I know we're focused here on power but if Pickles has any spare computing time can we get a chart showing where the dollars go for these mods as they relate to power? We know what Mag, Ripp and Prodigy cost. I spent $28k on the 6.4. Which of the FI kits puts the torque/dollar in the most efficient spot? I'm assuming there's nothing efficient about the cost of the hemi. Assume daily driving with a typical commute and weekend trail time.
Generalizations about hot pipes on turbo systems may not apply to the Prodigy system. The turbo is intentionally over-sized a bit for various reasons, so that it ends up not spooling much during typical cruising conditions. When the turbo is not spooled up and producing much boost, it's also not producing much waste heat beyond what a plain exhaust pipe would already do. If you're concerned about under-hood heat, then get the pipes ceramic coated. Also definitely put a turbo blanket on the hot-side of the turbo. The turbo kit also removes two sources of heat from under the hood: the catalytic converters. A new high-flow catalytic converter is included with the kit, and it's located about under the driver-side seat, underneath the vehicle (not in the engine compartment).Originally Posted by HahaJK
Off-road driving also does not spool up the turbo much in my experience. When I'm off road, I make use of gearing (4LO, low transmission gears) to keep RPMs up a bit in the mid-range area when I'm climbing stuff, which makes use of all the torque multiplication to keep engine load low, and throttle response good. Low engine load means low exhaust flow, which means minimal turbo spooling, and minimal extra heat from the turbo. The turbo itself, the wastegate, and some of the exhaust pipes are conveniently right behind the radiator fans and in airflow for cooling.
What "future problems" are you referring to?
Unfortunately, that still doesn't help me, because that's the stock automatic transmission. I currently have no way to model the behavior of an automatic, especially the torque multiplication of the torque converter whenever the converter is not locked up (which will especially affect the initial launch). I can only model behavior a manual transmission, so I'm limited to modeling a theoretical 6.4 Hemi with the Jeep's 6-speed manual (is that even a possible combination?). At least it's consistent for comparison to the rest of the power mods, which can definitely coexist with the stock manual transmission.
Not quote sure what you're asking for here. Could you be more specific?
I also still plan to make some more charts illustrating how each option can accelerate in more normal driving situations - not in the best transmission gear for max acceleration. This will allow you to compare, for example, how much acceleration potential is there at 50 mph in 5th gear, and how many gears would less powerful options need to downshift to get equivalent acceleration at the same speed. I can already tell you without any doubt that the Hemi will be the indisputable winner here, and will cause the Hemi to generally "feel" much more powerful in daily driving that all other options (including Prodigy), even if Prodigy's turbo actually makes more power and is capable of faster full-throttle acceleration.
Last edited by UselessPickles; 04-05-2015 at 10:17 PM.
BTW - my simulation based on dyno torque curve data has actually proven to produce realistic results for several vehicles already. My favorite example is a 2006 WRX STi. My brother bought one last year and was interested in using my simulation get some idea about how launching at different RPMs and different quickness of shifting gears might affect acceleration performance.
We found a stock dyno chart online, a measured coefficient of drag and frontal area, specs for transmission ratios, weight and tire size. Everything we needed.
First simulated run, launch hard at peak torque, assuming 0.5s shift times, and I got...
0-60mph: 4.9s
1/4 mile: 13.01s @ 104.4mph
One car website reported 4.9s 0-60, but no 1/4 mile time.
Another car website reported 4.5s 0-60, and 13.0 sec @ 103.5
Almost a perfect match to the reported 1/4 mile time, and a perfect match to one of the reported 0-60 mph times. But that quicker 4.5s 0-60 time from the other website was really bothering me. Which one was correct? 4.9 or 4.5? How could there be such a big difference? And what concerned me the most was that the website that had the 1/4 mile result that agreed with my simulation was the source of the 0-60 time that did NOT agree with my simulation! What have I done wrong!?!?!
Then I remembered that some car testers use a 1-foot roll-out (like a 1/4 mile race) for all acceleration-from-a-stop tests, including 0-60 mph tests. This produces quicker 0-60 results because there's a 1-foot head start before the timer starts. So back to the simulation to test this hypothesis...
Simulated 0-60 with 1-foot rollout: 4.57s
Much better!
I was then able to slightly tweak the launch RPMs and shift times, still within a reasonable range, and get results that even more perfectly matched the websites reported results.
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