2005 sliverado mod better fuel econ help

Hey all new to the forum,
hope yall can help me ,
well i have a 2005 silverado 4x4 and want to increase fuel economy. I was told to get a K&N 63 series air filter system?, Then to increase my exhaust from back end of catalict converter back to end a 3 inch ? im confused is there something  that will do that .. ie exhaust system.. whats best ect .. thanks all john lost  

Boy this is a hot subject that will yeild different answers for sure. First and foremost, use smooth treaded stock type tires at or near max pressure with no lift. Next on the exhaust, dual cat backs with 3 inch pipe will hurt MPG around town and throttle responce too as your engine is tuned from intaker to tail pipe from factory and if it was that easy to increase HP and MPG, it would come that way. It you want to do anything that may help a little, try a 3 inch single exaust with a flow master on it. On the air filter, there is no magic silver bullet and an real gains with a K&N are more a state of mind than anything. One more thing how you drive has a effect too and above 60 to 65, MPG can start to drop more , the faster you go. One question though, do you live at high altitude as your name suggests? If so I may have a few more tips.

Yes i do live in colorado at about 6961 elevation -in my area,  i also drive alot in the 6035 feet elevation colorado springs area.  Now this is a regular silverado truck 4x4 (not a rock hopper) that i drive to work , erands ect , daddy's taxi lol..
I have the michelins m&s all terrain tires i just love michellins tire.  Any advice from you snoman would be greatly thanked in advance.. ive read your posts , you have a wealth of knowledge so thanks in advance john...
 

Why thank you John.  I have traveled CO a lot and I love it and I am thinking of semi retiring out thre in about 5 year  (give or take). Okay a few things here, the altitude is hurting you because the air is thinner up there and efficency drops. There is a limitation in the ignition timeg on a GM truck, it can only retard or advance timing from 40 BTDC or 40 ATDC. Gnerally in the old day you could set your base timing up a extra 8 or 10 degrees  to help it out some in the thin air but you cannot do that easily on your truck short of a custom tune. You might think on that a bit. Next lets talk about axle ratios, I am guessing you have a 5.3 and if you have 3.42 axle you are hurting and even with 3.73's you are kinda light in the gear department for that altitude. You should realy have 4.10 at least as it will let your engine operate more efficently in thin air and upshift sooner too. This is kinda a pricey thing to do so I am not pushing it, just giving you options. On the tire Mic's are great tires as I run them on my 89 4x4 burg and love them but they are smooth treaded and rated at 50 PSI and I run about 50 in rear and 44 in front. Change you axle lube regulalry and now if it has never been done as it gets dirty and gritty and it can add extra marginal drag to vehicle when spliting hairs on MPG, same with Tcase lube and tranny and engine. Yes these are all small but a lot of smalls can add up. On engine oil you could try SYN as it may give you a bit more MPG and that with SYN 75w90 axle lube may give you 1 MPG or so improvement. Getting back to tires though you want a smooth tread for best possible MPG and a 75 or 83 profile (83 is best and yes this is a bit extreme but I am listing possibilties) as the more agresive the tread, the more power it takes to roll. Keep truck waxed and drive with tail gate down (or off) or with a bed cap as that will help too. (there is a lot of drag with gate up in open bed at higher speeds. Sorry if I rambled on but just giving you some options. Oh one more thing, you might try a higher octane gas. Out there regular is usually 85 or 86 ans plus is 87 or 88 as I recall and you ECM will retard timing before you can hear knock so jsut because you cannot hear it, it does not mean it is not trying too.  You ight find a few thing in link below interesting if you have not see it already.  Good luck and keep me posted.

http://forum.snoman.com/viewforum.php?f=51

Hi John,

Cat back systems are available from almost ever major aftermaket exhaust company, Borla, Flowmaster, etc.  Just check with Jegs or Summit.com.

Snoman says this is a hot topic because he is the only one in the world who doesn't believe improved air flow will improve HP.

In fact a cat back system and a K&N filter will improve HP, but HP increases don't always relate to better MPG.  If you don't change the way you drive to take advantage of the extra HP, your MPG would actually go down.  You see improved airflow in and out of the engine means you get more gas into the engine, more gas means more HP, but obviously less milage unless you lift up off the throttle.

It looks like Snoman has given you some other tips that may be helpful, I recently switched to fully synthetic oil in my Rodeo and I am getting from .5 to 1.0 MPG improvement instantly.  Next I'm going to switch to synthetic gear lube in the axles and see what happens! 

"Snoman says this is a hot topic because he is the only one in the world who doesn't believe improved air flow will improve HP.

In fact a cat back system and a K&N filter will improve HP, but HP increases don't always relate to better MPG.  If you don't change the way you drive to take advantage of the extra HP, your MPG would actually go down.  You see improved airflow in and out of the engine means you get more gas into the engine, more gas means more HP, but obviously less milage unless you lift up off the throttle."

Snoman is one of the few that realizes that modern closed loop engine are tuned from intake to exhaust but there are those like you that seem to know more than those that make them and given the MPG and HP wars in Detriot if your claims were valid, they would come that way because detriot would love to be able to get extra "free" MPG and power. Get real. Not only are K&N's more of a state of mind than anything, they filter less too and let more grit through (see link below) and why do you want less filtration??? Also the way the expanding hot gas is scavanged from cylinders plays a big roll in MPG and lower RPM torque and responce because you do not want the pressure is cylinder to blow down too quickly when exhaust opens do you can get that last little bit of energy for expanding gases (this is why you will loose low RPM torque with dual and with it in town MPG. (above 3000 RPM or so it changes a little but this too depends greatly on cam timing and is far more complex than with the old carbed engines) You should go work for Detriot because you could tell them how to get more HP and MPG to boost sales and profits. If you like the sound of duals have at it but you will pay for it in your wallet.

http://forum.snoman.com/viewforum.php?f=57

(fixed a few typos)

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  The SnoMan
www.thesnoman.com

I respect both of you guy's responses.  But as a 96 Sub owner, I understand the ups and downs of cat back and airflow.  Before I changed things on my rig, I was getting 12mpg in the city and 18 on the highway.  Now, with the changes I have made (see below) I get 14.75mpg in the city and 23 on the highway.  Yeah sure they have cost me some money, but since Katrina, they have paid themselves back several times over.

1.  Fuel Injection Performance Kit.  Air Tube, Air Box (Not Open), HD Air Filter, High Performance MAF Sensor, and Throttle Body Spacer.

2.  Hyperchips Performance Computer Programer.  This allowed me to change my shift points, rev limiter and speedo so I could accurately measure my mileage.

4.  True Dual Exhaust Headers (Ceramic Coated) with O2 Sensors from 3500 Chassis Cab (they have dual exhasut on the 8.1 Litre Engines.

5.  High Performance Cat's (2)

6.  High Flow Resonators (to help with low rpm back pressure)

7.  High Performance Off Road Racing Mufflers.  Made by Flowmaster for C.O.R.E. racing trucks.  ($150/ea)

8.  2-1/2" mandrel bent tubing from collector, thru cat and resonators, thru Mufflers and turn downs behind rear tires.

9.  Run Maximum air pressure when daily driving, then change pressure when offroading.  (I have an engine driven air compressor)

10.  Run mid-grade fuel during daily commutes and low octane fuel when on the highway for long trips.

11.  Keep your rig clean and waxed.  Helpful hint, wax your windshields and side windows to give less drag.  Bugs and dirt add drag to your rig.

12.  Bug guard to not only deflect bigs and rocks, but to also pull hot air from engine bay thru the cowl area.

13.  Cowl induction hood with two layers of heat shield underneath.

14.  Even though I use 4x4 tires on my 2wd, I still lowered the ride wher my 31x10.50x15's fill teh fender and lower my center of gravity allowing for less drag.

15.  Lastly, change all motor oil to synthetic, in tranny and reaends I switched to lucas oil (amsoil or Royal purple will work too).  This allows for less rotating mass weight and slippery movements inside of the engine and gears.

But hell, what do I know.  I have only been building hot rods, motorcylces and 4x4 for almost 20 years.

I seriuosly question your 23 MPG (unless you draft behind semis or drive 50 mph) because there is not that much energy in a gallon of gas for that much weight.  At 65 MPH that would be about 3 gallon a hour or 150 HP hours. At 27% efficency (about average) you would have 40 HP to power car, accessories, overcome driven train losses, tires will use about 12 to 15 HP or more to roll and then there is areo dynamic drag too. Number do not add up. At 19 mpg you would have about 50 HP to play with or about 25% more HP to power vehicle. My 89 is tweaked to max with smooth stock tires and timing advanced 8 degrees over stock with 93 octane and it can make 19 if I keep it under 65 on flat ground, under 60 it "might" do twenty but that is stretching it. BTW, I have been doing it for 35 plus years too and was driving 12 sec cars before you even knew what one was.

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  The SnoMan
www.thesnoman.com

Snoman, the facts don't support your comments.

You keep talking about how long you've been doing this, but you aren't the only one who's been around for 30+ years.  I've met mechanics that have been doing it for decades that can't change oil without hurting the engine.  I've also met people that have been doing it for 2 or 3 years who better understand how to make horsepower.

I respect the obvious knowledge you have regarding what parts are in what vehicles, but on the issue of air flow and HP, you are just wrong.

also the tailgate trick is completely wrong.  if u watch mythbusters they proved it that even tho it sounds completely wrong the tailgate up ACTUALLY gets u better mpg.  there is a certain current behind the cab in the box that circulates because of the tailgate and kind of pushes the truck more.  with the tailgate down it doesnt stop the air so the air jus goes right back out the back.  if u ever have a bunch of light stuff in the back of your truck you will see the stuff flying up and then back n then down again.  if the tailgate is down then it will jus fly out the back end.  

"You keep talking about how long you've been doing this, but you aren't the only one who's been around for 30+ years.  I've met mechanics that have been doing it for decades that can't change oil without hurting the engine.  I've also met people that have been doing it for 2 or 3 years who better understand how to make horsepower."

Maybe you know some mechs that do not know but I am not one of them. I am not a mech by trade but as a labor of love and a hobby. I also have a engineering background and studied IC engine design and theory in college and wrote a few papers on it too long ago on how to improve effeciency. Unlike you and many others fully I understand the dynamics of it's operation and efficency. I also know how much energy is availible in a gallon of pure gas (about 50 HP depending on blend and a lot less in gasahol) and how much of it can be converted to work to power vehicle (about 25% to rear wheel if you are lucky with a current gas motors running low octane fuels) To suggest that you can get 23 MPG in a truck like that is foolish because that means that at say 69 MPH you would have to consume but 3 gallons a hour of fuel in a 3 ton truck and deliever no more than 36 HP to rear wheels to overcome friction and drag as maxiumum possible efficency. Your tires alone will consume 15 to 20 HP if they are smooth treaded and more if they are aggresive and this leaves less than 20 HP to overcome all other drag and loads (power cooling, AC and wind drag and work to climb grades) and the numbers do not add up. The forums are full of "experts" that got there "degrees" from reading posts and advertisements that claim they know more than detriot and have magic fixs for HP and MPG while not compling with emissions. If it was so simple to gain HP and MPG, Detriot would do it given the presuure they are under in HP and MPG wars but the after market is feed by those that want to believe that there is magic cures but they are more a state of mind than reality. (like the ones that beleive in magic air filter that filter air less and dual exhausts which can realy hurt in town MPG a lot at times and they old 50 MPG carbs that they are hiding) When someone tells me that they get 20 MPG plus in a truck like that I take it with a grain of salt. (I knew a guy in the 80's that bragged about getting 38 MPG with his 4wd Subaru wagon but he tailed semi closly to ride in their slipstream and you would not find riding with him pleasant) Also, you should know (but likely do not) that when detriot runs MPG tests, they use hand built trucks (not regualr production models) running 93 octane that are prewarmed up and they limit rate of acceleration too and during the highway MPG cycle they never exceed 59 MPH and the average speed to test is 48 MPH. Nobody averages 48 MPH on highway and few do under 59 but if they ran tests based on real world speeds and driving condition (the test allows them to take up to 30 second to reach cruising speed with no one does) the numbers would be much lower and would hurt sales further so the myth is kept alive. One more thing, on the subject of making HP, it does not take a lot of smarts to make some more HP but it does take a lot to balance it against best possible efficency too in needed usage which most greatly lack. I could write more but what is the point as you will not beileve it as it is a science, not smoke and mirrors and snake oil.

"also the tailgate trick is completely wrong.  if u watch mythbusters they proved it that even tho it sounds completely wrong the tailgate up ACTUALLY gets u better mpg."

Their tests are not sceintific or valid. (you can fix any test like Detriot does with MPG tests)  I have seen first hand since 70's that there is a improvment in MPG with T gate down. Usually around 1 MPG or so depending on truck. I know first hand from repeated long trip trying it both ways but that aside you can see the aero dynamics of it and visulize the turbulance that it can cause and this turbulance causes drag and they have long known in aviation industry that you must keep turbulance to a minimum for maximum efficeny and range and the same applies to vehicles. The blind leading the blind.

Be very easy on the go pedal or but yourself a compact car.  

"If it was so simple to gain HP and MPG, Detriot would do it given the presuure they are under in HP and MPG wars"

Hogwash, Detroit is under pressure to sell cars, period.  If you increase the air flow in an engine, you increase the amount of noise it makes, both on intake and exhaust.  People (in general) don't want noisey new cars.  Detroit is required to meet certain milage standards, but they do it as an average over the fleet, if they keep the trucks quiet and lose 1 to 3% in efficency it is a good trade off against the number of vehicle that would be returned for warranty service because they were noisey.  They can make up the difference in the fleet mileage with some of the extremely efficent new vehicles they have. 

By your logic the computer reprogramers out there (Jet Chip, Banks, etc.) are just giving us smoke and mirrors, and lying through thier teeth when they provide computer programs that increase horsepower, because Detroit has squeezed every drop out of these engines already.  Every dynometer test that we've seen, and all of the seat of the pants testing we've done is wrong.

"you should know (but likely do not) that when detriot runs MPG tests," 

"and the average speed to test is 48 MPH. "

Now that's damned insulting Snoman.  First "Detroit" doesn't run the tests. They are managed by the EPA.  Secondly, that average speed is set at 47.5 mph to be exact because it is well documented that gas engines run most efficently around that speed.  It was first proven in Japan in the 70's and adapted by Detroit later.  Of course you knew that and no one else reads.

"Nobody averages 48 MPH on highway and few do under 59 but if they ran tests based on real world speeds and driving condition (the test allows them to take up to 30 second to reach cruising speed with no one does)"

I guess I'm nobody.  I try to maintain 50 mph when the speed limit is 55 unless it becomes a traffic hazard (i.e. when traffic is heavy the guys doing 80mph in the slow lane will kill you).  By the time you figure on-ramps and cross roads and construction and traffic I'm sure I average 48mph or less.  I've found I can improve my gas milage substantially by using a slow steady acceleration to that 50 mph.  Most of the time I can keep my engine RPM below 1500 and I get, in combined driving, 19MPG out of my 89 F150 4.9 and 19 to 19.8 out my Izusu Rodeo 3.5L 4x4 daily driver.  Heck I even got 16 to 17 mpg out of my 2002 Wragler 4.0L with auto and air conditioning.  I would have much higher averages if I was doing all highway driving, but that's not real life. 

Of course I do stupid stuff that doesn't help, like using synthetic oil and gear lube, and I buy low restriction air filters.  I don't have high flow exhaust, but only because I haven't needed to replace my exhaust on anything I currently own yet (except the VW Cabrio which is getting 30-33mpg now and doesn't need any more help).  You see I drive a lot, and I work for myself so I don't get reimbursed for milage.  Since I'm on the road 6 hours a day, I've found that getting somewhere 2 or 3 minutes faster rarely makes any difference, and will only mean I'm back on the road again that much sooner.

"When someone tells me that they get 20 MPG plus in a truck like that I take it with a grain of salt."

Better pick up your salt shaker, I rented a new Dodge Ram 1500 Quad cab 4x4 360 V8 for 3 weeks last fall.  I was averaging 18MPG in it combined and got 22MPG on one trip that was almost all highway driving (27 combined miles, 220 mile trip).  I saw the trip computer in it at one point of that highway trip registering 27MPG.  If I'd had it longer I'm betting I would have been able to get better numbers out of it.

The last thing I have to say on this subject is: 

Detroit doesn't try to get the most HP out of each engine anymore, they do try everything they can to improve MPG, up to the point where it will cause customers to complain.  If they lose any more sales, the HP ratings and MPG will be moot as they will have to close thier doors.  Increasing air flow through the system will improve HP, but will increase noise, and with the average driver more HP does NOT result in higher mpg anyway. 

Think about it Snoman.  There are engines out there based on factory blocks that are making in excess of 1500 HP.  Detroit is NOT concerned with getting the max HP out of each engine.  They are concerned with striking a balance between HP, MPG, emissions, dependability and drivability.  People on this forum are less concerned with a loud engine or exhaust note then the average showroom car buyer.

You are so clueless here. Detriot does conduct the test themselve with hand picked cars not the EPA. They are talking about changin it to be more consistant. You can right a long comment but you do not know what you are saying. You would like to believe that tests are performed but a independant 3rd part but they are not. Nor do they use AC, heaters, headlight or any other potenetail power robbing accesory during test. In the link below if you check out page 28 of the PDF file it links to you will see the actual hiway test cycle and remember they do not accelerate rapidily during test because there is no mandate to do so. If you go to the link below, you will find several links on MPG tests and if you go to the second sub link in this link and to page 28 of the PDF file it links to you will see the actual CAFE speed and test cycles in graphic forum.

http://forum.snoman.com/viewtopic.php?t=193