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check out rippmods
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Have you actually made noticeable power yet?
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Everyone knows stickers add HorsePower!
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Super chargers typically increase MPG from what I've learned.
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Gears, Gears, Gears. Your 3.8l is doing about all it can do! Naturally aspirated. And if you have put larger tires on, without regearing, you have really killed the power that it does have. K&N= dirt; if you do any offroad stuff. I threw mine in the dumpster and went back to factory without noticable difference in power or performance. It just doesn't sound as powerful.. I have a '10 2 dr and went from the stock 255/70-18's (32's)
to 285/75-16's ( 33's) with 6 speed manual and have not yet regeared and that made a HUGE difference at hiway speeds. That really robbed the power that it does make!! I now hardly ever shift above 4th gear because 5th and 6th just do not have enough power to pull itself properly. Will be putting in 4.88's with selectable lockers in near future, which will put RPM's about same in 6th as I now have in 4th. And this will also make a big difference in offroad capabilities.
Good luck. Don.:thumb:
Experience= that is what you get right after you need it the most!
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236 Posts
No supercharger on the Jeep (at the moment), however I have built a few supercharged engines, the last being a roots based Eaton MP62 on a Miata. Fuel economy went from a reliable 32mpg no matter the driving conditions to a whopping 25mpg if you didn't get your foot into it. Under boost playing around it got right at 10mpg! When you supercharge an engine you are adding massive amounts of air, which in turn allows you to add massive amounts of fuel to keep the air fuel mixture at or near stoic. I just can't see how adding boost to an engine is going to increase fuel economy. Yeah there is going to be more power in relation to the weight of the vehicle, but that extra power is coming at the expense of burning more fuel. Only way I can see to increase the power and fuel economy is to swap in a larger engine that is already more fuel efficient in a heavier truck, then you gain some in the HP to weight ratio and could see an increase in MPG.
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236 Posts
Yeah, and they may actually be on to something with the centrifugal setups...I haven't played with any of those. In theory it would be possible to move the torque curve down enough to actually bring the overall efficiency of the engine up to a point where your usable power range is in an area where you could see an increase in fuel economy. But it would require you to drive very very very responsibly...and where is the fun in that? You've got a supercharger!!! PLAY WITH THAT SUCKER!!!
unk:unk:unk:
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236 Posts
Was just sitting here thinking about this a little more and I can actually see where you might be able to get an increase in fuel economy with a supercharger. Everything I've set up has been built for racing, high rpm high horsepower, but on a Jeep or a truck in general you are likely not going to be looking for max HP, you are looking for max torque. Set up right a SC can give you an almost DC motor like torque curve, from off idle up to about 4000rpm, at 5250rpm HP passes torque on the curve, 5250 is actually the constant used for figuring HP, at that point torque will never be higher than HP. It's above 5250rpm where you are making the most power and needing to increase fuel rate almost exponentially to keep ahead of pre-ignition. I doubt most people in normal driving rev their Jeep past 5000rpms...So yeah, it is possible to see an increase in mileage with a supercharger, even taking into account the minor parasitic mechanical losses. I'm guessing that the centrifugal SC's may be a tad more efficient as to parasitics in comparison to a roots type. Hrmmm...I'll have to dig out some of my old simulation software and see...like I say I've never bothered running the numbers on a high torque low rpm setup lol, I always just built to get through the 1/4 mile as quick as possible, fuel economy be damned!
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I'm looking forward to getting mine and getting it installed...unfortunately MPGs of any reasonable numbers will never be in my future with these 1600lb tracks:banghead:Yeah, and they may actually be on to something with the centrifugal setups...I haven't played with any of those. In theory it would be possible to move the torque curve down enough to actually bring the overall efficiency of the engine up to a point where your usable power range is in an area where you could see an increase in fuel economy. But it would require you to drive very very very responsibly...and where is the fun in that? You've got a supercharger!!! PLAY WITH THAT SUCKER!!!
Right now my biggest hope is that I dont tear up my 70,000 mile engine. From what I understand Ripp does sort of "tune down" there set up to something like 3 or 4 or 5lbs instead of the 10 its capable of...I'll post something when I'm smarter!
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