500+ ft/lbs from an IDI with non wastegate Banks? If my IDI is putting out 500+ ft/lbs my 460 which I believe to be in the neighborhood of 550 ft/lbs would have to be at 800+ ft/lbs solely by the butt-dyno comparison. Towing with my IDI feels about like towing with my old 351w... If I'm talking nicely, it gets the job done. In fairness the IDI gets double digit MPG towing which my 351w never did but my 460 does.
My cruise EGT is low (I think) with the Banks 2600 RPM at 65 MPH unloaded pushing 3 psi it's about 400*-500*. Bump that to 3000+ RPM at 75+ MPH and 8-10 psi and it's about 900*. With a load though the EGT gets high pretty quick.
Your first mistake is to let the butt dyno or "beliefs" even enter the conversation. Strap your 460 to a chassis dyno, get an average of three runs in the 1:1 gear, add 20-30% and you'll have an approximation of flywheel power output. 500-550 is not unreasonable to expect from a good non-stock 460 built right. Same goes for your diesel. Strap it to the dyno and you'll know. Anything less is just mechanical ************ ( : < ).
As I said, peak torque is extrememly difficult to get on a chassis dyno because you can't load most of them down to 14-1800 rpm to get the engine's highest peak rating. Usually, you are stuck with getting a torque reading at or near peak power at 3000 rpm. OK for comparing other rigs tested the same way but not for getting peak torque numbers.
As to the Banks rating, I have posted their
FLYWHEEL OUTPUT dyno graph a couple of times here (and again now). As I said, it's likely a best case scenario and it was taken from a brand new engine back in '86, but it was a real number (at least as much as any aftermarket mfrs. number can be called real). The graph for the 6.9L (which I couldn't find this time) is identical to the one they posted for the 7.3L a few years later.
What's wrong with non-wastegated turbos? They can make the same power/torque as a wastegated, but they generally do it only at a specific midrange rpm point. Wastegated turbos generally produce higher EGTs and higher drive pressures too, because they are smaller and get restrictive starting in the midrange, so while they offer a big increase in acceleration from a dead stop, under a constant towing load they are restricted on the drive side. Most people want that off-line snap and don't like waiting for the boost to come in, hence a general preference for the wastegated type. Doesn't necessarily make them "better" just more suited to the market desires.
My experience is that a more or less stock 460 (maybe dual exhaust and the funky carb replaced) and an aftermarket turbocharged 6.9L (pumps settings per the kit mfr. ) are a pretty even match in the performance department. Back in the early '90s, I had a neighbor with an '86 F250HD 4x4 that was nearly identical to mine except his was a 460 (bone stock). Mine had the Banks kit (not fair to compare an NA 6.9 to a 460). Both of us automatics with 4.10:1 axle ratios. Both of us towed trailers around 30 feet long. In a solo drag race, of course, he walked all over me. On a good day, he was happy to break into low double digits for solo mpg. I was never lower than 15 solo. Towing, we were more even performancewise. We were a bit competitive and eventually timed a trip to leave together. We both started off in Grand Junction, going east. Going over the Rockies to Denver, with approximately equal loads, yielded very similar performance. Sometimes he had an edge, sometimes I did. The biggest difference I noted was that if I lost speed (and boost) that took the engine out of the sweet spot, I had a LOT more trouble getting it back. He had at least 1500 more rpms to play with and could bounce back from the slowdowns much better/faster by revving up. The higher the altitude, the better my turbo diesel performed and the more his gasser wimped out. Nearing 10K feet, he couldn't keep up at all and the only thing that kept him in sight was that he could rev to the moon. We parted ways in Kansas or western Missouri, him going north and me south. His BEST mpg over the time we traveled together was 7.5 mpg and that was my WORST. Climbing the mountains, he claimed to be able to watch the fuel gauge go down!
Nothing wrong with gassers, especially the 460 which is one of my top-ten Ford engines. The gas vs diesel thing will always be hotly debated. The price premium between the two used to pay off better when diesel fuel was a LOT cheaper than gasoline but as gassers got better and better with fuel injection (power, performance and mpg) and diesel fuel got to costing 30-35 percent MORE than gasoline, the equation has tilted the other way. You can buy a LOT of gasoline for the $8000 price premium of a modern diesel pickup. I our truck's era, the $3000 difference was actually a bigger piece of the pie than it is today but diesel fuel was 30 percent less than gas and the gassers did so much worse per gallon. All this is why my newer truck is a gasser. It actually gets BETTER mpg than the old Ford, plus it drives nicer, is rated to tow and haul more and uses fuel that is 30 percent cheaper.
If your turbo diesel can't do better towing than a 351W, then I suspect something's wrong with it. Or the 351W was bilt-to-the-hilt.
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This is the first gen kit like I have.
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These are the second gen kit c1990, still non-wastegated. The Sidewinder was soon to appear and you can see the 6.2L Sidewinder kit depicted
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