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  #41  
Old 02-07-2010, 06:08 PM
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Mikel Mikel is offline
 
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Quote:
Originally Posted by scotty
it was comments like this that originally got me into diesels. i see claims of 19 to 30 mpg out of diesel engies. my favorites are the guys that claim to get 20mpg while towing loaded trailers

my experiences are very different. my 4wd C&C crewcab chevy with a heavy flatbed has a n/a 6.2/rebuilt 700r and 4.10 gears,and very short tires. it weighs about 7000 lbs.

back before the introduction of ULSD if i babied the crap out of it(readut accelerated by kids on bikes ) i could get about 18/19 mpg. since ULSD with the same ultra conservative driving style,it now gets 15/16.

believe it or not i have towed with it. pulled my scout to the trails a couple of times-75ish miles each way,stop/start thru towns and some good grades and i had my foot ont he floor 95% of the time. towing it got about 8mpg.

comparatively my 96 4wd dually ext cab dodge gets about the same mileage round town-15/16. best highway mielage was 23 with a pair of d70s in the bed,and kept the speed at 55. towing my 36 foot gooseneck with 2 jeeps on it to the same trails it gets 9/10. of course thats easily twice the load as the small bumperpull trailer with 1 rig on it. towing smaller trailers i get anywhere from 12-16 mpg depending onthe size,and the route.

my whole point here is that it takes a certain amount of power/energy to move a relatively unaerodynamic mass down the highway at whatever speeds.

i would not have high hopes for getting 20+ mpg in a FSJ with a small underpowered turbodiesel. even with bigger,more powerful TDs to get good mileage youll have to keep your foot out of it and your cruising speeds slow.

having said all that, i think the 4bt is the best choice for a FSJ thats purpose is mainly DD suties,and maybe some mild towing.

My 4BT-powered J300 consistently gets 23-25MPG on the highway with me driving like a maniac. Gearing is too tall to drive any slower For a truck with Dana 60/70 axles and a NP200 T/C, I'm not complaining one bit.

I'm switching from 3.08's to 3.73's shortly. Gearing is fine for most of what I do, but I want to be able to do some towing. The engine puts an estimated 150HP and the truck feels faster than some 360 FSJ's that I've had.



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Last edited by Mikel : 02-07-2010 at 06:12 PM.
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  #42  
Old 02-07-2010, 07:06 PM
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AMC-J/20 AMC-J/20 is offline
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Quote:
Originally Posted by scotty
it was comments like this that originally got me into diesels. i see claims of 19 to 30 mpg out of diesel engies. my favorites are the guys that claim to get 20mpg while towing loaded trailers

my experiences are very different. my 4wd C&C crewcab chevy with a heavy flatbed has a n/a 6.2/rebuilt 700r and 4.10 gears,and very short tires. it weighs about 7000 lbs.

back before the introduction of ULSD if i babied the crap out of it(readut accelerated by kids on bikes ) i could get about 18/19 mpg. since ULSD with the same ultra conservative driving style,it now gets 15/16.

believe it or not i have towed with it. pulled my scout to the trails a couple of times-75ish miles each way,stop/start thru towns and some good grades and i had my foot ont he floor 95% of the time. towing it got about 8mpg.

comparatively my 96 4wd dually ext cab dodge gets about the same mileage round town-15/16. best highway mielage was 23 with a pair of d70s in the bed,and kept the speed at 55. towing my 36 foot gooseneck with 2 jeeps on it to the same trails it gets 9/10. of course thats easily twice the load as the small bumperpull trailer with 1 rig on it. towing smaller trailers i get anywhere from 12-16 mpg depending onthe size,and the route.

my whole point here is that it takes a certain amount of power/energy to move a relatively unaerodynamic mass down the highway at whatever speeds.

i would not have high hopes for getting 20+ mpg in a FSJ with a small underpowered turbodiesel. even with bigger,more powerful TDs to get good mileage youll have to keep your foot out of it and your cruising speeds slow.

having said all that, i think the 4bt is the best choice for a FSJ thats purpose is mainly DD suties,and maybe some mild towing.

my truck holds 30 gallons and goes 550-650 miles per tank . . .

550/30= 18.34mpg towing & 650/30= 21.67mpg empty

so i lied its more like 18-22mpg

My apologies, Maybe my turd isn't doing so bad then still doggy as piss

Mike
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  #43  
Old 02-07-2010, 10:11 PM
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http://www.4btswaps.com/forum/showthread.php?t=7042
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  #44  
Old 02-07-2010, 10:17 PM
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Quote:
Originally Posted by Mikel

I'm switching from 3.08's to 3.73's shortly. Gearing is fine for most of what I do, but I want to be able to do some towing. The engine puts an estimated 150HP and the truck feels faster than some 360 FSJ's that I've had.


I'm curious how you're getting 150 HP from your 4BT.
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  #45  
Old 02-07-2010, 10:30 PM
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I would like to get ahold of one of our (Cummins) new light duty diesel engines. I don't know much about it except it is a V-8 and I believe it is 5 liter. It was in a new Dodge Ram 4x4 for testing not too long ago.
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  #46  
Old 02-08-2010, 04:39 AM
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Quote:
Originally Posted by tgreening
I'm curious how you're getting 150 HP from your 4BT.

HY35 turbo, 3200RPM governor spring, intercooler, turning the fuel pin to its deepest setting and maxing out the power screw... Again, notice I said "estimated".
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Last edited by Mikel : 02-08-2010 at 06:13 AM.
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  #47  
Old 02-08-2010, 08:01 AM
tgreening tgreening is offline
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Quote:
Originally Posted by Mikel
HY35 turbo, 3200RPM governor spring, intercooler, turning the fuel pin to its deepest setting and maxing out the power screw... Again, notice I said "estimated".


I'm not disputing your claim. I just want to know how you did it. I have one I'm putting in a J20 and I'm curious what power improvements I can make during install without having to crack open the motor. Since an intercooled 4BT is factory rated @120 I don't see your estimate as unreasonable I "guess". I guess only because I don't know what mods net what as far as HP/torque go.

I'd like to keep mine stock as far as the turbo and injectors go (for now at least) and see what I can get with just tuning. I don't intend to go after maximum numbers but I'd like to get what I can out of the relatively stock set up.
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79 CJ7 Q/T, 258, 31's
77 CJ5, V8, 33's
94 Cherokee, 31's
68 J-3000, 232, 3 on the tree (under the knife soon)
78 J10, 360, Q/T, auto. Sacrificial lamb.
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75 J20, 360, Q/T, auto. Reprieved sacrifice.
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  #48  
Old 02-08-2010, 08:29 AM
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granted i dont know alot about the 4bt,but with an intercooler and pump tweeks 150 seems like quite a reasonable estimation to me.

with mods a VE pumped 6bt is capable of about twice that with 2 more cyls.

id love to stuff a 4bt into my DD xj
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  #49  
Old 02-08-2010, 11:44 AM
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Quote:
Originally Posted by tgreening
I'm not disputing your claim. I just want to know how you did it. I have one I'm putting in a J20 and I'm curious what power improvements I can make during install without having to crack open the motor. Since an intercooled 4BT is factory rated @120 I don't see your estimate as unreasonable I "guess". I guess only because I don't know what mods net what as far as HP/torque go.

I'd like to keep mine stock as far as the turbo and injectors go (for now at least) and see what I can get with just tuning. I don't intend to go after maximum numbers but I'd like to get what I can out of the relatively stock set up.

Hello,
No offense taken at all. If you haven't already, I would visit www.4btswaps.com There is tons of information on the matter there. I have seen dyno numbers of a stock CPL 858 4BT (the most common breadvan, non intercooled type) reaching 188HP and about 400lbs-ft to the flywheel just playing with the pump. I would think mine is at about that level, but I do have to keep an eye on the EGT's, which force me to take my foot of the gas sometimes, specially during long uphill stretches of highway.

Easy things I haven't done yet is advancing the timing (bolts behind pump are hard to reach) and replacing the injectors (easy but $$). I hope bumping the timing will bring me closer to 200HP.
Mikel
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Last edited by Mikel : 02-08-2010 at 12:09 PM.
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  #50  
Old 02-08-2010, 03:20 PM
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Quote:
Originally Posted by tgreening
I'm not disputing your claim. I just want to know how you did it. I have one I'm putting in a J20 and I'm curious what power improvements I can make during install without having to crack open the motor. Since an intercooled 4BT is factory rated @120 I don't see your estimate as unreasonable I "guess". I guess only because I don't know what mods net what as far as HP/torque go.

I'd like to keep mine stock as far as the turbo and injectors go (for now at least) and see what I can get with just tuning. I don't intend to go after maximum numbers but I'd like to get what I can out of the relatively stock set up.

click on my 4bta build thread link in my signature to see the above mentioned mods installed on 4bta and then isntalled into a jeep chief. highly recommend the intercooler.
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  #51  
Old 02-08-2010, 05:57 PM
tgreening tgreening is offline
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Quote:
Originally Posted by Mikel
Hello,
No offense taken at all. If you haven't already, I would visit www.4btswaps.com There is tons of information on the matter there. I have seen dyno numbers of a stock CPL 858 4BT (the most common breadvan, non intercooled type) reaching 188HP and about 400lbs-ft to the flywheel just playing with the pump. I would think mine is at about that level, but I do have to keep an eye on the EGT's, which force me to take my foot of the gas sometimes, specially during long uphill stretches of highway.

Easy things I haven't done yet is advancing the timing (bolts behind pump are hard to reach) and replacing the injectors (easy but $$). I hope bumping the timing will bring me closer to 200HP.
Mikel


Oh yeah, been there a bunch. Enough to know that nothing brings out the accusations and finger pointing like the posts in the performance thread! Hehe. The one thing I haven't been able to find of there is a step by step performance tune on the stock setup. There's a bunch of tunes there but they're all with this turbo and that turbo, these injectors, that pump etc etc. I'd like to find the thread titled "Getting the most out of the stock intercooled 4BT."
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79 CJ7 Q/T, 258, 31's
77 CJ5, V8, 33's
94 Cherokee, 31's
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78 J10, 360, Q/T, auto. Sacrificial lamb.
78 J20, 360, Q/T auto. Future unknown.
75 J20, 360, Q/T, auto. Reprieved sacrifice.
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  #52  
Old 02-09-2010, 01:22 AM
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Quote:
Originally Posted by tgreening
Oh yeah, been there a bunch. Enough to know that nothing brings out the accusations and finger pointing like the posts in the performance thread! Hehe. The one thing I haven't been able to find of there is a step by step performance tune on the stock setup. There's a bunch of tunes there but they're all with this turbo and that turbo, these injectors, that pump etc etc. I'd like to find the thread titled "Getting the most out of the stock intercooled 4BT."


thats your mistake. stock doesnt cut it. stock is made for the hp/ torque that it is rated for. diesels and gas are different animals.



pretty simple but you have to mix and match to make things work.

think Dodge with a 6bt with a turbo and Intercooler from 1991-1993 was capatible with 160hp/420 ft/lbs so a 4bt seeking to achieve the same hp numbers needs similar turbo cfms and intercooler surface area.

I ran a HY35/9cm combo, a later designed turbo cabable of supporting simlar 235/hp numbers and 430 ft/lbs + usually underrated added that to a intercooler of similar capacity like the 91-93 cooler and you have a combo with sufficient ooling capacity, good spool up and all using stock injectors stock pump.

a stock pump and stock injecotrs are capacble of putting out more fuel than the stock turbo and motor can cool until you upgrade. the stock fuel system can typically only cool about a 15% increase maybe 20 on a after cooled motor that is about it. It is a process read on 4btswaps.com one thing begets the other that requires the next. if youwant more powe rit is about matchint he whole system not using stock parts. stock parts are matched to the stock power ratings obviously anything over tha will require parts that acomodate hp levels over stock and changes to keep it cool


the only stock intercooled 4bt is the 4bta 130 hp the 4bta 120hp had the darned water after cooler most the time and tha tdoesnt have the surface area to support much over 2 turns of the screw. the performance section has 3 thread abotu stock tunes on different 4bts and 4btas with stock components about 140 hp is all you'll get and cool
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Last edited by dusty : 02-09-2010 at 01:24 AM.
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  #53  
Old 02-09-2010, 09:19 AM
tgreening tgreening is offline
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Quote:
Originally Posted by dusty
thats your mistake. stock doesnt cut it. stock is made for the hp/ torque that it is rated for. diesels and gas are different animals.


I "get" what you are saying but some of what's over their doesn't completely support it, unless I'm completely misunderstanding you.

I'm not looking for huge numbers. I don't want to squeeze every last drop out of the motor. I found pretty much just what I was looking for in the dyno thread (of course. stupid me). A guy has a pretty much stock (parts wise) 4BT, changing only the exhaust housing and governor spring, and only tweaking everything else. He claims 162 HP and 392ft lbs TQ and claims more than acceptable EGTs with it. I would be MORE than happy with that. My superduy puts down 310 / 425. I can live with those numbers in a truck that isn't intended for extreme heavy loads.
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79 CJ7 Q/T, 258, 31's
77 CJ5, V8, 33's
94 Cherokee, 31's
68 J-3000, 232, 3 on the tree (under the knife soon)
78 J10, 360, Q/T, auto. Sacrificial lamb.
78 J20, 360, Q/T auto. Future unknown.
75 J20, 360, Q/T, auto. Reprieved sacrifice.
73 J20, 232, D20, 3spd. Axle sacrifice
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  #54  
Old 02-09-2010, 10:32 AM
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the changing of the exhaust housing causes the turbo to spool faster increasing exhaust pressures and spinning the compressor earlier and harder. pushing more air than the stock configuration was intended to do.

lets say his motor came with a 18cm exhaust housing and he drops to a 12 to increase turbo speed and does not change the compressor wheel. with the 18cm housing the turbo had less exhaust drive pressure at that level the compressor could only push so much air on the intake side now it has higher exhaust pressures pushing the compressor at higher speeds creating a situation where you have more cool air. the compressor is capable of pushing an increased amount of air where it might have only pushed 16 psi max now that same compressor might push 23-24. its a balancing act all dependant on what stock turbo he has, what the compressor side is capable of sustaining. too much drive pressure and you'll over speed the compressor and that will result in super a super heated intake charge or insufficient air. most guys have figured out by reducing the exhaust housing to a smaller size like the 12 they can get sufficent air flow to support upwards of 40-50 hp beyond stock. but that is using a non-stock exhaust housing and it depends on what the compressor side of his turbo is capable of. i can't remember so don't take this for verbatum but some turbos on the 4bts had 50 mm compressors and 18cm exhaust housings and the compressor were capable of something like up to 325 cfm but in stock for only was pushing maybe operating at 60% so 195 cfm. others came with a 16 cm exhaust housing and could push a little more air. point is dropping the exhaust housing size with an aftermarket exhaust housing or a housing from a different model engine to 14 or 12cm resulted in the turbo reaching the needed cfm levels earlier, at a lower level and pushing it further into the efficiency range.

there is a point of diminishing return where teh compressor will cease to be able to supply the air needed but alot of these turbos are not operating at max efficiency they are operating at the efficiency necessary to support stock hp levels for multiple applications hence why changing the housing allows you to unlock a little more of the stock turbo's air flow capacity.


I'm having a heck of a time trying to write this out this morning. just know the changing of the exhaust housing is a major contributor to cooling the additional fuel. the stock injectors and pump are usually capable of supporting around 160-175 hp max. thats usually what everyone is concerned with when talking about max capabilities of the motor. then we all start to swap turbos around to get it to start to spool at lower rpms, clean up the soot and push more cool air into the motor dependant on what our fueling levels are at.

sometimes though you have to increase exhaust housing size to reduce drive pressure, this will slow spool up but also will help reduce exhaust temps at some mid and higher rpm levels while raising them at lower rpm levels. it takes heat and pressure to move the turbo and the cool air it pumps keeps you from melting the pistons. So in the above example if i found that i was pushing enough fuel that the turbo was spinning 28 psi but anything past 24 psi was resulting in the exhaust temps climbing too high i might have discovered that my compressor was beyond its efficiency range. so i might decide to ditch my 12 cm housing and go to a 14 to reduce the exhaust pressure levels. my spool up would slow some but i can count on the turbo not having as much exhaust drive pressure and so the compressor will slow down some. dodges with the 6bt used to run into this they had a 56mm compressor and a 12 cm exhaust housing spool up was great, drivability and hp potential was there but under load the drive pressures were too high when you turned up the pump. the solution for some was a 14cm exhaust housing. it still allowed the turbo to spool at close to stock speeds especially since there was additional fuel and heat pushing them but on the top end it provided that little bit more exhaust flow to prevent the compressor from being overdriven.


Dont know if any of that made sense but if you start playing with exhaust housings you are no longer dealing with a stock motor.


the intercooler in my opion just helps prevent heat sinc on long towing grades etc.

I don't like pushing all my parts to thier max. i seek out the hy turbo because they are cheap usually $300 +/- it has a 54mm compressor on the early models and a 9 cm exhaust housing, the heavier compressor requires a little more pressure to get it spinning but it will push more air once it gets going and the smaller exhaust housing helps increase the drive pressre on the exhaust side to get it spinning. you have to add fuel to create the additional heat & pressure also. it's a balancing act when you want more air. i could change exhaust housings but the hy is a newer design and seems to fit the 4bt really well. id pay $100-$150 for an aftermarket exhaust housing and id still have an old turbo design and turbo or i can sell mine for $150-200 and buy anhy and have more potential down the road.
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Last edited by dusty : 02-09-2010 at 10:40 AM.
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  #55  
Old 02-09-2010, 03:53 PM
tgreening tgreening is offline
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Quote:
Originally Posted by dusty

I don't like pushing all my parts to thier max. i seek out the hy turbo because they are cheap usually $300 +/- it has a 54mm compressor on the early models and a 9 cm exhaust housing, the heavier compressor requires a little more pressure to get it spinning but it will push more air once it gets going and the smaller exhaust housing helps increase the drive pressre on the exhaust side to get it spinning. you have to add fuel to create the additional heat & pressure also. it's a balancing act when you want more air. i could change exhaust housings but the hy is a newer design and seems to fit the 4bt really well. id pay $100-$150 for an aftermarket exhaust housing and id still have an old turbo design and turbo or i can sell mine for $150-200 and buy anhy and have more potential down the road.


I get the bulk of what you are saying so you're doing fine explaining. Maybe I:m the one coming up short. I don:t mind making some non stock modifications, I just didn:t want to get into changing pumps, injectors, doing head studs, O-ringing the head etc ect. I don:t have the desire to go after the kind of performance I think necessitates those kinds of changes.

Swapping in a new turbo I don:t mind as long as the cascade effect doesn:t get too extensive. OTOH, if I can jsut change the housing, maybe the gov. spring, tweak the screws etc, and get the numbers I'm after without it running on the ragged edge I'm fine with it.

I don:t intend to be putzing around with this motor on a never ending quest for more power and torque. I want to get what I want/need and then put the thing to work and be done with it.
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83-ish V8 CJ/7 SOA 37" MTR
79 CJ7 Q/T, 258, 31's
77 CJ5, V8, 33's
94 Cherokee, 31's
68 J-3000, 232, 3 on the tree (under the knife soon)
78 J10, 360, Q/T, auto. Sacrificial lamb.
78 J20, 360, Q/T auto. Future unknown.
75 J20, 360, Q/T, auto. Reprieved sacrifice.
73 J20, 232, D20, 3spd. Axle sacrifice
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  #56  
Old 02-09-2010, 07:23 PM
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My advise go in stages. you'll keep costs down and be able to figure out what your needs are without spending buckets of cash.

install the 3k gov spring because that helps with drivability

drive the rig.

turn the full power screw in a couple of turns

drive the rig

then valuate your like and dislikes. ie too much smoke off the line or hazey and slow to spool or hot exhaust temps while cruising or hot exhaust temps when towing or both these things will help you identify and tune the system to the power level that suits your driving.

adjust some more

drive it again. you'll find the spot that seems to be the right balance of power and mileage.


O ringing the head, twin turbos, pump changes, cams and head work are all big $$$$ and not necessary.

when i did mine, my first objective was making sure that even when at WOT towing the rig would not risk melting a piston and making sure nothing was being over worked. Iknew i wanted to turn things up and i knew i wanted close to 180 hp and 420-440 ft/lbs but i also wanted the option to push thepower to 210/500 and not have exhaust heat issues. after i set that benchmark i adjusted things around under that point. to find the happy medium that worked for my driving and towing around. Nice thing about a diesel it only makes that kind of power when you pour the coal to it so everything for the most part can be regulated by your right foot, you can always go a few hp over what you think you'll need and then odds are you'll probablynever use it but its sure nice to have it when you need it.

anything under 34 psi is safe stock head bolts will suffice on a 6bt it seems 40-45 psi on stock head bolts before you have hg issues. but i think a big part is letting the rig warm up before taking it out for a drive. my rig spent very little if any time over 28 psi and really never needed to be over 24 psi but i had the fuel and throttle there that if i really needed the hp i could pull out a 32-33 psi puff and go session. injectors arent really necessary unless you end up with one that goes bad then spend the money and have them built for 20 or so hp over stock. they are easy to change out about 20 minutes (like spark plugs) and then dial back down the injection pump.


other than that i would leave the turbo till after you find the acceleration and towing power that is sufficient for your needs then decide if the egt's need some help and look at your options via turbo change or exhaust housing.


Cionsider changing the lift pump from diaphram to piston style far more reliable with todays dry fuels


on the mild end of the 4bta things 200-210 hp and below there really isnt a cascade its just tuning and adjusting to your needs. above 250 hp look out now you are double what the factory rating was and thats asking to spend money and it takes alot to get there.
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Cherokee S Chief Widetrack W/ Cummins 4bta Diesel, 91 dodge intercooler, hy35/9, AC NV4500/D300 3.54's Ploks 4" BJ's w/ 33's, scout 33 gal fuel tank ( Sold, to a good fsj home)
The 608.9 hybrid dana 44 build

AMC 401 supporter

GO UM Montana Griz

"Dont worry the Coors light engineering department will be documenting this accordingly."

Last edited by dusty : 02-09-2010 at 10:21 PM.
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Old 08-25-2012, 05:33 PM
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Southern Gorilla Southern Gorilla is offline
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Join Date: Apr 05, 2010
Location: Euless, TX
Posts: 532
I fight myself over this question all the time. The 6bt looks like the obvious choice because of all the aftermarket support and cheap mods. But all those parts and mods will also work on the 4bt. So is the 4bt the right choice? But my experience with the big diesels tells me that Caterpillar makes the most reliable, hardest working engines. Not to mention the added bonus of having that gorgeous Yellow Motor under the hood.

One thing I know for certain... if money were no object, and I could actually find one, there would be only one choice;
http://www.youtube.com/watch?v=B4S4NqqU9FQ&hd=1
That sound... oh, that sound.
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It's not an SUV. It's an SEV: Surface Exploration Vehicle.

'76 Cherokee NT
360/T-18

Trailers belong behind trucks, not under them.

Why? Because nobody in the history of 'wheeling has ever said, "good thing I put those smaller tires on my rig."
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