331 vs 347

[89CopCoupe]

I care about money more than power And I REFUSE to EVER put a cowl hood on my car. I would have needed one to run the right efi intake on a 408. Believe me, I considered it, then I realized a 347 was my only real bet.

Mike

Well, I'll have to make the drive out to NY so my 331 can put the spank on your 347

Joe

 

[Grn92LX]

Lets do it!!

Whats your combo by the way? I didn't know you had a 331.

 

[89CopCoupe]

Lets do it!!

Whats your combo by the way? I didn't know you had a 331.

It's a quick street combo:
'89 low option ex-SSP notch
3062lb with me
DSS 331 (5.315) lvl 20
AFR185's 58cc
XE266HR w/1.6s
RPMII
Edel 70tb
75maf w/ CAI
30#/190lph
FRPP A/C Delete
130amp
MSD ignition
FRPP ceramics/Magna catted mid and catback
All tree-friendly stuff
DF Centerforce
T5Z
FRPP alum driveline
3.55 trak
Steeda FL SFC and STB
Steeda alum u/lca
Steeda Superlite springs w/ alum CC
Plus other misc. including a bottle, but maybe not

 

[_jb_]

My 347 with the 5.315" rods has the same "extra meat" as the 331 because I use 331 pistons Its the same part # if you look on coasthigh.com.


If you were gonna sell the 165's for different afr's get 205's. Even though the 165's are a bit small, they'll still make good power especially with a charger. To make a small head make big power, you'll need a good custom cam as valve timing will be critical.

I'd do at least a 347 since its a dart block. 3.40 stroke for sure, you pick the bore size.

Won't 205s be to big?

 

[MeanMussy]

the 165s will be fine on that motor. your power will come on a little sooner, and you'll loose a little more on the top end vs. the 185s, but you'll be fine.

The 331 will have a slightly better rod ration vs. the 347 (reduced side loading). I believe the 331 ratio is as close to the stock 302 ratio as you can get w/ a stroker. but unless you are really worried about side loading, I wouldn't let it change your preference.

Generally speaking, the 331s will rev a little higher, and the 347s will make a little more low end TQ.

But, in the broad view of things, they're the same motor. If you're looking for a brute force build up, go w/ the extra cubes. If you want to get nick picky about it, do your research and pick the mill that best fits your objectives for the motor.

 

[MeanMussy]

Won't 205s be to big?

205s will let it scream up top.. but it will make it a little more gutless in the first couple thousand rpms vs. the higher air velocities of the smaller heads.

 

[Grn92LX]

Won't 205s be to big?

For a supercharged dart block stroker, no.

Generally speaking, the 331s will rev a little higher, and the 347s will make a little more low end TQ.

Not true at all. The parts you choose for your stroker engine are what ALLOW it to rev. Case in point, look at my 347 and copcoupes 331. Mine will rev higher. Probably easily 1000 rpm's of useable power. Why? Well, because I CHOSE parts to allow me to make power up top and rev where as he chose a milder camshaft. His will probably make better power under 2500. My cam is designed with a 3200-6400 rpm band (which is what I wanted). Figure a 6600 or so shift point for optimal track times.

 

[MeanMussy]

"generally speaking"... as in, this is not ALWAYS the case

 

[89CopCoupe]

A big factor in turning high r's is keeping the valvetrain operating effectively at higher engine speeds ... a valvetrain that stays in check will keep the bottom end held together better ... floating valves or improper detonation will destroy the rotating assembly. Based on this a 347 and 331 are equal participants.

The use of a longer rod helps to negate side loads on all rotating assembly pieces as well. Also a crank with a shorter throw will experience less stress. Based on these factors a 331 can be built to spin more rpms than a 347 when confined within a 8.2" deck height block.