331 vs 347

91LX_5L

Founding Member
May 13, 2002
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British Columbia
What would you take and why? Blown with a S-trim. Built to boost. AFR heads. Good cam that goes well with boost etc. In other words good parts built right.

What kinda power would I be seeing out of either? NA or with boost approx? I know its hard to estimate but a nicely done 331 or 347 is what im thinking.

Thanks :hail2:
 
It doesn't matter which you pick for boost. Both will work fine with a blower. Done right and it'll make a LOT of power. I never recommend putting set ups like this in a stock block. I either recommend putting a GOOD n/a combo together or get a good block. Mild blown strokers can work though. I would probably say 331 for this application ONLY because the 347 will make more power and no reason to go too go overboard in a stock block. My friends got a blown dart 347.

Assumming stock pulleys on your S trim, i'll say 550rwhp.

I would personally recommend building a n/a higher compression 347 as the smarter choice.
 
As of right now Im running a 347 on a stock block putting 310rwhp and 380rwtq I have a powerdyne blower im going to be adding this winter plus changing the set up around a lil.. But on the side im saving to buy a dart block and work off of that. Im looking for like 400rwhp with the stock setup. Im not going to push more out of the stock block i dont feel like having problems
 
sonicblue87lx said:
As of right now Im running a 347 on a stock block putting 310rwhp and 380rwtq I have a powerdyne blower im going to be adding this winter plus changing the set up around a lil.. But on the side im saving to buy a dart block and work off of that. Im looking for like 400rwhp with the stock setup. Im not going to push more out of the stock block i dont feel like having problems

That seems awfully low (numbers) for a 347...Is everything put together and tuned right?


Mike: We actually agreed on something :lol: and I wanted to restate what you said that on a Dart 347, power adders are fine.

In my case, You know (but starter of the thread doesnt) that I wanted a N/A 347. Since I already have the Vortech (and spent $700 to repair it) I just felt like taking it down to a 331, get a forged internals AFR long block, and put the Vortech back on it...I want a REALLY Safe tune with that...so Im looking at 500HP "only" and take it from there.

RC
 
The 69 block is one of the most sout after production 351 blocks. I'm not sure about the older 302 blocks. If you got one, you'd need the crank link bar lifters to make it roller capable. They're $400 or so.

You can run a 347 in a stock block just fine, I recommended 331 for your application b/c the 331 will make less power and theres no need to make extra power when your block is the weak link. Although you're still taxing the block with a h/c/i blown 331. Keep the rev's under 6000 and tune it safe. If it were a n/a set up, hands down 347.

Mike
 
94GTLaserRC said:
That seems awfully low (numbers) for a 347...Is everything put together and tuned right?


Mike: We actually agreed on something :lol: and I wanted to restate what you said that on a Dart 347, power adders are fine.

In my case, You know (but starter of the thread doesnt) that I wanted a N/A 347. Since I already have the Vortech (and spent $700 to repair it) I just felt like taking it down to a 331, get a forged internals AFR long block, and put the Vortech back on it...I want a REALLY Safe tune with that...so Im looking at 500HP "only" and take it from there.

RC

No it is not tuned. Ive been changing stuff around so much I didnt want to put the money down for a tune when i would have to retune the car.. Once my final setup is done ill have a tune for it with new numbers
 
Yeah the 331 will make just a bit less power and have less sidewall loading. I also believe they add extra "material" to the 347 pistons to counter this or atleast try. sirsureshot39 made 550rwhp I believe with his "little" 331 with a S trim. Yeah they can't be made fast:)
 
I say if your goin with the stock block then definatly a 331 but if your going with a 4bolt definatly go with a 347... with a dart block there is vitrually no chance of cracking the block unless your making insane power numbers! :nice: