Cherry Bomb Exhaust

camo · **Posted:** Sun Apr 08, 2012 8:50 pm

Nice info guys. Thanks. One more question though, on straight piping. Do I have to remove the CAT too in order to achieve those goodies? or can they be achieved by only removing the muffler?
Thanks again gang.
:JEEPIN:

geordi · **Posted:** Sun Apr 08, 2012 9:27 pm

A big part of the restriction is there is a narrow section of the pipe near the cat, I can't remember if it is before or after it. If you don't remove the cat because you have some reason to keep it, you at least want to deal with that narrow spot and get that out of there.

camo · **Posted:** Sun Apr 08, 2012 9:58 pm

I have read on some threads that removing the CAT makes the diesel smell a bit harsh, how truth is that?
thnx.

geordi · **Posted:** Sun Apr 08, 2012 11:23 pm

Yea... It kinda does. I think it might have been worse when there was more sulphur in the fuel, as I don't really notice it any more these days. It was bad when I first did it, but I also had a few tanks of low sulphur (as opposed to ULSD) and maybe even one of high - STANK.

Now, everything should be all ULSD, less than 15 parts per million of sulphur in the fuel.

mk38tech · **Joined:** Thu Dec 08, 2011 7:25 pm **Posts:** 72

you guys act like im your enemy. let me share some facts with you just so there's no confusion here.
fact #1. 06 vw jetta tdi Displacement: 116 cu in, 1896cc
Power (SAE net): 100 bhp @ 4000 rpm
Torque (SAE net): 177 lb-ft @ 1800 rpm TRANSMISSION: 6-speed manual with automated shifting and clutch Curb weight: 3306 lb
liberty rolls in at 4300 lbs give or take...
•Displacement:171 CID (2,768 cc)[7]•Stroke: 3.94 in (100 mm)[7] •Bore: 3.70 in (94 mm)[7]•Power: 160 hp (120 kW)[7]
•Torque: 295 lb·ft (400 N·m)[7]
now look at those numbers and think about what they would look like with the GDE tunes we all run. i may just go get this thing on the dyno just to see what power im getting these numbers from. the thing has probably TWICE the torque of the jetta, and its not even CLOSE to double the weight. i dont know the weights of the engines themselves but i can almost promise you there's a factor in that one too. my cummins weighs about 1150 pounds and you would be saying the same thing about it if i told u what i was getting per gallon, or was lol. let me share the other facts with you.

on december 21st 2011 i made a 75 mile trip. all on highway 98, it ranges from 25 to 70mph on my trip. i use the same two stations for fuel, one here, one there. both are chevron.(i do think i need to take a trip on the interstate sometime and just do a circle so i can come back and fill at the exact same pump yes.) for the 75 mile ONE way trip, i SLOWLY filled my tank to 1.7gal. thats about 42mpg. this is just one trip where i documented everything. i also had a bottle of zmax in the crank. since that time, i have added a big spectre air filter like i have on the truck, i removed the air box and sensors, i removed the spare tire that i dont need since the insurance company tows me for free, i honestly cant remember if i had the back seat in or not, i do alot of car audio stuff, i think there's 500+ feet of wire in this thing. i dont have big heavy offroad bumpers or 35 inch TSL's lol in fact my notes say i filled the tires to 55psi before i left here and they are all stock
im using man. spec. synthetic oil. i do add a little 2 stroke maybe 5 oz per tank. i CLEAR my turbo out about once or twice a week.(by that i mean i stomp the skinny one till i get smoke and hold till about 90mph) i have ran my ccv to the ground just like it is on my truck. from what i understand positive crank case pressure is a bad thing lol. obviously i have a GDE tune and its the eco tune for ecm and full torque tune for tcm. when i make trips i usually stay 50-55 mph. everywhere i drive, work, road trip.. whatever, i speed up to 55 let the vehicle shift to 5th and i drop back down to 50-52 mph. thats where i seem to be hitting the prime. when i first bought the jeep which was about 7 months ago, they gave me records saying they replaced the rear pinion seal due to it leaking so im guessing they replaced the races and everything else. not sure. i dont use a/c. im a man not a school girl going to prom. when i see a light that i know for a fact is going to be red by the time i get there, i will shift to neutral as long as i know im coming to a complete stop before i shift back to drive. im a pretty conservative driver. my rpm for fuel economy(powerband) seems to be 1500 rpm. i have a few more plans, with exhaust and im ordering an intake elbow so i can start looking at tapping ideas for water or a methanol injection. i do notice my turbo looks pretty dirty when i take the intake tube off, custom stuff to come. any other questions u guys got man just ask. i have no reason to lie to you. but ill tell you this i would love to take this mechanical fan off and see what happens and id like to put a lift pump on soon bear with me this site hasn't been alerting me when i get a response. yall take care.
one other thing ive had multiple trips of 42-43 mpg before but i haven't taken any trips since the other minor mods so i hope to soon.

Dave01 · **Posted:** Mon Apr 09, 2012 11:45 pm

Mk38tech, nobody thinks you are the enemy, you sound like a decent guy that enjoys talking about your CRD, like everyone here. You have to recognize that all of us here have real world experience with our rigs, just like you, and that kind of mileage just isn't realistic in a CRD.

A few things - first, you can't get reliable mileage figures from a 75 mile trip. I get enough variance tank to tank that I usually average at least 2 tanks, maybe 800 or more miles, to get some good real world figures. At a minimum you want to run a full tank, at least an 18 gallon fill, to get usable numbers. Please let us know what you've gotten on a multiple tank, mixed driving continuous test.

Next, if you are running stock tires at 55 psi you are taking a serious safety risk. You can run 40 psi safely, I've heard a few people run 42-44 though I think that is pushing the limits, but 55 psi is well beyond the design rating for the tires. If you have E rated tires it's a different story, but you said stock.

You also are suggesting high torque numbers mean high mpg, and I don't believe they correlate. It's not the high power output that makes it efficient, it's running in the sweet spot of the powerband.

I hope you don't take this the wrong way, but nothing you explain will make me say "ok, so this guy really does get 45 mpg". Sorry about that.

mk38tech · **Joined:** Thu Dec 08, 2011 7:25 pm **Posts:** 72

Dave01 wrote:

mk38tech wrote:

dont be like some of the idiots on the cummins forum. if u cant believe that its possible to take a 5k pound vehicle and get 45 mpg with what, 300+ lbs of torque, then somethings wrong with you. thats like the guy that told me its impossible to get 50 plus mpg with a truck. try a lowered ram 1500 with a 12 valve cummins. people build things like this every day. call garmons diesel performance, they would love to laugh at you when you tell them they are wrong. if you really want to see it come to pensacola florida and we will take a trip together to my house in panama which is exactly 114 miles. and when i show you the numbers on paper you can laugh at the proof all you want. you guys talk alot of talk but ill still be here seeing numbers like 28-30 mpg in town haha 8473448033

So the other hundreds of us that get in the 25 to 32 mpg range are idiots, but you are the lone CRD owner getting 45. Do you see why it doesn't add up?

It's not about the torque numbers. It's that diesel fuel has 138,000 btu/gal and that energy can only do so much work in an internal combustion engine. It's physics, pure and simple.

speaking of physics.... dont you guys have HILLS in NH? ive got family in PA and im pretty sure i see lots of mountains up there that destroy automatic transmissions lol as i specified before, i am in north florida. there are no hills or mountains here. im looking at 28-30 mpg on a week to week, daily (city) driving basis. i have noticed this... (remember my mileage numbers are whats on paper and proven by the receipts) my overhead estimated mpg numbers go up untill i get to a half tank, which is where i like fill up, i dont like going beyond half tank but if i do my numbers seem to go down for a while after that then at about a quarter tank the numbers shoot back up. i watch it every single week its the same thing. dont know what that means. i realize that they are always off but in reference to it going up and down i would imagine that part is true. my overhead has been 4 mpg over actual but it changes every time the battery is disconnected. if you guys really want to get into some fuel economy why dont you start looking into timing. most of these new engines base timing on air intake temp. for example... if i take a 1/2 watt 2.2k(or 3.3k) ohm resistor and stick it in the IAT sensor on the cummins(1999), and that resistor has a switch hooked to it and its mounted to my dash, when i look at my engine monitor(quadzilla) and i flip the switch, i can watch my IAT change from say 65 degrees to maybe 145 or 150. therefore my timing is going to be confused into thinking that its 150 degrees outside, therefore using less fuel per say if most sensors are clean. this has worked out to 1 maybe 1.5 mpg in addition. depending on other fuel and timing mods. ever wonder why someones dodge dakota or some mini van hauls it when its cold outside? the engine gets more fuel. THAT, is plain and simple. in my opinion a more important topic is what the hell is my best option for getting rid of these glow plugs that ill never need haha :juggle:

mk38tech · **Joined:** Thu Dec 08, 2011 7:25 pm **Posts:** 72

Dave01 wrote:

Mk38tech, nobody thinks you are the enemy, you sound like a decent guy that enjoys talking about your CRD, like everyone here. You have to recognize that all of us here have real world experience with our rigs, just like you, and that kind of mileage just isn't realistic in a CRD.

A few things - first, you can't get reliable mileage figures from a 75 mile trip. I get enough variance tank to tank that I usually average at least 2 tanks, maybe 800 or more miles, to get some good real world figures. At a minimum you want to run a full tank, at least an 18 gallon fill, to get usable numbers. Please let us know what you've gotten on a multiple tank, mixed driving continuous test.

Next, if you are running stock tires at 55 psi you are taking a serious safety risk. You can run 40 psi safely, I've heard a few people run 42-44 though I think that is pushing the limits, but 55 psi is well beyond the design rating for the tires. If you have E rated tires it's a different story, but you said stock.

You also are suggesting high torque numbers mean high mpg, and I don't believe they correlate. It's not the high power output that makes it efficient, it's running in the sweet spot of the powerband.

I hope you don't take this the wrong way, but nothing you explain will make me say "ok, so this guy really does get 45 mpg". Sorry about that.

i can run here, there, wherever man. as long as im on flat ground and its fairly warm out, the mpg game continues. there are no variables. the longest trip i can remember was from pensacola florida to newnan GA and i spent two whole hours offroad in the pasture once i got there trying to get the jeep stuck in the early morning dew on the side of hills to test my front and rear axle(jeep was new to me at the time) it was a single tank and i still saw 27 mpg when i filled up. my tires say 60 psi on them but they are stock size. and i believe i mentioned the powerband earlier. trust me im not new to this. i know my truck can only go 62 mph and get its maximum fuel economy with a 2.5 inch lift on it. my powerband as it is now is 1750 rpm. i dont use cruise control for a reason. so like i said, 1500 rpm for the kj

mk38tech · **Joined:** Thu Dec 08, 2011 7:25 pm **Posts:** 72

http://www.dieselpowermag.com/tech/1110 ... fications/

remember... these guys have also got 30 mpg from a 1 ton DRW 12v cummins. i think people dont understand that the people that do this are trying to do this. not slamming the skinny pedal constantly

galatron · **Posted:** Wed Apr 11, 2012 3:08 pm

pulled the muffler off two jeeps crds last weekend. they both sound different. but man,, they coast like mad! definite improvement!
Mine which has all the EGR crap removed is a little louder and deeper
My friends' CRD still has the EGR but has the GDE tune, you can certainly tell when the egr opens and closes. the exhaust tone is a bit quieter, but then gets louder and deeper, although not as loud as mine.
Either way, the jeeps coast great, improvements in MPG were astounding AND the fact that either jeep is not louder than my 6.0 excursion is great! happy day!

mk38tech · **Joined:** Thu Dec 08, 2011 7:25 pm **Posts:** 72

galatron wrote:

pulled the muffler off two jeeps crds last weekend. they both sound different. but man,, they coast like mad! definite improvement!
Mine which has all the EGR crap removed is a little louder and deeper
My friends' CRD still has the EGR but has the GDE tune, you can certainly tell when the egr opens and closes. the exhaust tone is a bit quieter, but then gets louder and deeper, although not as loud as mine.
Either way, the jeeps coast great, improvements in MPG were astounding AND the fact that either jeep is not louder than my 6.0 excursion is great! happy day!

anything noticable with that mechanical fan removed? and what are u putting in the egr's place if you physically removed it?

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