[jcp123]

Can’t comment on BSFC stats since I don’t have them for that engine, but I will comment on getting a “big boy” transmission. I drove rigs with predominantly 10-speeds and they were strictly adequate behind the detroit diesels in the Freightliners we used - I always thought a 13 speed would be ideal for not making shift patterns too painful, but would be enough to cover some dead spots in the gearing. I always felt too wound up in 7th, but borderline lugging and no power in 8th at 35mph, for instance, ditto at 45 with 8th and 9th. The gears were technically close enough to work but any speed limits on the 5’s were in reality between gears, so a 13-speed would have been nice, and when they gave me a minty-fresh power unit with a 12-speed automated manual behind a basically identical DD15 power plant (550hp, 1650lb-ft, redline around 2000rpm) from my previous truck, I found it covered the power better than a 10-speed as well. But lacking a turbo I don’t know how to account for gearing on the IDI engine.

I low-key want an old heavy duty pickup with a smallish Detroit two stroke, though. A one-ton with a 3-53t and ten speed could get a LOT done.