306 vs 331

Slow5.0 · Sep 16, 2005

Here is a deal, i have plan build bottom end with 8.5:1 compression ( have boost in mind)
This motor will be used in my Stang whose summer, so it have to be streetable , i mean not high maitenance
I like to travel with my car so i don't need oil eater
I have talked with a few people about 306 vs 331 ,some says 306 some 331

So i was wandering what do you think which is better, get nice 306 kit or get 331 stroker kit

94GTLaserRC · Sep 16, 2005

I too have thought about this. If the price was significanly less for a new 302 or 306, I could see it....BUT, the cost is barely less. It's not like a 331 is unreliable. I dont see any reason to "upgrade" to a 306 from what you have. What are your power adder plans?

RC

bimmertech · Sep 16, 2005

i voted 306, but i also would only build a long rod 306. if you are not going with longer rods then a 331 would be my choice.

Redsnake2 · Sep 16, 2005

I like the 331 combo. Not like a 347 were you get alot of side load on the pistons and a 306 is a waste of time to me. A 302 bored out 30 over, if the engine is going to be rebuild and you have to spend the money go with the 331.
Feels like a 347 with a little less torque..

? Why 8:5 comp ratio? You only need that low a comp if you are running like 15 to 20lbs of boost. If your going supercharger 9:5 to 9:1 is cool for the street, but if you pick a turbo you can run 8:5 with adjustable boost.

Heres a secret, it was told to me by a racer like John Force.. The more compression you run the less boost you need and the less compression you run, the more boost you need...

Got it???

Killercanary · Sep 16, 2005

Ernan, the way I look at it you have a heavy car and it could us all the cubes you can get. There would be NO question in my mind on which route I'd take if it was me. As for the long rod 306 that was recommended, there has been more than enough discussion on the subject lately to steer me away from them. At one point in time I was all caught up in the increased dwell time, etc that was supposedly associated with a long rod combo, but there just isn't enough gain to show where its worth the extra cash. If you even concider this do a search on hardcore and even the corral as both places have had some LENGTHY and good discussions on the subject. I think after you read it all you will not even concider entertaining the idea of a long rod 306.

Go 331 is my recommendation.

blksn955.o · Sep 16, 2005

Killercanary said:
Ernan, the way I look at it you have a heavy car and it could us all the cubes you can get. There would be NO question in my mind on which route I'd take if it was me. As for the long rod 306 that was recommended, there has been more than enough discussion on the subject lately to steer me away from them. At one point in time I was all caught up in the increased dwell time, etc that was supposedly associated with a long rod combo, but there just isn't enough gain to show where its worth the extra cash. If you even concider this do a search on hardcore and even the corral as both places have had some LENGTHY and good discussions on the subject. I think after you read it all you will not even concider entertaining the idea of a long rod 306.

Go 331 is my recommendation.

I actually went threw this last year when I was buying my new shortblock. describes my thought to a tee I was dead set on getting a 306 long rod. Except I stayed with the 306 instead of 331. In the end I wanted a fun street car that had a good amount of power to work with the heads/intake/cam I already had. The reg. rod 306 filled my needs after doing research on the subject on here and hardcore. I honestly do not plan on going any faster with this car, than what it can do with what it has right now.

That said, go 331. It realy is not that more expensive like said and the extra cubes are worth it. You also have heads that would work well on a 331 already (not that the stuff I have wouldnt make power, just that I felt the better combo on my college budget was to go 306).

Slow5.0 · Sep 16, 2005

Well guys my plan is 8.5-9:1 compression (I like to go nuts,so just forsafety)

Call me stupid but i forget what long rod 306 means, i have asked this one guy before and he told me ,but i forger
All i know 347 makes too much crank pressure, and it wears a lot faster than 331/306

BTW my plan is using stock 302 bluck and make it stronger ,and my goal is 450-500 HP/TQ

Grn92LX · Sep 16, 2005

Slow5.0 said:
All i know 347 makes too much crank pressure, and it wears a lot faster than 331/306

Not true in any way, shape or form.

What type of power adder are you gonna use? I thought you had said once before you wanted turbo? I would not build a turbo h/c/i stroker engine out of a stock 302 block.

WhiteDevil · Sep 16, 2005

Grn92LX said:
Not true in any way, shape or form.

Yeah 347 isnt gonna wear out any faster than a 331 thats for damn sure.

bimmertech · Sep 16, 2005

a long rod 306 would use a 5.4 inch rod instead of a 5.09 inch rod. the only reason i would go with a long rod 306 is that i had a chevy 306 with 6 inch rods, solid cam, etc.. i loved the sound of that beast at 9k rpm's. i really like a high revving engine, hence long rod short stroke. as far as the benfits outweighing the cost, prolly not to you cuz you will never spin the daylights out of it due to your low compression. i don't know what the guys on corral or hardcore talk about cuz this is the only internet site i really chat on, but i would assume any bashing of a long rod 306 is unjust very much like the bashing of a 347.

blksn955.o · Sep 16, 2005

Hardcore is just that, people like Ed Curtis, alot of racers, the guy who owns or runs CHP. A bunch of very, very smart active people in the area of racing fords.

If your thinking of running a stroker and boost, get a aftermarket block. I would be worried even with one or the other (I am with my 306 and "150" shot with a stock block) so both.....

final5-0 · Sep 16, 2005

I also think the Hardcore site has many peeps with a good bit of knowledge about putting sbf motors together.

That site and many others have said the following things about a 347.

The oil probs of early 347 combos have not been an issue for years.

The rod ratio thing, like the oil probs, is just another one of those internet myths.

You can find those same rod ratios and worse in OEM motors that go over 100K miles.

No way would I go for a 302 stroker and stop at just 331. No reason to give up the 16 cubes.

Grady

Slow5.0 · Sep 16, 2005

And BTW this motor will never see more than 6300pms , so i have no plan with high rev motor

Grn92LX said:
Not true in any way, shape or form.

What type of power adder are you gonna use? I thought you had said once before you wanted turbo? I would not build a turbo h/c/i stroker engine out of a stock 302 block.

It won't be stock 302 block

Like i said 450-500 is my goal

95COBRA241 · Sep 16, 2005

If you are gonna build another motor bigger is better. If your 302 just needs a rebuild it'll end up a 306 when they clean up the bores anyway.

nmcgrawj · Sep 16, 2005

Slow5.0 said:
It won't be stock 302 block

Like i said 450-500 is my goal

450-500 rwhp? or 450-500 hp? What block do u plan on running?

I would stroke it...and if you still want more power and it will be SAFE, then run a couple pounds of boost from a turbo or something.

Like was said above, a stroker wont hurt you unless you make TOO much power. And it will only help you down low...man u need ALL the cubes you can get for that 4050 lbs!

bimmertech · Sep 16, 2005

i feel any stroke can effectively max out a stock block. since he is going to an aftermarket block, the poll should read--9.5" deck height or 8.2" deck height. would it be a debate then?

nmcgrawj · Sep 16, 2005

Well if u dont have to worry about the block at all...then why not stroke it?

donkey_punch · Sep 16, 2005

bigger is always better. but if your going turbo and looking for 450-500 hp. just put the turbo on it and a supporting fuel system. i don't see where the set-up you have + a turbo you can't see 450-500 hp.

and just so no one gets their panties in a bunch, the above statement is just my opinion

Killercanary · Sep 16, 2005

With a dart block you can otain a 347 cubic inch motor with a 331 stroker crank and rods and 4.1XX overbore pistons. My buddy Mike just did this with his dart block.

5spd GT · Sep 16, 2005

If money isn't an option go with the 331. In general it will cost another $500 bucks for the shortblock over a 306 (a bit more actually). Figure in the added price of a 28 oz flywheel and matching balancer.

A 347 will "burn" more oil over a 331 over prolonged period of time in a controlled enviroment. Increased cubes equals increased oil burning potential. It is minimized much more than "yesteryear" but you can't change the engine dynamics.

There is a reason why they make a 331. If the 347 had the same pros as the 331 with no side effects the 331 would not be made. It just wouldn't be practical in the enthuisiast market.

If your going for a blower the sidewall pressure will be greater with the 347...but a dart block could cure that...but it will also "cure" your wallet

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