Food for thought

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gmctd

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Ah, confusion, contentious conflict and chaos - my work here is done..............

So, ok, my bad on several points - musta had too much eggnog - the 3.7L 90* DCJ V6 is obviously not just an upsized 60* Mitsu V6 - it is close enuff in displacement to use one of the Mitsu turbos for mild power upgrades, and the parts are readily available in most boneyards - about that piston land position preventing puffing, I'd need more info on the pressures and rpms where any breakage occured - a turbo is no extra load on the engine, where a supercharger is increasing load as rpm and Boost increases, resulting in less net power - where you may get 45 extra hp from an exhaust-driven turbo at a certain Boost level, the crankshaft-driven supercharger will require 45hp to make that same Boost, which is a tremendous load on the pistons for nothing but overhead, which means you won't feel it in the ole buns dyno - plus, the turbo output can be ducted thru a charge-air cooler for reduced manifold air temperature - cooler air is denser air, meaning reduced Boost levels will give same power as higher Boost levels of heated air - stock engines live longer at reduced Boost levels

My bad on the trans also - the 42RE is baby brother to the 48RE behind the Cummins, but which would have made the drivetrain too long for the KJ platform, so they used the 42RLE, a derivative of the FWD 4sp auto trans beside the V6 in the minivans
 
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Ry' N Jen

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I like every other Alpha male who wants extra power have looked into turbo's, blowers, No2.
This, as you will see, is no longer available:
http://www.kennebell.net/superchargers/dodge/liberty37/libert37.htm
Turbo's? You will still need a reprogrammed ECU or a stand alone unit which is way to costly IMO and for the money, I think that tjkj is on to something with a 4.7ltr. V8.

Ofcourse, you could always opt for one of these!
http://www.jcwhitney.com/STREET-FRE...MS/GP_2011788_N_111+10201+600002080_10101.jcw
That system looks effin choice!
Heck, it looks just like the blower I have in my 1979 998cc. Mini!
Oh... But thats my heater blower! :D
I breath out more cfm than that thing!
 

Marlon_JB2

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Not that cheap here, but certainly 6-7500.00 for 03's

This girl at my school has an '02. Her father bought it for $2500 back in '06... blown 3.7L. It didn't look like much and is a 4x2 but it works!
Something like that, at the right price would be a great candidate for the 4.7L swap!
 

gmctd

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Good post - thanks for that input - also, the V8 may be an alternate choice, but you'd need the engine cradle and front suspension components from the KJ CRD, all heavier duty componentry necessary to support the heavy Diesel engine
 

tjkj2002

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Good post - thanks for that input - also, the V8 may be an alternate choice, but you'd need the engine cradle and front suspension components from the KJ CRD, all heavier duty componentry necessary to support the heavy Diesel engine
The cradle for the 3.7 V-6 is needed for the 4.7 V-8 swap since the motor mount locations are the same and in the correct location.Putting in a CRD cradle will not work and you would need to cut out and weld in new motor mounts.The 4.7 is about 70lbs heavier then the 3.7 so the OME HD coils up front will be more then enough,but why keep the weak D30A,SFA it baby:D.
 

gmctd

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Intent is: altering the engine supports in the cradle is not much price to pay to get the HD stuff under the heavier, more powerful V8 - plus the steering knuckles and associated componentry is hd - better to do it during the swap rather than find out on the trail that you should have done it
 

tjkj2002

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Intent is: altering the engine supports in the cradle is not much price to pay to get the HD stuff under the heavier, more powerful V8 - plus the steering knuckles and associated componentry is hd - better to do it during the swap rather than find out on the trail that you should have done it
Actually the early '02 and '03 KJ's with the 3.7 have a beefier cradle then even the CRD's(thicker metal and more bracing).Using a CRD cradle is a waste of time and money since you would need to cut off the mounts and re-weld new ones on,then you would need to get the different CV shafts since the CRD cradle moves the front diff to the drivers side more to clear the diesel engine's oil pan,and then you are limited to 2" of lift as not to destroy the drivers inner CV boot,again not worth it.Oh and the "knuckles" on CRD's is the exact same ones used on all KJ's,gas or diesel,even the unit bearings are the same.The whole drivetrain is the same between the gassers's and CRD's minus the engine and transmission,but if you have a '02-early '03 KJ with the 45RFE you have the same strength trans as the CRD since they are basically the same trans as the 545RFE(minus one overdrive ratio).
 
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gmctd

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Any of the heavier duty parts will need to be swapped in, then - not only is the V8 heavier, it wouldn't be very functional if the extra power ripped anything loose first time the extra ponies were unleashed

Intent of adding the turbo to the V6 would be more low-end torque for towing applications while not decreasing the original fuel economy when not towing - adding more cylinders eats more fuel, even when idling.
 

tjkj2002

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Any of the heavier duty parts will need to be swapped in, then - not only is the V8 heavier, it wouldn't be very functional if the extra power ripped anything loose first time the extra ponies were unleashed

Intent of adding the turbo to the V6 would be more low-end torque for towing applications while not decreasing the original fuel economy when not towing - adding more cylinders eats more fuel, even when idling.
I'm not thinking you understand that there is no difference in the drivetrain parts between the gasser KJ's and the CRD's,same t-case,same diffs,same CV(granted length is different),same LCA's,same UCA's,same driveshafts,same bearings,same steering.The only difference is the transmission,spring rates,and of course the engine.



Actually adding a turbo on the 3.7 V-6 would net less mpg's then adding a stock 4.7 V-8.Adding a turbo on a gas engine you also need to add more fuel,more then 2 more cylinders would take.Adding a turbo on the 3.7 would add about 30-40lbs so the 70lbs extra the 4.7 weighs in not a concern.Plus the added low end power that the v-8 has over a v-6 would actually gain mpg's in a KJ if the v-8 was left stock.The KJ is a heavy pig and the 3.7 is kinda lacking in the low end torque,the 4.7 V-8 would give it that extra low end grunt and since the 4.7 V-8 is normally in a much heavier vehicle it would sipe fuel and return better mpg's then a stock 3.7 or a turbo 3.7.If you get one of the newer 4.7's with that MDS crap and have it adapted to work when transplanted you'd get far better mpg's then even the CRD.


Let's just face it your out of your legue in the gas side of things,might want to stick to burning used oil.
 
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Marlon_JB2

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I dunno about FAR BETTER MPG than the CRD... I've had one. It's certainly capable of some really high MPG numbers, but anyways...

There's no MDS in the 4.7L.

But regardless... there's some strange belief that the Liberty CRD is "so special" in several ways other than an engine. This has been proven many many times but nobody seems to "get it" but a select few. I can't really understand why....
 

JeepJeepster

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idk but that new 4.7 would be insane in the kj... If only I was out of college and had some extra money... Maybe someday...
 

gmctd

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Actually the early '02 and '03 KJ's with the 3.7 have a beefier cradle then even the CRD's(thicker metal and more bracing - if you have a '02-early '03 KJ with the 45RFE you have the same strength trans as the CRD since they are basically the same trans as the 545RFE(minus one overdrive ratio).

According to one self-proclaimed "expert" in this thread, some KJ components are heavier duty - or was that just blowing smoke for the sake of argument?:^o
 

tjkj2002

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According to one self-proclaimed "expert" in this thread, some KJ components are heavier duty - or was that just blowing smoke for the sake of argument?:^o
That was cost saving,just like the 42RLE replacing the the 45RFE,just cost reductions.If you compare the cradle from a '02 to one in say a '05 you will see the difference,not much but you can tell.The '02 and early '03 KJ's where built a little different due to trying to get them to hit the market and fill the role of the XJ,when it did not they cost cut on them to add techno gismo's to appeal to a different crowd who did not the beefier stuff,and yes that includes your CRD's.You where saying that the CRD has HD parts over the gasser which is not true,the front coils having a higher spring rate is about it.
 

gmctd

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Exactly, and I recommend any heavier duty part(s) be installed with the V8 - I don't yet know specifically which parts fall in that category, because, as I indicated, this is food for thought, which is thinking out loud in the planning stages - any constructive input is therefore appreciated - I've been turbocharging gasoline-fueled engines since back in the '60's, when most people couldn't even spell turbocharger, much less know what one is - but, again, I do not as yet know all the particulars of the KJ chassis\drivetrain - only that DCJ usually designs, or modifies to heavier-duty, parts for heavier engines, same for more powerful engines - and, they thoughfully provide wiring harnesses with include optional upgrades

So - a turbocharger is free power, no engine loading - a supercharger is constant engine loading, requiring ever more overhead as power increases - therefore, if anyone has specific facts and numbers vis a vis the supercharged 3.7L piston failures, it will be very helpful in determining reliability for turbocharging - 'nuther words, hearsay isn't helpful, as even eyewitness accounts vary considerably
 
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CHUD

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That was cost saving,just like the 42RLE replacing the the 45RFE,just cost reductions.If you compare the cradle from a '02 to one in say a '05 you will see the difference,not much but you can tell.The '02 and early '03 KJ's where built a little different due to trying to get them to hit the market and fill the role of the XJ,when it did not they cost cut on them to add techno gismo's to appeal to a different crowd who did not the beefier stuff,and yes that includes your CRD's.You where saying that the CRD has HD parts over the gasser which is not true,the front coils having a higher spring rate is about it.

They did do some upgrades to the KJ post-2002, for example they went from drums to discs in the rear.
 

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