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  1. #31

    SC vs. HEMI - Let the TRASH talk begin!

    Pickles. (Friendly trash talk coming) I just have to ask a question on your data. Do you really weigh 140 lbs.? Every time I read through the posts and replies I see all the discussion about this and that data point and assumptions. And I keep saying to myself does anyone else notice he weighs 140lbs.?

    On a serious note. When I put Cherry Bomb (getting used to the name) on the dyno should I ask for specific data or output in a specific format/file type for you?

  2. #32
    Yes, I really am a 140 lbs, 6-foot tall pole. If I turn sideways, you might not be able to see me

    When you put your Cherry Bomb on a dyno, try to use a shop that has the same type of Dynojet dyno that JeepLab has already used for stock, RIPP and Magnuson (harass Ross, aka "JeepLab", for details).

    Also, ask them to email the dyno run files to you. Not an image of the graph, not a scanned copy of a printout of the graph. The actual raw run file from the dyno software. This file can be viewed with Dynojet's WinPEP 7 Dyno Run Viewer program, which can be found here: https://www.dynojet.com/Downloads/So...Firmware-Other. It lets you zoom around, pick different display options, print out your own graphs, etc.

    More importantly, the dyno run viewer program can export the raw data at 100 rpm intervals in a format that I can easily load into my simulation, rather than requiring me to take measurements from an image of the graph.

  3. #33
    Quote Originally Posted by UselessPickles View Post
    When you put your Cherry Bomb on a dyno, try to use a shop that has the same type of Dynojet dyno that JeepLab has already used for stock, RIPP and Magnuson (harass Ross, aka "JeepLab", for details).
    The dyno we're thinking of is here in NJ not far from me and is the same dyno that Sweat Pea went on with the Mag S/C. I'll print your post and press them to release the files in your desired format. Importing is much easier than trying to read from of a crocked scan!

  4. #34
    I figured I should also make a power chart to go along with the torque chart. Here's both charts together for your convenience. I also updated my first post in this thread to add the power chart.

    click for full size


    click for full size

  5. #35
    Time for some data that can really help you understand how each of these mods might affect more realistic/common daily driving situations. I already showed how each power mod does at maximum acceleration through all the gears. Here's a refresher:

    click for full size



    That's all well and good, but it's missing the full picture of how each one can accelerate throughout the entirety of 2nd through 6th gears. You probably want to be able to see how much potential acceleration you might have at the ready in 6th gear while driving 70mph to have a good idea of how well you'll be able to manage hills or adjustments to speed without downshifting. So I created an acceleration chart for each of 2nd through 6th gears, showing the entire rpm range of each gear.

    After the charts, I'll provide some examples of interesting comparisons you can do by cross-referencing between these charts.

    **** BEFORE YOU LOOK AT THE CHARTS AND DRAW CONCLUSIONS ****

    Some things to keep in mind:
    • These dyno charts all started around 2000 rpm, so I obviously can't show you how the Jeep would accelerate in 5th gear at 1500 rpm, for example. This is why you'll see the charts starting at fairly high road speeds in the higher gears.
    • The scale for acceleration is "zoomed in" progressively further for each higher gear. It's very important to keep scale in mind. For example, you'll see that at 70mph in 6th gear, the Magnuson can accelerate about twice as fast as stock. TWICE AS FAST! That sounds AMAZING! But that's twice as much of a very small amount. Go out in your stock jeep at 70 mph in 6th gear (if you have a manual trans) and and push the pedal to the floor. Not very impressive at all. Twice as quick as that is still not going to be impressive at all, and you're still probably going to want to downshift.
    • Also on the topic of the "zoomed" acceleration scale in higher gears... margins of error are also "zoomed in", or multiplied, when viewing the data for higher gears. What looks like a significantly big difference may very well be a much smaller small difference, or vice verse, if the torque data for one power mod had some positive error, and another had some negative error. My data points from the dyno charts will also be "spread apart" across road speed more in the higher gears' charts, which is another loss of precision/accuracy.
    • The "legal speed" area in the charts for higher gears is in the low rpm range (2000-2500 rpm in 6th gear). These lower rpms are just after the beginning of the dyno pull, which can sometimes have some misleading results, depending on how exactly the dyno operator pressed the throttle at the beginning of the pull, and how the computer reacts/compensates for different speeds of throttle transition. This is where the least trustworthy torque data will exist.
    • I'm particularly suspicious of the big "hump" in the RIPP torque curve from 2000-2700 rpm. This is not at all typical of the gains usually produced by centrifugal superchargers. I would not expect such large gains from the RIPP in that RPM range. I'd really like to see if this "hump" exists in other dyno results for the RIPP.
    • The Prodigy torque curve is quite possibly pessimistic in the low RPM range (below 3000 rpm). My torque data for Prodigy up to about 4200 rpm is based on an old dyno chart from last summer. Since then, there have been very noticeable improvements below 3000 rpms due to updates to the tune. I'm hoping someone will soon get updated dyno results starting from low rpms with a recent version of the tune.
    • In summary, the low rpm acceleration in higher gears is going to be the least reliable of all the data I have presented. It's not completely useless, but be sure to treat it as "vague approximation". The precisely drawn lines on the charts will trick your brain it to really wanting to think it means the data itself is precise. RESIST THE TEMPTATION!



    click for full size


    click for full size


    click for full size


    click for full size


    click for full size



    Now for some interesting example comparisons between charts...

    Want to experience for yourself approximately how one of these power mods might feel? If you have a manual transmission, YOU CAN! Well... only if you have approximately the same tire-size-to-axle-gear-ratio ratio as me. My ratio is about 28.5 (tire diameter) / 3.21 (axle ratio) = 8.88. Multiply that number by your axle ratio to find out what tire size would be exactly equivalent. For example: 8.88 * 3.73 = 33.1, so a tire diameter close to 33" with 3.73 gears will have about the same relationship between engine speed and road speed as used in these charts. Follow these steps.
    1) Pick a combination of speed, gear, and power mod. For example, 70 mph, 6th gear, Hemi.
    2) Take note of the G-force for that combination on the appropriate chart: Just under 0.1 G for my example.
    3) Look the stock acceleration on the other charts at 70 mph, looking for one that is around the same amount of acceleration: 4th gear is the closest match for my example.
    4) Now go out on the road at 70 mph in 4th gear. The amount of available acceleration at that point is similar to how it would feel in 6th gear with the 6.4 Hemi!

    NOTE 1: For some combinations, you won't find a close match at the same exact speed in another gear on the stock acceleration curve. In this case, you can just find where the stock acceleration IS a close match at some other speed, then go test at that speed in that gear. For example, The Hemi accelerates at about 0.175 G at 95 mph in 4th gear. The stock wrangler accelerates the same amount at about 45 mph in 3rd gear. So the amount of "pull" you feel at 45 mph in 3rd gear in a stock wrangler is similar to how much pull you would feel with a 6.4 Hemi at 95 mph in 4th gear!

    NOTE 2: These acceleration graphs will generally scale down with additional weight. Because of aerodynamic drag, it's not quite a direct relationship, but you can still look at the relative/percentage differences for a close approximation for a heavier jeep.



    Another interesting example is to look at a particular speed across multiple gears, and see how each mod stacks up against the others at the same speed, and how that changes in different gears. The two most polarized options are Prodigy vs Magnuson, so they will have the most extreme variations through the different gears.

    For example, 70 mph:
    • In 6th gear, 70 mph, Hemi is king, and Prodigy... well, not so much at all. RIPP and Magnuson are doing much better than Prodigy here too.
    • In 5th gear, 70 mph, Prodigy and RIPP are now essentially the same, Magnuson is better, and Hemi is still king.
    • In 4th gear, 70 mph, Prodigy and Magnuson are now on par with each other, both doing better than RIPP, but still taking a beating from the Hemi.
    • In 3rd gear, 70 mph, Prodigy has taken the throne from the Hemi, and both RIPP and Magnuson on par with each other way below the Hemi.



    Again, keep in mind all the things I warned you about at the beginning of this post. And really think hard about what you really want out of a power mod before making a decision.

    It's actually quite amazing to have such a wide range of options available for the Wrangler. There really is something for everyone. Between Magnuson, RIPP and Prodigy, there's quite a range of options for balance between having low-end torque for less downshifting during normal driving ("feeling" very powerful at lower rpms) at the expense of maximum acceleration potential (Magnuson), all the way to huge maximum acceleration potential at the expense of low rpm torque such that more downshifting is required to access the fun (Prodigy), with a good compromise in the middle (RIPP). Then there's the 6.4 Hemi, which nearly allows you to have your cake and eat it too (low rpm torque AND huge max acceleration potential!), but it will cost you dearly.

  6. #36
    Not to rain on your parade but Centrifugal Superchargers were the preferred type of forced induction systems on large aircraft engines for about 4 decades-- and these engines operated their entire lives between 1000-3000rpm. The key to the performance of a centrifugal unit is the gear-ratio or ratios the unit uses to spin the compressor (some units where two or three speeds). Since Ripp might have asked for a specific gear ratio in the gearbox from Vortec it is hard to say that you find performance at x rpm hard to believe without knowing more about Ripp's specific setup.

  7. #37
    You may think you are raining on my parade. But in reality, my parade has already gone by and the lingering crowds of people are watching as you stand in the middle of the street pissing fiercely into the wind.


    I'm not saying that a centrifugal supercharger in general is not capable of producing big gains at low rpm, ever, on any engine, with any configuration. As you said, it's just a matter of the supercharger's gearbox ratio.

    However, we are speaking specifically about a centrifugal supercharger that is known to produce a peak boost of about 7-8 psi on an engine that revs up to 6500 rpm.

    The boost produced by a centrifugal supercharger is directly proportional to the square of the speed of the supercharger, and therefore directly proportional to the square of the speed of the engine.

    Due to the fact that increasing engine speed reduces the amount of time available for air to flow in the intake valves, the gain in torque of a centrifugal supercharger ends up being approximately directly proportional to the speed of the engine (not the square of the speed of the engine, as the boost pressure is). This means an approximately linearly increasing gain in torque across the entire rpm range.

    Again, that is approximately linearly increasing torque gains, starting with minimal gains at very low rpm, increasing fairly steadily to maximum gains at/near maximum engine speed (gains may taper off a bit near max engine speed due to the compressor falling out of its efficiency range).

    Armed with this knowledge of how centrifugal superchargers work, and within the context of the entire RIPP torque curve across the rpm range, I can quite confidently say that the large bump/hump in the torque curve at low rpms is unexpected. See the following picture where I have circled the area in question, and drawn a line that approximates a reasonable expectation for the shape of the torque curve. I'm not saying the shape of the torque curve is impossible. It could be something about tuning, relative to the stock tune being intentionally de-tuned in that area for various emissions/efficiency reasons, etc.. I'm just saying just that it's unexpected, so I'd like to see whether other people have gotten similar results to see if this "hump" is consistent, or is this just a misleading side-effect of how this specific dyno run was performed.




    The truth is most likely somewhere in between.I'm also a bit suspicious of the dip in the stock torque curve in that same area (I've seen other stock dyno charts without this dip). If we assume that dip in the stock torque curve is a fluke, then this is about what I would expect from the RIPP torque curve:


    Last edited by UselessPickles; 04-08-2015 at 11:12 AM.

  8. #38
    Quote Originally Posted by UselessPickles View Post
    You may think you are raining on my parade. But in reality, my parade has already gone by and the lingering crowds of people are watching as you stand in the middle of the street pissing fiercely into the wind.


    I'm not saying that a centrifugal supercharger in general is not capable of producing big gains at low rpm, ever, on any engine, with any configuration. As you said, it's just a matter of the supercharger's gearbox ratio.

    However, we are speaking specifically about a centrifugal supercharger that is known to produce a peak boost of about 7-8 psi on an engine that revs up to 6500 rpm.

    The boost produced by a centrifugal supercharger is directly proportional to the square of the speed of the supercharger, and therefore directly proportional to the square of the speed of the engine.

    Due to the fact that increasing engine speed reduces the amount of time available for air to flow in the intake valves, the gain in torque of a centrifugal supercharger ends up being approximately directly proportional to the speed of the engine (not the square of the speed of the engine, as the boost pressure is). This means an approximately linearly increasing gain in torque across the entire rpm range.

    Again, that is approximately linearly increasing torque gains, starting with minimal gains at very low rpm, increasing fairly steadily to maximum gains at/near maximum engine speed (gains may taper off a bit near max engine speed due to the compressor falling out of its efficiency range).

    Armed with this knowledge of how centrifugal superchargers work, and within the context of the entire RIPP torque curve across the rpm range, I can quite confidently say that the large bump/hump in the torque curve at low rpms is unexpected. See the following picture where I have circled the area in question, and drawn a line that approximates a reasonable expectation for the shape of the torque curve. I'm not saying the shape of the torque curve is impossible. It could be something about tuning, relative to the stock tune being intentionally de-tuned in that area for various emissions/efficiency reasons, etc.. I'm just saying just that it's unexpected, so I'd like to see whether other people have gotten similar results to see if this "hump" is consistent, or is this just a misleading side-effect of how this specific dyno run was performed.




    The truth is most likely somewhere in between.I'm also a bit suspicious of the dip in the stock torque curve in that same area (I've seen other stock dyno charts without this dip). If we assume that dip in the stock torque curve is a fluke, then this is about what I would expect from the RIPP torque curve:



    Not even wrong!


    1) Centrifugal Superchargers have a gearbox so they can produce optimal compressor speeds no matter the speed of the crankshaft. So, let's say you have a 4.5:1 ratio gear box on the back end of this hypothetical CS unit-- that will give you 4.5 x times the input rpm. So let's say at 2000x4.5 gives you compressor speed of 9000rpm. This might create depending on the units size anything from 0.5-2.0psi in manifold pressure, but here is the big issue that you never seem to get this unit might be capable of putting out at >2.1psi 10-15lbs-minute of air mass-- which is what makes it possible to burn more fuel and more air at those low pressures.

    2) Volumetric Efficiency is usually lower as well at low rpms in an engine and higher at higher rpms. So, let's say you have in our hypothetical engine at 14.7psi (standard one atmosphere at sea level) an air mass of 50lbs-minute being processes by each cylinder. If this is say 50% the engines maximum volumetric efficiency for Normal Aspirated induction. So, since the cylinder has 50% less air mass in it it is very easy to squeeze in 10-25 lbs-minute of air mass into the cylinder without really needing 20PSI to do so. So you can boost volumetric efficiency very easily at this point. So going to 65lbs-minute air mass is an increase of 15% in Volumetric Efficiency.

    3) As the engine increases its efficiency as it increases RPM-- the amount of boost needed to reach higher and higher Volumetric efficiency ratings requires higher boost! So, to squeeze more air into the cylinder you have to use more PRESSURE or combine that with an increase in the size of the combustion chamber- i.e. reduce compression ratio usually via piston design.

    4) Torque gains might not be minimal at low the end of the RPM spectrum... Again you can alter the horsepower and torque gains by changing the size of the unit and gearbox ratios to fit the needs.

    5) The hump isn't what is odd-- it is the dip after it that is far more telling... The hump is pretty expected. The Dip, says that something in the engine radically changes and the super is no longer as efficient in supplying the required air-mass to maintain sufficient combustion to create the same levels of power. It could be that Vortec unit isn't able to keep pace with the rising Volumetric performance of the engine between 2400-2900rpm. It is boosting the performance over stock but the unit isn't keep up with the engine's own internal pressure. It could be related to only this unit. If you chart is right it isn't giving the supposedly expected 300ft-lbs of torque at the rear wheels either. That is odd too.

    6) Like I said the units gearbox pretty much makes it impossible to use your squared proportional formula and get any meaningful data for generalization. What is really important is knowing how the gearboxes ratios affect the compressors speed for a given rpm and that has nothing to do with the square of the engine's rpm. The the impeller itself will be rotating at different velocities from the centripetal forces of the air being pressed against housing. Sure, you need to use the square of the radius impeller itself. But for just figuring out the actual impeller's increase in rpm over that of the input shaft-- that is simple multiplication. Ratio times input rpm!!!

    8) Not all superchargers are created equal-- however, to determine what sort of Volumetric Efficiencies, Boost Ratings and Adiabatic Efficiency also known as Parasitic Efficiency...

    9) Finally, I'm still trying to figure out what in the hell you are talking about with the valves. Is just puzzling it sounds like you're talking about the engine's VE but combining that with valve surge. Here is the thing like any device it has a small spectrum of efficiency where it reaches nearly maximum theoretical performance and then it falls off.

    10) It's been a blast...

    11) You do need more samples in your data set to make any general statement at all about these modifications and performance... That is a fact. Also you need better testing methods i.e. you first have to determine is your stock engine making advertized torque and hp at the crankshaft before you turbo it and then do it with the modification. Then get data on the drive train and then work it with the turbo unit replace it into the Jeep and do the same tests. Otherwise all you're doing is guessing. But I can tell you this for your 33% loss figures to be accurate would mean that you have to have 585HP at the Crankshaft for a 360ish WHP ratings... You're not getting 585Hp at the crankshaft without doing some serious modifications to the engine internally. NRE is getting those sort of numbers on pump gas, but, they are totally blue printing the engine to do that sort of thing! That is not the power you're getting from a bolt on modification and 93 pump gas. IT is more likily you're getting 90-120hp at most and only loosing 60-80hp.
    Last edited by KaiserBill; 04-08-2015 at 07:36 PM. Reason: To be more me..

  9. #39
    Quote Originally Posted by KaiserBill View Post
    Not derp derpy!


    1) Duuurp Derpity duuurp a duuurp so duuurp can derp derpy derpy hodor no duuurp the derpity of the derpy. So, let's say you derpy a 4.5:1 derp derpity box on the derpy end of derpity derpity CS derpy-- duuurp derpity derp you 4.5 x derpy the derpity rpm. So let's say at 2000x4.5 derpy you duuurp derpity of 9000rpm. Derpity derpy derpy derpity on the derpy hodor duuurp derp 0.5-2.0psi in derpity derpity, but derpity is the big derp derpy you derp duuurp to get duuurp duuurp derp be derpy of derpity out at >2.1psi 10-15lbs-derpy of air duuurp-- derp is derpity derpity it hodor to duuurp derpity derpity and duuurp air at derpy low derp.

    2) Derp Derpity is derpity derpy as duuurp at low derpy in an duuurp and duuurp at derpy derpy. So, let's say you duuurp in our derpy derpity at 14.7psi (derpity one derpy at sea duuurp) an air derpy of 50lbs-derp derpity hodor by derpity derpity. If duuurp is say 50% the derpity duuurp duuurp derpity for Duuurp Duuurp derp. So, derpity the derpy has 50% derp air derp in it it is derpy derpity to derp in 10-25 lbs-derpity of air derpity derp the derp derpy duuurp duuurp 20PSI to do so. So you can derpy duuurp derp duuurp derpity at duuurp duuurp. So duuurp to 65lbs-duuurp air hodor is an derpity of 15% in Derpity Derpity.

    3) As the derp derpy its duuurp as it derpy RPM-- the derpity of duuurp duuurp to duuurp hodor and derpy Derpity derp duuurp derpity duuurp derpy! So, to derpy derp air duuurp the derpy you derpy to use derpity DERPY or derpity derpity derp an derp in the derp of the derpity duuurp- i.e. duuurp derpy duuurp derpy via derp derpy.

    4) Derpity derpity duuurp not be derpity at low the end of the RPM derp... Derpity you can duuurp the derp and derpy derpy by derpy the derp of the derp and duuurp derpy to fit the duuurp.

    5) The derpy isn't derp is odd-- it is the dip derp it derp is far duuurp derpy... The derpy is derpy duuurp. The Dip, derpity duuurp duuurp in the derpity derpity derp and the duuurp is no derpy as derp in derpy the derp air-derpity to derpy derp derpity to derpity the derp derp of derp. It derp be derpity Derpity derpy isn't duuurp to duuurp derpy derpy the duuurp Duuurp derpy of the derpity derp 2400-2900rpm. It is hodor the derp duuurp derpy but the derpy isn't duuurp up duuurp the derpity's own duuurp derp. It duuurp be derpity to derpy duuurp derpy. If you derpy is duuurp it isn't duuurp the derpity derp 300ft-lbs of duuurp at the derpy derp duuurp. Derpy is odd too.

    6) Derpity I derpity the derpy derpity derpy derpity duuurp it derpy to use derpy duuurp duuurp derpity and get any derpity duuurp for duuurp. Derpy is duuurp derpity is derpity how the derp derpity duuurp the duuurp derp for a derp rpm and derpity has derp to do derpity the derpity of the derpity's rpm. The the derpity duuurp derpity be derpy at derp derpity derpity the derp derpity of the air duuurp derpity derp hodor. Duuurp, you derp to use the derp of the duuurp hodor derpity. But for duuurp derp out the derpity duuurp's derpity in rpm derpy derpy of the derp derpy-- derpy is duuurp hodor. Derpy derpity derpy rpm!!!

    8) Not all derpity are derp derpy-- derpy, to derp derp derp of Derp Derpy, Duuurp Derp and Derp Derpity derpity derpity as Derpy Derpy...

    9) Derpy, I'm derpity derpy to duuurp out derpity in the derpy you are derp derp derp the derpity. Is derpity duuurp it duuurp derp you're derp duuurp the derpy's VE but derpy derpy hodor derpy derp. Duuurp is the derp duuurp any derpity it has a derp derpy of derp derpity it derpy derpity duuurp derp derp and derpy it derpy off.

    10) It's derp a hodor...

    11) You do derpy hodor derp in derpy duuurp set to duuurp any derpity derp at all hodor derpity duuurp and derpity... Derpy is a derpy. Derp you derpity duuurp hodor duuurp i.e. you derpity derpity to duuurp is duuurp derpy derp derp derp derpy and hp at the derpity duuurp you derpity it and derpy do it derpity the derpity. Derp get derpy on the derpity derp and duuurp derpity it duuurp the derpity derp derpy it derpity the Duuurp and do the derpity duuurp. Derpy all you're derpity is derpy. But I can derpy you derpity for derp 33% duuurp derpity to be derpity derpity derpy duuurp you duuurp to derp 585HP at the Derpity for a 360ish WHP duuurp... You're not derpy 585Hp at the derp duuurp derpy derp duuurp derp to the derp derp. NRE is derpity derpity derpy of duuurp on hodor gas, but, derpity are duuurp derp derpity the derpity to do derpity duuurp of derp! Derp is not the derpy you're derpity derpity a derpity on duuurp and 93 derp gas. IT is duuurp derp you're derp 90-120hp at derpy and derpy duuurp 60-80hp.
    Just a reminder that this is what all of your posts now look like to me. This helps prevent me from wasting my time trying to actually discuss/debate your mostly irrelevant, non-interrelated, and/or just plain incorrect points.

    If anyone thinks any of KaiserBill's points are valid or worth discussion, please re-post any specific questions you have that you would like me to respond to

  10. #40
    Quote Originally Posted by UselessPickles View Post
    Just a reminder that this is what all of your posts now look like to me. This helps prevent me from wasting my time trying to actually discuss/debate your mostly irrelevant, non-interrelated, and/or just plain incorrect points.

    If anyone thinks any of KaiserBill's points are valid or worth discussion, please re-post any specific questions you have that you would like me to respond to
    You might try reading books on engine design and turbo-super charging design instead of eating them.

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