For those running big strokers (>= 2.3L) with a low rod ratio (< 1.6), what have you seen in terms of long term, real world durability?

Obviously, rev capability is diminished for the big stokers but if it's > 100K miles between rebuilds, that's probably acceptable.

Love to hear some data points from those running the BC 2.6L on a 4G64, too.

If you could include your displacement (cc), rod ratio, mileage, and abuse level (subjective opinion on how hard you are on your motor, whether you race, etc.) that would be awesome.

Interestingly, the SRT-4 had 2429 cc & 1.495 rod ratio from the factory; the BC 2.6L is 255x cc, 1.47x rod ratio (I think).

Thanks!

 

That is interesting, the SRT does only rev to a little over 6k though?

 

Rod/stroke ratio is pretty much laughable for the average owner to even worry about. I used to have many in-depth arguments with my old shop boss about the benefits of having that close-to-perfect rod/stroke ratio, and more or less I started coming around to his way of thinking.

For a decent comparison, look at Honda's B16A motors, they had a near perfect r/s ratio (1.74 IIRC) while making 160hp from a 1.6 liter. Biggest downfall was lack of torque, around the 111ft/lb area @ 7000rpm, and made max hp @ 7600 to 7800 rpm. To look at the power curve pretty much showed how gutless it was, even though at 100hp per liter in n/a form was extremely good for the time and still is. In contrast, look at the B18c5 1.8 liter motors, almost 200hp in stock n/a form with a much lower r/s ratio (1.58). It made peak power output of 195hp @ 8000rpm and 135ft/lb @ 7500rpm.
Why then does the engine with the lower r/s ratio make power just as well in the high rpm range as the one that is closer to "perfect"? Because it doesn't hold much bearing on engines that are turning under a 10k redline IMHO. Balancing is more key to revving higher than r/s ratios that we're going to be running on stroked Evo motors, and I've done it personally with a stroked out Honda 1.8 liter going to 2.1 liters and still maintaining a 9800 rpm redline. And while I never ran that motor for 100k miles, it did last me a good solid 40k miles before I went to something different, and as far as I know is still running in the new owner's car.

That being said, I really don't see why r/s would affect longevity if the build-up was done to tight tolerances with proper balancing.

 

Wow - great perspective; thank you!

 

I believe that was accurate. And it vibrated like a bad washing machine on a spin cycle during its idle.