More Performance for the 3.7

[tommudd]

Yes normal highway mileage, around town if I stay out of it I get 16 or so but its hard to do that. Never could drive like Grandpa. :roflsquared:
Last long trip was about 23 mpg
Of course I'm almost stock p:

 

[JeepCoMJ]

the mathematic difference between 3.73 and 4.10 is absolutely negligible if you think about it. Will it help, yes. But how much? certainly more in the city, stock or lifted. 3.55 to 4.10 is a noticable power difference in other vehicles.

That said, high end rpm with 4.10's and stock tires would limit you to 65-70mph comfortably and result in better low speed mileage and likely worse high speed mileage. lifted, with bigger tires, it will bring you back to the optimum power range at speed I'm sure.

Gearing is always the number one thing to do. But why don't we really answer the question. What honestly is out there for aftermarket ENGINE support?

 

[tommudd]

Ah never mind someone will argue the pint anyways
I know what works for mine and even stock KJs with stock size tires and gears can't touch me on take off

 

[bassmanbob]

I had some great experience with the Hypertech tuning module. I purchased a used model #52001 off craigslist for around 100$ and its made a world of difference. Significantly increased throttle response, better shifting, and more consistent highway mileage. Well worth the purchase and unlike the JET or "interference" tuners this tuner reprograms the ECU as opposed to interfacing with it to dupe the readings. I have had this for about 6 months now and cant be happier with the results. Hypertech also sells a new #52501 tuner which does the exact same thing, but its around 300$

 

[Thelt]

Power has never been a concern for me on my Jeep. It has plenty for my needs and even wants. I would happily give up some of it for better fuel economy. Of course I am in my 40s now and probably feel different about that than I would have 20 years ago.....

 

[JeepCoMJ]

Mine is stock.

235/75r16, 3.73 gears, 8.25 rear, 4x4, 3.7l v6 with 45/rfe and np242.

I get 14.3mpg city, can get 20 highway, if I'm light on it. best average has been 16.7mpg

the lifted one is identical with JBA 3" on 32x11.50's with 4.10 gears. It gets 15mpg city, capable of 22mpg highway, best mixed 18.9mpg.

Both have similar miles. stocker wasn't maintained, but has junkyard motor that does not burn oil or leak, no issues with it. lifted one was well maintained and I have all history on maintenance.

Performance disparity between the two says simply that the stock one doesn't run as well. I cannot get past the fact that I can feel it running, whereas I cannot feel the lifted one running (much less choppy at idle), and neither throw codes or use fluids.

I've chalked it up to probable issues with injectors on the stock one, but the simple fact is that there is no way in hell I'm putting stock single spray hole injectors in it.

There is not one person on this board who will disclaim any real knowledge of engine modifications, and that is simply frustrating.

 

[Thelt]

I wish mine was a CRD.....

 

[tommudd]

Power has never been a concern for me on my Jeep. It has plenty for my needs and even wants. I would happily give up some of it for better fuel economy. Of course I am in my 40s now and probably feel different about that than I would have 20 years ago.....

Good Lord, I'm 59 and still bury my foot on every take off , still do some light to light speed tests if the car beside me wants to. I was just coming down the interstate with the trailer on and testing some guy in a new Dodge pickup. Hopefully I'll still have some kind of vehicle to have fun with at 85. I never will be one to say well I'm xx now so I have to settle down.
:happy175::happy175:

 

[tommudd]

I wish mine was a CRD.....

Never not in a KJ
was never enough support etc to make me want one

 

[tommudd]

Mine is stock.

235/75r16, 3.73 gears, 8.25 rear, 4x4, 3.7l v6 with 45/rfe and np242.

I get 14.3mpg city, can get 20 highway, if I'm light on it. best average has been 16.7mpg

the lifted one is identical with JBA 3" on 32x11.50's with 4.10 gears. It gets 15mpg city, capable of 22mpg highway, best mixed 18.9mpg.

Both have similar miles. stocker wasn't maintained, but has junkyard motor that does not burn oil or leak, no issues with it. lifted one was well maintained and I have all history on maintenance.

Performance disparity between the two says simply that the stock one doesn't run as well. I cannot get past the fact that I can feel it running, whereas I cannot feel the lifted one running (much less choppy at idle), and neither throw codes or use fluids.

I've chalked it up to probable issues with injectors on the stock one, but the simple fact is that there is no way in hell I'm putting stock single spray hole injectors in it.

There is not one person on this board who will disclaim any real knowledge of engine modifications, and that is simply frustrating.

disclaim any real knowledge ??
I thought you knew all there was :whip::ROFLJest:

 

[Thelt]

Good Lord, I'm 59 and still bury my foot on every take off , still do some light to light speed tests if the car beside me wants to. I was just coming down the interstate with the trailer on and testing some guy in a new Dodge pickup. Hopefully I'll still have some kind of vehicle to have fun with at 85. I never will be one to say well I'm xx now so I have to settle down.
:happy175::happy175:

Nothing wrong with that....

 

[JeepCoMJ]

disclaim any real knowledge ??
I thought you knew all there was :whip::ROFLJest:

In no way have I ever said or presented that I know all there is to know. I'm confident in the knowledge that I have. But I definitely don't have ANY aftermarket 3.7 performance parts knowledge, and that is what the original question was about.

Where I come off poorly on this thread is that I'm not happy with the general "regear it" response in every one of these threads I've searched through. That is not an answer to the question. The answer should, then, be "I do not know about engine mods, but here is what you could do, and here is what does not work"

 

[tommudd]

I guess that its been discussed so many times before that after a while most go for the short and obvious answer, gears.
Since there are no real hop ups, no headers, no turbo's, supercharger's etc then short answer is gears.( unless you have very deep pockets and want to experiment ) And gears do make a big difference, period

PLUS now lets also look at something else
IF anyone would take the time to look he is running 32 inch tires etc. SO even if you did or could do some hop up, gears would or should be done as part of the "enhancements " anyways . So gears comes into the answer one way or the other. Sure you can throw 500 horsepower in something and over power it to where it will run , BUT in the end its a combination or motor / suspension and gearing .
Anyone knows when building any motor vehicle its a combination of parts so nay answer has to include them all

 

[JeepCoMJ]

Gears do make a difference. You are correct. But multi-hole injectors are not terribly expensive, if they could be cross-referenced to match, and better atomization can make a world of difference.

Tuners don't do a lot in my experience, at least without bad side-effects.

What about truthful, unbiased reports on performance spark plugs? I personally stick with stock spec plugs, but am up to try anything to improve the performance of a 3.7.

How about real, unbiased opinions with factual flow charts and dyno testing on bored throttle bodies? Specifically using a stock throttle body bored out rather than a million dollar "hope and dream" custom option.

Any positive results or opinions on bored cylinders and oversize pistons?

Porting heads?

Opening up exhaust affordably (no headers available, but any pinch points in the stock exhaust that can/should be removed and/or left alone to improve exhaust flow without negating necessary back-pressure)


Doing gears is all fine and dandy, but all of these things could be done in combination to increase performance for less than the cost of gears, carriers, plus install....Nevermind carrier break on the d30a and the wasted $1500 spent on a steel D30 housing, considering cost of that vs. cost of SFA being negligible in difference.

Not everyone has $1000 to throw down in one go on R&P sets plus bearing and shim kit plus carrier (if necessary...I know the 8.25 doesn't have a carrier break outside of stock option gears, not sure on d30a) plus cost of professional install since you CAN NOT install gears on your own and expect them to be correct your first time out.... It is too expensive to get wrong.

I certainly could toss $300 on new performance injectors and perhaps performance plugs, and since I do own and have access to exhaust bending equipment, I can entertain those thoughts as well. I could even mill up some new manifold flanges and bend up some higher flow manifolds. Heck, for the cost of a gasket set and some time, I could port and polish the heads myself...but I would need some specifications to go off of.

I guess maybe I'm going more in depth than you want to. I understand your frustration with the same question being asked over and over. That is the reason I got away from cherokee and comanche sites...I'm sick of the idiot questions and lack of basic comprehension of the search function.

But on this subject, on this forum, I have searched. There are no *good* responses that actually go into detail. People like you, Tom, and TJKJ and others who have been around the block and poured more sweat and blood into this site surely have seen some of these options be discussed, tried, and proven or disproven. Perhaps all of that data can be correlated into one thread and stickied so you can simply link it for these, removing any real necessity for you to bother getting frustrated or delivering the same bland response over and over.

Thanks,

Pat

 

[JeepCoMJ]

Another thought I've had:

By nature of design, these v6 have a high heat exchange rate between the valley and the bottom of the plastic intake manifold.

Higher temperatures expand air. Hot/expanded air means less volume flows through to the cylinders, and less fuel as well. Combustion occurs at high temperatures, but a momentary increase of temperature to lower temperature air will displace more pressure.

With that being the case, and cold air intake being the ideal situation, has it occurred to anyone that it would be wise to install heat shielding between the intake manifold and the valley? Doing so *could* increase engine temperatures below the shielding overall, but a healthy cooling system with proper spec coolant, a full core radiator, and proper fan setup (even adding a pusher fan to the front) should negate that.

There have been claims of higher performance from doing something as simple as that with other V style motors.

 

[JeepCoMJ]

Doing some research, it appears that there are even solid lash adjusters available for the 4.7. Without delving much more into it, safe bet is that they could be used in a 3.7.

The obvious gains are a tighter valve train, elimination of the common lash adjuster collapse, and removing the reliance of oil pressure to provide lash adjustment. This can mean a more solid, smoother range of power.

The negatives are simple....you have to manually adjust in correlation to the way it is driven, with an average of 15000 miles.

http://www.airram.com/product.php?categoryid=502&productid=1417

 

[4x4kayak2112]

Did you know you can put the 4.7 throttle body on the 3.7, according to the dodge fourms it gives a better skinny pedal feel.

I'm gonna hide now

Sent from my Home Phone using Tapatalk

 

[tommudd]

All of this "dreaming " is all fine and good. But in the real world how many would actually do it? Sure a few may complain about the lack of power but its hard enough to get them to buy a decent lift let alone spend the same amount or more on the engine. Sure say with a SBC it would be cheap and easy, but with the 3.7s almost anything you do is either going to be custom or expensive so maybe 1% would jump and in spend that kind of $$$$. Then add in the fact that a lot complain about the mileage now they would really complain if you did any hopping up on the engine. Now some would say Oh this would not only give more power driving normally but who has more power and not use it everytime you could.

 

[jankerson]

All of this "dreaming " is all fine and good. But in the real world how many would actually do it? Sure a few may complain about the lack of power but its hard enough to get them to buy a decent lift let alone spend the same amount or more on the engine. Sure say with a SBC it would be cheap and easy, but with the 3.7s almost anything you do is either going to be custom or expensive so maybe 1% would jump and in spend that kind of $$$$. Then add in the fact that a lot complain about the mileage now they would really complain if you did any hopping up on the engine. Now some would say Oh this would not only give more power driving normally but who has more power and not use it everytime you could.

Or tires for that matter, start talking $200 a tire for top quality tires and people act like they are going to pass out....

 

[JeepCoMJ]

I build engines with more power and do not use it. The juice is worth the squeeze.

My stroked 4.0 I averaged 17-23mpg depending on how i drove it. Typically, I drove it nice, and averaged 21-23mpg. I could pound on it and get worse, and I did, but not very often.


I have the self control necessary to use the kind of performance I'm talking about getting from a 3.7. Maybe not everyone does, but the simple fact is power to weight is an increase in MPG, if driven nicely. there is no arguing that, it is fact. Whether you get MPG's out of it is your own deal.

The 3.7's are complete and total dogs. I am not "dreaming" when I say I need more engine performance. I have stock height, stock tires, 3.73 gears. No way in hell am I changing to 4.10's...wouldn't be able to travel on the interstate then.