Why no love for the 3.6? - Page 3 - Jeep Garage - Jeep Forum

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  #25  
Old 07-24-2015, 05:02 PM
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Re: Why no love for the 3.6?

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Originally Posted by f1anatic View Post
ahhh the bimmer zealots. Yeah bro, it is inline, but i would never own one hence i thought of the audi and then by extension, of both the range rover and the ripp v6 pentastar. Just about the only bmw i would ever own would be the 4 series gran coupe 435i xdrive. But before i drop $60,000 on one of those, i would consider a few other cars.

Subaru also does twin-scroll in their new 2.0 turbo engines, with cylinder separation and one impeller and has used twin scroll technology for nearly 2 decades now. Back in the day (2005ish) the jdm subarus came with a twin scroll that also featured a valve that redirected exhaust gas flow to either the low pressure side or both.



I know they are low pressure. I asked you about it in the other thread and you mentioned 6-7 psi. My concerns with supercharging a normally aspirated engine are several fold and have nothing to do with your solution and your approach, which is commendable. I am a firm believer in forced induction, with a few reservations, mainly in that i would have liked to be designed like that from the factory.

People over the years learned to supercharge factory normally aspirated engines like the infiniti/nissan vq35 engine with great success, and others have both super- and turbo- charged the factory 2.5 n/a subaru engine successfully. But i am yet to see anyone on those forums holding on to a car long enough to prove their reliability. Here are some of my concerns:



compression. A turbo or supercharged engine is factory built to either a lower compression ratio or with different thicker cylinder walls and heads than its normally aspirated counterparts. E.g. Subaru's sohc 2.5 n/a vs. Dohc 2.5 turbo engines.

it is important to note, that the pentastar family of engines was created with fi in mind (see maserati ghibli) though it is purpose built for that function.
When comparing, ej series subaru engines, you need to take into account that this is an old design architecture (though it has evolved) first introduced in 1988. (having a 02 wrx, and having built it, over and over, i can write pages related to it). Metallurgy and structural designs have come a long way since then. It is also important to note current engine management systems, and the fail-safes that are built into them (the 3.6 pentastar has 2 knock sensors where the boosted ej
's have 1). In the "tuner" world, it is common practice to tune and run things at the ragged edge of failure in the name of that almighty power number. Our product is not a tuner product, our product are designed with the wrangler owner in mind. What we mean by that is, when your 15 miles (5 hours) deep in a trail, aaa is not coming to get you. Reliability is paramount when your wheeling. If we had a reputations of blowing up motors, we would not be in business today. We carry that same philosophy forward when it comes to our wk2 program.

We can also say that we have put this (3.6l v6) motor through it's paces during our 22 months of development before releasing the kit. In that time since, we have moved close to 1000 systems with no reports of engine failure.


boost pressure. No doubt 6 psi is low but it is low in comparison to what? It is low in comparison to the average stage 2-3 subaru (18-20 psi) or a similarly modified mitsu evo (20-22 psi). It is similar to a factory calibrated audi 3.0 v6 t (~7 psi); it is half the factory boost pressure on a subaru (~14 psi depending on model).

But for the pentastar, it is 6 psi more than what the engine was built to operate at (barometric pressure). To put it in perspective, the power increases with the rip are equivalent to:

A) upgrading a subaru to a cobb stage iii (ecu reflash, up-pipe, down-pipe, larger intercooler, larger turbo, injectors and fuel pump) for a mere ~6 psi boost increase over the factory boost.

B) upgrading an audi 3.0 v6 tsfi to an apr stage ii 3.0 tsfi v6 pulley kit + ecu flash which brings up the boost ~7 psi.

But these engines were designed to operate above atmospheric pressure, and will take a ~6 psi boost increase, with no large reliability penalties. I am not so sure about the normally aspirated pentastar that sees 6 psi of boost.

the type of compressor we use is a main factor in our reliability. The above mentioned vehicles use different types of compressors than our system.

Subaru is turbo, a load and exhaust velocity(rpm) based compressor, that is regulated by the opening and closing of a wastegate dependent on engine load.

Audi uses a positive displacement compressor (roots, paddle, twin screw specifically in this). Sudden onset of boost, and is definitely best to have an engine built for this type of compressor.

We use a centrifugal compressor, a vortech v3 si type manufactured for our applications by airpower group. Best described as a belt driven turbo for layman's terms. The way we develop boost is more linear and progressive, easier to tune, no sudden onset for no "shock" to the, rod bearings, ring landings, and wrist pins, lower onset loads also help save the rods from bending.



transmission. I’ve blown a clutch within 6 months of going stage 2 (pipes and boost turned up). On the forums, there are virtually no owners of stage 2+ cars that have not had transmission problems. With 10 years on the legacygt and nasioc boards, i've seen people blow more than just a clutch - entire gear sets, differentials and half shafts.

More importantly, there are no happy subaru automatic transmission (5eat) owners out there despite replacing valve bodies, torque converters, solenoids. The transmission was not built for that kind of torque increases. It appears that the 8hp70 transmission should be the one matched to the supercharged pentastar, not the 845re, based on the power gains.

specifically talking about the v6 wk2's, they are mated to the nag1 (wa580/w5a580/mercedes-benz 5g-tronic/mercedes 722.6). That have an input shaft rating of 796 lb-ft and the same transmissions used in wk1 srt8's as well as sl65amg (twin turbo v12). The only issue for these transmissions, as far as longevity is concerned, is fluid temperatures and fluid condition.

so to summarize it, i am afraid of boost on a normally aspirated engine given the kind of damage done by 6 psi boost increase to a powertrain that was designed to take the abuse of forced induction. And that being said, i absolutely think forced induction is the way. I acknowledge that 6 psi of pressure in a 3.6 v6 is not the same as 6 psi of pressure in a 2.5 h4 but if i had a jeep v8, i would feel a lot more comfortable supercharging it at 6 psi.

the 3.6l v6 is a much better flowing motor than the 5.7l hemi.

3.6l v6= dohc, 4 valves per cylinder.

5.7l v8= ohv(pushrod) 2 valve per cylinder

with the ripp kit, is there a way to turn down the boost for the pentastar to ...2 psi ? Probably it would have to be done via a mechanical solution such as a pulley? Manual boost controller ?

you could, with a larger pulley, are tunes are scaled so np, if you really wanted to...

ripp

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  #26  
Old 07-25-2015, 12:24 AM
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Re: Why no love for the 3.6?

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Originally Posted by f1anatic View Post
Ahhh the Bimmer zealots. Yeah bro, it is inline, but I would never own one hence I thought of the Audi and then by extension, of both the Range Rover and the Ripp V6 Pentastar. Just about the only BMW I would ever own would be the 4 Series Gran Coupe 435i xDrive. But before I drop $60,000 on one of those, I would consider a few other cars.
I'm a Bimmer zealot? Then why did I sell my Bimmer and buy a Jeep?

No zealotry here just 32 years of wrenching on everything with 2 to 18 wheels and pretty much everything in between (and some beyond...good lord there are a lot of bogey/idler/drive wheels on an Abrams).

I appreciate the engineering behind things more than the name-tag associated.

I completely agree with you that a purpose built forced induction engine is going to ultimately be the more reliable solution so I am not entirely sure why you had to start slinging insults in my direction.
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Old 07-25-2015, 01:02 PM
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Re: Why no love for the 3.6?

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Originally Posted by ZLTFUL View Post
I'm a Bimmer zealot? Then why did I sell my Bimmer and buy a Jeep?

No zealotry here just 32 years of wrenching on everything with 2 to 18 wheels and pretty much everything in between (and some beyond...good lord there are a lot of bogey/idler/drive wheels on an Abrams).

I appreciate the engineering behind things more than the name-tag associated.

I completely agree with you that a purpose built forced induction engine is going to ultimately be the more reliable solution so I am not entirely sure why you had to start slinging insults in my direction.
I am sure the humor was not well transmitted so please accept my apologies regarding the BMW zealotry statement.
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  #28  
Old 07-28-2015, 01:16 PM
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Re: Why no love for the 3.6?

to answer my own question, the prodigy turbo would in fact work on the GC but obviously all the piping would have to be changed. They stated that they plan to make a turbo kit for the 3.6L but no time in the near future.
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Old 07-29-2015, 08:46 AM
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Re: Why no love for the 3.6?

So, to wrap things up here, we are talking about a V6, 5000lb SUV originally built for comfortable offroading and asking why it doesn't have the same performance aftermarket as an Audi or BMW sports sedan.

I think this is a no-brainer.
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  #30  
Old 07-29-2015, 12:54 PM
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Re: Why no love for the 3.6?

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Originally Posted by dcorn View Post
So, to wrap things up here, we are talking about a V6, 5000lb SUV originally built for comfortable offroading and asking why it doesn't have the same performance aftermarket as an Audi or BMW sports sedan.

I think this is a no-brainer.
I think you got the original point of this thread wrong, I believe it just a demand issue for said kits for the 3.6L, and Ripp just happens to be the only one making a Kit. To say this SUV would be originally built for comfortable offroading? with this stock suspension I believe would be wrong to, I believe it to be designed more toward the everyday "mallcrawler" driver.
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Old 07-30-2015, 03:19 AM
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Re: Why no love for the 3.6?

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Originally Posted by dcorn View Post
So, to wrap things up here, we are talking about a V6, 5000lb SUV originally built for comfortable offroading and asking why it doesn't have the same performance aftermarket as an Audi or BMW sports sedan.

I think this is a no-brainer.
Well here's why. Blame the Wrangler market and the Hemi market for it.

Nobody really needs massive torque and wheel horsepower when going offroad. Thousands of Wrangler owners off-road their Pentastar-powered beasts without problems. Yes yes diesel would be nice to have but off-road wise, that old saying "as slow as possible, as fast as necessary" is so very true. As for every other application out there where the owner demands power and speed, there is not one but 3 Hemi (5.7; 6.4 and the supercharged Hellcat) engine choices.

With sufficient power for 4x4 in the off-road market from the V6 (where owners focus more on tires, suspension, differentials etc.) and the availability of a powerful V8 engine for almost any other application demanding speed, the ubiquitous Pentastar was not developed by the aftermarket manufacturers.
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