Top mpg

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Originally Posted by hammsaveo

You can do it, some of the biggest things to get you there are driving habits and tires (of course stripping out the interoir of your car helps some too :mrgreen: )

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I would do just that if I was single but then again if I was single I would be driving a gen 1 insight. I have newer tires on now 80k mile warranty. I didn't even know about the LRR tires at the time. Mine are aired to 44 psi max sidewall. What was the biggest thing for you getting the big numbers? Coasting in n with engine off is one I try to do as much as possible. I am working on trying to get a scan guage to help me see when i'm wasting fuel. Anymore advice on it? What do you drive now?[/quote]


Some of the things that helped were stripped interior, i cant remember my intake at the time but it was probably my CAI, my full exhaust (ported manifold highflow cat and all the piping), my underdrive pulley, staying between 55mph-60mph on the highway, keeping A/C off, keeping rpm under 3k, and popping it into neutral to coast to stops...im driving an 06 forenza now, just got it friday

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Originally Posted by serega12

LRR tires, wouldn't you loose some performance with those? i.e. snow/wet handling? From what I understand the better performing the tire, the less life/FE you get out of it...

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In comparison to what though? Obviously a summer performance tire is going to have the best dry grip, but has worse wet & snow grip. Every tire is a compromise is some way unfortunately. For everyday driving I bet most newer LRRs out there are as good as most season tires. I think older LRRs used to have worse traction, but the technology has really come a long way in the past 5-10 years. Plus, many OEM tires are already LRRs to get the car's EPA rating higher. I don't think the newer LRR tires are really not much of a compromise, but they probably are a little bit. So, for my daily drivers, they get LRR tires, but for my fun cars, they get sticky tires. :)

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Some of the things that helped were stripped interior, i cant remember my intake at the time but it was probably my CAI, my full exhaust (ported manifold highflow cat and all the piping), my underdrive pulley, staying between 55mph-60mph on the highway, keeping A/C off, keeping rpm under 3k, and popping it into neutral to coast to stops...im driving an 06 forenza now, just got it friday

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What do you mean by underdrive pulley? I keep my car below 3k at all costs.... I saw that you got the Suzuki on another post ,cool, bummer it's the auto but It will be cool to see what avg.you can get from it? Any mods planned for it right away? Do you drive alot of highway for city? Hope it's hwy for the sake of the tranny.I was wondering if an exhaust system would help me much as far as mpg..? I don't care about the hp part. What you think? Would swapping the muffler to something like a flowmaster would it help mpg's much? I was planning on trying to get the best I can with it all stock but if I can have additional help with the mpg..I'll take it!

A high flow muffler won't help. It only needs to flow lots of air when you are using lots of horsepower (more horsepower used, more exhaust air to flow). Since you keep it under 3k rpms, you're never really even using close to peak horsepower. And, while the stock muffler may be restrictive at peak horsepower, it certainly isn't at 3k rpm.

I had thought of this very thing after posting. Well saving money then. :D

Under drive pulley reduces rotation mass thus the engine has less work to do, thus saving gas and increasing power. A full exhaust can help because it let's the engine again run more effeciently (but also means you'll want to floor it more for the cool sound, thus negating the mpg gained,) but one can also go too big with exhaust and lose low end power, with exhaust it's always a fine balance

As for my Forenza...yes it will mostly be highway, 36miles one way to work. As for mods for it, I've got a K&N already on the way and I think I may go with a catback exhaust with a Borla muffler.

The actual best effiency for an engine is the horsepower/torque crossover point (usually around 5280rpm) but that's also not practical for most driving

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Originally Posted by Daox

In comparison to what though? Obviously a summer performance tire is going to have the best dry grip, but has worse wet & snow grip. Every tire is a compromise is some way unfortunately. For everyday driving I bet most newer LRRs out there are as good as most season tires. I think older LRRs used to have worse traction, but the technology has really come a long way in the past 5-10 years. Plus, many OEM tires are already LRRs to get the car's EPA rating higher. I don't think the newer LRR tires are really not much of a compromise, but they probably are a little bit. So, for my daily drivers, they get LRR tires, but for my fun cars, they get sticky tires. :)

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Good points there... It was time to change the tires on my HHR so I got some Continental ExtremeContact DWS (Dry/Wet/Snow traction) which are 100% as good as the reviews say they are... I'm not sure if they're LRR tires (didn't find that info on the tirerack website, but then again, I didn't look that hard), but I did see the improvement in the MPG numbers over the last 6k miles that I had the tires on it...

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Originally Posted by y2daniel1981

The actual best effiency for an engine is the horsepower/torque crossover point (usually around 5280rpm) but that's also not practical for most driving

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It's usually quite a bit lower than that. If you've seen some brake specific fuel consumption (bsfc) maps, they typically show peak engine efficiency (most power produced for the least amount of fuel burned) is around 2000-3000 RPM at about 75%-85% load.

Here's a map for a DOHC 1.9 engine:

http://ecomodder.com/wiki/images/3/3..._dohc_bsfc.jpg

In the above image, the most efficient engine operating range is inside that 250 g/kWh zone.

Of course, that doesn't mean you want to *cruise* at that RPM if you have the option of going to a higher gear - only that if you need POWAH!, that's the most efficient range to generate it. If MPG is your goal, you should still cruise at the lowest practical RPM. But if you need power to climb a long hill (or accelerating), trying to keep the engine as close as possible to that 250 island would yield best results.

All your driving tips are good.

And what's that in RPM in our cars??

From all the BSFC charts I've seen it always seems to center roughly around 2500 rpm. Unfortunately, its VERY rare to find BSFC charts for engines.