Originally Posted by UselessPickles
I read your statements. You're once again making too many assumptions based on too little data. You've derived this figure of 30-33% loss due to drive train without actually having any really good baseline information about the Pentastar Engine that I can see. You're seeing Wheel HP figures and attempting to working backwards to a Flywheel/Brake HP figure without having enough data about the engine. I've not seen one add on kit that talks about BHP and not WHP... In fact all of them state the fact that they only test on chassis dynos.. Which sort of makes me wonder what they are trying to fudge with the for marketing purposes. People will say "Oh Wow... It is has to be so much more at the flywheel..." and purchase this kit. And they don't take the engines out and really dyno them.
If you want to really find out how much your engine is loosing between transmission, transfer case, axles and so on you have to take the engine out and dyno it and find out what sort of power you're getting. And then if you want to talk about Jeeps in general you have to get a very respectable sampling size of all the possible combinations from the factory so you can say okay -- Engines alone had this tolerance in power +/- over the stated horsepower, then hook it up to the transmission and dyno that combination and that will give you the ability to see what the power loss is in that combination, then you can check out the axle ratio combinations. Then you can build a baseline and come up with same average performance numbers and say okay-- this what A JKU with 3.6L V6 and 6spd Manual with 4.10's averages out to or model x , z, y... and then you say okay lets play with this variable or that one. Right now all your data is vehicle specific and it is way too general to even make any meaningful conclusions about performance extending past a few controlled variables.
For example if this AEV kit makes 400Hp at it sees a 27% loss in power it is down to 292WHP ... I'm skeptical that you will see the types of losses you claim the wrangler is seeing. For example if the Ripp system creates 325 hp at the rear wheels and that is after it has lost a 1/3 of it's power that means it must have well over 400hp at the crankshaft! They want you to believe that you making what nearly 200hp extra at the crankshaft with a bolt on turbo kit and not affecting the compression ratio and so on. I could see a 125-136hp at the crank shaft and loss of about 30-40hp through the drive train at best.
I think you've done a lot of hard work but the problem is you need more data still to make any really interesting conclusions beyond that of your vehicle.
The next person to do a V8 conversion should look into NRE-- they are the real deal. A NA 454cid engine that makes 625hp and 580ft-lbs of torque on Pump gas is pretty amazing for a daily driver engine.
http://www.nelsonracingengines.com/p..._454bbc_na.pdf
I have not discussed at any point or attempted the idea of calculating bhp for any of the mods. Torque at the wheel is what matters, is what the dyno charts provide, and is what I use.
We know the SAE ratings for bhp for the stock engines. Pentastar is 285 bhp. JeepLabs stock dyno shows 190 whp. That's a 33% loss from bhp to whp. If the SAE rating is not a solid enough baseline bhp for you, then that's not my problem.
Again, all this talk of drivetrain loss was just to get an estimation of torque at the wheels for the 6.4 Hemi Wrangler in the absence of a dyno chart for this vehicle, to get some better estimations of how it performs compared to the superchargers rather than pure speculation based on hunches. Take it for what it is, ignore it if you think it's garbage, I really don't care. I hope we can get a dyno chart soon so I can update my model of the 6.4 Hemi Wrangler with actual measured torque at the wheels.
Keep in mind, these numbers are with 3.21 geared 2 door wranglers. (probably).
Stripped down to bare bones.
real jeeps dont do those times.
Pickles turbo might. Thats a soft top 2 door right? What do you say pickles, can you do a 4.8 0-60?
Yes, if you read one of my first posts in this thread, I lay out the exact conditions/assumptions. I based it on my Jeep (base model 2-door sport, manual trans, soft top, 3.21 gears, stock 29" tires, etc). I wouldn't say it's "stripped down", because I haven't removed anything. I'm even using a vehicle weight that includes a full tank of gas.
I also pointed out that it's not the exact numbers/times/results that are important here, but the relative differences. It gives a good indication of how each power mod performs compared to each other, all else being exactly equal (a comparison that is not likely to ever happen in the real world because of the huge variety in vehicle configurations for Jeeps).
I could re-run all the simulations with heavier Jeeps with bigger tires and different axle gearing, but that's a lot of work and I'm lazy :-p
I used the configuration of my Jeep because... well, that's how my Jeep is, so that's what I'm most interested in. I may be self-centered, but at least I'm sharing my findings
I'll take my Jeep to a drag strip this summer to see how close I can get to the 0-60 mph and 1/4 mile predictions from my simulation.
BTW - You hurt my Jeep's feelings by implying it's not a "real" Jeep. It gets around off road just fine for my purposes:
SAE rating is not written in stone. SAE is just a set of standards for measuring-- those measurements will still have a tolerance. You're jeep is built to SAE standard inch pattern tolerances and guess what not every Jeep is exactly the same. So, your point shows me you've never worked with any manufacturing process otherwise you would know just as I do that advertised power or torque is often less than or greater than what you get out of an engine. Because of various factors found within the manufacturing process.
I don't think what you're doing is garbage. I just think you need to realize that when you take into account all the possible areas for margin of error in the process you will find that 33% drivetrain loss is pretty high. Usually, most studies show less loss than that in a drive train.
I didnt mean your jeep wasnt a real Jeep. I mean that when the power mod companies give out those numbers, its not an unlimited rubicon they are using.Yes, if you read one of my first posts in this thread, I lay out the exact conditions/assumptions. I based it on my Jeep (base model 2-door sport, manual trans, soft top, 3.21 gears, stock 29" tires, etc). I wouldn't say it's "stripped down", because I haven't removed anything. I'm even using a vehicle weight that includes a full tank of gas.
I also pointed out that it's not the exact numbers/times/results that are important here, but the relative differences. It gives a good indication of how each power mod performs compared to each other, all else being exactly equal (a comparison that is not likely to ever happen in the real world because of the huge variety in vehicle configurations for Jeeps).
I could re-run all the simulations with heavier Jeeps with bigger tires and different axle gearing, but that's a lot of work and I'm lazy :-p
I used the configuration of my Jeep because... well, that's how my Jeep is, so that's what I'm most interested in. I may be self-centered, but at least I'm sharing my findings
I'll take my Jeep to a drag strip this summer to see how close I can get to the 0-60 mph and 1/4 mile predictions from my simulation.
BTW - You hurt my Jeep's feelings by implying it's not a "real" Jeep. It gets around off road just fine for my purposes:
They are using the lighest possible jeep configuration. Wich almost all of us do not have. Got a hard top? those are not your numbers anymore. Got a 4 door? those are not your numbers anymore. Aggressive gearing? Not your numbers anymore.
Your jeep is plenty real. REAL FAST.
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).
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.
I think you're missing the point of all of this. I am well aware of manufacturing tolerances. The goal here is NOT to perfectly simulate one specific vehicle with its own specific combinations of variations within tolerances. That would be ridiculously complicated.
The goal is to get a general comparison of potential between the different power mods. Just like when comparing dyno charts, it must be taken with a grain of salt with the understanding that there are margins of error. I cannot possibly actually take into account all margins of error in my calculations to produce a "range" of possible results. The best I can do is acknowledge that there are margins of error. I have provided full disclosure on where I got my data, what assumptions were made, etc. It is up to you, the viewer, to take this all into consideration when viewing the results and realize that the results are not perfect, but are at least good enough to identify larger scale differences and trends.
Maybe we're just talking completely different languages. When I say "drivetrain loss", I am specifically referring to what is is commonly called "drivetrain loss" among automotive enthusiasts, which is a representation of the difference between manufacturer claimed crank hp numbers, and whp numbers as measured by a chassis dyno during an dynamic acceleration sweep through the rpm range.
By this definition, you cannot possibly tell me that 33% is not correct for the Wrangler, because that is exactly what multiple sources have found to be the difference between the manufacturer's claimed crank hp for the Pentastar in the Wrangler (285 bhp) and the measured whp on a dyno (~190 whp). 190 is 33% less than 285. This is not debatable.
You may be talking about steady-state drivetrain loss, which is the amount of drivetrain loss while maintaining a steady speed. As I described in an earlier post already, this completely removes the drivetrain lost due to moment of inertia because there is no acceleration occurring. This leads to dyno results that are much higher, and therefore drivetrain loss amounts/percentages that are much lower. However, this is not a realistic result for analyzing how quickly a vehicle might be able to accelerate, because in order to accelerate the vehicle, you must accelerate the drivetrain, which will cause additional drivetrain loss due to moment of inertia of drivetrain components resisting rotational acceleration. Steady-state drivetrain loss is most useful for analyzing a vehicle's steady state cruising efficiency.
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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