OMG...Prodigy...TURBO!

[UselessPickles]

There's some people poo-pooing all over my thread about the turbo over on the wranglerforum, with comments such as, "When are you ever going to get the RPMs high enough to even get the turbo spooling off road?"

I decided to actually do some basic math and answer that question, and I think the results are interesting enough to share over here. The following is a copy/paste of my reply...



Since we don't have details on the 3.6 turbo kit, let's talk in terms of the existing 3.8 turbo kit, 12 psi. Here's the torque gains at a few rpms (refer to the dyno chart I posted earlier if you want to confirm the numbers):

2000 rpm: 25 ft-lb, 16% gain
2500 rpm: 55 ft-lb, 33% gain
3000 rpm: 105 ft-lb, 68% gain
3500 rpm: 185 ft-lb, 116% gain

Now let's look at the speeds attained at the same rpms.

First, let's assume my plain old stock Wrangler Sport with 29" tires and 3.21 gears, in 1st gear, 4LO.

2000 rpm: 5.3 mph (25 ft-lb, 16% gain)
2500 rpm: 6.6 mph (55 ft-lb, 33% gain)
3000 rpm: 7.9 mph (105 ft-lb, 68% gain)
3500 rpm: 9.3 mph (185 ft-lb, 116% gain)

So there you have it. Significant gains in the 5-10 mph range. That is a very common speed range for me on the off-road trails that I drive on. If you are not focused on extremely slow rock crawling, then this is usable torque for you.

But that's pretty tall gearing for off-roading. How about a Rubicon with the 4:1 transfer case, 33" tires and 4.10 gears?

(EDIT: corrected a miscalculation of speeds)
2000 rpm: 2.7 mph (25 ft-lb, 16% gain)
2500 rpm: 3.4 mph (55 ft-lb, 33% gain)
3000 rpm: 4.0 mph (105 ft-lb, 68% gain)
3500 rpm: 4.7 mph (185 ft-lb, 116% gain)

I'd say that looks pretty damn usable for low-speed off-roading. Maybe still not extreme rock-crawling usable, but I'm not a rock crawler, so I don't know.

The kinds of trails I drive on, I'm often in the 5-10 mph range in 4LO and 1st gear. Yes, I actually keep it in 1st gear so I can make use of the mid/high rpm range and the power that comes with it!

I hope this answers your question.

[JeepLab]

There's some people poo-pooing all over my thread about the turbo over on the wranglerforum, with comments such as, "When are you ever going to get the RPMs high enough to even get the turbo spooling off road?".

I've gotten the same note in each supercharger thread.

Its a short sighted opinion that is easy to throw out with little knowledge of superchargers and their uses offroad.

The answer to this question, is when your offroad, you can crawl in lower gear, at higher rpm WHEN you need more power. RATHER than goose the throttle.

I did a video on this technique. Its a very simple concept, and I dont understand why some people cant grasp it.

The extra power is useful when your slow offroad and fast on the highway, You just need to manipulate the RPM to use it... when its called for.

[UselessPickles]

It's kind of a strange conflict of priorities I see. People want to gear down their axles (numerically higher) a lot for better low speed off-road grunt, but then there seems to be a general fear of using anything over 3000 rpm. The whole point of gears, 4LO, and the transmission is to have the ability to take advantage of the engine's power as best as possible at any speed. By the very definition of power, if you have any sort of decent torque curve, peak power will be in the upper RPM range. Numerically higher gears in the axle allows you to reach higher power levels of your engine at lower ground speeds. If you continue to always shift below 3000 rpm after re-gearing, then you're kinda missing the point.

I had someone tell me in a thread that they "couldn't conceive of ever running any vehicle at 4000 rpms under any conditions". It was a thread where he was complaining about wanting stronger acceleration. If you want the power, downshift and rev it up! There's a rev limiter around 6400 or 6500 to keep you in a safe operating range. You will not hurt the engine.

[Gunner]

I've videoed my 2013 auto doing 0 to 100 on the dry lake bed twice. Once bone stock and once with a 3.5 RK lift, 35 KM2's,4.56's and a Procal flash. The gears and tires were the quicker of the two. Not by a lot though. It just ran up to 100 and stopped accelerating when the speed limiter kicked in.

[JeepLab]

I've videoed my 2013 auto doing 0 to 100 on the dry lake bed twice. Once bone stock and once with a 3.5 RK lift, 35 KM2's,4.56's and a Procal flash. The gears and tires were the quicker of the two. Not by a lot though. It just ran up to 100 and stopped accelerating when the speed limiter kicked in.

Is there a link to this video? I'd love to see it.

[Pznivy]

When is this thing coming.....?

[Snarf77]

I have a question; maybe for pickles as he's in-the-know: What type of exhaust system is Prodigy envisioning using behind the turbo system?

[UselessPickles]

When is this thing coming.....?

Don't know for sure yet. "Soon".

I know that they definitely want to have everything ready so they can show it off at Jeep Beach Week, promote it, and generate sales: http://www.jeepbeach.com/

Based on that, I would expect it to be available at least by late April. Of course, they are trying to make it available much sooner if possible. We should hopefully get some more details this week as they finish up their final tune testing and start preparing for production.

I have a question; maybe for pickles as he's in-the-know: What type of exhaust system is Prodigy envisioning using behind the turbo system?

As far as I know, the kit is intended to work with no additional supporting mods necessary, so stock exhaust is expected/supported (except for the parts of the exhaust replaced by the turbo kit).

The kit includes fine tuning via email based on data logs (at least the 3.8 kit did). I imagine that if you wanted aftermarket exhaust, your best deal would be to get it installed before or at the same time as the turbo so that the fine tuning via email will be fine tuned for whatever exhaust you are running. This would definitely be a topic worth discussing with Prodigy directly before making any decisions just in case there are any compatibility concerns. It seems to me that a turbo system could benefit from a more free-flowing exhaust system (more power to the wheels instead of fighting back-pressure in the exhaust, cooler exhaust pipes, etc).

[UselessPickles]

We'll have to wait longer for dyno results

Getting the prototype pipes uninstalled (already done) to setup for production took priority. Dyno testing will happen "probably next week".

[Snarf77]

We'll have to wait longer for dyno results

Getting the prototype pipes uninstalled (already done) to setup for production took priority. Dyno testing will happen "probably next week".

A few pictures of said pipes would sure be exciting. I'm still stuck on exhaust. I'm thinking an AFE Mach Force Hi-tuck system was ideal before the turbo. Now I wonder if something more free-flowing would be better. I feel like the pressure to get the exhaust right early on (based on your point) is worth the stress. Unfortunately, Jeep exhaust reviews aren't terribly relevant to me now unless they have boost. I'm sure AFE's system would be a good starting point.