Prodigy Performance 3.6 Turbo DIY Install

[KaiserBill]

I don't know why you are shouting the obvious at me and think you need to give it to me as a clue. Your "clue" is not inconsistent with anything I have said. Please stop. Your lack of comprehension is hanging out and it's embarrassing.

I'm going to send this new understanding of volumetric efficiency to my buddies over at Caterpillar. They will love it.

P.S. A turbo doesn't have a 1:1 Ratio between exhaust pressure and boost. One impeller is compressing the air flow so it has a different geometry than the one that gases push against! These differences make a big difference in how much boost you get for specific volume of gas accelerating the unit. Also you will notice that the Intake housing is smaller than the exhaust housing[sometimes you need to measure it to see the difference]-- this is because the intake is trying maximize pressure by having a higher rotational speed than the turbine. Where as the exhaust is trying maximize the volume of gas pushing the against the turbine thus increasing the speed of the compressor. It is like having an overdrive where you get more rotations out of the smaller compressor wheel to keep up with the bigger slower rotating turbine.... So really you have more a 4-5 or even 10 to 1 ratio in favor of boost pressure over that of exhaust pressure. This is why the turbo becomes more efficient as the exhaust pressure increases and compress wheel's rpm goes up! You know it is the damn centripetal force formula.

[UselessPickles]

OK, KaiserBill. You win. Kinda...

All of this completely tangential talk of volumetric efficiency got me thinking...

KaiserBill may be right, either by coincidence for the wrong reasons, or he could just be bad at putting together a coherent/consistent explanation. I really don't know.

The key to this could be a difference in volumetric efficiency at low rpm. The turbo system will have higher exhaust back pressure. KaiserBill did point this out (a few times I think), but never followed through with the connection that it could be reducing the engine's volumetric efficiency.

Ideally, during the intake/exhaust valve opening overlap, exhaust will completely flow out and be replaced with fresh air from the intake manifold before the exhaust valve closes. Then the intake stroke will continue pulling in more fresh air from the manifold. With more exhaust back pressure, it could resist that complete expulsion of exhaust, and leave some exhaust gasses trailing behind when the exhaust valve closes. That exhaust gas is now taking up space and reduces the amount of new fresh intake air that makes it into the cylinder. The total amount of gasses in the cylinder could end up being the same, but not all of it is new, combustible, fresh air from the intake manifold. This both means less fresh air for combustion (less power), AND less amount of air is consumed from the intake manifold. Less air consumed from the manifold means that air is flowing through the engine at a lower rate, which would be represented as a lower volumetric efficiency. And if the engine is consuming air from the manifold at a lower rate, then air would have to be flowing into the manifold (from the turbo) at a lower rate to maintain the same boost level as system with higher volumetric efficiency.

So there's an explanation of how a turbo and supercharger on the same engine could be operating at the same boost level, same engine speed, same temperature, etc., but the supercharger could be flowing air faster than the turbo and producing more power. I still maintain that it is not the flow capability (CFM rating) of the compressor that causes this difference, but the flow capability of the engine itself. I just previously failed to see that the engine's flow capability could be different between the supercharger and turbo.

I would be surprised to learn that exhaust back pressure from the turbo is enough to account for a 40% difference in power. I still suspect it has more to do with the tune.

[UselessPickles]

I'm going to send this new understanding of volumetric efficiency to my buddies over at Caterpillar. They will love it.

Just be sure to send it to them properly revised with my own correction of myself that it's all relative to atmosphere rather than the intake manifold. I got it wrong initially, but my error was really irrelevant to the point I was trying to make.

My revised summary of my understanding/explanation of volumetric efficiency:

The ratio of the amount (number of molecules) of fresh intake air that enters into the cylinder compared to the amount (number of molecules) of air present in a cylinder-displacement volume of local ambient atmosphere, expressed as a percentage.

Like you've pointed out a couple times, it's the amount of air (molecules) that matters, which is why I said "volumetric efficiency" is a bit of a misnomer. Volume alone does not describe an amount of air.

P.S. A turbo doesn't have a 1:1 Ratio between exhaust pressure and boost.

I never claimed it did. I only mentioned TiAL's wastegate spring ratings that are based on an assumed 1:1 exhaust:boost pressure ratio. See the fine print in the lower-right of this image:

Spring Pressures are calculated based on a 1:1 back pressure ratio. It is not uncommon to see a +/- 2psi differential.

Now I could be completely misinterpreting this, so please correct me if I'm wrong. They only mention "back pressure", which I assume to be exhaust back pressure. And it's a ratio of "back pressure" to something. Since a wastegate involves a balance between exhaust pressure and boost pressure fighting against the spring pressure, I assumed they are referring to a ratio between exhaust back pressure and boost pressure.

The spring in the Stage 2 turbo kit is rated at 7.25 psi, but it produces about 8.2 psi when used in this particular kit. Therefore, if that ratio TiAL refers to is correctly an exhaust:boost pressure ratio, then my exhaust:boost pressure ratio must be less than 1:1.

I have been unable to find anything that explains what "back pressure ratio" is in terms of a wastegate or turbo system. If anyone can point me to info about this, please do.

I previously claimed that due to this, boost pressure would be higher than exhaust back pressure in the 1800 rpm 0.3 psi situation being discussed. I now admit that I don't understand this exhaust:boost pressure ratio stuff enough to make that assumption. The more I think about it, the more I expect that exhaust:boost pressure ratio would not be constant, but would vary throughout different engine speeds and engine loads. In fact, I'm pretty sure a couple psi of exhaust back pressure is pretty normal even for a NA engine, which is clearly more than the amount of boost in that situation. The turbo would almost certainly create more back pressure than the stock exhaust system... then flow from this idea back to my previous post about how the extra back pressure would lead to lower volumetric efficiency...

[KaiserBill]

Just be sure to send it to them properly revised with my own correction of myself that it's all relative to atmosphere rather than the intake manifold. I got it wrong initially, but my error was really irrelevant to the point I was trying to make.

My revised summary of my understanding/explanation of volumetric efficiency:

The ratio of the amount (number of molecules) of fresh intake air that enters into the cylinder compared to the amount (number of molecules) of air present in a cylinder-displacement volume of local ambient atmosphere, expressed as a percentage.

Like you've pointed out a couple times, it's the amount of air (molecules) that matters, which is why I said "volumetric efficiency" is a bit of a misnomer. Volume alone does not describe an amount of air.




I never claimed it did. I only mentioned TiAL's wastegate spring ratings that are based on an assumed 1:1 exhaust:boost pressure ratio. See the fine print in the lower-right of this image:






Now I could be completely misinterpreting this, so please correct me if I'm wrong. They only mention "back pressure", which I assume to be exhaust back pressure. And it's a ratio of "back pressure" to something. Since a wastegate involves a balance between exhaust pressure and boost pressure fighting against the spring pressure, I assumed they are referring to a ratio between exhaust back pressure and boost pressure.

The spring in the Stage 2 turbo kit is rated at 7.25 psi, but it produces about 8.2 psi when used in this particular kit. Therefore, if that ratio TiAL refers to is correctly an exhaust:boost pressure ratio, then my exhaust:boost pressure ratio must be less than 1:1.

I have been unable to find anything that explains what "back pressure ratio" is in terms of a wastegate or turbo system. If anyone can point me to info about this, please do.

I previously claimed that due to this, boost pressure would be higher than exhaust back pressure in the 1800 rpm 0.3 psi situation being discussed. I now admit that I don't understand this exhaust:boost pressure ratio stuff enough to make that assumption. The more I think about it, the more I expect that exhaust:boost pressure ratio would not be constant, but would vary throughout different engine speeds and engine loads. In fact, I'm pretty sure a couple psi of exhaust back pressure is pretty normal even for a NA engine, which is clearly more than the amount of boost in that situation. The turbo would almost certainly create more back pressure than the stock exhaust system... then flow from this idea back to my previous post about how the extra back pressure would lead to lower volumetric efficiency...

Useless Pickles, as I've said I applaud what you are doing trying to figure out if Ripp's claims are legitimate claims. That is good for everyone. People who can and do test these claims are important. The problem is that most manufactures are really dodgy about the details of their systems on purpose. While they do put little disclaimers on their products like "*** Our Results We Obtained In A Controlled Lab-- Real World Road Experience Does And Will Differ..." That want to blind people with my 86PSI of manifold pressure at 15,000RPM claims. Which is all about marketing-- damn those Madison Avenue Bastards. It is a shame these guys just don't come out and give a full spec sheet of the units capabilities. It would make comparisons so much easier. Then again it would probably daze and confuse a lot of people with way too many numbers.

Back Pressure is a bad term. Let's call it resistance to flow. The impeller creates it in a turbo unit and the exhaust system itself creates it in a Normally Aspirated System. You cannot really get rid of it completely. And yes, you are correct, the Normally Aspirated Engines do indeed have back pressure that is lower than their Turbocharged counter parts. I'm sure that Prodigy has reduced this to a minimum by keeping the lengths of exhaust as short and straight as possible. Increasing the diameter of the exhaust will help a lot too from the turbocharger unit itself. If you are using stock exhaust from the turbo to the catalyic converter and muffler you getting more resistance on the back end of the exhaust then you would if you increase that size. This will make the turbo operate more efficiently at lower pressures. But you might not be able to change those diameters too much. They might have specified a system that uses pretty stock stuff. But I would call up Prodigy and ask what sort of benefit going up a .25 inch or even 1 inch in diameter would do for me. The lower the back pressure is at any rpm the better.

Well, if you are getting 8.2PSI on the manifold but are still using 7.25PSI rated waste gate spring-- then well there is your answer the stage two kit's Aftercooler is giving you 1.17... to 1 ratio of boost ratio. That's good actually. However, freeing up the exhaust system and getting the absolute least restrictive design can improve those numbers. Also letting the turbo operate at higher Boost Pressures can see an improvement on those too.

[From looking at Garrett's website that turbo class the 550HP can put out a lot of Boost depending on the specific size of the unit- they have a couple different ones in that class. But they all create killer power levels at 20-30psi. If you don't like your warranty much-- I would suggest getting a waste that can handle a 30PSI spring or greater. You know one that never actually lets the exhaust gas bypass the turbine... Add Water Methanol Injection and of course custom deep-dish pistons (increase the chamber volume a little and drop the compression ratio from 9.5 to 1 down to 4.5 to 1 or less ) and then stand back and see how much power your 3.6L engine creates! Of course this is only if you really don't like your warranty and your jeep is not your daily driver! It is not impossible to get a 180BHP per L with out much effort doing this. You know 648HP at 6500rpm has a way of intoxicating the owner/operator of the vehicle-- insurance companies are however never that impressed...]


The big problem with the Jeep's hood is that they didn't give you much room to play with in the engine compartment. That's a real bummer actually. Because the ideal setup on a V6 or V8 engine is a twin turbo kit. That will let you maximize the exhaust pressure from each bank of cylinders into its own turbo unit. However, that doesn't seem like it would fit under the hood given the space they have under their. But that would probably let you have a system with better low end performance but you might not be so hot at 6500rpm.

If you want to really want increase your analysis and ask Jeeplab if they can send you their raw data from dyno of the system. If you get the torque numbers you can actually calculate Volume Metric efficiency of the engine for any given boost level. Which means that you can really see if their claims are true or not. Of course I would call anything within 5% of the 40% percent claim too close to call. You will need to get the air-fuel ratio numbers too... you might have to use a range of those to get approximations-- but hey like I said if you get within 5% of that Ripp number then you know it is at least possible to do. And it should be possible to do that sort of performance with the Vortech unit.

Here are some more fun formulas for you:

http://www.turbobygarrett.com/turbob...choosing_turbo

[UselessPickles]

Here's some fresh turbo porn from Prodigy:




They also mentioned on facebook that they got 382 hp and 380 ft-lbs out of their stage 2 test jeep now! Compared to the previous 359 hp and 373 ft-lbs, that means there's a small bump in peak torque, but more impressive is that the peak hp gain implies that torque falls off less after peak torque. This must have something to do with their recent efforts to improve the tune. I hope they finish it up soon and let us try it

[KaiserBill]

"This is the Stage 2 Upgrade Kit for the PRO-2001 Prodigy Turbo Kit for the 2012-2014 Jeep Wrangler. This is a complete Jeep Turbo Kit upgrade that adds our legendary front mount intercooler and increases boost by and additional 2PSI. Everything you need to get the power your Jeep needs on or off-road. With 7 years of development, the finest turbocharging components, OEM level engine management calibrations and extraordinary dyno proven results this package will make your Jeep perform as good as it looks! More Powerful than ANY supercharger!"

From the Prodigy Website... That is funny- Legendary Front Mount Intercooler??? That is funny-- considering this sort arrangement has been around for decades-- one would be almost forgiven if they mistook Prodigy for being the inventors of front mounted intercoolers. And for all that legend what do you get 2 extra PSI!!!! I hope they decided to turn up the boost a little.

[UselessPickles]

Yeah, "Legendary" seems a bit excessive, but that's marketing. The intercooler is very nice, though. Very solid and custom sized to just barely fit behind the grill on the Jeep.

And for all that legend what do you get 2 extra PSI!!!! I hope they decided to turn up the boost a little.

You also get much lower intake temps, so the gains are better than just a small boost increase.

They have plans to turn up the boost, but this seems to be as much boost as they are comfortable selling as a reliable kit on the stock engine. All I know for sure is that they have shared pictures of some forged pistons. They're going to strengthen the engine before adding more boost.

BTW - I heard that one of their customers took it upon themselves to turn up the boost (to somewhere around 12-14 psi, I believe), and ended up requiring an engine rebuild due to the damage that was caused.

[AGOM]

4 pages of catch-up reading and 4 Advils later and i must say that i enjoyed it.
I have to Applaud both UslessPickles and KaiserBill for their efforts and a great read, it tickled and teased my brain in more ways than one !! Lots of info.


Thnx guys

[KaiserBill]

Yeah, "Legendary" seems a bit excessive, but that's marketing. The intercooler is very nice, though. Very solid and custom sized to just barely fit behind the grill on the Jeep.



You also get much lower intake temps, so the gains are better than just a small boost increase.

They have plans to turn up the boost, but this seems to be as much boost as they are comfortable selling as a reliable kit on the stock engine. All I know for sure is that they have shared pictures of some forged pistons. They're going to strengthen the engine before adding more boost.

BTW - I heard that one of their customers took it upon themselves to turn up the boost (to somewhere around 12-14 psi, I believe), and ended up requiring an engine rebuild due to the damage that was caused.

I'm not saying the intercooler is bad. I'm just marveling at wording of the ad. From the description you would expect that this Legendary Custom Intercooler would make you espresso coffee, turn your engine into a 500+hp engine, and keep the kids entertained. It looks like a nice package.

My one question about it would be proximity to the to the rest of the engine stuff in your engine compartment-- you have the turbo very close putting out amazing heat. You have the engine putting a decent amount heat, then you have the radiator which is also putting out extra heat and then you have the exhaust manifold. You've got all those heat producing elements in such close proximity to the intercooler tends to reduce efficiency.

Air to Air systems work great at high speeds due to the volume of air flow you get. They tend to really drop of the performance charts when you get off road with slow moving air-speeds. Couple this with the close proximity of the everything under the hood and you start to see performance from your intercooler drop off. It is just one drawback of attempting to put extra things under the hood the original engineers didn't account for or ever intend for you to put under their. I wouldn't scrap the intercooler-- I just wouldn't be surprised that if I spend 4 hours off road at 15mph to see the same sort of performance as I would at 70mph cruising down the highway.

This is specially true for the air intake being right by the engine I understand why they want the turbo to get a nice short straight shot of air. However, that is right in the nexus of heat if you will. It is high up where all the hot air is going to rise to and it is next to the engine. I would like my air intake outside the hood in the clear away from extra heat sources. But that is just me. You're on the trail all day and the air is 80F ambient, then you have the above sources of heat and almost no air flowing into the system other than what the fans for the radiator can draw. I would increase those myself.

Also, does Prodigy offer an oil-cooler kit? That would be a great addition to the system.

[2k13jk]

Do you think itll be worth selling my ripp kit in my 2013 for a prodigy turbo kit