The new wheel/tire combo is requiring the motor and transmission to work a bit harder, since the tires are over an inch taller than your old stock size tires. Your transmission may also be slipping a bit, too. Have you adjusted the bands in the transmission?

As for the gear ratio, if it's never been changed, there should be a metal tag on one of the bolts on the rear inspection cover that has the gear ratio stamped on it. You can also check the truck's build specs under the hood, as it may list it there, too.

 

A gearing change would greatly improve acceleration with those taller tires. Something in the neighborhood of 4.10 would be great, however, a gearing change isn't cheap, since your truck is a 4x4, the gearing change would have to be made to the front and rear differentials. If you only change the rear gearing and not the front to match, you will have some carnage if you put the truck in 4x4 mode.

 

Brand new transmission actually I stalled less than 20k miles ago. And yeah you may be right about the tires but I've had this problem with the truck LONG before I changed the wheels. I've put over 10 grand into this truck keeping it on the road in the last 3 years. I refuse to let it die haha. But I've always been unhappy with how slow it is, so now that my rear main is leaking oil and my freeze plugs are oozing coolant as thick as tooth paste I'm going to replace the motor and build it to have a little more get up and go. I rarely tow anything and I'm careful to never let it get above 4000 rpm no matter how demand I need speed. I just want more acceleration on the low end while maintaining its ability to be used as a truck if the time calls for it.

 

Brand new transmission actually I installed it last year and probably has around 20k milss on it. And yeah you may be right about the tires but I've had this problem with the truck LONG before I changed the wheels. I've put over 10 grand into this truck keeping it on the road in the last 3 years. I refuse to let it die haha. But I've always been unhappy with how slow it is, so now that my rear main is leaking oil and my freeze plugs are oozing coolant as thick as tooth paste I'm going to replace the motor and build it to have a little more get up and go. I rarely tow anything and I'm careful to never let it get above 4000 rpm no matter how demand I need speed. I just want more acceleration on the low end while maintaining its ability to be used as a truck if the time calls for it.

 

I changed my gearing from 3.55 to 4.10 and it greatly improved my acceleration capabilities, since I'm running 285/75-16 tires. That was with no added engine changes..

 

I might look into the gearing problem if I build this engine and I still find it slow. Since my truck spends 90% of it's life bellow 3000 rpm I'd prefer lower gears to keep wheels spinning in mud and dirt. Just want a little more top end power for maintaining speed on hills and overtaking the inconsiderate driver camping the road going 10 under the speed limit.

 

I guess you can say my issue isn't with acceleration but with throttle response? Stomping the pedal and having to time my overtake to make sure I have enough speed to get around the car and beat the oncoming lane. So no 0-60mph but 45-80pmg acceleration. If that makes any sense. Even at a slow roll going less than 10mph if I stomp the throttle it will take 1-2 seconds to get the engine above 3000rpm. Feels like the engine is just bogged down pulling a ton of weight. Can't even road rage properly because stomping on the pedal just means I'm matching traffics speed. Just gutless for a v8.

 

Improved gearing would certainly help your overall acceleration issue, especially since you have an automatic overdrive transmission (46RE). Your engine is working harder than it needs to. Are you planning to keep running regular fuel with the new, enhanced motor?

BTW, keep in mind if you're pulling a heavy load, overdrive should be disabled to keep from killing it. Also, with the new transmission, have you removed the check valve in the transmission line, as noted here, to help keep it from overheating? - https://dodgeforum.com/forum/2nd-gen...46rh-46re.html

 

Yes I want to be able to use pump gas to keep this truck a daily driver. And yes the check valve is gone, it's a straight hose when I installed it. This is the 3rd transmission in the truck to my knowledge, the last shop routed the cooling hoses wrong routing it only to a external cooler and not through the radiator burning it up. Left me stranded with 6 neutrals. And I've only hooked up a trailer to my truck once out of the 4 years I've had it.

 

As for your camshaft selection, you should probably speak with camshaft manufacturers or camshaft re-grinders regarding your goal of keeping regular gas. I suspect that you also want to continue using the factory PCM with an enhanced camshaft without having to tune the PCM? As for compression, you should likely stay around 9.5:1, especially if you're running iron heads and regular fuel. You can speak with these folks about re-grinding your stock camshaft to an improved profile that will fit your needs (https://www.oregoncamshaft.com/) or check with some of the new camshaft manufacturers about what your desires are and they can help with your camshaft selection. As for intake manifold, you are limited in available choices - you have the Hughes fuel injection air gap (pricey) or the Mopar M1 fuel injection 2 barrel intake (no longer made and have to find in the used market)