Does Jesse's Girl's 4.88 Gearing shorten the power band?
Does Jesse's Girl's 4.88 Gearing shorten the power band?
The difference between the dyno charts is the correction factors that were used is different. The SC vehicles received no correction factor in order to deliver the highest number. Strap all the vehicles on the same dyno, on the same day and the numbers will speak for themselves. We designed our turbo system to cruise in vacuum to avoid surging or excessive acceleration at highway speeds. The Jeep comes alive and makes more HP and torque 3,000 rpms sooner than the Jeep was able to do using the entire rpm. It now delivers over 100% more power. Especially in the midrange, where Jeeps need it the most contrary to most beliefs.
So this is one of the reasons you specced out the turbo build boost above typical cruising RPMs?Originally Posted by boosted1
It makes sense now that I think about it. If the turbo was specced to build boost at low RPMs, then you would need a good electronic boost controller (more expense, complexity and tuning effort) to avoid boost during freeway cruising, plus there's the issue of extra strain on the engine with boost at low RPM. The Wrangler is probably especially difficult in this area because it's not very aerodynamic and requires quite a bit more power than typical cars. More power required = more engine load = more exhaust flow to spool up the turbo, compared to typical cars.
Just for comparison, the Subaru Impreza WRX is just about exactly twice as aerodynamic as the Wrangler. That means it requires almost twice as much power to keep the Wrangler cruising on the freeway compared to the WRX.
For the record (and I've discussed this before elsewhere on forums), I'm of the opinion that the *need* for more low-end torque is over-rated in the Jeep community. Use gearing (transmission AND 4LO if necessary) to your advantage while off-road to keep the engine in the mid-range for more power available on demand, and a smoother/happier engine. While on-road, downshift when you need to accelerate quickly so that you can use the power of higher RPMs. People that complain about the Wrangler being too sluggish while also refusing to exceed 3000 rpms have no valid complaint.
I was never expecting the turbo to produce big low RPM gains, and I don't demand big low RPM gains. I was actually surprised when I saw "HUGE LOW END POWER" on the brochure.
It sounds to me like there was never any intent to create "HUGE LOW END POWER" with this turbo kit, and there's nothing wrong with that. Maybe the claim on the brochure was just a miscommunication between engineering and marketing?
I see 2 separate issues that need explanation:
1) Why does the brochure promise "HUGE LOW END POWER"? Based on the information available, it appears that it must be either a mistake in marketing, or false advertisement. If the turbo is not designed for big low RPM gains, then don't advertise "HUGE LOW END POWER". Advertise the strengths and benefits of the turbo. I think that section of the brochure could be easily changed to be 100% truthful by just changing the heading to "HUGE MID-RANGE POWER" (well, I would technically classify it as "huge upper-mid-range power"). The upper-mid-range is where you have a big advantage over the superchargers (more "usable" power for quick acceleration, etc).
2) Why is there a LOSS of low-end power below 2700 RPMs (according to your publicly-released dyno chart). While I don't think the Wrangler needs MORE low-end power, I also think that it is unacceptable to REDUCE low-end power. We need all the low-end power that we already have in stock form. I still think that there is *something* incorrect about your stock dyno results that is causing an incorrect (to your DISadvantage!) comparison between stock and turbo in the official Prodigy marketing material (ignoring specific numbers, the overall shape of the torque/power curves just does not at all match up with other stock dyno results; power should not peak below 6400 rpms). I really think that if you put another stock Wrangler on the dyno with its speed limiter disabled via an InTune, that you would get results that make more sense AND show an even larger increase in torque with the turbo.
Stating that we are using different correction factors is stating that we are using UNCORRECTED for one and SAE for the other, I think we are using SAE for all and Im sure Ive posted both charts UNCORRECTED and SAE for pretty much all the dynos. Thats a software thing, not a specific dyno thing. The chart I posted was SAE as Prodigy's chart is SAE. I can change it to UNCORRECTED if you want to show the difference.
Is the Dyno that Jesse ended up on broken? If the stock number comes out far off our other 9 stock dyno charts, then we'd have to put JG on a new dyno or bring her back to NJ and run her on the same dyno as the SCs.
We are comparing stock vs turbo, and will get a stock jeep on the same dyno to see the difference between that chart and the stock dyno charts used earlier in this thread.
This may sound too silly to be possible... but I noticed that the JeepLab stage 2 results have very similar peak numbers to Prodigy's stage 1 results. Is there any chance that you have the wrong wastegate spring, and are only getting about 7psi boost instead of about 9psi? A data log of full throttle in 2nd gear should be easy enough to confirm you're getting stage 2 boost levels.
Also, when do we get to hear about the rest of the install? You left off here, 4 pages ago: http://jeeplab.com/showthread.php?14...ull=1#post2200
Last edited by UselessPickles; 08-07-2014 at 02:08 PM.
I personally changed the wastegate spring; non-issue. I will do a data log of a 2nd gear full acceleration and send it your way nonetheless.
Did you have the 7Psi spring that came with the kit? what did you replace it with? 10Psi? My kit came with a 7Psi spring.. Stage 2 is suppose to be running 9 Psi right?..
The spring was in a small bag that came with the stage II setup. Nothing was on the spring to indicate the PSI that it represented. I just followed the instructions and replaced it. I believe if someone goes directly to a State II from stock - the correct spring may be pre-installed. On my setup and yours, the parts required slight modification (i.e. spring).
Yeah i have the lil bag with the spring inside it.. It is tagged with a "7psi" label..
Alright Folks! Just received the stage 2 kit today!! Bad news though the shop cant get me in until late next week, and maybe not even then..At the latest, week after next..(the week of the 18th). I will be out of town all week next week and ill be dropping off the jeep at the shop Monday (11th). Hopefully they can dyno stage 1, install stage 2, dyno again while im out of town and document the dyno and install. At the very least if they cant do a video, ill have the dyno passes pre stage 2 and post. Keep you guys updated.
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