donaldmejr

easy guys...I do know my 70 MPH is ~3600 RPMs...anyone else with a 06+ can tell me what there 70mph RPMs are?

rrounds

easy guys...I do know my 70 MPH is ~3600 RPMs...anyone else with a 06+ can tell me what there 70mph RPMs are?
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I have a '06 and I do 76 @ 4000, so if I did my math right I would be running 3684 rpm's @ 70MPH but most of the time I'm at 75 to 85(4500 rpm) out on the open road. I have put 14k miles on my "S" in 5 months so I do have a lot of freeway miles. Oh and by the way I get between 27.4 and 28.9 MPG on most tanks of gas(I do the math, miles divided by gallons used).

ROD

rugsr

Interesting stuff guys

Kinda off topic but kinda not

It was said that RPMs don't effect your MPG and it was load that matters(which I don't believe but who am I)
But my question is this: there are times where I'll be driving in the city going about 30-35 and I'll put it in 6th.
RPMs are suuuuper low, like 2k, and if I need to pass or go faster I will drop to 3rd or something.
But considering the load theory, are you saying that at 2kish RPM I'm burning more gas then if I was at 4k, due to there being more load on the motor?
That being said, what's a good RPM range to stay at to conserve on gas?

Oh and to the statement before about $4 a gallon...yea here in NY I'm paying $4.09 a gallon.
In Canada I think it's around $6 and in Europe I think it's around $8 or $9

So for them this mod migh pay of in 2 or 3 yes, depending how many miles they put on the car

Xzibit A

yes and no, load is based off alot of things one of which is TP, or throttle postion, at cruise @2500 your not using much gas if any, but if you start to accelerate your "load" value will increase rapidlly. so yes it can burn more gas but not until something happens like accelerating or if you come up on a hill. Heres the thing about RPM which makes that statement the most false. Lets say your injectors are firing with a time of 3.5ms @ 2000 rpm, with the same load on the engine( lets say steady cruise @50 flat roads), if you were to downshift 2 gears and you were now at 4000 rpm. and your injectors are still firing with a pulse width of 3.5ms. you are squirting twice as much fuel into the engine every minute. even if the DC dropped to 2.5ms your still burning through more fuel. the fuel injectors have to firing once every rpm no matter what.

FWIW, my intentions of the change had nothing to do with fuel economy, i know that 1-2 mpg will not ever pay itself off. i just dont like the touchiness of cruising at 70-75mph. you barley back your foot off the gas and your speed drops to 65. nudge it forward and your doing 80. so with out using CC its annoying to drive. It reminds me of my yamaha r6 i had that cruised at 6000 rpm on the freeway. then i got an r1 that ways way easier to ride since it cruised at 4k.

ElGerardo

So does anyone know if we can swap 6th gear with a taller gear? Because it would be nice to install a 4.77 final drive and sit at 3000 Rpm at 75 in sixth you know have the best of both worlds.

jaor.s2k

all i have to say is, if you're looking for good mpgs, maybe you should've gotten a different car

i honestly don't think the mpg is that bad. going 75 i'm at 4k rpms. with the top up/hardtop i get 29mpg on the freeway and top down i get 26mpg (06 ap2)

JDMpearlwhyteZ

I was averaging about 30/31 mpg on my 6 hour drive to Houston with my top up and ac bumping.. @70mph

Weasel497

Actually, rpm doesn't play that much of a role in mpg. The reason being is that in a lower gear, you'll be in a higher rpm range, but the engine is also under less load. Think of it like a mountain bike. Depending on the load of the engine, the ecu will be sending more or less fuel through the injectors, no matter the rpm.

faxter18

Nice color combo on those wheels. I average about 30mpg on all highway 23mpg on stop and go.

Gernby

This is an oversimplification, and could only be true if losses due to friction wend down at higher RPMs. It is true that you can achieve the same speed by running the engine at higher RPMs with reduced load, but the percentage of the total load that actually makes it to the wheels will go down. Basically, the load due to increased friction will go up, so the overall efficiency will go down.