High RPM's ??
 

Hi guys,

I just got my protege. Its a 2002 LX lefty. I love the car, but i've got a question. Has anyone noticed that driving on the highway how high the RPM"s are ? I dont know if its normal for a pro, because this is the first i've driven. With other cars I've driven, some with smaller engines, going 80 or so the RPMS are at arond 3 grand, plus or minus a few hundred. With the pro, i'm up to about 4 grand. even 75 mph is about 3500. THis is in 5th gear, of course. Is it just the gear ratio ? any ideas ?

they have high finall drive ratio
and close gears to make up for the lousy power

When I drive with my snapon mt2500 scanner, I found that my tach reads 1500 RPMs then the car is actually revving.

really?
have any changes been made to the driveline?

If you think that is bad/strange

Imagine driving a 1.6L on the highway
doing 70mph, doing like 3.2K rpm

damn! and as stated before,
the engine power sucks too

Re: High RPM's ??
 

yup that's perfectly normal, Proteges have lower gearings compared to its competitions

most other company's compact cars are geared for fuel economy, while Mazda gear it so it's more fun to drive :)

Re: Re: High RPM's ??
 

There is NO REASON at all for having a "short" 5th gear... With only 130hp even 4th gear won't be used on any road course (not even at the end of a 1/4 mile dragstrip when it is stock).

Mazda should have geared 5th (and 4th on the auto tranny) to have 70mph cruising available at just under 3000rpm...and maybe around 2800rpm for the auto tranny. 1st through 4th could be short but 5th should be taller than it is...if you need to pass on the highway downshift. They probably could of even hit closer to 32-33mpg highway gas mileage.

Realise that gas consumption is not a direct function of rpm, but rather of Brake Specific Fuel Consumption, which could be lower at 3500RPM than 3000RPM.

Exactly....

And the reason for a shorter fifth is better passing power on the highway + not having to down shift every time the road starts to creep uphill. If you had to downshift every time you wanted to pass a truck on the interstate, this thread would be dedicated to "why do Protege's have such a tall 5th gear?"

If the throttle position is the same at 3000rpm and 3500rpm I can guarantee you that the BSFC will be lower at 3000rpm. Only when it takes a greater throttle position at the lower rpm will the BSFC be higher than at a higher rpm...

My wife's Protege is auto and it automatically downshifts out of overdrive every time I am on a hill...If you REALLY wanted to pass someone you don't do it in 5th gear. It is ordinarily the "cruising" gear not the passing gear.

Lets see my Mirage with a tiny little 1.8L engine runs at about 2800rpm in 5th gear when cruising at 70mph. I NEVER have to downshift on any hills...I don't even need to downshift if I am passing someone unless I am trying to pass them extremely fast. My engine is only 113hp stock with a peak torque that is at 4500rpm so you would think that my BSFC would be much higher at low rpms than the protege's due to the lower peak torque (signalling volumetric efficiency is reached at a lower rpm in the protege).

Better fuel mileage
 

You want better mileage, pump up the air pressure in your tires from the recommended 32 psi to about 35-36 psi.

I actually like the cars reactions better at this air pressure. My last trip from Pittsburgh to Altoona, then over to State College and back to the Burgh netted me about 32.4 mpg, and this is a combination of four lane, two lane and lots of gradient and speed changes. This on an '02 ES manual tranny with only one person in the car. Speeds ranged from stop and go to about 85 mph.

Protege's use grade logic and automatically deactivate O/D when traveling up hill. Prevents it from hunting...

I have no trouble accelerating on most hills, or picking up 15mph when passing on a highway in 5th gear. Top gear acceleration in a Protege5 is the best in it's class according to Car and Driver.

How much does your Mirage weigh?

It should be best in it's class with the gearing it has (and the fact that this isn't a tiny ultra high rpm tuned engine compared to others in its class). My remark on the auto tranny was actually geared towards the remark you made about not HAVING to downshift...but in her protege we have no choice but to downshift.

Stock the mirage weighed 2400lbs actual weight (fully loaded) currently my race weight is 2180lbs and everyday weight is around 2250lbs or so. [this brings up another complaint...wish the protege were 100lbs lighter but the wife probably enjoys the quietness afforded the protege by the extra weight]

And my remark about you having to downshift in her protege was due to the grade logic function of the gearbox...??...

I agree with you that the auto could have a taller top gear, becuase regardless of the gearing it will downshift if you coax the throttle enough...

your Mirage is much lighter than a fully loaded protege...That is why it gets away with a taller top gear...A 3k+ lb loaded protege would not go anywhere in top gear if it was that long despite having more power. 2800 rpm cruising revs is way too far away from the meat of the power band with that weight to accomplish anything but wet spark plugs...

I don't mind...my previous car was a 1983 Rabbit GTI...the close-ratio tranny was at 4500 RPMs at 80.

c'mon c'mon where's 6th? :shift:

at least Mazda gave us a 14+ gallon gas tank.:rolleyes:

yeah, me either. I love having the power to pass in 5th without even downshifting if I'm already going 70 or so. I recently made a trip from L.A. to Phoenix (around 400 or so miles each way). At about 75 to 80 miles per hour the entire trip, I averaged about 30 or 31 miles per gallon. Thats good enough for me. I'd prefer to have the power and not have to take my cruise off than get another mile or 2 per gallon.:)

actually, I have the sport tranny and if you are doing above 65 and want to pass it doesn't downshift (in automatic mode). It has plenty of pull. Now if it ain't gettin there fast enough, I'll bump over and downshift it myself. In fact, for normal driving, the sport tranny will usually shift where I would normally shift if I were driving a manual. It really loves to wind up.

what's interesting is that my 3.4L V6 (Grand AM) gets better mileage on the highway than the protege :rolleyes:

How high is too high?
 

Is there any danger running the engine at very high rpms for long periods of time? I travel a lot for work and on the last trip I was running at 4k for almost 6 hours straight... How bad is this for the engine?

-Sp

Re: How high is too high?
 

If the engine's well maintained, it will be perfectly fine. It's designed to take it. :D

The high rpm's are less than ideal for good gas mileage, but that topic has already been beaten to death so much on this forum that I don't really even want to bring it up again. :rolleyes:

Yeah but look at how mush power it puts our relitive to it's size....175hp out of 3.4l? That's pitiful.

msg deleted (duplicate)

your point? this discussion has to do with rpms and mileage *obviously relating to highway mileage* nothing to do with hp/L

Also, a large engine turning slowly is generally more fuel efficient becuase it will have lower frictional losses than a small engine that must turn much faster to generate the same amount of power. Although there are many other variables that come into play when you talk about fuel economy, but it's perfectly likely that a 3.4L engine may get better mileage than a 2.0L engine. Camaro Z28's have 5.7L engines and get 30+ mpg on the highway. :D