331 vs. 347

sleeper89 · Jan 27, 2004

CobraGT87 said:
theres so many threads now about the 331 or 347 issue, side loads, rod ratio etc. For a N/A street motor, the life expectancy is the same. If I was building a blower motor setup, I would of gone 331 as well, simply because it's more rev happy. I built mine for N/A TQ for street driving, no 1/4 stuff..

Take Care,
Scott

...nuff said IMHO.

-steve

90Notch · Jan 27, 2004

"For a N/A street motor, the life expectancy is the same. If I was building a blower motor setup, I would of gone 331 as well, simply because it's more rev happy."

Yup that's my point that a 331 and 347 life's expectantcy is the same but correct me if I'm wrong but don't you have last statement backwards? A longer rod will be more rev happy not the shorter.

"If I’m not mistaken CHP offset the pin location to help this side load problem"

I forgot about that and I guess technically your right but wouldn't offsetting the pin only help one direction and make other worse?

We can aurgue this crap all day so I'm done after this one comment. Oil issues are from poor machine work and attention to detail during assembly not from the wrist pin intersecting the oil groove.

93cobra12 · Jan 27, 2004

I have a question, If you had the same builder build a 331 and a 347 for a N/A combo, and two people drove the car exactly the same, just mashing on it 24/7.. which would you guys say would have a longer life?

Same question but set up for a power adder.. Which would have the longest life span?

Gearbanger 101 · Jan 27, 2004

Just a comment in general, but aside from CHP’s claim of the offset pin location reducing side load in the cylinder bore, one pretty much has to rely on the math to debate their longevity. I don’t see how anyone can say how the 347 would last as long as a similarly built 331 or 306, when nobody has had one of these running long term on the street yet? Claiming 40,000 miles with no problems is hardly long term when you consider the majority of the stock 5.0 HO’s out there are touching on 150-200,000 miles with little wear, if any at all. I pulled my stock engine apart at 244,000km just for piece of mind and it still had the original cross-hatched pattern in the cylinder walls. Only time will tell if the same can be said for a 347.

sleeper89 · Jan 27, 2004

90Notch said:
"For a N/A street motor, the life expectancy is the same. If I was building a blower motor setup, I would of gone 331 as well, simply because it's more rev happy."

Yup that's my point that a 331 and 347 life's expectantcy is the same but correct me if I'm wrong but don't you have last statement backwards? A longer rod will be more rev happy not the shorter.

no, a 347 has greater piston speed at any given rpm due to its longer stroke and therefore will experience greater wear and abuse on the associated parts. just think, everytime the piston gets to the top or bottom it stops, lots of load on bearings/rods/pins etc.

"If I’m not mistaken CHP offset the pin location to help this side load problem"

I forgot about that and I guess technically your right but wouldn't offsetting the pin only help one direction and make other worse?

-steve

We can aurgue this crap all day so I'm done after this one comment. Oil issues are from poor machine work and attention to detail during assembly not from the wrist pin intersecting the oil groove.[/QUOTE]

90Notch · Jan 28, 2004

"I don’t see how anyone can say how the 347 would last as long as a similarly built 331 or 306"

Alright I lied, two more comments:

1st friend 347ci 10.5:1, AFr185, RPM intake, custom cam, etc... made 380rwhp has roughly 65,000 on his

2nd friend 347ci 9.7:1, TW heads, TracK Heat intake, F303, etc....made 350rwhp has 54,000 on his

Both still burn zero oil and are running as good as when installed.

"I have a question, If you had the same builder build a 331 and a 347 for a N/A combo, and two people drove the car exactly the same, just mashing on it 24/7.. which would you guys say would have a longer life?"

No reason both won't last as long as each other

"Same question but set up for a power adder.. Which would have the longest life span?"

For a SC combo get a 331ci, the pistons have more meat on top of piston so if tune goes bad you don't have to worry so much about burning through it.

"no, a 347 has greater piston speed at any given rpm due to its longer stroke and therefore will experience greater wear and abuse on the associated parts. just think, everytime the piston gets to the top or bottom it stops, lots of load on bearings/rods/pins etc."

So Acura motors make as much if not more than most Mustangs HP/per CI yet they have worse rod ratios as 347s and they have no problem lasted 200,000. I guess the greater wear and abuse on their parts don't apply?

sleeper89 · Jan 28, 2004

90Notch "no said:
if you read the post prior to mine (the one to which the response was directed) you'll see i was explaining why the longer rod is not more rev happy. i am not going to argue about wear/abuse. i have stated previously in this thread that the additional wear on a 347 vs a 331 will be negligible. with all due respect who cares what acura is doing. we're talking about two totally different beasts here. the 302 is essentially the same as the 289 which was designed in the early 60's. i'll bet the acura motor was a fresh design somewhere around the 80's, maybe even 90's. either way there is so much more that goes into this topic than simply who has the longest rod.

-steve

93cobra12 · Jan 28, 2004

I got a question about my set up if you guys can answer this really quick.. I have a 331 w/ a sportsman block, 8.8:1 compression, all forged internals, crower cam, tfs intake, v2-sq stock pulley, bbk long tubes, 3" exhaust.. Im really trying to hit over the 500+ rwhp mark w/ a stock pulley. Think Im going to need to get a smaller pulley?
if so whats the most boost you guys would put into this engine?

Xtreme Limits · Jan 28, 2004

First things first,

1. A 331 will be easyer on parts because it has a better rod ratio,(1.667).
This is not a myth, it is a proven fact.

2. A 331 will beable to rev to 7000rpm before the motor starts stressing parts.

3. A 347 will beable to rev to 6600rpm before the motor starts stressing parts.

4. A 347 with the same parts will make more HP and Tq. (20-40) more avrage.

5. Now days a 347 are fine for 100,000+ avrage miles if bulit rite, 5 years ago, youd be lucky to get 45-65,000 miles but not so anymore. A 331 is good for 130,000+ avrage. But its all in what the engine is built for. and what Hp, and RPM youll want to be pushing.

6. All in all if your useing a stock block, in a strreet car, and dont race all the time, use a 331, it will give u a big power incress and will be more then enuff power, for street tires. A 347 will be awsome in a street car, but youll beifit in strip car, or a car with raceing tires so it can hook, on the street a 347 mite have too much Tq and a 331 would be faster, but once agian its up too you what are you going to use it for what heads cam intake, N/A, Supercharged, Turbocharged, each stroker motor has its place, So 1 is better then another, but its all on what parts your useing..........

mattkimsey · Oct 14, 2005

opps, posted reply in wrong thread....forgot I did a search lol

5spd GT · Oct 14, 2005

A 347 (under equal circumstances) will wear out quicker than a 331. They both will last with some nice mileage taken care of. The 347 has more sidewall loading which equals more friction. The friction is experienced by the rings. The rings prevent the oil from blow-by (burning oil). If the rings start experiencing friction that equals wear.

It is a horrible argument to say "well why would companies continue to make 347 if it was so bad?" Most people that buy a 347 do it for power not for reliability...lol...think about it.

I choose 331 for a blown application or for a daily driver personally.

You can't overcome physics. It literally is impossible...right?

CoupedUp · Oct 15, 2005

A few more whacks at the dead mule ...

Let's just say both sides of the discussion are right for a minute ...

Okay good, now focus dullardly just for a second.

Ugg, ugg, me never, ever, ever hear "myth"/"reality"/"concern" that ugg 331 consume oil ...................... yet 'tis "rumored" of zee 347, no?

Problem solved.

Deck height hasn't been mentioned yet, so I'll throw that in ......

... and the big thinker attempting to compare a tin can honda rotating assembly and design has to "weigh in" the factors of mass and force to arrive at a complete conclusion ....

Where's my aspirin?

Gearbanger 101 · Oct 15, 2005

5spd GT said:
A 347 (under equal circumstances) will wear out quicker than a 331. They both will last with some nice mileage taken care of. The 347 has more sidewall loading which equals more friction. The friction is experienced by the rings. The rings prevent the oil from blow-by (burning oil). If the rings start experiencing friction that equals wear.

It is a horrible argument to say "well why would companies continue to make 347 if it was so bad?" Most people that buy a 347 do it for power not for reliability...lol...think about it.

I choose 331 for a blown application or for a daily driver personally.

You can't overcome physics. It literally is impossible...right?

Agree 100%

5.02GO · Oct 15, 2005

Hey, didnt ford put a 347 in some production car in like australia or something? I either read that on this site or corral.

Anyone heard of that?

95COBRA241 · Oct 15, 2005

Compaing a 331 to a 347 is compareing apples to oranges. Go with whichever motor is your flavor. I have friends with both and none of them complain about oil use. With te amount of mods some them have I don't the rod issue will be the downfall of either motor. Ironically, a 331 isn't a stroker option from Ford unlike a 342 or 347.

331 vs. 347

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