: Increasing fuel efficiency



smoothcruiser
02-08-09, 02:41 PM
I have searched trying to find some tips and suggestions for making these engine as fuel efficient as possible for long highway trips. I pick up a 2005 De ville on monday and am looking at what can be done to make this car even better for travelling. The car has 49,000 on it so I have had the scheduled 50,000 mile service done already, new Michelin Harmony tires installed, load balanced and filled with nitrogen. (Free service from auto seller). Thinking about a KandN air filter. Thought I might do my first trip with stock filter and then replace and compare the results.
The car had a slight whine in the steering unit when the wheel was turned 3/4 of the way to the left. Turing right was fine. The dealer said that the PS hose needed replacing. Any thougts? Suggestions? Links to threads I couldn't find?
Thanks in advance

Ranger
02-08-09, 04:44 PM
The factory already did it for you. You should see 26+ MPG highway. Not bad for a full size , 275 HP, 4000# luxury car. Skip the K&N and stick with a factory pleated filter. K&N will pass more dirt. The factory filter is not restrictive, even at WOT it will pass all the air the the Northstar can handle.

About the only thing that may improve mileage a bit is to pump up the tires.

Submariner409
02-08-09, 06:38 PM
As Ranger said, run about 34 psi COLD in the tires and do not bleed them hot. A recent GM Technical Bulletin reminds owners that the benefits of nitrogen filled passenger car tires are slim and none (Don't forget that the air we breathe is 80% nitrogen already...). Your car will run just fine on 87 octane gas, but Google "top tier gasoline" and do some studying. If you feel that an air filter may be of some help, take a look at a WIX or NAPA Gold panel filter which has excellent filtration and more surface area than ACDelco or Fram. You already have a very efficient cold air intake system, so throwing money away on aftermarket hype is not the answer. If you go crazy and upset the air/fuel ratios beyond design and control parameters, you'll have driveability problems.

Yes, GM has already done your performance and economy homework. Keep it clean and drive the snot out of it.

If the steering has a slight whine at some turn radius, and is not leaking fluid, drive the car for a while, keep an eye on the p/s fluid level, HOT, and do not overfill it.

Know that your transmission is a dry sump unit and will show NO fluid on the dipstick with the engine off. Check it only in P, engine running, warm. Do not fill past halfway up the hashmarks.

Same with the 5W-30 engine oil - DO NOT fill it past halfway up the ADD-MAX hashmark. Good brand of oil, either standard or synthetic, whatever tickles your fancy.

Go to the top of the page, in the black bar, and rear the entire Cadillac Technical Archive.

smoothcruiser
02-08-09, 08:13 PM
The nitrogen in the tires is something that this delaer does to all the vehicles he sells. Even includes 1 year of free nitrogen top offs if needed. With the power steering, I figured that since it is almost out of warranty it would be a good idea to have them check it out as a condition of the sale. I have never even considered an extended warranty on anything before, car or otherwise but I have had to people suggest it for a cadillac because of the higher repair prices. Seems like two grand would cover a lot of repairs though.
Filling halfway is a good tip. I usually top off right to the full mark.

Krashed989
02-08-09, 09:57 PM
Tips on saving gas:

~Keep weights low; dont take what you dont need and clean out the car so there isn't any garbage in it when you go out.
~Fill up tires; Although you will save gas by doing this, you will reduce the life of your tires by almost half.
~Keep low rpms; slow and smooth is more energy efficient than the "Punch it! We're getting on the freeway!" method
~Turn off the engine in traffic jams; Although you may love that cold a/c blasting your face, you're wasting gas
~Stay on top of engine maintenance; there are many many many elements on the engine that make it efficient. If you miss a tune up, you could be paying for it in gas.
~High octane gasoline will give you better gas mileage by about 2-3mpg and it's $0.20 more expensive than the other stuff, that's $3.40 and up to 51 more miles you could travel (17gal tank). Even with the extra gallon or so that you can buy with the lower octane gas, you wouldnt match the range of the higher octane. This makes the higher octane gas a better deal.

Submariner409
02-08-09, 10:03 PM
You will pay someone $2,000.00 up front, right now, for an "extended warranty" that you will have to fight tooth and nail to make them honor. Better to take the money and stick it in a money market: it remains your dollars, you get the interest, and you can use it for emergencies. Don't fall for the same shell game that the government plays with your tax money.

Nitrogen is another form of snake oil. Yes, you get it "free" now, but the service will bite you in the butt after the year is up......for zilch gain. Hate to burst your bubble, but even GM says it ain't worth the trouble.

97EldoCoupe
02-09-09, 12:52 AM
Way out of the capabilities of most, including myself, (but something I have experimented with) building yourself a gasoline vapor injection system. I hit over 50 MPG with my 1989 Oldsmobile Ninety Eight Touring Sedan, 3.8 liter engine. I used an electric air pump to force air through a reserve tank of gasoline, forcing the vapors into the engine. O2 sensors automatically tell the injectors to cut back on fuel.

It's been done numerous times in the past, starting with a guy by the name of Charles N. Pogue, in 1935, who resided in Winnipeg, Manitoba Canada. I managed to get a small 5hp engine driving a 78amp alternator to use only 1/4 of the fuel by running it on fuel vapor. The engine ran cool and the exhaust was so clean you could blow dry your hair with it. I could breath the exhaust- no smell, but of course there would still be CO and CO2 in the exhaust that you have to be careful of.

But in order to work flawlessly there are so many things to work out, and safety is another concern altogether. I would love to work on this further and adapt it to my supercharged Northstar plan, but there's just so much involved. The gasoline has to be heated to above it's boiling point (90 degrees F) and even higher to promote TCC. But I've seen it work, done it myself.

BlackCaddy87
02-09-09, 01:38 AM
i cut a small square in the my intake where it dips under the the washer fluid. its on the side facing the bumper cover. another thing that kills gas mileage is cruising at 80. 80 vs 70 is a big mpg difference

Krashed989
02-09-09, 02:27 AM
Way out of the capabilities of most, including myself, (but something I have experimented with) building yourself a gasoline vapor injection system. I hit over 50 MPG with my 1989 Oldsmobile Ninety Eight Touring Sedan, 3.8 liter engine. I used an electric air pump to force air through a reserve tank of gasoline, forcing the vapors into the engine. O2 sensors automatically tell the injectors to cut back on fuel.

It's been done numerous times in the past, starting with a guy by the name of Charles N. Pogue, in 1935, who resided in Winnipeg, Manitoba Canada. I managed to get a small 5hp engine driving a 78amp alternator to use only 1/4 of the fuel by running it on fuel vapor. The engine ran cool and the exhaust was so clean you could blow dry your hair with it. I could breath the exhaust- no smell, but of course there would still be CO and CO2 in the exhaust that you have to be careful of.

But in order to work flawlessly there are so many things to work out, and safety is another concern altogether. I would love to work on this further and adapt it to my supercharged Northstar plan, but there's just so much involved. The gasoline has to be heated to above it's boiling point (90 degrees F) and even higher to promote TCC. But I've seen it work, done it myself.
That's interesting... I've heard of water injection systems that improve gas mileage. It uses one water injector in the TB to spray a mist in the intake. The water goes into the cylinders and when the fuel ignites the water turns to steam giving a more powerful BANG.

You dont want to put too much water in though because you risk hydrolocking the engine. Other than that it's cheap, clears the cylinders of carbon, and gives you better gas mileage.

dkozloski
02-09-09, 03:16 AM
The purpose of water injection is to cool the intake air on a supercharged engine. It originated during WWII as a means of being able to pull higher boost without detonation. Alcohol was added to the water to keep it from freezing in cool climates and high altitudes.

dkozloski
02-09-09, 03:19 AM
Way out of the capabilities of most, including myself, (but something I have experimented with) building yourself a gasoline vapor injection system. I hit over 50 MPG with my 1989 Oldsmobile Ninety Eight Touring Sedan, 3.8 liter engine. I used an electric air pump to force air through a reserve tank of gasoline, forcing the vapors into the engine. O2 sensors automatically tell the injectors to cut back on fuel.

It's been done numerous times in the past, starting with a guy by the name of Charles N. Pogue, in 1935, who resided in Winnipeg, Manitoba Canada. I managed to get a small 5hp engine driving a 78amp alternator to use only 1/4 of the fuel by running it on fuel vapor. The engine ran cool and the exhaust was so clean you could blow dry your hair with it. I could breath the exhaust- no smell, but of course there would still be CO and CO2 in the exhaust that you have to be careful of.

But in order to work flawlessly there are so many things to work out, and safety is another concern altogether. I would love to work on this further and adapt it to my supercharged Northstar plan, but there's just so much involved. The gasoline has to be heated to above it's boiling point (90 degrees F) and even higher to promote TCC. But I've seen it work, done it myself.
Maybe you could partner up with D3 and get it on the market. It sounds just like the flavor of snake oil that would appeal to them. LOL

http://www.mikebrownsolutions.com/fish3.htm

PSRmark
02-09-09, 04:44 AM
Maybe you could partner up with D3 and get it on the market. It sounds just like the flavor of snake oil that would appeal to them. LOL

http://www.mikebrownsolutions.com/fish3.htm

Wow, I'm biting my tongue.

But I'm sure you are just looking for something to pass the time, just looking for a reaction.

are you only good for :stirpot: ?

I've added my 2 cents about you now, you are on my ignore list. Congrats, you're the first :)

Krashed989
02-09-09, 04:46 AM
The purpose of water injection is to cool the intake air on a supercharged engine. It originated during WWII as a means of being able to pull higher boost without detonation. Alcohol was added to the water to keep it from freezing in cool climates and high altitudes.

Except that the engine I'm talking about is my Auto Tech instructors old friends which has no form of forced induction at all. Just an old toyota 4 banger.

97EldoCoupe
02-09-09, 08:14 AM
Maybe you could partner up with D3 and get it on the market. It sounds just like the flavor of snake oil that would appeal to them. LOL



Nothing that I mentioned in that post is impossible. Gasoline vaporizes. The vapor burns. Heat helps it vaporize. I didn't believe an engine could be run purely on the vapors coming off a pool of gasoline until I tried it. I won't say efficiency like 200MPG is possible, because I don't believe it, but I know for a fact that VFI does increase efficiency. I will not argue about it, everyone's entitled to their own opinion. But how much efficiency can be gained is something I don't know. I know that it would take a lot of engineering to get a VFI system to operate properly. More time and research than I am able to give a project like that so screw it, I'm happy getting 25MPG in a 300HP car.

97EldoCoupe
02-09-09, 08:31 AM
http://www.dslreports.com/forum/r18626048-Ale-Fuel-vapor-car-gets-92-MPG

The car is small. But check out the figures. The 1/4 mile time isn't too bad for a car that gets 92MPG. It's not a Cadillac, that's for sure.

dkozloski
02-09-09, 10:44 AM
Nothing that I mentioned in that post is impossible. Gasoline vaporizes. The vapor burns. Heat helps it vaporize. I didn't believe an engine could be run purely on the vapors coming off a pool of gasoline until I tried it. I won't say efficiency like 200MPG is possible, because I don't believe it, but I know for a fact that VFI does increase efficiency. I will not argue about it, everyone's entitled to their own opinion. But how much efficiency can be gained is something I don't know. I know that it would take a lot of engineering to get a VFI system to operate properly. More time and research than I am able to give a project like that so screw it, I'm happy getting 25MPG in a 300HP car.
In order for gasoline to burn it must first be vaporized. Liquid gasoline will not combust. Believe it or not; the purpose of the nozzle in a modern fuel injection system is to vaporize the fuel by injecting it as a fine mist into the intake airstream which it does very efficiently. In fact it accomplishes the task much more efficiently than any heat system.

dkozloski
02-09-09, 10:49 AM
Except that the engine I'm talking about is my Auto Tech instructors old friends which has no form of forced induction at all. Just an old toyota 4 banger. The heat robbed from the combustion process by the conversion of water to steam would subtract from the ability of the combustion gases to expand and provide push to the piston on the power stroke. At best the whole thing is a push. The benefit from water injection is the cooling of the intake airstream and nothing more. The laws of physics get in the way of all kinds of wonderful ideas.

dkozloski
02-09-09, 10:59 AM
http://www.dslreports.com/forum/r18626048-Ale-Fuel-vapor-car-gets-92-MPG

The car is small. But check out the figures. The 1/4 mile time isn't too bad for a car that gets 92MPG. It's not a Cadillac, that's for sure.
When I was a kid, one of the universities was getting 150-200 MPG from an old stovebolt six-cylinder Chevrolet that they had modified as an entrant in a contest among engineering colleges. They raised the compression as high as they could and still get the engine to run. They reduced friction by running as light of lubricants as they could find.They installed a carburetor off a Briggs and Straiten lawn mower. They removed all but high gear from the transmission. They stripped off all excess weight. They would start the engine and slowly accelerate to 20MPH, shut off the engine and let it coast to a stop. They'd restart and repeat the process. Their efforts were monitored by their peers and scientifically verified by somebody other than sales promoters.

97EldoCoupe
02-09-09, 11:00 AM
That is true dkoz. All I'm saying is that with the engines I tried this on, efficiency improved. Mind you a 1989 Olds Touring Sedan probably won't have the most efficient form of fuel injection to begin with. Then again that car acheived 30MPG at best, gutless, but pretty good for the era.

Small engines are inefficient. They still use carbs.

I still say that even with the fuel injection of today there's still more efficiency to be had. If it worked all that great, cat converters would no longer be necessary. Gasoline under 2000psi and the right injector probably would completely vaporize the fuel. But 42psi of gasoline with plastic fuel rails scares me enough already. My opinion is that any fuel under pressure should have stainless steel line and flared/compression fittings. Even the old carbureted cars had steel tubing and threaded fittings, running only 5 psi. Safety is not what it should be. Neither is efficiency.

dkozloski
02-09-09, 11:00 AM
When you're looking for the best in fuel milage the first thing that gets in the way are the laws of physics and chemistry. Mother nature is a bitch.

dkozloski
02-09-09, 11:33 AM
If you want to experiment with fuel vapor in your car. It's relatively simple. Install a natural gas conversion. At this point all fuel is 100% vaporized. Most natural gas conversions I've seen run pretty good but the gas milage doesn't jump off the charts. In fact most of the time it's pretty much a wash and the economy comes from cheaper fuel. Milage increases come from weight, aerodynamic drag, and rolling resistance reductions. Build a tiny little motorized roller skate with a slick body and watch the milage jump

97EldoCoupe
02-09-09, 11:38 AM
True, very true. I once scrapped an old RWD Pontiac. I removed the fuel tank and that 305 idled for over 15 minutes on the fuel left in the line. I timed it waiting for it to die. I was amazed it ran that long.

The only way to make a gasoline engine more efficient is to reduce the loss of heat through the engine block, exhaust, and cooling system. If you can get an engine to run cooler, more of that power is being used to drive the vehicle. I believe in these laws. But there's still more to be done on the internal combustion engine. Auto manufacturers won't let all the good stuff out. They know more than they're saying about thermal losses and inefficiency, and what can be done to improve it. The automobile was designed to consume gasoline and it does that very well. If a 75MPG Cadillac were to actually exist, do you really believe they'd let that technology out?

It depends on how much energy content is in the fuel. How do they measure the BTUs? Is there another way of consuming the fuel that would change the way they rate the energy content? It also depends on where that energy is going. Through the drivetrain, out the tailpipe and radiator.... friction(heat)....

If tires had as much rolling resistenace as everyone thinks, would you even get 40,000 miles from a set of tires?

Nobody can comment on these things without actually doing trial and error testing. Not me, not the scientists/chemists/etc.... There are so many factors that come into play. One can guess, but the end result is what matters. And the end result is that we apparently have rockets that have reached the moon, over a 1/4 million miles away, without re-fueling, but cars that acheive 25 MPG. Something is wrong. I'm not complaining, I'm just saying that we can't believe what "they" say because sometimes it's just what they want us to hear.

dkozloski
02-09-09, 01:27 PM
That's interesting... I've heard of water injection systems that improve gas mileage. It uses one water injector in the TB to spray a mist in the intake. The water goes into the cylinders and when the fuel ignites the water turns to steam giving a more powerful BANG.

You dont want to put too much water in though because you risk hydrolocking the engine. Other than that it's cheap, clears the cylinders of carbon, and gives you better gas mileage.
A layer of carbon on the surfaces of the combustion chamber actually promotes efficiency. It provides insulation so that the heat of combustion is not lost to the cooling system and reduces the effect of the combustion chamber surfaces chilling the burning charge and causing incomplete combustion. One of the experiments of the automakers to try to increase engine eficiency is to coat the combustion chambers and piston tops with a ceramic insulating material.

Ranger
02-09-09, 01:42 PM
High octane gasoline will give you better gas mileage by about 2-3mpg and it's $0.20 more expensive than the other stuff
This is a myth. I'm surprised no one caught it.

dkozloski
02-09-09, 02:03 PM
This is a myth. I'm surprised no one caught it.
Actually it's kind of a loaded statement.

If you're using fuel in your car that is so poor that it requires the EMU to pull timing to reduce detonation then you may see an increase in milage with a higher octane rating fuel that will allow the EMU to put the timing back.

Ranger
02-09-09, 05:50 PM
That is true, but the original statement was that higher octane will deliver better mileage, period. You know as well as I do that higher octane does not in itself produce more power, burn cleaner, deliver better mileage or any of the other myths that are out there.

BlackCaddy87
02-09-09, 06:35 PM
E85 has a much higher octane rating but the cars usually get worse mpg while on E85 compared to regular. The cars perform better on E85

dkozloski
02-09-09, 06:38 PM
That is true, but the original statement was that higher octane will deliver better mileage, period. You know as well as I do that higher octane does not in itself produce more power, burn cleaner, deliver better mileage or any of the other myths that are out there.
You are correct. High octane fuel has a greater resistance to detonation and burns more slowly. If your car does not require high octane fuel the engine can actually operate less efficiently because the fuel isn't being burned at the high pressures and temperature it was designed for.

dkozloski
02-09-09, 06:48 PM
E85 has a much higher octane rating but the cars usually get worse mpg while on E85 compared to regular. The cars perform better on E85
E85 contains 85% alcohol which has much less heat value per pound than gasoline. If no compensation is made for the change from running pure gasoline the fuel mixture will be so lean that you'll be lucky if the engine runs. Alcohol has an octane rating of about 113. The advantage to running alcohol is that the latent heat of vaporization is much higher than gasoline so as it evaporates in the intake system it cools the intake charge. This cooling plus the increased octane rating allows the use of much higher compression ratios and gives increased power with a huge penalty in fuel milage because of the richer mixture required.

Submariner409
02-09-09, 06:58 PM
Trouble is that for many people Octane = Power. That assumption is patently false, especially when the mechanical plant does not have the capability to use the combustion control afforded by different fuel grades.

If your Widget 400 Screamer engine was tuned to the Nth degree, the manufacturer would undoubtedly require some level of "premium" fuel. If it is not so tuned, using higher octane gasolines is a waste of money because your Widget2 Econobox can't properly digest what you put in it.

BlackCaddy87
02-09-09, 07:12 PM
increasing the timing is easy power. in many cases increasing the octane will get the maximum benefit.

Submariner409
02-09-09, 07:45 PM
Wrong. Not in a PCM controlled FWD Northstar, the main subject of this forum.

Correct, In any number of engines with either distributors or electronic triggers which can be mechanically or electronically adjusted to take advantage of increased compression.

(You might be able to tune a PCM Northstar to run on 93 exclusively, but to what end ? Any HP gains would be minimal without internal modifications which do not currently exist as an across-the-counter purchase.)

BlackCaddy87
02-09-09, 07:48 PM
well i know that sub...i was just saying in general. 5.0 mustang, 350.

my Northstar has a nice timing advance. i got lucky we have 93 around here. i've heard it knock on 91 before haha

Submariner409
02-09-09, 07:58 PM
Yeah, that......I went through an '83, '84, and '85 Mustang 302, the last of the Holley carb bunch. Dumped a slew of money into them, and always had something that would absolutely eat my STS alive without trying (straight line....I'll guess the F55 STS would take the Mustangs on a road course.....BUT, with suspenson mods.......see, it never stops !).

Completely different cats, though.......

smoothcruiser
02-09-09, 09:50 PM
Wow lots of input today. It's greatly appreciated. I have always heard about the high octane gas giving more mpg. I know someone who does a lot of trips of 200 miles or so on the same route and he has tried this and insists that he gets 2 to 3 mpg better on high test. It sounds like most of the hard stuff has been done by Cadillac and the only things left are common sense maintenance. Makes me feel better about this car already and I haven't even picked it up yet. Should get it tomorrow around lunch time.

Ranger
02-09-09, 10:04 PM
Trouble is that for many people Octane = Power.
The product of good marketing and false advertizing.


I've heard it knock on 91 before.
Something is not working right. Mabye your knock sesnor, because you should never hear it....... even with 87.

BlackCaddy87
02-10-09, 12:55 AM
well its a 95 deville...my compression is 10.5/1. it has 185,000 miles and has had premium for every one of them. fastchip increased the timing so i'd say thats probably about right. can't get too picky with 185k. just wish i had my over drive back :helpless:

Submariner409
02-10-09, 09:25 AM
Sometimes, when folks increase timing a bit or experience ping with lower octane fuels in a knock sensor engine they forget that a ping, particularly a part-throttle or light load acceleration ping, can be caused by a "sticky" EGR valve.

One way to absolutely cripple your Northstar is to have the management system permanently retard spark, not because of fuel, but because of the EGR. When that happens, no amount of octane or tinkering will substitute for either cleaning or replacing the EGR valve.

dkozloski
02-10-09, 10:12 AM
A RWD Northstar doesn't have EGR except indirectly through manipulating exhaust timing.

Submariner409
02-10-09, 12:17 PM
A 2005 Deville, the subject of the OP question, is listed as having FWD with a 4T80E transmission.

BlackCaddy87
02-10-09, 03:09 PM
i'm just trying to make it until the semester is over.

dkozloski
02-10-09, 04:03 PM
I wasn't trying to be argumentative. I was just making an elucidating remark about features that have appeared in newer Northstars.

dkozloski
02-10-09, 04:33 PM
A 2005 Deville, the subject of the OP question, is listed as having FWD with a 4T80E transmission.
Many a slip twixt the cup and the lip.

smoothcruiser
02-23-09, 12:16 AM
Well I have completed my first trip on the new caddie and my first impression is wow!! Smooth ride, great acceleration and to my passengers pleasure the passenger seat lays back almost flat. As for fuel economy, on the trip down running premium gas and a lot of cruise control I got an average of 25.4 mpg. I ran the tank out till I was showing less than 60 miles till empty. Filled back up premium and immediately the mpg jumped up to 26.6. That suprised me! Later while stopping for a bathroom break at a raceway gas station I put in 5.9 gallons of regular unleaded gas and the mileage dropped back to 25.2 mpg. That made a believer out of me for the premium gas! I put almost 700 miles on the car this weekend and it was perfect. I'm going to check my oil tomorrow and see what consumption was if it used any. I'm very impressed with this car and the northstar engine!