From this thread: JkOwners.com - The Community for Jeep JK 4x4 Owners
The question was; Why use RIPP instead of Avenger? (centrifugal vs roots). You should read the thread there is a lot of good stuff there but this was the meat of it. This is also discussing there stage I kit. The stage two kit has even BETTER tuning.
Thank you for your points, they are valid – but a bit out of context. We get this question a lot and we answer it as ethically and complete as possible. Here is a modified answer for this community we also recently posted in another.
The 3.8l V6 found in our JK’s are a narrow angle design. By nature they do not make any power at lower RPM. There simply isn’t any rotating mass there to help it along. Hence going with boost – when we approach any new program we take it seriously and with the JK community we took it even further…
As you may or not be aware of RIPP is firstly a hands-on-performance-shop and secondly manufactures a forced inductions systems. We know exactly what your implying and why you would bring these points up. It goes without saying that choosing a positive displacement blower like a roots unit would bring power is sooner, and tuning from the ECU out delivers sound results – but there’s valid if not proven point why we went our way and not the other.
Consider how Jeepers use their Jeeps, where they go, how far they are from home on any given weekend and when stuck in a rut how you need throttle control. It’s for that reason we chose to routes we did. Secondly consider who installs and tunes these kits and lastly (if not most importantly) if something should go wrong what would need to be done to get you home safely.
We chose a centrifugal because they deliver liner manageable boost at precisely the correct RPM and exactly when the engine can handle it. Vortech Superchargers build boost based on volumetric efficiency. Meaning as the engine goes up in RPM it increases its ability to move air. As it moves air it build boost increasing the power band by a nominal amount, in our case 100-120 rear when HP and 80lbs or torque. The best thing about this is its efficiency, it takes a mathematical 7-11 crank HP to deliver that meaning it’s the most efficient belt driven blower on the market. Also by being so liner the ECU deems it a consistent and works with the additional air. ECU cooperation means all the OEM safety systems are still present and all fuel trimming and ecological trimming at part throttle are 100% active. This delivers both better than stock fuel mileage and reduces your carbon foot print (for what its worth).
A roots unit will build boost real early in the RPM band, in fact below the 2200rpm we deliver at, however by experience the consequences (when it matters) far outweigh the pros. Given the narrow angle and lack of volume at lower RPM, cramming 4-6psi at 1500-2500 rpm causes havoc. Firstly it builds a tone of cylinder pressure the engine cannot displace, often leading to bent rods, blow head gaskets and a host of other pressure related issues including cracked ring landings. Secondly while the boost has been built as you go up in RPM the blower loses its efficiency,( which is ironically counterproductive) it actually starts to take more crank HP to power it – as much as 30hp to produce 4-6 psi – so the efficiency simply not there. Additionally throwing boost at lower RPM also requires much more tuning. You need a lot more fuel and timing control correction to make it smooth which leads us to our most important point the tuning.
With our system you’ll note we provide you with a pre-programmed controller, 2.5bar map sensor and two supplemental injectors. With this style system the end user is not required to install a fuel pump, regulator or larger injectors. This makes the initial install easier and by default fewer things can go wrong. But what it really delivers is security. Security because you’re not relying on a re-flashed ECU which can and will get canceled out with one trip to the dealer. Instead we approached it from the sensory side, translating the language of boost electronically to the ECU – so the ECU does the tuning for us and monitors the entire running condition, the experience is OE with more power. This provides the security you need knowing when your off road if you should ever need to take our system out of the loop you simply remove the supplied belt and reinstall your stock one and you’re up and running again. With the suggested roots blower, larger primary injector, fuel pump and regulator approach, if something goes wrong you’d better hope you have cell service. If the ECU is flashed for more fuel and air and suddenly the air that’s needed to lean out the fuel isn’t there - it’s not likely you’re going to get it home without a significant amount of work. On the trail you can’t HP tune your 440cc injectors to work!
So ALL things considered – we stand by our initial statement – ours kit is a logical choice for Jeepers.
The following is from a post in the other forum; we modified it to fit the issues being addressed here.
Speaking from our 18 years experience with small displacement forced induction systems our position is – been there - done that. Roots blowers are simply not as reliable on a whole and by nature only deliver 60-70% efficiency per pound of boost. Additionally they deliver air pulsations throughout the rpm band which act like jack hammers to the internals – no amount of tuning can fix that. These air pulsations also wreak havoc to the MAP sensor relied upon by the factory ECU, needing more tuning, leaving it all in the hands of the programming unit. Lastly, because they deliver boost in a take it or leave it fashion, throttle modulation off road can become tricky. Confessed wrangler TJ owners (we also produce and support the 4.0 straight six wranglers) who have wheeled with roots blowers, said that when they were propped up against rocks with inches of their tire and needed to move is a controlled manor, they found it hard to modulate the throttle properly and often found themselves over powering the obstacle/brakes. And guys who liked to play in the mud holes said when they were powering threw the sticky muck; they could feel the power fall off in the upper RPM. Combine that with the added fuel consumption, lack of mid to upper power, ease of heat soak and in our professional performance tuning opinion, it’s not an ideal fit for Jeepers and what they have to rely on.
Conversely, centrifugal superchargers like the self contained V3 Si-Trim Vortech we use, build boost in direct relation to the natural air flow of the engine. This simply makes the engine feel larger in displacement throughout the entire RPM band and by default more efficient. There is no rubber banding in the power band, making tuning, ECU related or deflective, much easier. We’ve tested JK engine longevity for nearly 3 years/66k miles, and many of our clients who use their jeeps different ways have provided us with input. Like anything else there is no one product that can do everything. There are hundreds of tires and suspension packages that approach the task differently. We approached it as a whole, we took our knowledge and expertise and envisioned a kit that would deliver great on road power and excellent off road reliability. That’s why we waited until we accrued 33k miles on our test mule before we put units out on the field, and even then it was in limited quantity and with the understanding that we needed valuable input. We found our clients all experienced the same HP goals and made adjustment. We can safely say that our systems have universally been challenged in extreme heat, extreme cold, towing, water crossings, relied upon by rescue services and a host of enthusiast based wheeling. Our dealers like it because they can easily tech any issues that may arise and if needed it can be removed at a moment’s notice for any reason. Lastly the unsolicited user input has been invaluable.
Pair that to the way we fitted it completely on the outside of the factory system and there is little to no risk of you getting stuck in the middle of nowhere. So our message remains – our kit –as a whole - makes sense for the way a Jeeper uses their Jeep. Additionally you’re not limited in the future should you decide to build your engine up to run more boost.
With respect to methanol – we are not advocates of straight methanol/alcohol injection in this application… Pure Meth can and will corrode aluminum, if you’re looking for engine longevity (which most Jeepers are), this should directly impact their decision. Sprayed at the diluted levels we are using it, it evaporates before the chemical touches any metal – this delivers both air density and added octane with little risk. But it’s not a 100% necessity and if it’s not present it will only cost you a few HP and not risk knock. When we were in testing stages running in a continuous state for 10mins on our eddy current loaded dyno – we measured air temps at the intake as high as 180-200 degree’s. The meth brought it down a peak of 100 degrees and a minimum of 50. It did suppress knock and provide cooling at any speed and RPM giving us the ability to run in ignition advance and thus more efficiently. A point we want to make abundantly clear is a roots is known around our industry as the hottest type of supercharging available. Air temps can idle higher than our operating temps. Yes, you can run a sandwiched intercooler in-between the blower and the cylinder head, but you’re still relying on the heat dissipation of the front mounted heat exchanger, a pump that can fail and hose throughout that can be cut of ripped off. This leads to running your tune a bit on the rich side to bring cylinder and Exhaust Gas Temps (EGT) down, prompting waste. If you’re wheeling at 5-10mph and are looking for efficiency in all aspects, you’re not going to find it in a roots or its supporting components.
You don’t need us to tell you that you should only invest in what you’re convinced is the right thing for you. But don’t under estimate our system – it’s not an over inflated bunch of components in a box. We use high quality components throughout. For example we use stainless steel idlers and hardware; powder and black oxide coat all bare metal, SKF precision bearing in all rotating assemblies, and check for shaft concentricity down to the .001. Combine that with a turnkey system and a network of skilled ready -willing and able dealers around the world, a customer service department that never leaves you feeling alone in your investment, and the few supporting mods we have coming out for 2010 to make more power– and that’s what your spending money on at RIPP!
Your argument is legitimate – but it's one from one perspective – a roots will deliver from 1800-2500 – We feel we deliver the whole package.
Don't take our word for it call one of our dealers and get their opinion, we've added 30 over the last year alone.