its getting to be that time, my 94 is getting up in miles and winter is coming. so whats everyones view on going to a 331 or 347? i will be using my block, but after that, aftermarket. and who has the better kits? my futture motor, afr 185 heads, 1.6 rollers, custom cam , trickflow track heat intake,( i have already 24lbs injectors, 75 mm throtle body, 75mm maf, bbk 1 5/8 equal leangth headers already.) also on my mind is a supercharger, probably vortec.(will swich to shorty headers after supercharger) so this is all must be in consideration when looking for the right kit, 331 or 347?? also have for trans a t5, and 373 in the rear end. ok now its up to you, what do you have to say?
331 or 347????
- Thread starter madmax680
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In my limited knowlege...
There are pro's and con's to both but I would go with a 347. A 331 has a better rod ratio, which puts less stress on the cylinder walls, but that is about it. It used to be that with 347's the oil rings intersected the pin, making them consume oil, and thier rod ratio was bad so they tended to break walls. That was then, this is now, and those problems have been corrected. The 331 of course is going to have better rod ratio, but the 347's isn't bad anymore.
There are pro's and con's to both but I would go with a 347. A 331 has a better rod ratio, which puts less stress on the cylinder walls, but that is about it. It used to be that with 347's the oil rings intersected the pin, making them consume oil, and thier rod ratio was bad so they tended to break walls. That was then, this is now, and those problems have been corrected. The 331 of course is going to have better rod ratio, but the 347's isn't bad anymore.
MMFF says.....
according to the new MMFF that just came in the mail, on their "331 ways to kill an LS1" article... and this is if i read this correctly.... the 331 will make about 40 more HP than the 347, but the 347 will produce 40 more ft/lb torque. i thought that was very interesting. they say if you have a heavy car---like you 94 vs a fox---- the torque is better.
Either way....i dont think that you can go wrong.
according to the new MMFF that just came in the mail, on their "331 ways to kill an LS1" article... and this is if i read this correctly.... the 331 will make about 40 more HP than the 347, but the 347 will produce 40 more ft/lb torque. i thought that was very interesting. they say if you have a heavy car---like you 94 vs a fox---- the torque is better.
Either way....i dont think that you can go wrong.
I havent read that yet but I am sure it all has in the way your build it. There are only 16 cubes between them. Can't go wrong either way. I think you could build the 347 with a larger H/C/I setup and gain more HP without loosing TQ or gain more TQ without loosing the HP.
As far as power goes, I don't even look at peak numbers, I like to see the powerband. Which makes the most average power in the range you would be using durring a race?
Also, the pure street guys are getting into the 10's now, which is all motor >310 cid. It's all in the build.
As far as power goes, I don't even look at peak numbers, I like to see the powerband. Which makes the most average power in the range you would be using durring a race?
Also, the pure street guys are getting into the 10's now, which is all motor >310 cid. It's all in the build.
bluevenom867
I will have images of molesting stuffed animals in
331 with a solid roller cam will smoke a 347, but it would not be a street car because it cant ideal on the street without over-heating.Plus you need about a 5500 stall converter and a C4 w/trans brake or a heck of a 5 speed.
But thats for a race car,for the street the torque of the 347 is nice.
But thats for a race car,for the street the torque of the 347 is nice.
I dunno WHERE this stuff comes from ... 
I have NEVER built a 347 that wouldn't make at LEAST as much power as a 331 with the correct components.
It's the same reason you're building a stroker, CUBES. It's the same reason our cars are faster than 4 cylinders, CUBES. It's the same reason race classes run displacement limits and give weight breaks to smaller displacement engines, they flat out make MORE power.
Just because one car outran another is MEANINGLESS, they're different combo's, different cars and different scenerios.
If you're looking for the most power build the 347. If you're concerned about pin intersection use the 5.315" rods. If you REALLY think that changing the rod ratio .1 is going to make a combo then you should probably stick with a 302.
Brian
I have NEVER built a 347 that wouldn't make at LEAST as much power as a 331 with the correct components.
It's the same reason you're building a stroker, CUBES. It's the same reason our cars are faster than 4 cylinders, CUBES. It's the same reason race classes run displacement limits and give weight breaks to smaller displacement engines, they flat out make MORE power.
Just because one car outran another is MEANINGLESS, they're different combo's, different cars and different scenerios.
If you're looking for the most power build the 347. If you're concerned about pin intersection use the 5.315" rods. If you REALLY think that changing the rod ratio .1 is going to make a combo then you should probably stick with a 302.
Brian
ScatStroker said:I dunno WHERE this stuff comes from ...
I have NEVER built a 347 that wouldn't make at LEAST as much power as a 331 with the correct components.
It's the same reason you're building a stroker, CUBES. It's the same reason our cars are faster than 4 cylinders, CUBES. It's the same reason race classes run displacement limits and give weight breaks to smaller displacement engines, they flat out make MORE power.
Just because one car outran another is MEANINGLESS, they're different combo's, different cars and different scenerios.
If you're looking for the most power build the 347. If you're concerned about pin intersection use the 5.315" rods. If you REALLY think that changing the rod ratio .1 is going to make a combo then you should probably stick with a 302.
Brian
Brian is 100% correct, I always tell guys it is personal prefrerence when they ask about the whole 331 vs 347 I'll build both, they are fairly equal. Mad Max, either will work fine for you, you'll need a dish piston to keep compression down in the 9:1 range, I know on the kits I have delt with a 14.2cc dish is common. If your stuffing all these parts in a stock block a cast assembly will hold up very well, longer then the block in most cases. I prefer the SCAT cast 9000 series crank, SCAT I beams and Probe pistons, good rings and bearings.
keep the mail comeing, this isnt just for me any more, its for everyone else woundering the same thing about making the chose's. in addtion, i do want to keep runing pump gas. i will admit to this, do to gas prices, the 89 octain is what i run. im sorry if i dissapoint anyone. after the build-up, i still will probably run 89-91 octain. theas days, u must watch what you spend.
Michael Yount
Mustang Master
Let's see - a supercharged, AFR headed 332 (I'm on a mission here to get the correct displacement out there for the 4.03 bore X 3.25 stroke motor!) or 347 either of which will likely easily knock down at least 450-500HP, is gonna cost a small fortune in parts to build, won't win any fuel mileage contests, and you're concerned about the price differential between 89 and 92 octane? That is making me chuckle.
Given the damage that's done by detonation under boost, you're likely gonna want to run the high octane stuff once you've boosted it. Cause you'll spend alot more repairing it than you will on higher octane fuel.
Given the damage that's done by detonation under boost, you're likely gonna want to run the high octane stuff once you've boosted it. Cause you'll spend alot more repairing it than you will on higher octane fuel.
Legendary
Founding Member
bluevenom867
I will have images of molesting stuffed animals in
Legendary said:
Not if you had the manual trans, but a 8inch 5500rpm stall converter on a 331 with a solid roller will over heat.
bluevenom867 said:
A 5500rpm converter has no place on the street
Micheal, we made 465/425 to the wheels @ 5800rpm on a very basic blown 331, 9.6:1comp, Cast iron GT-40's, Extrude Honed Cobra, Crane 2031 cam, stock 1.7 rockers shorty headers, 83mm MAF, 75mm TB, 36# inj, 255lph HP pump, full exhaust and cats, all emissons and cold A/C
Michael Yount
Mustang Master
Thanks Rick - I was relatively confident my "at least 450-500HP" was accurate. Virtually no one on the boards measures at anything but the wheels; I was referring to rwhp. What octane fuel did you use on the pulls/on the street with it? How much total timing at peak?
Ok guy's theres no difference between a well built 331 and 347 other than the 16 ci. also the amount power an engine makes dosent determine drivabilty! I have had several 600+ hp. engines and daily driven them! The stall on the converter is directly related to where the engine makes peak power and Tq. so if you street drive it you must choose the right cam, and cylender head, so you dont need that 5500 converter!
I'd build the 347 with as big of head the budget would allow,( and dont scream you'll loose tq) and cam it for it's use such as daily driver, street strip, or mostly race but sometimes street driven!
I'd build the 347 with as big of head the budget would allow,( and dont scream you'll loose tq) and cam it for it's use such as daily driver, street strip, or mostly race but sometimes street driven!
Michael Yount
Mustang Master
Zmann (howdy!) said - "...also the amount power an engine makes dosent determine drivabilty! "
Well, there's some subjectivity in the statement, but for naturally aspirated powerplants without the benefit of variable cam timing or variable intake geometry (most 5.0 variants), peak power levels have a big impact on drivability. The reason is that as peak power levels climb, the rpm at which the power occurs climbs too - and with it, the bottom end gets softer and softer. And even with 300-350 cubic inches, when you put something that peaks up in the 6500-7000 rpm range in something that weighs 3000-3500 lbs., the bottom end torque production (below 2500 rpm) often gets weak enough that they become a real pain in the butt as daily drivers. Lopey idles, high rpm clutch slipping starts, bucking/chugging below 1500 rpm, dismal fuel mileage in stop and go, etc. Can they be driven on the street? Yes. Are they much fun to use a daily driver slugging through summer heat with the a/c on in bumper to bumper traffic -- most folks would say no.
One of the benefits of making big peak numbers with boost is that the bottom end torque characteristics can be preserved (even enhanced in properly sized turbo or positive displacement supercharger applications) so that good drivability is preserved.
Don't misunderstand - I'm not suggesting that very streetable and robust (peak power) packages can't be developed; clearly they can. But to say that the amount of power an engine makes doesn't determine drivability without any more specific context seems like an over-reaching generalization to me. Just my thoughts though....
Well, there's some subjectivity in the statement, but for naturally aspirated powerplants without the benefit of variable cam timing or variable intake geometry (most 5.0 variants), peak power levels have a big impact on drivability. The reason is that as peak power levels climb, the rpm at which the power occurs climbs too - and with it, the bottom end gets softer and softer. And even with 300-350 cubic inches, when you put something that peaks up in the 6500-7000 rpm range in something that weighs 3000-3500 lbs., the bottom end torque production (below 2500 rpm) often gets weak enough that they become a real pain in the butt as daily drivers. Lopey idles, high rpm clutch slipping starts, bucking/chugging below 1500 rpm, dismal fuel mileage in stop and go, etc. Can they be driven on the street? Yes. Are they much fun to use a daily driver slugging through summer heat with the a/c on in bumper to bumper traffic -- most folks would say no.
One of the benefits of making big peak numbers with boost is that the bottom end torque characteristics can be preserved (even enhanced in properly sized turbo or positive displacement supercharger applications) so that good drivability is preserved.
Don't misunderstand - I'm not suggesting that very streetable and robust (peak power) packages can't be developed; clearly they can. But to say that the amount of power an engine makes doesn't determine drivability without any more specific context seems like an over-reaching generalization to me. Just my thoughts though....
Legendary
Founding Member
Well I have gt-40 cast iron heads, b303 cam and the cobra intake and I always wanted to stroke to 331 but was afraid that I would be disappointed with the money spent-to-power ratio. Would I make decent power going to 331 staying N/A and pump gas?
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