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so you can put a 3.4 in. crank in an 8.2 inch deckheight stock 302 block and have a better piston to rod ratio than a 3.5 in. crank in a 9.5 inch 351 block?
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so you can put a 3.4 in. crank in an 8.2 inch deckheight stock 302 block and have a better piston to rod ratio than a 3.5 in. crank in a 9.5 inch 351 block?
What is a "better" R:S ratio? ...... .... what is the importance of the R:S ratio? Does it take any precedence over the weight of the rotating assy. in the acceleration department? .... Would it markedly make a difference in reliability and endurance? The OEM cases mentioned previously, are typical examples how that generalization does not apply:
347: 5.4 rod 3.4 stroke = 1.59 R:S
347: 5.315 rod 3.4 stroke = 1.56 R:S
OEM
3TC: 123mm rod 78mm stroke = 1.57 R:S
300 I6: 6.210 rod 3.980 stroke = 1.56 R:S
454 BBC: 6.135 rod 4.00 stroke = 1.53 R:S
__________________ ACRONYMS:
LUK=Let Us Know, GL=Good Luck, LMK=Let Me Know, JIC=Just In Case, BTSTDTRT=Been There Seen That Done That Repaired That, YCYDYP=Your Car Your Dough Your Prerogative and the classic... DILLIGAS=Do I Look Like I Give A S***
1986 GT-X303-289 heads-1.72 rockers-RG 4+1 Trans.
Quote:
Originally Posted by Joel5.0
Great thoughts will overwhelm a feeble mind.
There is never money to do it right, but there's always money to do it over.
The proof of understanding is the ability to explain it. (H. Torruella)
see this is where I am out of the loop. They must of done something to reduce friction of the 347. I have read many tech articles and heard from many mechanics how a 347 side loads the block and reduces horsepower.
I would go for a 351 over a 347 anyday. Rebuilding purposes for one. I may be fine with a 500 horse motor this time but, next time I may want more.
Might as well already have the block.
Since Joel already explained it all, all I'm going to say is: FAIL.
__________________
89 LX Coupe: Factory 5.0, common performance and suspension bolt-ons (306 build inprogress)
86 GT: (current 1/4 project) will have primarily Team Z suspension and chassis additions, 408 with nitrous in the works
2003 Mach 1: programer, exhaust, 4.10'
I would trust a 331 as far as reliability and durability at 500 hp to wheels more than I would a 347. Look at how much friction is going to be lost by running the same rod length with a 3.4 crank vs. a 3.25 crank. Less friction in a 331 is going to give more hp.
Now I understand that an engine isn't anything more than an air pump. The more air it takes in and gets out the more power it makes. The 347 obviously wins in that department. It is hard to believe though that DSS told my friend a myth when they sold him the 12:5:1 331 motor over the 347 for the reason of hp would be better in his lighter car and it would last longer. ya know?
I would trust a 331 as far as reliability and durability at 500 hp to wheels more than I would a 347. Look at how much friction is going to be lost by running the same rod length with a 3.4 crank vs. a 3.25 crank. Less friction in a 331 is going to give more hp.
Now I understand that an engine isn't anything more than an air pump. The more air it takes in and gets out the more power it makes. The 347 obviously wins in that department. It is hard to believe though that DSS told my friend a myth when they sold him the 12:5:1 331 motor over the 347 for the reason of hp would be better in his lighter car and it would last longer. ya know?
How much friction that is? How does it convert into a reliability problem? If a 347 is obviously a "bigger air pump" than a 331, how does that "friction increase" nullify its horsepower potential? Why did the 331 example shown below, needed some NOS to barely win over the N/A 347?
Why did DSS told your friend a myth to sell him a 331 over a 347? .... overstocking of 331's? .... The fact that "DSS said it".... doesn't mean it's less of a myth.
__________________ ACRONYMS:
LUK=Let Us Know, GL=Good Luck, LMK=Let Me Know, JIC=Just In Case, BTSTDTRT=Been There Seen That Done That Repaired That, YCYDYP=Your Car Your Dough Your Prerogative and the classic... DILLIGAS=Do I Look Like I Give A S***
1986 GT-X303-289 heads-1.72 rockers-RG 4+1 Trans.
Quote:
Originally Posted by Joel5.0
Great thoughts will overwhelm a feeble mind.
There is never money to do it right, but there's always money to do it over.
The proof of understanding is the ability to explain it. (H. Torruella)
The 2 primary magazine mail order short block companies are DSS and CHP. To compete with CHP's 347 (CHP's biggest seller) DSS pushed the 331 as a better engine based off of rod/stroke ratio and got alot of people to believe in the myth.
If you go back about 8 years and look at both companies adds you will see CHP primarily sold 347's, you could get a 331 from CHP but for a substantial increase in cost, DSS primarily sold 331's, you could get a 347 from DSS for a substantial increase in cost. It's marketing.
__________________
89 LX Coupe: Factory 5.0, common performance and suspension bolt-ons (306 build inprogress)
86 GT: (current 1/4 project) will have primarily Team Z suspension and chassis additions, 408 with nitrous in the works
2003 Mach 1: programer, exhaust, 4.10'
that gray car was pulling away at the end and it looked like he let out of it like it was a time dialed in. I can't tell which one is which but, the grey one claimed a 10.83 @ 127 the week before.
The 2 primary magazine mail order short block companies are DSS and CHP. To compete with CHP's 347 (CHP's biggest seller) DSS pushed the 331 as a better engine based off of rod/stroke ratio and got alot of people to believe in the myth.
If you go back about 8 years and look at both companies adds you will see CHP primarily sold 347's, you could get a 331 from CHP but for a substantial increase in cost, DSS primarily sold 331's, you could get a 347 from DSS for a substantial increase in cost. It's marketing.
you know, I don't really doubt that at all. I read that in a magazine about that long ago.
I thought I read it in the one that had the 331 ways to outrun an ls1. I looked it up on the internet and didn't see it in the article. If I can find that magazine, I am going to see if it is a different write-up for the article. I know it was somewhere between 2002 and 2004. I built my 393 in 05 and quit buying magazines.
They did claim the 30 or 40 horse over the 20 lbs of torque.
Here you go, here's the generalization article that started spreading all that myth........ to the "T"....
The addition of the "In some extreme cases, the poor rod ratio can even collapse cylinder walls as it side loads the piston in the cylinder really hard." comment really tops it all. I guess that doesn't apply to 351w strokers?..... or to Toyota 3TC engines running turbo with NOS for years?.... like the one used by the owner of the machine shop I take my business to..... = http://agracingvideo.com/p/videos/ponce/19feb09/15.wmv
Not bad for a setup overly side-loading those cylinders, causing a lot of friction + forced induction + NOS..... for years on a stock block.....
__________________ ACRONYMS:
LUK=Let Us Know, GL=Good Luck, LMK=Let Me Know, JIC=Just In Case, BTSTDTRT=Been There Seen That Done That Repaired That, YCYDYP=Your Car Your Dough Your Prerogative and the classic... DILLIGAS=Do I Look Like I Give A S***
1986 GT-X303-289 heads-1.72 rockers-RG 4+1 Trans.
Quote:
Originally Posted by Joel5.0
Great thoughts will overwhelm a feeble mind.
There is never money to do it right, but there's always money to do it over.
The proof of understanding is the ability to explain it. (H. Torruella)
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.... what is the importance of the R:S ratio? Does it take any precedence over the weight of the rotating assy. in the acceleration department? ....
Would it markedly make a difference in reliability and endurance? The OEM cases mentioned previously, are typical examples how that generalization does not apply:
.... overstocking of 331's? .... The fact that "DSS said it".... doesn't mean it's less of a myth.
