Is this a fair radiator?

I mean, yes, that's accurate. You're only adding more heat when you're actually making the extra horsepower compared to stock.

But there's a couple things I think you're overlooking. First, all the extra horsepower is not added just at the peak. For a strong engine, that extra horsepower comes in before the old factory peak. For example, a stock '71 340 was rated at 275 hp @5,000 rpm and 340 ft/lbs of torque at 3,200. Let's take goldduster318's 340 and compare. I'm using him as an example because he has a non-stroked 340 he posted dyno info for. His 340 dynoed at 470 hp @ 5,800 and 455 ft/lbs at 4,400 rpm. So lots higher, but higher peaks too. But that 340 is making 275hp at only 3,369 rpm. That's not maxed out on the drag strip rpm. That's everyday driving. Heck that was everyday on the freeway for me before I added the T56, I was frequently running at 3,500 rpm for extended periods. And torque? Well, the lowest recorded torque for that engine is 408 ft/lbs at 2,940. So it's pretty much always making more torque than the stock 340 ever did. That's heat too.

So yes, you're only adding more heat when you're actually making the power, that's true. But you don't have to be redlined at the SilverState Classic to be making that extra power and therefore that extra heat. With a strong engine, a stroker, etc, you could be adding more heat under everyday conditions. Thanks to @goldduster318 for posting his dyno info. MRL Performance 340, WOW!


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I would add that this engine runs extremely cool all the time, I have the 26" Champion 3 row and Contour Fans and a 180 Thermostat. The High speed did not even come on during the Woodward Dream Cruise on a nearly 90 degree day, and that's a parking lot. I can't take the heat before the engine gets even worry some. The High would kick on in my case at 205 degrees. It's not going to hurt the engine whatsoever. I'd have to check my datalogs again but the car runs down the road at 182-187 degrees most of the time in any weather condition which is totally fine for a 180 thermostat. For all I know that could be the error in the sending unit or calibration.

I would argue also that the 340 in it's current state is significantly more energy efficient than an original one. Before I installed the T56 magnum it got the same fuel mileage as the original 318-2bbl with a 750 Double Pumper, a little better than that with the EFI, and much better with the OD.