture from a big name engine builder.  I'd love to talk to Joe and see how he arrived at his conclusion.  I find that in a lot of similar situations a builder maybe tried something early in his career and the engine he tried it one made more power than any engine he ever built, he became convinced it was this one thing he did, so he just started doing it on every engine he built.  IMO that engine making so much power on such a tight budget had a lot more to do with Joe being a master of head porting, and pairing that with the right cam.  Out of half a dozen engine builders I've talked to over the years the one thing they kept coming back to me with was this statement: in a street engine there's no magic in the bottom end.  All the power is made by what you put on top of it.  Obviously the bottom end has to survive, and you must have good ring seal, but beyond that things like internally balancing vs. externally balancing, etc. make no measurable difference.  Now, possibly when you are making 750HP and spinning to 8 grand things are different, and in racing 5% more HP is an easy way to win races, but most street engines of 500HP or less likely won't see any benefit for all the tricks they use in racing.