2.5 / 4.0 l Performance

[Gearhead]

There won't be any time spent on manifolds , the intake is quite difficult , frankly almost impossible to reach into the runners by hand , the only practical method I can think of is a process called extrude hone , where an abrasive medium is forced through . It's a paste and is heavily laden wth abrasive material , pushed through from end to end , I've only read about it and not aware of this service being offered in Canada. The exhaust is a Banks header , which is about as good as it gets.
Torque is a function of many factors , valve timing , displacement , stroke being of greater importance than bore , cylinder fill , air velocity , Header primary tube length , collector size and position and more. My goal with this is to increase air flow while maintaining air velocity , in doing so there will be no losses at low rpm . I'm very interested in getting some more top end to fatten up the entire power  band , right now it feels flat above 3500 , the valve train noise concerns me too . I'll be  going with an increase in oil flow to help keep the lifters and cam happy by using a Mopar performance high volume oil pump . The Comp cams beehive valve springs on order for this project  are more stable than the springs that are in there now , greatly reduced harmonics , less inertia and manufactured out of high quality materials.     I'm hesitating to change to a different cam right now , the bottom end torque  is great as is  and I would like to maintain the efficiency of this engine , most of the other cams have a narrow lobe separation angle , this gets you more overlap ,the result being a less efficient engine .  Most cams offered for efi use are ground with a wider lobe separation angle than cams for carbureted engines . Efi specific cams ,with thier shorter overlap are also desireable for use in forced induction applications ( turbo).

[hps4evr]

are there roller lifters for the 4.0L??? i have a feeling there arent, but figured id see if they are out there...
i do understand the air flow and air speed. i guess over all helping the engine breath easier is the ultimate goal here. what is limiting top end power after 3500 rpm? is it the air flow or is a cam/timing issue?

[Marco]

very imformative,im learning alot keep up the posts!

[Gearhead]

are there roller lifters for the 4.0L??? i have a feeling there arent, but figured id see if they are out there...
i do understand the air flow and air speed. i guess over all helping the engine breath easier is the ultimate goal here. what is limiting top end power after 3500 rpm? is it the air flow or is a cam/timing issue?

Roller lifters ?  , nothing I'm aware of ,  this would require a camshaft that has yet to be invented , the lifters themselves would need a means of preventing rotation in their bores .   Other than Hesco , Mopar , Bank's and a few other companies , those of us seeking Jeep performance products have few choices.

My goal with this round of mods is to widen the powerband and  lessen the noise of the valvetrain. I had mentioned earlier that it felt flat above 3500 , this is not entireley true , my expectations were not met with the present configuation , the bottom end power has surpassed what I'd hoped for .  the 3500 & up part  ? , I thought it might be better and it's certainly no dog at any RPM , I  feel that  limitations , if  any ,   may be tuning ,  all of the engine management stuff is stock and un molested. I do have an adjustable fuel pressure regulator which is still in it's package ,  thinking , some day I'll buy some dyno time and have the air / fuel ratio sampled before just slapping on a regulator that's not needed.   Also  , the way the stock regulator works is , under vacuum the pressure is reduced , when you mash your foot into it , the fuel pressure increases  as the vacuum reaches  atmospheric pressure .  An adjustable regulator can be set to a higher pressure  for cruise / light load / high vacuum conditions but the upper end of what pressure is available at the fuel rail is limited to what the pump can produce.

[hps4evr]

it would be nice if there was a plug and play stand alone  fuel set-up for this engine.i think Painless has a harness for the 4.0L and can come with a new cam with their own computer tune. but i doubt it is as wild as you are going jeff. maybe a stand alone set-up could be adapted. would take a lot of time and effort though. a wide-band O2 sensor could help to dial it in as well i bet.

[Gearhead]

it would be nice if there was a plug and play stand alone  fuel set-up for this engine.i think Painless has a harness for the 4.0L and can come with a new cam with their own computer tune. but i doubt it is as wild as you are going jeff. maybe a stand alone set-up could be adapted. would take a lot of time and effort though. a wide-band O2 sensor could help to dial it in as well i bet.

The engines / vehicles I work on day to day have some very nice software available to use on our dyno , an interface that marries itself to the vehicle being tuned and offers a variety of tuning variables that can be manipulated to create a custom map  suited to the particular engine configuration that has been built. Tuning parameters include , air fuel ratio for each cylinder , volumetric efficiency , startup fuel , warm up fuel , acceleration enrichment , deceleration enleanment , injector size , spark advance , the displacement can be altered using the software as needed , handy when editing each cell in a fuel table , limits are set and can not be exceeded , fooling the software is enabled by increasing the displacment of the engine in the tuning constants tab or by editing fuel injector flow rates , this allows more fuel to be added when required. Dyno runs are made at various throttle positions ( % ) and rpms while sampling air fuel ratios in real time , this data , when sampled and interpreted can then be used to edit fuel tables  and a variety of other items . The engine configurations that can be built are staggering , a wide variety of cams , a plethora of exhaust systems , compression ratios , fancy cylinder heads and matching pistons with whizzy domes , stroker cranks , big bore kits , a wide choice of engine displacements ,  several  different throttle bodies , larger fuel injectors , each build requiring it's own custom tune. The release of this software has enabled possibilities on fuel injected engine builds which in the past had to done on a more conservative and civilized level.
A while back we sold piggy back tuning devices too that I'm  not very fond of , the tuning product as described above just make more sense.   It would be nice if there was software available to tune our Jeeps , there are liabilities to this , in the wrong hands  it's not difficult to have a meltdown and wreck stuff.  Oh , our dyno , it's motorcycles only , and the badly needed dyno time I might ever get  for my Jeep will be at a location , yet to be determined.

[Gearhead]

Last month Scott had started a thread about cams n' lifters , then it died off , I figured this discussion was going to lead to some talk about cams and timing ,  the needs of a fuel injected engine and why there are cams ground specifically for EFI configurations .

 http://forum.calgaryjeep.com/index.php?topic=10554.0

[hps4evr]

i heard once the reason why nobody really has a plug and play computer that comunicates with the oem computer is because it is physically too difficult to access the factory computer. its easy to get at but chrysler coated the whole ting with that clear hardened goo. but, i think there are ways around that, just nobody has tried hard enough.
then again i did read about the Unichip available for the 4.0L... but  iwonder how far you can go with this Unichip...

[Gearhead]

i heard once the reason why nobody really has a plug and play computer that comunicates with the oem computer is because it is physically too difficult to access the factory computer. its easy to get at but chrysler coated the whole ting with that clear hardened goo. but, i think there are ways around that, just nobody has tried hard enough.
then again i did read about the Unichip available for the 4.0L... but  iwonder how far you can go with this Unichip...

Unichip is  (A)  piggyback   (B) expensive for what you get...

The PCM   , is it not blank when new in it's box ? then needs to be flashed to put the correct programing into it ?


Man   ,   I wish I knew more about this Jeep / Chrysler stuff , at Harley ,  an ECM arrives blank , we then install and flash it with a stock EPA  legal map for that model of vehicle. Stage kits are some times used like mufflers and K&N filters , simple mods like this can be  tweaked with a stage kit flash  , using our laptop and proprietary diagnostic software , this is a one time chargeable deal and further mods will require race tuner software . There are several levels of reflashes but they are not to be stacked  or loaded on top of each other  , as in , adding additional speed parts later will involve the purchase of software  so the customer should just go ahead and have it done at the begining rather than pay for a reflash , then change their mind , add more go fast stuff and have to pay for a flash followed by race tuner software. Also  , fewer stage flashes are available now than previously due to 2008 emissions laws in the USA , further and tighter emissions laws are coming , it's gonna get hard to get any performance flashes at all , in some states there are very large fines for tampering.

[Gearhead]

It's snowing , so I've got to work inside but the job continues.

Much of the exhaust port and seat work is done but the final details , this week I'm going after the intake side.

Here's the unmolested intake seat 




The intake valves are + .o6o" larger so , like the exhaust side the seats need to go bigger.

It begins with a 45 degree cut , stopping just before the cut reaches the size of the valve head.



A 30 degree top cut establishes the outer edge of the seat , a 60 degree establishes the inner edge  then a 75 degree cut , four angles .



This process is repeated across all six intake seats before the blending and throat / bowl work begins.

[Gearhead]

Once all six intake seats are cut and enlarged a Carbide burr in a die grinder is used to blend the bowl area. Attention once again is spent on uniformity , duplicating  / enlarging the venturi / throat to suit the larger valves , removing casting flash and smoothing the flaws created during the casting process. Some filing around the valve guides , a bit of tapering to the guide , very little removal of material  from the runners , especially the floor ,  just file down the casting flash and high spots followed by sanding and smoothing.

Here's the first couple being roughed in , ten to fifteen minutes spent on each bowl with the file burr , sanding begins after this.

 

[Gearhead]

Once I'm happy with the port work , I'll go back and touch up the seats with a fine set of stones , so far it's been coarse stones being used. Several more hours of sanding and blending to do yet , THEN ...............

The spring pads will need to be re-worked. The valves are tilted to the left 15 degrees , creating a small challenge in set up. I'd like to do the machining on a verticle mill , rather than use a hand drill , for a number of reasons. A mill will produce a much more tidy finish , you have greater control on depth of cut by using the dial on the down feed , it's just a whole lot more stable and controllable using a mill.  The set up challenge is , the head must be mounted in such a way as to enable the cutter to face the spring pads on a verticle axis , keeping in mind , the valves are tilted 15 degrees. What I do to fixture the head with the guides and spring pads in verticle alignment with the mill spindle is to machine a pair of pedistals which pilot off of the valve guide and seat. The pilots have shoulders that are inserted into two of the valve seats and guides when the head is on the milltable ,  the spring pads are now in a position where they are square with the mill spindle and can be accurately machined. A Bridgeport or similar milling machine has a head that can be canted at various angles , mine doesn't , it can be rotated or tilted side to side but that is not usefull for this application , the head must be tilted on the mill table.

Heres the pedistal being made
 


Then I made a short .312" pilot to enter the bore of the valve guide
 

Two pedistals  , both identical are used to suport the head for milling , this is one of them. I'll be using two 5/16" long studs made out of round bar and threaded on each end , one end threads into a T slot nut in the mill table , the other end protrudes above the guide and a nut is used to hold down the head securely , two hold down studs are used for this.

[Gearhead]

Both pedistals are made , some of you may have been wondering what the hell I was talking about , this should make it all clear..................





Studs and T slot nuts are used  to secure the head to the mill table for  spring pad machining.

The material to be removed is the area surrounding the valve guides , and to clean up the spring pad itself , shown below.



A bunch more blending to do on the intake ports yet and , my cutting tool for the spring pad machining is on order.

Working inside , sanding  n' grinding sucks , ugh , dust n' grit.

[Gearhead]

Some recent progress , and a down turn in the existing engine.

First the good news

My parts order has arrived , including the springs , retainers , locators , locks and the spring pad cutting tool. The sanding and blending continues and is nearing completion , looking good too !   I also ordered a pushrod length checker which is an adjustable / variable length pushrod , used for mock up , to determine the optimal length that the pushrod should be , when custom length pushrods are being ordered. The last time I ordered shorter pushrods I  subtracted the amount of material machined from the cylinder head and block when those were resurfaced and decked , from the length of the stock pushrod , to determine what length of pushrod to order. This works well  and allows the lifter to live happily with out being overly compressed , as can happen when using pushrods  that are too long. The length checker tool is a more professional way of doing this , being a sucker for gadgets and a certified tool junkie , I just had to have one to add to the valvetrain tool collection. 

Now the bad news

Last week  a second rocker arm has failed on the way to our club winter camping trip. This happened just south of Longview , strangely within a mile or so of last years rocker arm breakage , that time on the way home. The first incident was north bound on # 22 , the #5 intake rocker broke in half. This time it was the #3 intake. I turned around returned home and changed out all twelve rocker arms  , back to the stamped steel stock rocker version , outside in the yard during a howling blizzard , then headed out to make the camping trip without further incident . The engine ran flawlessly  for the remainder of the trip.  Now , the mystery is , why am I breaking rockers ?  , AND  , why are some of the other rocker arms showing evidence of the roller tips being side loaded and chewing into the aluminum rocker arms ? . At this stage I can only speculate .

My theory ......... normally in V8 applications , using roller rockers , guide plates are installed  under the studs which fasten the rocker arm to the head , to align the pushrods and keep the rocker arms centered over the valve tips , this tends to keep all the parts aligned and happy , getting along together. The mopar performance rocker arms  for 4.0 / 2.5  applications do not call for the use of guide plates , resulting in , what I feel to be a lack of stability. The design of Mopar rockers places them  in pairs on a shaft , a pair for each cylinder. The rocker arms are located axially on their shaft with thrust washers and retaining rings. They are held down with a 5/16" cap screw , passing through the shaft and a small spacer / pedistal , two being used for each pair of rocker arms. Also , pushrods in these engines are quite long , would there possibly be some sort of flexing / deflection / harmonic deal going on , contibuting to the instability of the valvetrain ?

Until I figure this out or get  an answer , I'll not be using roller rockers. I have seen the use of other brands , such as Crower ( AMC V8 ) and guide plates  ( OLDS ) on  a 4.0 head , requiring some extensive modifications . Whether this is worth it , was a success or not is a grey area ,  the guy who masterminded it had issues with pushrod / guide plate material incompatability resulting in severe wear / damage to the pushrods. Also I'm aware of a few guys using other brands of roller rockers , some having been in use for a very short time period , I hope this ( my ) situation is unique to Mopar  roller rockers and doesn't affect these brands . I'd suggest to these persons , that they moniter and keep an eye on this , it takes very little time to pull a valve cover for inspection.

PICS OF THE FIRST BREAKAGE , Note ! in this pic , the pushrod looks bent , it's not , the picture simply makes it look that way.




What's a real issue here is , it's about a G note to install this junk , including the 1/2" spacer required for the valve cover and thermostat housing , two high end  ( reusable ) Felpro valve cover gaskets are $140!!!!

[hps4evr]

very odd indeed jeff. many very out of this world things can happen to an automobile. even things that top techs and teachers will tell you cannot happen... do happen.
something like this makes me wonder if a hydraulic lifter stuck at full length pushed on the pushrod and past the rockers ability, thus breaking it in the exact same spot as the last one. something is causing that push rod to push too high and break the rocker. or, weird as it sounds, the valve is sticking to its seat? i know. very weird. again, weird things happen. but all you can do is narrow down the possibilities.
 a bad batch of rockers came from the manufacturer?
aluminium is typically a very stiff material. used where a part is needed to be stiff and have no flex. so im also wondering if a harsh blow caused it to break. and like you said, there is  some side loading you cannot explain. maybe a harsh blow as it has some heavy side loads???
but, 2 rockers in 2 years... maybe was just a bad batch of them;)