Posted: 4/17/2008 4:11:42 PM EDT
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So, seeing as I drive like 90 miles a day five to seven days a week I am looking for ways to get better mileage. I have been using cruise control and conservative driving techniques (going speed limit, not passing all of the time) to good effect. Problem is I am at the limit of the machine. I need to make changes to the car to get any better mileage. I drive a PT cruiser and get 28 to 30 mpg. The cost of gasoline is still hurting me, more gas means less guns and ammo. I had some ideas on how to get more mileage: I read after market fuel injectors could increase fuel efficiency but this doesn't seem to make sense to me. Is this bunk or not? High flow filter assembly with cold air intake (KN or the like). Not sure what I will get out of this but it isn't terribly expensive. Good return on investment I guess. Anybody use one of these? Synthetic oil. I have a service plan with the dealer so I am good for oil changes through 100,000 miles or so. I would like to switch over as soon as I use up the oil changes I have coming. Also want to switch out the gearbox oil for synthetic. High flow exhaust. I would like to get this but it is too spendy. Porting could help but that is spendy too. Methanol water injection. Anybody know what kind of % efficiency increase a guy could see by using this on a naturally aspirated engine? They claim there is an fuel efficiency increase but I am not sure as they offer no numbers. Timing advance with methanol water injection. The 2.4 L engine runs at 9.5 to 1 compression. I was wondering if the computer could advance the timing to get a 14-1 compression or so. This is supposed to be a sweet spot for efficiency. This compression combined with the methanol water injection to avoid premium gas might save me some fuel. Anybody have any advice on this? Too bad I couldn't get rid of the power steering, don't need it and it eats gas. Any feedback on the above or other good ideas? |
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Personally I don't see any of that stuff making any significant difference, especially for the amount of money it will cost to perform those mods. A good ECM tune would probably make a more significant difference, if you can find someone who is able to tune for economy. |
| since your in MN; cold front grill and block/oil pan heaters. they will keep fluids warm, shorter warm up time will help mileage. cold weather driving still kills you though, ill get 15mpg in the cold and 20mpg in the warm. lucas oil fuel treatment helps a little too. |
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I put a K&N drop in filter in both of my vehicles. I couldn't tell a difference, but for the price of changing the filter every 6-12 months its a good deal. I don't know if the whole filter and intake kit would make a difference. Its about $300. Good luck in whatever you decide and let us know anything that works. |
Who would even do this kind of work? |
Now they have a max tire pressure listed on the sidewall. Will cranking up the psi increase the wear on them? Or do you really have to over inflate them to do that? I need numbers, I have a spreadsheet with money saved vs. efficiency increase. If I had numbers I could see what increase would pay for themselves. I drive so much that according to my calculations even relatively small increases in efficiency will pay off. |
Man I want to! I work for a startup company outside of the metro area. I'm not sure we're going to go all the way so I am hedging my bets until I know for sure. If we make it my ass is moving like yesterday. I would hate to move 40 miles out of the metro, lose my job, and have to drive 40 miles into the city. My commute sucks but right now I drive against traffic both ways for the most part. Those poor bums going the other way however... |
It's not gonna wear the tires out. It will probably reduce the tire wear, especially on the outside shoulders of the front tires. |
| Most go-fast mods only hurt your gas mileage. Intake and exhaust mods allow more air to flow in and out of the engine, which in turn will cause the engine to run lean, which will cause the ECM to compensate by increasing the pulse of the injectors, allowing more fuel into the cylinders. Bigger fuel injectors won't change anything, because the ECM will see a rich condition and compensate by lowering the injector pulse. The total measured amount of fuel will still be the same as you had with the factory injectors, though. Smaller factory injectors with a longer pulse is roughly equal to larger aftermarket injectors with a shorter pulse. Being that the ECM is what decides your air/fuel ratio and spark timing, I'd say to find someone in your area that will do a custom tune on the vehicle with fuel economy in mind, instead of the regular goal of more horsepower. |
Conversely, it WILL wear the center of the tire faster, seeing how it WILL be the main driving surface during commuting. I do agree that tuning is about the best method to improve what you have. I have not looked at PT cruisers, but seems like most popular vehicles have programs out there. If not a packaged tuner, a rice-boy auto performance shop should have something available. I personally bit the bullet and bought a used VW jetta TDI. I average 44 MPG in the winter, 48-50 MPG in the summer and once saw 58. This was on an 04. I laugh at the hybrids. Edited for fat finger syndrome. |
No it won't. You'd have to go significantly over the maximum inflation pressure listed on the tire's sidewall to cause that kind of wear.
I'm not sure what you mean by "tuning", but I think by any reasonable definition, your statement is not correct. The PT Cruiser, like pretty much any other gas-powered car on the market, is going to be closed-loop feedback-controlled. The feedback system provides a constant correction to the fuel curve. So in order for any "tuning" to make an improvement, the engine's computer would have to be wrong. And it's not wrong. There is no magic "fuel mileage" electronic manipulation that you can perform to a car to "adjust" the fuel mileage to a higher number. The engine is still just an air pump. The only computer modifications that will actually improve fuel mileage are those that provide additional spark advance. On some vehicles it works, and on some it doesn't. If it does work, it will probably cause the car to spark rattle on regular 87 octane. So you are forced to run higher octane fuel, which is more expensive, negating any possible cost benefits. |
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It's been a really long time since I've studied this stuff, so somebody please feel free to correct me wherever I mess it up: An engine is just an air pump. And normal late-model 4-cycle gasoline-powered passenger car engines do a pretty good job. Typical BSFC (Brake Specific Fuel Consumption) numbers for engines with normal VE (Volumetric Efficiency) numbers should be around .5 pound of fuel per horsepower per hour. The BSFC should be lowest at the torque peak, and highest at the horsepower peak. But a 300 horsepower engine does not use 150 pounds of fuel per hour on the freeway, because you're at part throttle- you're not using 300 horsepower. If it takes 10 horsepower to push your car down the road at 60 mph, then it's going to use about 5 pounds of fuel per hour. So if you can reduce the amount of horsepower that it takes to move your car down the road, your fuel mileage will go up. The biggest factor is aerodynamics. Way ahead of vehicle weight and frictional losses from rolling resistance. But there's not much you can do to improve the aerodynamics of most vehicles. The next biggest factor is rolling resistance. This is the one that you can influence hugely. I'd estimate that about 95% of all cars on the road have tires that are low. Air up the tires to the spec on the door sticker, and your fuel mileage goes up. Air them up to the max on the tire sidewall, and it goes up more. Vehicle weight is a factor also, but it is not practical to make significant reductions, nor is it cost effective. |
Have you never heard of tuning chips, inline modules or better yet, a dyno tune? I have tried all of these, trying to get more HP and they all work to some extent, with a custom dyno tune being the best. Motorsport Technologies here in Houston got 14 additional rearwheel HP out of my 2005 Silverado with a custom dyno tune. All they do is put the vehicle on a dyno a get a baseline HP/TQ reading, then plug in a laptop to the port under the steering wheel and, using software like "LS1 Edit", they can adjust the spark/fuel tables in the ECM. They also removed GM's "Torque Management", which pulls timing as the transmission shifts as well as increased the tranny line pressure. If they can do all of this for HP gains, I'm know that they can go the other way with it to gain fuel economy while losing some HP. Look up Hypertech Power Programmer 3. They offer a fuel economy program in their module, though I can't say how good it would work, because I've heard bad things about them. But there are options out there, none the less. |