OneFine89Mustang

347

88stangaruu

Shorter stroke engines are almost always more stable at higher rpms. Like a 302, is an over-square engine, the bore is larger than the stroke. 4.00bore 3.00 stroke. and it actually comes out to about 301.6inches or something like that but Ford just rounded up and there you go, 302. Look at the trans am series engines of the 1960's. The cubic inch limits on those engines was 305ci until 1970 when it went up to 350ci. Some of the best high-revving power plants produced were street versions of the trans am racing cars i.e.....Fords Boss 302, Chevy's Z28 302, Chryslers 304 etc. All of these engines are big bore short stroke engines.

TtopFoxRod50

Is there a difference in compression ratio?
Is there a range in getting more or less rpms?
Would the block need to be notched to make room for the movement of the connecting rods?


-Matty

silver91gt

all stroker blocks need to be notched at the bottom of the cylinder wall so the crank doesnt hit it.

347 all the way, more CI = more HP.
a 342 is with a standard 4.00 bore
a 347 is with a 0.030 overbore
and a 349 is with a 0.040 overbore.

Twister

the compresion ratio can be anything, there are too many variables
a shorter stroke engine has the potential for more RPM
a 347 has to be notched

silver91gt

rpms are based on the cam and what valvetrain you have.
you can build any motor to spin to 9500 rpm.

FullAuto

+1000

For pretty much all intents and purposes that people on this forum will be concerned with, valvetrain will limit rpm long before bore x stroke ratio ever comes into play.

Twister

note...I said potential

TAPOUT

347 is the way I chose to go for performance, but there are a million more important factors with building an engine. What is your ultimate goal? If you really want to spend a ton of loot, build a stroked 351 motor to 408, and call it a day. If you want something streetable, not too expensive, yet wild, go with the 347. Use compression to determine power. Use cam/intake specs based on your usage needs to design drivability. I had a 13:1 331 motor last year, and it was built cheaply by the previous owner (use a good balancer). Now I paid big money, and had a 347 professionally built, and it is awesome. I am also ok with the idea of tearing the engine down every 15-20K miles to replace rings and check for wear. My car is for weekend use, cruising, and drags primarily, your needs may be different. I drove my car 130 miles, each way, to my grandmother's on July 4th, so it is very reliable.

Bad Karma

You're gonna spend more money (or get damn close to) building a nice reliable 331/347 as you would starting with a better/stronger 351W based Stroker. For the money, you are going to get closer to higher HP, more reliability, and a stronger starting point.

The lower block area of the 302 based engines is where the weakness is, that is undisputed.

Once you start cutting into the block, which is what you will do when stroking a 302, you are going to compromise the structural integrity of the block and create a situation where you have to reinforce the block to support higher RPMs and/or Horsepower. Stud girdles won't be much help and what's the point of spending the extra $ to add 4 bolt mains to strengthen?

In my ever so humble opinion, most guys that build 331/347's wanted to do it to get more HP. There are those that like the bandwagon as well and did it becuase it sounded like a "cool" idea.

If you are looking at getting the most for your money, you cannot discount the 351W based Stroker. All of your accessories bolt right on, minor mods (enlarging the bolt holes on your heads and one accessory bracket has to be modified) are all that takes to make it happen.

Oh yeah, and then there's the HP. What's the most that a 331/347 is going to make NA? Maybe 375 is it is crankin' and running good.

An efficient 393Ci will produce close to 400HP without any major work or tricks.

To me, that's a better deal and you have a way better startnig point from which to build onto an already monster motor.

My opinion but take it from a guy who was dead sold on a DSS 347 until I started to read up on other websites and talking to actual people who have done (both 331/347 vs 393) and learned to teach what they found out the hard (read:expensive) way.

Great luck to you,
Ivan