HP Increases for 4.7L Flex Fuel

Has anyone done significant mods to their 4.7L and what are your HP gains? I have done all the standard "bolt on" mods except throttle body. I have been looking to install a blower on it (preferably a twin screw) and get about 400 HP out of the thing, but would settle for the mid 300's. I am not sure this is even possible. I would like to stick to a supercharger given all of the issues with turbos in aftermarket mods. I know many will ask "WHY?" - Let's just say "JUST BECAUSE" :cool: Yes, I should have purchased a Hemi and all that jazz so lesson learned. Any input would be appreciated. I have talked to Kanne Bell and they don't offer anything for the 4.7L

Forget the blower. If you want some serious passing power what you need is what I have disquised as a storage pod. It's a J.A.T.O. rocket. Gaurenteed to give you a kick in the pants when you just gotta pass that other guy.

https://theultimatejeep.com/images/i...10/jato2-1.jpg

HAHAHAHAHA!!!! That is a great photo HueyPilotVN! Good commentary too.....I'm still laughing!

Straight from a C-130 to the rooftop of your commander! If you want to go cheap you can go to a hobby store and buy some Estes Rocket kits and tape the engines on the back. Be sure to post some pics if you do though.

So I have talked to Lysholm, Kenne Bell and Vortech. No one seems to be interested enough in the 4.7L to do aftermarket mods such as this. Seems like they are steering away mainly from re-flashing the ECU especially when 4WD systems are involved.

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Originally Posted by strokeZ

So I have talked to Lysholm, Kenne Bell and Vortech. No one seems to be interested enough in the 4.7L to do aftermarket mods such as this. Seems like they are steering away mainly from re-flashing the ECU especially when 4WD systems are involved.

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Well dude this is half the fun bro. Making stuff work and fit that is not made for it will make it a one off mod. If you want one get one thats close and invent the rest to make it fit. I think finding one to fit will be easy. The hard part dealing with the computer that will be the challenge.

yeah unfortunately today's vehicle electronics make it tough to do this type of mod. But I agree it is half the fun!

maybe some of the guys who have programmers can let you know what kind of option it comes with. Is there anything in there that can be set to handle a supercharger.

From my limited experience there are all sorts of things to worry about. Not only the ECU programming, but you should not go more than 90% of the fuel pump more than 95% of the time. Also I would need proper sizing of larger fuel injectors to handle the increase demand That plus intake issues gets it pretty messy pretty fast. Maybe there are more bolt on options that I can do before this type of project.

I wonder if anyone makes headers for the 4.7 liter enigne that could be modded to work on the XK.

I think you need to figure out where else this engine is being used and cross reference the parts you need that might help.

It was used in the Durango's for sure and quite likely the Aspen. I was just looking at headers yesterday but found nothing specific. So now I am thinking bigger throttle body, headers and maybe free flow cats. For the size of the displacement, there should be a decent amount of power left in it. I might call a few performance shops to see what they might have done or if they have any other options. If I could eek out 330 HP w similar torque gain I would be a happy guy......

I just searched the net for headers and it looks like were out of luck. It seems like there wasnt enough room in a lot of the engine compartments that the 4.7 L came in.

That is exactly what led me to research a supercharger 07JeepXK. Short of swapping out the cam at a hardcore shop, there seems to be little that can be done from a bolt on application standpoint.