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Unread 12-22-2013, 09:39 PM   #1
Jeep_Fanatic
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4.7 bored?

I've got the standard renix 4.0L in my MJ paired with the pos BA10/5, both are leaking really bad.

I'm looking into a project soon, and i want to see if anyone out here has actually tried making the 4.7L strokers bore bigger as well as shaving the cylinder head a bit to increase compression.

so far all ive heard was that the 4.7L can be made by adding a 4.2L crankshaft into a regular 4.0L, i dont know if there was any more there seems to be patches of info scattered across the forum and its not too clear to me.

I was thinking about getting 4.0L HO motor and ECU from a later model cherokee and pair it with the AX15 and NP249 for my MJ(yes i prefer full time 4x4)

while doing that I could bore the motor to fit larger pistons, shave the head for compression, install roller cams, alot of aftermarket valve assemblys, and of course add the stroker kit. I might as well skip the power steering, AC, and use electric fan and open cooling system. I'll have to use a bigger radiator and an 'on-top' alternator as well. I do want to ask more about a dry sump system if they make it for the 4.0?



thoughts?

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Unread 12-23-2013, 03:39 PM   #2
StanF
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Here's some good links:

http://www.jeepstrokers.com/forum/in...f8595c2d59af63

http://www.jeep4.0performance.4mg.com/stroker.html

http://www.505performance.com/JP_magazine_NOV_2009.html
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Unread 12-23-2013, 04:54 PM   #3
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Second link very helpful, thank you

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Unread 12-23-2013, 06:31 PM   #4
jsawduste
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The second link is by Dino "Cheromatic" from the UAE" While it works OK in the land of sand it is not the best choice for American based fuels. Take his information with a healthy grain of salt.

505 and the owner Zach has been a subject of many bad threads. Poor parts, poor customer service and some of his business actions are questionable. Personally I not let him wash my tires much less buy anything from him.would let him.

You want good stroker information then by far Hesco is the way to go.
http://www.hesco.us/


FWIW I run a stroker and a fairly healthy one at that. Pushing close to 300 horde as measured on the dyno. My build was a little bit different then the norm but has proven itself to work pretty well.
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Unread 12-23-2013, 09:04 PM   #5
StanF
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Quote:
Originally Posted by jsawduste View Post
The second link is by Dino "Cheromatic" from the UAE" While it works OK in the land of sand it is not the best choice for American based fuels. Take his information with a healthy grain of salt.

505 and the owner Zach has been a subject of many bad threads. Poor parts, poor customer service and some of his business actions are questionable. Personally I not let him wash my tires much less buy anything from him.would let him.

You want good stroker information then by far Hesco is the way to go.
http://www.hesco.us/

snip
I just picked out a couple of interesting links for him to review. I definitely wasn't recommending any company - with the research that I've done, my impression is that none of the stroker companies have a stellar reputation. Maybe Hesco is different. They don't have pricing on their webpage, unfortunately.

For the OP, use google, use the search function on the forum, and you'll get a ton of information. Research, research and research
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Unread 12-23-2013, 11:20 PM   #6
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Quote:
Originally Posted by StanF View Post
Maybe Hesco is different.
Back when AMC was into offroad racing they contracted Hesco to build and run the race program. Which meant that the engines were mostly 4.x based. Bennie and Leee (yes, 3 E`s) have forgotten more then most others will ever learn. Aluminum heads, rare crankshafts, several different ignition systems, cams etc etc. Not the cheapest but in the stroker world regarded as the best.
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Unread 12-28-2013, 09:10 AM   #7
ltrail
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I'm just getting my 4.7 going and working out some bugs in my 91 xj. Used comp cam(not too big), 4.2 crank(needed spacer), 4.2 rods, ho block/head, .030 over, decked a pinch, valves and seats cut. That seems to be the sweet spot, I have heard of 4.9-5.0L buy seems they bore block to ~.090-.120 and sonic check walls to ensure that it won't crack under load.

Personal preference says 4.7 is plenty. Once you have a block apart measure 1/8" around all the cylinders and see how close they come together and it'll scare you back down to a reasonable displacement. You're gonna have to bore the thing and hopefully the casting allows the size. It was enough for me to want longevity over size.
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Unread 12-28-2013, 08:08 PM   #8
jsawduste
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Have to look at things a bit different.
Went + 080 on mine. Increase in displacement but more important is a bit more un-shrouding of the valves. Bit more airflow at higher lifts.
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Unread 12-29-2013, 10:34 AM   #9
ltrail
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How much displacement do you believe to have achieved @ .080, and long rod or short?
I used the crank and rod from 4.2, and .030 over piston. from a couple online calculators I should be 4675cc(4.7L) I added all the head work, milling, deck block etc.
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Unread 12-30-2013, 09:48 AM   #10
jsawduste
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Quote:
Originally Posted by ltrail View Post
How much displacement do you believe to have achieved @ .080, and long rod or short?
Used Eagle H beam rods which are longer then even the 4.0s. Custom Diamond Racing pistons to give me the 9.65 compression at 0 deck
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Unread 12-31-2013, 08:55 AM   #11
ltrail
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I won't start the long/short debate for hp vs tq, but I chose the short rod for a bit more low end crawling. My cam also was a lower end idea. It'll make power from ~600-4000 and dumps off.

Designed for what you do im sure the build makes the difference. A buddy is going long rod 4.7 also and I plan to eat him off the line and in rocks and he will get me in the go fast portions.

Still curious your overall displacement? And for op, the factory parts all jammed together should yield 4.5L according to my calculation. Machine work will make the difference here.

Must have missed this in op but how and where are you finding roller cam for 4.0? Seems impassable?
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Unread 12-31-2013, 09:35 AM   #12
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Quote:
Originally Posted by ltrail
where are you finding roller cam for 4.0? Seems impassable?
It exists, better than the flat system.

http://www.shop.505performance.com/p...?productId=178

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Unread 12-31-2013, 03:06 PM   #13
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Quote:
Originally Posted by ltrail View Post
I won't start the long/short debate for hp vs tq, but I chose the short rod for a bit more low end crawling. My cam also was a lower end idea. It'll make power from ~600-4000 and dumps off.

Designed for what you do im sure the build makes the difference. A buddy is going long rod 4.7 also and I plan to eat him off the line and in rocks and he will get me in the go fast portions.

Still curious your overall displacement? And for op, the factory parts all jammed together should yield 4.5L according to my calculation. Machine work will make the difference here.

Must have missed this in op but how and where are you finding roller cam for 4.0? Seems impassable?
The 4.7 engines are really rounded up from 4657cc`s. My +.80 gives an actual 4.704 cc`s. So interpret it as you wish.

The important fact is the rod length to stroke ratio is improved quite a bit with the Eagle rods. As is the bore to stroke ratio. Almost a square engine.

I`ll respectfully disagree with your short rod more low end comment and say that the overall engine setup that optimizes what you want the engine to do is more prevalent. Sure there are fundamentals in engine building that effect BMEP. Rod length to stroke and bore to stroke numbers have been pretty well proven.

In any case I`ve been on the dyno with numbers close to 300 hp and 275 lbs/ft of torque. I am happy with the results and the engine works just fine for my intended usage.

As for Zach at 505, I wouldn't believe a word he says or buy so much as a lock washer from him/them.
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Unread 12-31-2013, 11:02 PM   #14
ltrail
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Agreed on the displacement roundup, as said mine is ~4675cc according to online calculation. I can understand the disagreement on the bore vs stroke, but must say there's a reason engines like Honda (in NA form) don't make torque for their lives. You are reducing the piston acceleration by having more dwell with the shorter rod and longer stroke. I'm familiar with the performance of square engines, they have the best of both worlds.

Ive personally never seen a roller cam in 4.0 working properly and due to block design doesn't seem feasible with both lifters connected in that fashion.
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