The rod ratio, what do you think?

I'm looking at the 400->512 stroker kit from 440 Source. The con rod ratio is 1.537...
What do you think about using it for a street cruiser, occasionally doing some strip visits?
Engine is going to be strong at low and midrange, fuel is E85, static comp about 12:1, sequential fuel injection and ignition.
I'm mainly concerned about the con rod ratio...
Cheers,

I don't have the answer but maybe you can take your own conclusions reading here

http://victorylibrary.com/mopar/rod-tech-c.htm

I wouldn't care about the rod ratio. I would be more interested in looking at piston compression height.

I’d build it. I think the consensus is not to worry too much about the R/R on that particular combo. I believe the BB Chevy is somewhere close to that.

I believe that combo still uses a 1.32 (shelf) piston.

I like long rods, especially in stroker motors My original 512 400 stroker(now 518 C.I. with 4.300 stroke ) has 6.800 long CAT brand H beam BB Chevy type rods in it, going on 6 yrs of street and strip use My current 400 4.25 stroker has 6.700 long RPM brand BB Chevy type H beam forged steel rods in it, dyno time only so far The longer rods sure do make the pistons lightweight

That's a popular combo and seems favored for drag racing. It should do fine with some street use. Probably shouldn't expect 100k mile durability but I guess that doesn't matter much. It will need good breathing heads to handle the cubes and shorter rod ratio.

For reference I have the long rod/short piston cousin. 400 block, 4.15 stroke, 6.76 rod and short piston. 496 cubes. A lot of folks believe the short piston is a problem. I know mine is doing fine with 10k miles. Its set up for road race which I would like to do someday... I believe the longer rod ratio matters more when the engine is run hard for extended periods of time as it could be in road race. Not so much in drag race.

I hate to throw out Shivy info, but the 454 has 6.135" rods and a 4.00" stroke, and it seems to run OK. For a street engine, it might work better than a 1.9 rod/stroke ratio. I don't think people worry much about that anymore, it's light pistons and rods now.

Short rod ratio's will give better off idle torque. You alreay have that I bet !
Longer rods will reduce friction and wear.

The engine will be snapier with longer rods I bet.

If you plan on high rpm then go longer rods.

The engine will be snappier with the shorter rods.
For engine speeds 6500 rpm and below, shorter rods and larger ports seem to be the ticket to best average torque. Check out the Enginemasters series.

If you go back in the archives you will see that I was as rabid a long rod guy as there was. However, over the last 10 years or so I have come to understand that longer rods aren't necessarily better for a street engine.
For another example, the chevy HT383 is built by chevrolet with a 3.80" stroke and 5.7" rods. That's a R/S ratio of 1.50. This engine passed all the durability tests,which were quite frightening as I recall. They found that at 7000 rpm after hours of running, the connecting rod bolt heads would fail, so they built a new rod specifically for the HT that uses a capscrew. There was enough room in the engine to put in a 5.85" rod or even a 6" rod, they had the L99 rod which is powder metallurgy like what they ended up with and 5.94" long. But they chose to use the 5.7" rod and 1.50 ratio.

R.

The short rod ratio will be fine on the street. The longer rods would have more advantage at higher RPMs.

Many thanks for your comments, now I believe I can focus on other things than the con rod ratio!!!

longer means weaker but nobody ever brings that up.rod ratio in my opinion is old school mopar voodoo.the difference in the angle of a connecting rod in a 440 vs a 454 comes down to like a couple of degrees.

in engine masters before there was a compression limit guys were running like 13 to 1 on pump gas and doing it with a small bore long stroke short rod combo deliberately to pop the piston to the top of the bore and snap it down quikly to avoid detonation

Here is an interesting link about rod ratio and other theories from Reher-Morrison:
http://www.chevyhiperformance.com/tech/e...ps/viewall.html

Very good link and I have to say that none of the opinions expressed fly in the face of science.

R.

Worrying about rod ratio is like peeing in the ocean to raise the tide ...The rod connects the piston to the crank...that's all there is to it...

Quote:

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Worrying about rod ratio is like peeing in the ocean to raise the tide ...

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I just did that and look what happened to New Jersey!