Sinking Creek 4WD Association

I bought this jeep in July of 15' and have been taking it slow so far.

At this point I have:
-Installed coverking neosupreme seat covers
-Did the mesh grill mod
-Changed my oil 5w20 mobile 1 full synthetic
-Welded on JKS mini lower control arm skids
-Waxed it

Theres more to come however its going to be generally slow with pickups during wither and summer break

Love the "if you can read this roll me over" on the skid

Took the time to sand, grind, and brush all the surface rust off my undercarriage. Once I got it cleaned up I applied some Rust-Oleum and high temp grill paint to everything. Should get me through the winter I'd say.

Recently I installed a 3" AFE Mach Force XP Cat-Back system. This model is high tuck and does a good job of getting the exhaust out of the way. Also welded on some Teraflex rear control arm skid plates about a month back. Increasing the diameter of the exhaust pipe caused me to lose back pressure so I'll be installing a Snorkel or CAI to help with that. Unfortunately, my TIPM just went out and has to be replaced by Jeep... So the CAI may have to wait a while. Also drilled my frame to add a rear tow hook and installed some JKS discos and took out the rear swaybar

Those plates are sweet, Looks good! When I had mine, I installed a CAI and Cat back and still had no back pressure. You may need a tune or some other modifications to pull the power out of it (it seems to me like the throttle body spacers are pretty much BS on these). I also had the 3.8 on 35's, so more power would have been nice...

I installed a CAI and axle back on my '15 JK and have recorded a slight improvement in acceleration, but again that was an axle-back not a cat-back, and it did not increase pipe diameter. I was mainly doing it for the sound, so I was kinda of disappointed that my Volant CAI did not change the sound at all, but the aFe axle-back did obviously.

You could check to see if there are any exhaust leaks. I know mine leaked when I first installed it no matter how tight I tightened the clamp. I ended up having to use exhaust sealant which I still have if you need some.

FFHaselton wrote:Increasing the diameter of the exhaust pipe caused me to lose back pressure so I'll be installing a Snorkel or CAI to help with that.

What?

BadAssEddie wrote:

FFHaselton wrote:Increasing the diameter of the exhaust pipe caused me to lose back pressure so I'll be installing a Snorkel or CAI to help with that.

What?

Eddie, thank you for asking that question. In my attempt to answer it I realized that I was WRONG!

What I did was effect the "scavenging" of my exhaust system. Scavenging is the ability of an exhaust pulse to create negative pressure which "pulls" the next pulse along with it. This negative pressure makes it easier for the motor to "push" the exhaust out of my cylinders. By increasing the diameter of my exhaust pipe I have created a larger space for exhaust gasses to accumulate. This larger space reduces the speed, not volume, at which the gas is expelled due to the scavenging effect. A basic and somewhat appropriate example of this is blowing air out of a pen vs. a straw with the same force. The pen comes to a confining point at the end which causes the air to speed up in order to expel the same amount of volume. This example isn't perfect because an engine sends pulses of exhaust rather than a constant expulsion, especially at lower rpm. These pulses create the scavenging effect.

Here is one of the links I looked at to get a better understanding of this concept: http://www.dsmtuners.com/threads/exhaus ... re.168578/

So Eddie, or anyone else reading this, how would you deal with my loss of scavenging?

You aren't flowing a different volume of air. Its just going slower.


Installing smaller size pipe is the way to fix that. You aren't pushing any more cubes.

Thanks speedcracker, as noted in my previous post I now understand that I am moving the same volume at a lower speed. I'm trying to avoid going back to a smaller pipe ($$) but I of course recognize that returning to the stock sized pipe would correct this.

Installed a Rugged Ridge Cowl Snorkel and broke out the Bikini top. My girlfriend bought a 2016 JKU.

Over the break I changed the front and rear diff fluid, opted for the Lube Locker gasket for the dana 30 and the paper for the dana 44. Finally changed out the factory terminals which wouldn't stay tight for the Quadratec "heavy duty version". Also picked up some rubicon rock rails for cheap. The drivers seat unfortunately ripped so I sewed it up and ironed on a patch to prevent it from getting any worse.

Recently Installed a ARB front bumper and SmittyBuilt XRC winch. The bumper looks great but could have been easier to install. The pre welded nuts were almost too snug to get the supplied bolts to thread into, I had to thread them on the ground first, take them out and rethread them when we mounted it. There definitely were some bolts that were hard to reach. Unlike most bumpers this one also reuses the factory crush cans from the metal component to the factory bumper. I will need to find a new spot for my pa speaker and air tank now.

Have mounted a roller fairlead and put on a winch cover. Also installed a set of Mopar splash guards... I have also figured out how to make my pictures appear right side up. I will soon be switching to a heavier weight oil to help reduce oil consumption by the 3.8L.

Heavier weight oil likely won't help consumption. Need to find out where it's being consumed. Under warranty still? Also just Googling the 3.8 Jeep Motor Oil Consumption brings up countless threads about the problem. Somewhere in there, probably a lead as to why and potentially how to fix.