SC vs. HEMI - Let the TRASH talk begin!

[UselessPickles]

Here's simulated 0-60 mph times...

Stock:
7.59s

Magnuson:
5.49s

RIPP:
5.36s

6.4 Hemi:
4.62s

Prodigy:
4.81s

[Timmy]

Here's simulated 0-60 mph times...

Stock:
7.59s

Magnuson:
5.49s

RIPP:
5.36s

6.4 Hemi:
4.62s

Prodigy:
4.81s

I would love to see your 0-60 time Pickles and compare it to your calculations. 4.81s is just insane! Part of me is sitting here thinking, no way on earth are you going to see that, then the other part says, well... maybe so. I really would be shocked if you are below 5 seconds. An Audi S4 has a 0-60 of 5.2 seconds. That's a 6cyl with a supercharger on it producing 333hp that is geared for speed, weighs 3985 lbs (close to your weight) and has a drag coefficient of 0.30 compared to a Jeep somewhere north of 0.50 (stock.)

Drag Coefficient Comparison
Passenger Train 1.80
Ski jumper 1.20 - 1.30
Person (upright position) 1.00 - 1.30
Old Car like a T-ford 0.70 - 0.90
Tractor Trailer 0.96
Bike racing 0.88
JEEP Wrangler Modified 0.82 (stubby bumper, flat fenders, big-A tires ;-)
Brick Cube 0.80
JEEP Wrangler Stock 0.58 (stock)
Solid Hemisphere 0.42
Bird 0.40
Audi S4 0.30
Common Car like Open Vectra (class C) 0.29
Supersonic Fighter 0.016
Subsonic Transport Aircraft 0.012

[UselessPickles]

I would love to see your 0-60 time Pickles and compare it to your calculations. 4.81s is just insane!

I will refer you to this statement in my previous post

NOTE: I'm not claiming that my simulation will perfectly simulate the real world and make perfect predictions. Real world results depend on so many variable factors, human imperfection, etc. The goal of the simulation is not to accurately predict real-world results, but to compare relative real-world *potential* between different vehicles/configurations, using computerized perfection to remove the uncontrollable variables of the real world. This allows us to objectively/relatively compare stuff without arguing about whether the results were simply due to difference in driver skill, a bad launch, a poorly timed shift, bad weather conditions for traction, etc.

However, I do purposely use input (launch rpm, gear shift time) that seems reasonably attainable to get results that are reasonably close to what should be possibly in the real world. I definitely need to improve my launching skills before I can hope to approach the predicted results

Part of me is sitting here thinking, no way on earth are you going to see that, then the other part says, well... maybe so. I really would be shocked if you are below 5 seconds. An Audi S4 has a 0-60 of 5.2 seconds. That's a 6cyl with a supercharger on it producing 333hp that is geared for speed, weighs 3985 lbs (close to your weight) and has a drag coefficient of 0.30 compared to a Jeep somewhere north of 0.50 (stock.)

A couple things...

* Drag coefficient is not the full story of the vehicle's aerodynamic drag. A drag coefficient (Cd) only describes the shape, but not the size. The drag coefficient must be multiplied by the frontal area to get the drag-area coefficient (CdA), which is what is actually used in calculations to determine the force of aerodynamic drag. So the Wrangler has even a bigger disadvantage than you would expect from drag coefficients alone (compared to typical cars) due to its larger frontal area.

* Aerodynamic drag doesn't have a very big impact on 0-60 mph times. To illustrate this, I simulated the turbo Wrangler's 0-60 run as if it had the same aerodynamic drag as a 2006 WRX STi. The STi's CdA value I have is 0.694. That's less than half of the Wrangler's CdA of 1.762. The end result for a turbo Wrangler that is more than twice as aerodynamic than reality is 0-60 mph in 4.78s. That's only 0.03s faster. Power:weight ratio has a much larger impact on 0-60 times than aerodynamics, just because so much of the 0-60 mph run is spent at low speeds where aerodynamic drag is minimal.

* My Wrangler is almost exactly the same weight as the Audi S4 example, but with about 380 whp, compared to the S4's 333 whp. Given that power:weight ratio is the dominant factor in 0-60 mph times, the turbo Wrangler's simulated 4.81s vs the S4's 5.2s seems pretty reasonable.

[FLIPmeOVER]

Here's simulated 0-60 mph times...

Stock:
7.59s

Magnuson:
5.49s

RIPP:
5.36s

6.4 Hemi:
4.62s

Prodigy:
4.81s

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?

[UselessPickles]

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:

[FLIPmeOVER]

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:

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.

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.

[KaiserBill]

Ok, Ok, i know this is not one of those forums were people get flamed for asking a dumb question, and the atmosphere around here is all very friendly and educational. And thank god for that. So forgive my thread title. I was trying to get attention.

I dont know who really knows who around here so we may all be strangers, i know JL and Snarf hang out, and gbaumann and JL live near one another and all the jeeps have different gear and gearing.

Here is what Im getting to.... Black Betty, Vs. Cherry Bomb (did that name stick? I liked it) gbaumann's hemi. Maybe the turbo makes an appearance.

Not so much a pissing contest, but the actual facts of what we think would happen if we raced them..... And maybe provoke these two guys to find a stretch of pavement to answer all the questions.

If you really want decent data you have to some serious technology on the truck for data recording and you have to have a controlled environment like a race track.

However, isn't the point of a Jeep to go off road? So shouldn't the test be something more off road associated?



This is what I would try to do-- put the trucks into a real off road conditions!

[gbaumann]

Let's get all four power mods to the dyno for JeepLap Spring Dyno Day 2015. Then get them on the trail! As much as I'm dying to see the numbers I'm also looking forward to meeting some of you guys and getting a day out in the woods.

Comparing the SC Pentastar to the 6.4L hemi is easy for me in certain respects. I ran the Mag unit for almost 25,000 miles. It was a struggle to say the least due to the auto trans issues. But, of course, I know what forced induction does for the Pentastar because I could manually make conditions right and get her on boost when I wanted. I'm now driving the same truck with the 6.4L. So I'm experiencing it in real time. I'm not sure how to describe the difference. Every time I get in the truck convinced that I'm going to really study the differences I step on the gas and the logic center in my brain dumps all operations. The only result I get as output is a juvenile giggle that keeps looping until I turn the truck off.

[UselessPickles]

It's reasonable estimation based on known drivetrain loss of a 5.7 Hemi Wrangler, comparing dyno charts to crank hp ratings. Again, read all the things I already stated about this being a best estimate with the available data, to be used for comparing general trends and relative differences. More specifically, for comparing large relative differences. Any area where the differences are very small could be well withing a margin of error of the assumptions.

The data I have so far is enough to see that the 6.4 Hemi will clearly destroy the superchargers throughout the RPM range, will destroy the turbo at low RPMs, but the turbo will likely have some level of advantage in the upper RPM range.

I'll gladly update everything as soon as someone produces an actual dyno chart of a 6.4 Hemi Wrangler. The amount of drivetrain loss becomes irrelevant then, because we'll have an actual measured torque curve at the wheels.

[HahaJK]

Looking at this from the view of a guy that wants more power for primarily trail runs and the occasional rock crawl, prodigy seems to be the best answer dollar for dollar. The 6.4L is out of the question simply due to price, but Magnuson, RiPP and Prodigy are all in the same ball park.

Reading up on the hot side of the turbos and pipes as well as the future problems of the prodigy though, I'm more swayed towards RIPP with a high boost pulley.