I say thought exercise, but maybe someone here has access to all the engines and a dyno.
anyway, dad posed the question. (gm stuff because we are cheap)
Which is better? 262 V6 (4.3) or 265 V8 (4.3)?
I'm thinking the V6 because the lighter rotating assembly, and room for bigger valves means it could spin faster. Maybe.
Your thoughts?
*edit. but with the v8 you get more explosions per rotation... someone argue with me.
Assuming the same architecture, V6. If the stroke is the same, you have to have a larger bore on the 6, and that unshrouds valves for better breathing.
I don't know anything about those two particular engines, but if given free reign more cylinders with a shorter stroke is the path to greatness.
In reply to Appleseed :
In this example, 4.3 vs 4.3, the 6 has more bore and more stroke. And larger main journals, but the offset crank is a weak point. But the 8 gives a power stroke every 90* which has to count for something.
parker said:I don't know anything about those two particular engines, but if given free reign more cylinders with a shorter stroke is the path to greatness.
It's certainly the path to more rpm. Of course there's a million other engine specific factors to if you can actually make use of that rpm.
What's the bore-stroke relationship of each engine? Cylinder head design, what's the airflow? Lots of variables here. Which one is sturdier and can take more strain before going pop? I hesitate to answer without any facts to go on, but I'd guess the V6 just because it's more common and therefore a larger aftermarket may exist for it.
Didnt realize we were talking real engines. Derp.
Biggest deficiency with the 6 is the heads. They never, ever, had anything but garbage heads. They simply do not breathe. The original smallblock had the advantage of numerous, better head designs through the years.
I'd love to see what the 6 could do with LS style heads.
There is something to be said for the larger valves of the 6, but it is more than offset by the volume available through the extra two valves.
Speaking GM, more performance parts for the 8.
And the final vote, you can bolt 400 cubic inches or more right in the hole where the 265 was, and lie to people.
In reply to slowbird :
The aftermarket for the 4.3 is practically non-existent.
In reply to Appleseed :
Heh, goes to show how much GM knowledge I have. (none) 
Wow! I coulda had a V8!
The answer is V8. The V6 is an inherently imbalanced design that is the product of automakers' concerns for "packaging," not performance.
Now, an inline-6 vs. a V8 of equal displacement. That we could argue.
In reply to 1988RedT2 :
That is an argument he could have. Let's limit it to same displacement, same valve per cylinder, same valve train (ohv, sohc, dohc). At some point you have to consider a longer crank (v8 vs I6) is going to be heavier, same with the block. It's an interesting argument.
In reply to barefootskater :
Most of those 4.3 V6's have counter balance shafts to minimize vibration since they are 90 degree engines. That produces both first and 2nd order vibrations. The balance shafts eliminate the First order vibration.
The driving the counterbalance shafts costs about the same as the friction of the two extra cylinders.
60 degree V6 or 12's are naturally smoother.
since the 262. V8 has the same architecture as the 350 the minor weight difference tells you to go for the 350. With the added counterbalance shafts of the 4.3 the weight between a 4.3 and 5.7 is pretty minor.
Considering the available aluminum heads water pumps, and intake manifolds available for the 5.7 (350) again weight tells you to select the 350. Horsepower starts at 115 for the V8 Finally length. Surprisingly the longer water pump of the 4.3 requires very nearly the same space as a 350(5.7) with the short ( Corvette) water pump.
If speaking more generically, Ferrari played at similar in the 1950's with 6 and 12 cylinder engines for various formulas (sportscar and F1)
I think theres something to be said for the smaller cylinder size for controlling the flame front, but that does offset more moving parts. If you think about optimization with flame front time(bore), vs expansion time (stroke) and couple those with other variables in regard to displacement... As others point out, balance issues are another concern. A lot to be said if all other things equal (head design/architecture, internal engine packaging, etc)
I bet I could sit with Heywood (internal engine fundamentals engineering textbook) and pull out my old Diff-eq text and put something behind it, but I REALLY dont feel like it.
I bet someone has written and engineering term paper on it somewhere.
In reply to frenchyd :
Agreed, the 4.3 v6 is far from optimal on several fronts. I picked it because it is so close in displacement, and the architecture is as close to identical as possible with the very first small block.
Streetwiseguy said:There is something to be said for the larger valves of the 6, but it is more than offset by the volume available through the extra two valves.
I know nothing about the GM engines discussed, but in a theoretical sense with the same stroke, the available valve area would be the same.
The V8 would have more ring contact area (friction) and more cylinder wall area to lose heat to (bad for efficiency, but good for max power).
What's the definition of better? More power, better fuel economy, better drive ability, lower emissions, cheaper overall powertrain?
Kinda need to know what you are answering to.
In reply to alfadriver (Forum Supporter) :
Let's define better as a combination of power and longevity.
265 is better because a 400 bolts in the same spot.
Seriously, if you're thinking about putting a SBC in something, why use the small one?
If all you have room for is the V6, use the biggest V6.
In reply to barefootskater :
The early 283 ( or even 265 ) could be enlarged to around 331 cu in. Because they had smaller journals They tend to be about 20 pounds lighter but only the very rare 1957 Corvette had aluminum options. Since all 12 of those were recalled due to cracking ( they tried to use the cast Iron molds and found out Aluminum needs different considerations).
rumor has it not all of the Aluminum engines were turned in.
barefootskater said:In reply to alfadriver (Forum Supporter) :
Let's define better as a combination of power and longevity.
To me, that would be the V8. While there are two more pistons, given the shorter stroke and narrower bore, the mass of stuff rotating is actually less. Which then allows for higher engine speeds, which means you can optimize the flow at higher speeds- thus more power. And the increased speeds would actually be not worse in terms of durabilty.
There's still a prettty fine balance that one can make where the V6 is the better choice- with all of the P car vicories at LeMans, it would be interesting to see the win totals of V8's vs. V6s. And by V6, I mean a flat boxer 6- which is a very unique version of a V6. If it actually has to be a V, has there ever been an actual V6 engine that won the race? V8's have, V12's have, I6's have, I8's have, Flat boxer 6's have. The only time V6's dominated races on their own merit (not defined by the rules) was in the Turbo 1.5l era of F1 in the 80's.
And I do think racing is a good reference to get an idea of what configurations are best.
EDIT- quick googles- a 90deg V6 won in 1978 . So the V6 (not Boxer 6) has as many wins at Le Sarthe as the Rotary.
ShawnG said:265 is better because a 400 bolts in the same spot.
Seriously, if you're thinking about putting a SBC in something, why use the small one?
If all you have room for is the V6, use the biggest V6.
Actually the Chevy V8 will take up the same space as the V6. That's because the V6 uses the long water pump while the short water pump used in theV8 is far more compact.
ProDarwin said:Streetwiseguy said:There is something to be said for the larger valves of the 6, but it is more than offset by the volume available through the extra two valves.
I know nothing about the GM engines discussed, but in a theoretical sense with the same stroke, the available valve area would be the same.
The V8 would have more ring contact area (friction) and more cylinder wall area to lose heat to (bad for efficiency, but good for max power).
Haven't done the math, but would 8 1.75 inch valves not flow more than 6 1.94 inch valves? Plus, are we towing or racing? Smaller valves and ports would mean better low end velocity of the intake charge.
Pretty sure you can fit a 1.84" intake valve in a 265 bore
frenchyd said:ShawnG said:265 is better because a 400 bolts in the same spot.
Seriously, if you're thinking about putting a SBC in something, why use the small one?
If all you have room for is the V6, use the biggest V6.
Actually the Chevy V8 will take up the same space as the V6. That's because the V6 uses the long water pump while the short water pump used in theV8 is far more compact.
also most things that came with the v6 also came with the 4cyl.
You'll need to log in to post.
