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Looking for more power out of the 4.7

2K views 32 replies 15 participants last post by  McCallieJ 
#1 ·
Stock 4.7 right now, but the old ticker has 180k on her. Don't think I want to drop a bunch of coin on this motor. Have been tossing around the idea of

A- buying a crate motor tear it down to the heads and slowly as money permits rebuilding the 4.7 with forged pistons, high performance cams, etc etc...

B- buy a used motor with low miles off Craigslist, tear it down buy a rebuild kit and build it up.

C- buy a ready to go performance built 4.7 (if I can freaking find one?)

D- buy a HO 4.7 and beef it up.

Ultimately, I'd like to be sitting around 300 to 350 ponies. I've looked at superchargers and turbos. I don't know enough about either application and I'm doing as much research as I can find. I don't want more horsepower if it's going to sacrifice my life span on the motor. My goal as of now is to try to get a turbo running in the 9 to 15lbs of boost.

I've looked into different motor swaps, but the electronics and computers seem to be a nightmare on the posts I have seen. Think one guy said took 150 hours to get all the electronics dialed in😥 like to stay with something that's not going to take extreme fabricating and new wiring harness! What's your thoughts
Thanks Jon
 
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#2 ·
How's the compression on you existing motor? Does it need to be replaced? My WJ has 220,000+ on it and running strong. Granted, I just got it a little over a month ago. Still working out a few bugs.
 
#4 ·
Dan, have not done a compression test on my motor. Would be a good idea🤔. Just did all new plugs, switching to all synthetic fluids. It's a solid running motor, doesnt burn or leak anything. Just nervous with the miles. I guess I could do the work to this, run some 3" pipes, high flow cats, exhaust, throttle body spacer, ect, basically easy bolt one that can be pulled off. Get me like 15 extra horse. Worst case pull parts off if and when she's goes and put on either new or used.
 
#3 ·
McCallieJ said:
Stock 4.7 right now, but the old ticker has 180k on her. Don't think I want to drop a bunch of coin on this motor. Have been tossing around the idea of A- buying a crate motor tear it down to the heads and slowly as money permits rebuilding the 4.7 with forged pistons, high performance cams, etc etc... B- buy a used motor with low miles off Craigslist, tear it down buy a rebuild kit and build it up. C- buy a ready to go performance built 4.7 (if I can freaking find one?) D- buy a HO 4.7 and beef it up. Ultimately, I'd like to be sitting around 300 to 350 ponies. I've looked at superchargers and turbos. I don't know enough about either application and I'm doing as much research as I can find. I don't want more horsepower if it's going to sacrifice my life span on the motor. My goal as of now is to try to get a turbo running in the 9 to 15lbs of boost. I've looked into different motor swaps, but the electronics and computers seem to be a nightmare on the posts I have seen. Think one guy said took 150 hours to get all the electronics dialed indde25 like to stay with something that's not going to take extreme fabricating and new wiring harness! What's your thoughts Thanks Jon
IMO the best option if to get the low mileage one and build it up. But I don't fully understand why buy a crate and throw all those new parts away.

Lots of people *think* they want more ponies but really it's all about the torque ;)

It's not hard to get those numbers just gotta do your homework
 
#5 ·
I've been looking for just a 4.7 block, but seems most (that I have found) are mostly intact. If someone could point me where to buy just the 4.7 block that has at least been stripped down and gone over, that would be appreciated!
From what I've read the original 4.7 can handle up to 9lbs of boost. I'm still learning and researching what info I can find. Now with the torque, gears should fix that right?

Would I better off looking for a regular 4.7 or a HO? SRT would be sweet, but I'm not ready for that headache quite yet...
 
#14 ·
TB spacers give very small gains, but gains nonetheless. The blocks of the 4.7 &4.7ho are identical IIRC the benefits come in with the stronger internals. The heads flow a little more and the cams do too.

I really don't think I'm very far from your goals. ATM I don't have HO or 08+ heads because it looks like I'd be giving up to much TQ.

I'm not finished with my exhaust I may go 3" all the way and get the muffler and cats I been looking at. Currently just got rid of the stock stuff and still have 2.5" because the exhaust shop said he didn't think he could redoing the Y pipe. So it didn't make sense to go 3" if I'm still at 2.5 upstream. And if we ever get some Dyno numbers from the headers I may get them too

I don't have a TB spacer

But I have all the other mods I think ;)
 
#15 ·
TB spacers give very small gains, but gains nonetheless. The blocks of the 4.7 &4.7ho are identical IIRC the benefits come in with the stronger internals. The heads flow a little more and the cams do too.

I really don't think I'm very far from your goals. ATM I don't have HO or 08+ heads because it looks like I'd be giving up to much TQ.

I'm not finished with my exhaust I may go 3" all the way and get the muffler and cats I been looking at. Currently just got rid of the stock stuff and still have 2.5" because the exhaust shop said he didn't think he could redoing the Y pipe. So it didn't make sense to go 3" if I'm still at 2.5 upstream. And if we ever get some Dyno numbers from the headers I may get them too

I don't have a TB spacer

But I have all the other mods I think ;)
Thanks for the information. So did some more searching last night. Looks like I need to first find a good machine shop, that has access to x-ray a used block, be able to bore and hone and make sure head and cylinders are perfectly square and circle. Any play, I'll loose potential hp. It's a gamble going with a Craigslist find. But if I can find a 4.7 for under 200, get it to the shop. Have them x-ray it for cracks, or stress. If there is any, we'll there goes 200 and the price of the x-ray. However having it professionally gone through, will give me piece of mind. I would love to know how much horsepower you have now, and how you got there. There really (in my searching) isn't a great deal of info for beefing up the 4.7. Thanks again for the help. Also this project will be over the next few years. I don't have 10k just sitting in my wallet;,)...!
Thanks Jon
 
#20 ·
Honestly, the 4.7 has a pretty poor aftermarket. Seems like you'd be looking at a lot of custom (expensive) parts to add not a lot of power.

What's your actual goal with the vehicle? If you want a Grand with big power, you might be better off with a Hemi WK to start with since the aftermarket there is much larger.
 
#21 ·
Stock 4.7 right now, but the old ticker has 180k on her. Don't think I want to drop a bunch of coin on this motor. Have been tossing around the idea of

A- buying a crate motor tear it down to the heads and slowly as money permits rebuilding the 4.7 with forged pistons, high performance cams, etc etc...

B- buy a used motor with low miles off Craigslist, tear it down buy a rebuild kit and build it up.

C- buy a ready to go performance built 4.7 (if I can freaking find one?)

D- buy a HO 4.7 and beef it up.

Ultimately, I'd like to be sitting around 300 to 350 ponies. I've looked at superchargers and turbos. I don't know enough about either application and I'm doing as much research as I can find. I don't want more horsepower if it's going to sacrifice my life span on the motor. My goal as of now is to try to get a turbo running in the 9 to 15lbs of boost.

I've looked into different motor swaps, but the electronics and computers seem to be a nightmare on the posts I have seen. Think one guy said took 150 hours to get all the electronics dialed in�� like to stay with something that's not going to take extreme fabricating and new wiring harness! What's your thoughts
Thanks Jon
I guess one of the first things you should ask yourself is, "what is my budget?"

You can do pretty much whatever you want with the right amount of money, so a lot of it comes down to that. You should also figure out if you're going to need to stay emissions legal, etc...as it will make a difference on what you can do as well (ie standalone ecu, etc...)

Have you considered trying to swap in an '08+ 4.7L? Or even a top end swap to the newer head design/intake from one of those engines? You'd need the adapter that's available to use your original throttle body instead of the electronic one from the newer engine. Depending on the year of your WJ there could be some additional things like tone ring swaps, electronics(NGC or not) etc..That coupled with a custom tune from someone like SCT and you could be right in the ball park for what you're looking for. If my engine went out tomorrow I would honestly toy around with this idea myself as far as swapping in an entire engine and making it work. The newer 4.7 can make some good power. I think Superchips claims nearly a 50hp gain on top of the ~305hp it already has, so it's there to be made.

Just a thought....a turbo or SC with be the last thing I'd do, especially if you're looking for reliability to go with it.
 
#22 ·
If mine wasn't a DD I would put a centrifugal supercharger on It. Which I probably will In the future, along with a complete rebuild. But then these H.O.'s ain't that slow, mine gives a good fight with the WK SRT8. Although, I want to Increase the RPM to at least 6500.
 
#32 ·
I made a SC kit for the 4.7, top mount 6 pounds of boost. WOW it really wakes up the 4.7. With only 5 pounds of boost it adds 25-30% more power. No tuning required as it has it's own extra injector and controller for more fuel during boost. A real sleeper.

Any more boost and you risk blowing the fragile head gaskets.

You can PM me if you have any questions about supercharging the 4.7L.
 
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#33 ·
I think my goal as of now, is to keep a eye out for a good deal on a complete wj. Something with a blow trans, tcase, electrical problems, whatever. Use the block and start from scratch. Bore it, bigger pistons, upgrade cams, and do the intake on the newer 4.7. Do some better injectors, and 3" exhaust with high flow cats and muffler. I should be pretty close to my goal of 300 to 350. Once I regear, with my bigger meats if I'm still not impressed with the extra power I might go the SC or turbo route. I'd still be interested to see some pics and info on the one you made. This is something I'm planning on starting and working on for when my trusty 4.7 retires.
Thanks Jon
 
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