MSD ignition LEts see some

[MogifiedXJ]

This is what I'm referring to, being better for a 4.0 application than an MSD.

http://www.4wd.com/newsite/shop/productdetail.asp?pid=9398&model=cherokee&cat=7&kid=502&catid=502&mid=n

I've installed two of these kits and there was a noticable difference.

I heard adding red spark plug wires adds like 25 rear wheel horsepower...just imagine if you added a red cap too. Oh, man!!!























































ahahahahah....for the love of God I'm only kidding.

 

[streetpirate]

off subject, how much are people paying to get qaulity window tinting jobs around here...I'm about to drop 250 for 15% on all the backs, and 45% on the front two does that sound reasonable.

I tinted my own, did 20 on all rears and 35 on doors, and its way to light on the doors. i would reccomend 20 all around.
tint shops wanted 300 and up to do my jeep, i did it myself for 60-70, and it all turned out great exept i got a little dust under the first one i did, and tore it a little in the corner.

it was relativaly easy, after doing my jeep, i would feel quite comfortable tinting any car that didnt have curvy glass.

and as far as the curves, the rear window has enough of a curve to it to be a PITA



CANT POST PICS BECAUSE MY FIREWALL AT WORK THINKS PHOTOBUCKET IS BAD!
stupid thing

 

[streetpirate]

MR. gasket exaust cut out, straight pipes at the pull of a cable for $50

 

[BBeach]

WHY.... 4.0 makes peak power WAY before the 5250 rev limiter. and valves float around 5300-5400

I agree with you on that, i tried holding it to redline by puttin it in the "1-2" gear in the auto at around 4900rpm and it'll keep going till prolly 5300 and it felt useless and i got worse elapsed times (done at track not doing all the time). I think if you look at the dyno graphs they cut out either because of them not going further or the engine not working best? Also, does this mean that the valves stay open or something floating and all? Is this why some cars sometimes put out blue or white smoke near redline through the exhaust like gas not being combusted properly or maybe oil seeping through the rings??

 

[Bouncy]

Blue smoke is oil
White smoke is coolant

Blue is rings going
White is head gasket.

As for 5250 rpms on a STOCK motor. On STOCK valves. On STOCK cam and on a STOCK head...yeah I can see the dyno curve and charts too.

On a 4.7 STROKER with a higher lift cam and a fully ported head with massive work on the runners and larger valves. With stiffer springs on the valves. With a fully balanced assembly and good bearings and a better harmonic balancer. blah blah blah...you get the idea....IT MAKES POWER.

Simple...take a V8 motor and it red lines at 5200rpms...Motor is done...FROM THE FACTORY. Take that same motor..remove all the casting flash and clean it up. Hop up the cam and get rid of the rev limiter and you get more power and higher RPMs.

Consider this...my 5.2 in my truck reds at 5200 rpms...thank you mr. epa. My 1973 cuda with a 340 4bbl red lined at 7K rpm. Pretty much same block, same stroke, little bigger pistons, same technology, and worse tolerances in 1973. 20 years newer for the 5.2 and they say it "CANT" do any better above 5200rpms...Horsesh1t

As for the question about valve float. float is the point were the spring isn't strong enough to close the valve as fast as the timing gear is moving. Thus the cam has rotated off the lobe, the push rod wants to follow the lifter down on the base of the cam...The rocker wants to follow the rocker...BUT the spring is strong enough/applying enough pressure to push the rocker against the push rod and keep pressure on it for a smooth flow of the parts.

What happens is, the spring kinda pops open and the head of the spring hits the rocker making a metal on metal noise like a machine gun....Read into this as a domino effect. Rocker HITs the push rod, push rod hits the lifter and so on...All that metal hitting eachother instead of riding smooth is called valve float and can lead to a blow motor pretty quickly.

Also with valve float, you have to worry about the valve staying open longer than it should....The piston may come up and hit the valve that is open...This is one of the reasons motors are timed. So the piston chases the intake valve as it comes up through the cylinder.

 

[tealcherokee]

BlaH blah blah.

on paper, you might think thats right, and for a v8 it is.

In realitly thats completly wrong for an I6





I just talk to the guys from clifford, all they do is straight 6 stuff. The stuff they know is amazing. John clifford beat a top fuel drag car in an AMC in the 1/8 mile.

anyway, w/ all the races they've won, never once have they shifted past 4300 rpm.

straight 6's dont make power, they make torque, and they make alot of it.

cliffords engines make 450 WHEEL torque at 3000 rpm!!!

 

[Bouncy]

on paper, you might think thats right, and for a v8 it is.

In realitly thats completly wrong for an I6





I just talk to the guys from clifford, all they do is straight 6 stuff. The stuff they know is amazing. John clifford beat a top fuel drag car in an AMC in the 1/8 mile.

anyway, w/ all the races they've won, never once have they shifted past 4300 rpm.

straight 6's dont make power, they make torque, and they make alot of it.

cliffords engines make 450 WHEEL torque at 3000 rpm!!!

I understand torque at low rpms...thus my ram running around 450hp and 1200 tq at the WHEELS. cummins 6 cylinder setup. It was enough to pull a fully loaded steel hauler out of the snow. And yes it makes the power and torque in the low rpms.

On the jeep, you can spin the motor to higher rpms and still make power. I'm not an electronics expert by any means but more fuel in more power out. I'm not building a race motor but with 4.10 gears or 4.56s, the red line comes up too fast and I'm not in the market for a 2nd gear when I'm climbing some sandy hills. Or even going through mud for that matter.

In the end, I've built far to many race motors and have a few ideas about how to do a 6 for wheelin. Its not that my ears are closed. Its more simple math. Fuel, Air, Lift of the cam, compression all equal power.

 

[BBeach]

on paper, you might think thats right, and for a v8 it is.

In realitly thats completly wrong for an I6





I just talk to the guys from clifford, all they do is straight 6 stuff. The stuff they know is amazing. John clifford beat a top fuel drag car in an AMC in the 1/8 mile.

anyway, w/ all the races they've won, never once have they shifted past 4300 rpm.

straight 6's dont make power, they make torque, and they make alot of it.

cliffords engines make 450 WHEEL torque at 3000 rpm!!!

Im not sure if you're being specific to jeep/truck applied inline 6s but the bmw m3's s54 inline 6 screams to 8000rpm, and there are plenty of nissan engines seen in the skyline and such that go much higher than 5k. However, they are DOHC for the most part not the OHV like us truck guys. It would be really cool if someone could make the 4.0 into a dohc setup. It would involve a new head and somehow doing away with the old camshaft. Timing chains would have to be changed and well, a lot of things, but imagine the possibilties. :roll:

 

[Beej]

On the jeep, you can spin the motor to higher rpms and still make power. I'm not an electronics expert by any means but more fuel in more power out. I'm not building a race motor but with 4.10 gears or 4.56s, the red line comes up too fast and I'm not in the market for a 2nd gear when I'm climbing some sandy hills. Or even going through mud for that matter.

In the end, I've built far to many race motors and have a few ideas about how to do a 6 for wheelin. Its not that my ears are closed. Its more simple math. Fuel, Air, Lift of the cam, compression all equal power.

The high rpm harmonic that occurs in inline sixes is inherent to inline sixes. This is why a pushrod inline's limit is typically below 6000. As tealcherokee said, you can push the rpm limit higher, but why bother? Yes it will still produce power at higher rpm's but the peak power still occurs at lower rpm's. Your analogy about climbing a sandy hill is a good point, but can't you keep the motor in its powerband while climbing a hill without resorting to overreving?

When it comes to ICE's, rather than looking at more fuel in = more power out, think of it as more fuel+air in = more power out. The Jeep inline six's head is not the best for breathability and there's not much to work with in the head as far as re-porting for maximum high end rpm's. This is one of the reasons the Hesco head is desirable. In the regular head, you can jam in as much fuel as you want, if the head can't get enough air through, your power isn't going to increase, agreed?

Im not sure if you're being specific to jeep/truck applied inline 6s but the bmw m3's s54 inline 6 screams to 8000rpm, and there are plenty of nissan engines seen in the skyline and such that go much higher than 5k. However, they are DOHC for the most part not the OHV like us truck guys. It would be really cool if someone could make the 4.0 into a dohc setup. It would involve a new head and somehow doing away with the old camshaft. Timing chains would have to be changed and well, a lot of things, but imagine the possibilties. :roll:

All of those high revvers are SOHC or DOHC without exception. I'm with you on the OHC idea for the 4.0. If it was doable in an efficient manner, the possibilities would be exciting...

 

[MudDawg]

Send a block and head to Cosworth...along with a train-car load of $50's.
Or maybe to Yamaha...they designed and built the heads for those nasty little dohc Toyota 1600's. Hell their own engines are approaching 175 hp per litre. A few years ago Honda had a 1.8 engine that produced more hp per litre than any other production car engine. Ford built an experimental version of the old 2.0 that used composite component technology to rev over 12k and make nearly 300 hp.

The reasons the 4.0 will never be a 10k rpm screamer are as Beej pointed out, it's inherent rpm limitations..the harmonic will eventually kill the crank. And the production head will not support (without forced induction) the CFM requirement for high rpm...the engine was designed for low production cost, ease of fitting external components (intake and exhaust), and to provide suitable power output for it's intended purpose (power a normal street vehicle).

HP is a theoretical figure...is is not measured directly...the torque (measurable) is used with a formula to determine how much work can be done (hp).

 

[tealcherokee]

and the simple fact, how the inline 6 works, youd need to go to a coil pack set up, a distributor physically cant keep up, youll either have it retarded too much or advanced too much for the high rpms, and in the low end youll have nothing

 

[BBeach]

and the simple fact, how the inline 6 works, youd need to go to a coil pack set up, a distributor physically cant keep up, youll either have it retarded too much or advanced too much for the high rpms, and in the low end youll have nothing

Is that because the rotor thing inside the distributor cant keep up? As in just no be able to spin fast enough (accurately at least)? After reading the last few posts, im seeing our poor 4.0's just cant handle what some of us want. Seems perfectly suited for offroading though.

 

[Bouncy]

The high rpm harmonic that occurs in inline sixes is inherent to inline sixes. This is why a pushrod inline's limit is typically below 6000. As tealcherokee said, you can push the rpm limit higher, but why bother? Yes it will still produce power at higher rpm's but the peak power still occurs at lower rpm's. Your analogy about climbing a sandy hill is a good point, but can't you keep the motor in its powerband while climbing a hill without resorting to overreving?

When it comes to ICE's, rather than looking at more fuel in = more power out, think of it as more fuel+air in = more power out. The Jeep inline six's head is not the best for breathability and there's not much to work with in the head as far as re-porting for maximum high end rpm's. This is one of the reasons the Hesco head is desirable. In the regular head, you can jam in as much fuel as you want, if the head can't get enough air through, your power isn't going to increase, agreed?

All of those high revvers are SOHC or DOHC without exception. I'm with you on the OHC idea for the 4.0. If it was doable in an efficient manner, the possibilities would be exciting...

On the head porting issue. Spent the last 5 nights out working on porting a 7120 head. The exhaust ports are terribly restrictive. The intake ports aren't too bad. Cut the short side a bit on the intakes and clean it up a bit. Exhaust, could cut half inch out of the short side and a good quarter of an inch out of the runner...And thats not even matching the gasket.

The bowls were left with a huge ridge on both intake and exhaust. Nearly a 90 degree turn. Also a cut ridge from the mill when they machined the valve seats and bowl.

After cleaning it up a LOT, the more fuel...AND air will equal more power. Not arguing that you hit max power at lower rpms...that seems logical from all the dyno charts I have been studying.

As for hitting the rev limiter...I kinda wheel in 1st gear. Two foot the jeep for complete control. After I mod the tranny to lock in 1st gear only and not worry about 2nd...Its a matter of either hitting the limiter or not. Its rare that I hit a limit but at 5k rpms, my speed isnt up high enough for my comfort level. My other jeep has a 6k chip and it runs great...When its together. (Read into that..suspensions are a pita in custom rigs.)

 

[streetpirate]

OK

so we dont need a msd 6 box to run our engines, what DO we need to make sure the electrical is up to par on built 4.0's that may see high rpm's?

 

[Dr. Dyno]

Im not sure if you're being specific to jeep/truck applied inline 6s but the bmw m3's s54 inline 6 screams to 8000rpm, and there are plenty of nissan engines seen in the skyline and such that go much higher than 5k. However, they are DOHC for the most part not the OHV like us truck guys. It would be really cool if someone could make the 4.0 into a dohc setup. It would involve a new head and somehow doing away with the old camshaft. Timing chains would have to be changed and well, a lot of things, but imagine the possibilties. :roll:

The BMW M3's inline six has a forged steel crank, forged steel rods, and forged aluminium pistons to achieve that 8000rpm redline as well as all the other high rev breathing trickery. Other high revving inline sixes also have forged bottom ends.
You could build a bottom end for the 4.0 that would survive 7000 rpm if you opted for a custom billet crank, Eagle forged rods, and custom forged pistons with full floating pins (all fully balanced). If you also add a solid lifter cam, a ported head with bigger valves, heavier valve springs, shaft-mounted roller rockers, chrome moly steel pushrods, and a timing gear drive, you'll have a valvetrain that'll also survive 7000rpm. All you need is a fat wallet.

 

[tealcherokee]

The BMW M3's inline six has a forged steel crank, forged steel rods, and forged aluminium pistons to achieve that 8000rpm redline as well as all the other high rev breathing trickery. Other high revving inline sixes also have forged bottom ends.
You could build a bottom end for the 4.0 that would survive 7000 rpm if you opted for a custom billet crank, Eagle forged rods, and custom forged pistons with full floating pins (all fully balanced). If you also add a solid lifter cam, a ported head with bigger valves, heavier valve springs, shaft-mounted roller rockers, chrome moly steel pushrods, and a timing gear drive, you'll have a valvetrain that'll also survive 7000rpm. All you need is a fat wallet.

its all well and good that you can build it to survive it, but, its never going to make power up there, not w/o a overhead cam set up

 

[dzolcali]

so, has anyone wondered why the put the intake manifold right under the exhaust manifold...heat rises, and the intake manifold should be cool not hot, so then you got this hot ass exhaust manifold right below it, I'm thinking get a new exhaust manifold wrap it in heat wrap, and then get a higherflow intake manifold and a big ported throttle body, will that help with gas milage and power?

 

[Beej]

Yes it will help, but its best not to think of mods as helping both gas mileage and power. They aren't mutually exclusive, but they don't necessarily go hand in hand either. Wrapping the manifold will help, but Dr. Dyno has a neat trick on his site regarding heat shielding too. The larger manifold on 2000+ 4.0's helps some breathing too and so will the larger throttle body, but you'll need some other performance enhancers to really see large gains with those two. See Dr. Dyno's site for more information. He's got the comprehensive list of information all in one place...

 

[Dr. Dyno]

Actually, the '99+ intake manifold has smaller runners than the earlier manifold so it's oriented to making more torque at lower revs, not higher rpm horsepower. To make it flow better at higher rpm, you'd need to extrude hone it and add dual throttle bodies like Hesco's "double trouble" prototype.
If you want a high revving, free-breathing 4.0, you'd have to select the longest duration Crane solid lifter cam that's available, bump the CR up to about 11:1, get the best porting job possible on the Patriot Performance aluminium head, use Clifford's dual outlet header, add the Clifford X-pipe, and run a dual 2.25" exhaust system. This is in addition to what I mentioned earlier.
You don't necessarily need to have an overhead cam and a crossflow head to make an engine breathe well at higher rpm but they certainly help. A good example of this is the 7.0L LS7 engine in the C6 Corvette. It's a pushrod engine yet it'll rev to 7000rpm.

 

[tealcherokee]

Actually, the '99+ intake manifold has smaller runners than the earlier manifold so it's oriented to making more torque at lower revs, not higher rpm horsepower. To make it flow better at higher rpm, you'd need to extrude hone it and add dual throttle bodies like Hesco's "double trouble" prototype.
If you want a high revving, free-breathing 4.0, you'd have to select the longest duration Crane solid lifter cam that's available, bump the CR up to about 11:1, get the best porting job possible on the Patriot Performance aluminium head, use Clifford's dual outlet header, add the Clifford X-pipe, and run a dual 2.25" exhaust system. This is in addition to what I mentioned earlier.
You don't necessarily need to have an overhead cam and a crossflow head to make an engine breathe well at higher rpm but they certainly help. A good example of this is the 7.0L LS7 engine in the C6 Corvette. It's a pushrod engine yet it'll rev to 7000rpm.

some one needs to do something like this, and no matter what, ill put money on it youll never get peak power to break 5000 rpm, and peak torque to break 4000. and theres no point at revving to 8000 if peak is at 5000 and 6000 makes the same power as 4000