this is what im looking at for my 351w topend

olerodder,
What I'm about to say in no way is meant in any disrespectful way so please don't take it the wrong way. But... this way of thinking is old school, and what I mean by that is everybody used to think that way when comparing a 302 to a 351. Nowadays the 347 and 302 are vast different engines and you really cannot compare them. You're treating the two engines in your theoretical build very differently when they are actually very close in cubic inches. You automatically assume the 351 has more torque when the stroke is only .010" longer. The 351 will end up at around what, 357 with the overbore? That's not much of a difference to "take advantage of" (10ci).

You only use a 650 on a 347 which absolutley can use a 750 or more all day long, and you put a bigger cam and 3/4" headers on the 351 and not the 347 which puts the 347 at a disadvantage. All these things you're doing to the 351 are things the 347 can use equally as much. All this because you're assuming the 351 has more torque. I don't get it.

Plus the horsepower numbers are just that... numbers. We all know we don't race dyno's. The real test will be on the track where the reduced weight of the rotating and reciprocating assembly of the 347 will be a real advantage in accelerating. Those things you cannot see on a dyno.

Right now I just feel bad for the op for hi-jacking his thread.

 

I must have missed something; you are talking a 302 bored to 347 and minimum bore of a 351 as a comparison? If you bore the 302 and 351 to .030/.040 respectively, where does that leave you in cubes, potential hp/trq numbers between the two? :confused:

I'm thinking vast difference... As I said, I may have misinterpreted...

 

Sorry it took so long to get back, but the front and rear discs are giving me more trouble than they are worth.

No disrespect taken, everyone one has their own ideas and mine come from a few years drag racing SS classes when they were really Super Stock type cars.
I agree that my thinking is a little "Ole School", but I'm an old guy.
Ok, I don't want to take this off track much more, but I believe the 357ci motor will have more torque than the 347ci motor.
There are some little things that come into play here, one being piston speed and the other actual rod length/rod ratio. The 347 has a 5.40 rod length and the 351 has a 5.95 rod length, the rod ratio for the 347 is 1:59 and for the 357 it is 1.7. I know there is a lot of discussion on rod length and is shorter better or longer better........anyway I agree with what you are saying and if you would like to discuss this further we can start a new thread.
I am only going by personal experience and have used chassis dynos and engine dynos for various reasons..................and you are right, the real world is not on a dyno...........but a dyno can give you a huge head start to hitting the track/street running. The figures I quoted earlier did not come from any desk top dyno or some website, just my own guess from what I've done or seen in the past.
One last thing....................although this was a nice exercise, I think a 347 stroker and a stock 351 is just not practicle because you will spend the same amount of money on a 347 stroker kit for a 302 block as you will for a 393 stroker kit for 351w...................IMHO

 

Nah, "experienced mechanic" would better suite you considering I had just started Kindergarten in 1969... We need you guys!

 

Just so you know... I thoroughly enjoyed this discussion. Thank you!

 

I've enjoyed reading it. It's interesting when people can hold a gentlemanly debate without resorting to playground nonsense.

 

Thanks faceless! Hey ole rodder at least we can provide the entertainment huh bud!

 

I viewed this as education.

 

That's so cool you guys enjoyed it as much as I did. Not the end all but it gives everybody something to think about and some information to use in making their own decisions and not have "some guy on the Internet" tell you what's best engine.

 

John,

I enjoyed the discussion also, and glad everyone else did.
I hope you don't mind me calling you John.

 

Why would I mind if you called me by my name??? LOL! Trust me people have called me worse!

 

Given that condescending self-righteousness......what the hell....I could use another "profile infraction." You have zero idea who you're talking to, Slick. Pretty sure I've forgotten more "facts" about building these things than you'll ever know.

You are contradicting yourself in one sentence or you're deliberately attempting to slant things in your favor. A 347 is a bored and stroked 302. A 351 is a stock bore and stroke. "Similarly built" would mean a 408" engine. So would you like to compare apples to apples or continue to compare apples to car wax while trying to make yourself sound exceedingly brilliant?

Are you a Democrat? You single-handedly listed your own opinion of the 351's drawbacks while not once showing the 351's advantages nor the pros/cons of the 347.

Despite the heavier rotating assembly the 408" (since we're talking "similarly built" engines) will simply produce more torque per cubic inch than the 347" will make. Torque moves the car downtrack. Given airflow equivalent to each engine's cubic inches the 408 is a deep breather with much more draw through the cylinder heads.

Now, if you insist on comparing (unfairly) your 347 to a 351 all you have to do is keep in mind that that longer connecting rod will produce much more draw through the cylinder heads than the 347's 5.400" rod. More draw=more airflow; more airflow=more hp potential and torque. As mentioned previously, torque moves the car downtrack. Despite a heavier engine package the abundant torque will result in a quicker car. A 347 will not produce torque numbers near those of even a stock stroke 351. As long as both engines have adequate cylinder heads capable of feeding their respective cubic inch sizes the 351 will produce more torque and will be quicker going downtrack.

If you'd care to get into more precise numbers I'll be happy to prove you wrong in greater detail.

 

Thanks for clarifying my earlier question.

 

How is 60 cubic inch difference and a much longer stroke similar? I already said the 408 would have the advantage over a 347. The original poster said he was building a 351 so that and the fact that the 8.2 deck engine fits the car better is the reason for the comparison. You have your opinions and I have mine which is the 347 will rpm quicker due to the lighter components regardless of the possibility of a slight difference in torque. I won't continue to argue out of respect to the op. There is enough info here for people to use to draw their own opinion or make a decision. And I said all of that without being rude once. Shadowmaster I sent you a PM.

 

I don't care how quickly you accelerate a 3.400"/5.400" combination. Engine acceleration builds horsepower.....not torque. Besides, the difference in crankshafts is only 10 lbs. The 3.500"/5.95" combination will make more torque. Period. It will also move more air through the cylinder heads which builds more power (remember...air pump....more air in/out = more power). It also produces more piston dwell which builds more cylinder pressure than the 347 given equal compression ratios.

You can keep preaching that 347 stuff all day long. In the end you're only saving grace will be that the 8.2 deck engine fits the car easier. That's it. I've built more of both combinations than I care to count. In the car going down the track the 351 combo will be quicker & faster.