REDRX3RX8

That's called "thinking outta the BOX"!

PeteInLongBeach

It depends which aspect of "better" we are talking about:

REDRX3RX8

Pete, I really "likes your style", and would like to converse more sometime since I can tell you can think.

With my Scan gauge I can do the same, and I'm pretty sure if I have a mileage contest and drive about 50mph for several miles I can get CURRENT to show 32mpg.

So I know what you're showing is a honest test, and the best I ever got on TANK which is a more severe test is: 27.1.

8 Maniac

iTrader: (1)

That logic works assuming there are no other differences. Are you talking about engine wear or transmission? In terms of engine speed, it's only 2333 rpm vs 3000 rpm. Admittedly, that is still a significant difference. If you're comparing transmission wear, then you have to assume that you're putting 7k and 9k rpm on the same transmissions. If the 7k rpm transmission is a weaker design, then that could be worse than the 9k rpm. Have any of the transmissions really had worse results for longevity, assuming they aren't abused?

Another argument that could be made for the engine wear argument is carbon build up. Assuming the idea of "a redline a day" has some fact behind it, we could reasonably assume that the lower redline contributes to more carbon build up. I'd be inclined to believe that would be worse for the engine than the increased rpms, if you look at some of the information found from a lot of the failed engines thus far.

Are you trying to claim that automatics are somehow inherently capable of better mileage? With a proper driving style, I was under the impression that manual RX-8's would be able to get better mileage. I know some more recent manual cars have automatics that are able to get notably better mileage, but I didn't think the RX-8 fell into that category.

REDRX3RX8

Full throttle through the gears up to 7krpm puts plenty of heat load on the engine which is the point.

Do you have this image of the carbon somehow flinging itself off from centrifugal force?

High rpm up to 7krpm and high load heat the hell outta the combustion seals where that gooey oil and carbon are in the crevices.

The difference of 7krpm to 9krpm can really add friction and wear to the apex seals so I'm good with 7krpm, and olddragger tracks at 130 mph with a manual and says the same.

Yes, Pete and I are both claiming that the 6spd auto gets better mpg. I drive around town easy and get 20 mpg, get 23 mpg @ 80 mph, and 26 mpg @ 70 on the hwy.

Anybody show us you get 26 mpg on the hwy with a manual because the 6spd auto runs 2700 rpm @ 80 mph; does the manual?

8 Maniac

iTrader: (1)

From what I understand, part of the concern is build up around the ports. If the engine has higher flow at higher rpms, that should be more successful at moving the carbon. That would be my main reason for believing the higher rpm helps. If you account for when the last intake valves open, the short trip to the full 9k rpm should help as those would be open longer than a short instant.

A regularly tracked car compared to a quick redline are vastly different. Consistently holding an engine at higher rpms will have a much greater effect than a quick run through a couple gears. Not to question olddragger's knowledge, but the fact that he tracks his car at any speed is hardly proof of how the average street driven car will behave to regular quick trips to redline. My car had good compression when I sold it at 65k miles and I regularly redlined it the whole time I owned it.

Also, the engine speed is different. The engine rpm difference is 2333 and 3000 rpms, not 7000 and 9000.

I, admittedly, hadn't looked into what kind of mileage the 6 speed autos were getting. I do remember a lot of people complaining about the 4 port mileage. I regularly got 19-20 mpg in city, and I never drove "conservatively". I'm not sure if I would have been able to get much better mileage, but I was never dissatisfied with 19-20. I think the best I ever got on the highway was 23 mpg at about 75 mph. I typically got around 22 highway when maintaining speeds of 75-80. Not quite as good as your numbers, but I'm not complaining considering the higher output and higher revs of a manual. I'd say it's to be expected.

Honestly, the carbon build up and wear based on rpms dont have reliable enough data to be definitive in nature. If I remember correctly, the 4 ports did have a higher rate of failure than same model year manuals did, though there were multiple issues at hand there. We'd need a comparison between multiple cars driven with similar maintenance and driving habits to really find any accurate and conclusive evidence. The discussions of engine wear and carbon build up are generally over simplified for the fact that they tend to ignore other factors.

(Edit: Just wanted to add that I've been awake for way too long now and I'm about to go to bed and pass out.... Please excuse any poorly written sentences or thoughts that don't quite make sense. I know I struggled to put a few of my thoughts into words and my attempts may have been a little bit less than successful lol...)

REDRX3RX8

If you're worried about port build up, get some 2 cycle oil that tested to have minimal buildup, but I think the carbon buildup would be worse at the exhaust port, and good gasoline or Techron should prevent intake port carbon.

Yeah, add a track day like I do at H2R.

Are-Ex-Eight

iTrader: (1)

Can you put an auto into first gear at 45 mph. I think not. It won't let you...but that's a good thing. Oops!

Flashwing

Pot successfully stirred!

PeteInLongBeach

Yes, that's why I also posted the picture of the concurrent odometer/fuel display. That mileage was attained on a trip from Palm Springs to Los Angeles, with speeds generally around 65 - 70 mph.

PeteInLongBeach

In the A/T, both 5th & 6th gear in lock-up mode are higher ratios (25 mph & 30 mph per 1000 rpm) than 6th gear in the M/T (20 mph per 1000 rpm). So, generally speaking, one would expect better steady state mileage from the A/T in those gears. The M/T is geared more for performance, and to minimize the need for downshifts for highway acceleration. It's a mixed result in lower gears, because the torque converter lock-up only happens in 5th & 6th. But, the A/T tends to minimize RPMs in automatic mode when driving conservatively, so it can optimize fuel consumption in all gears. Of course, the driver can override this by changing to manual / paddle shift mode.

Phil's 8

iTrader: (3)

Jeez Todd, why don't you start up the super charger vs turbo thread again. As far as I know that one died out over a year ago. You would really be the sh#@ stirrer by doing that. Leave this dead horse to die from lack of interest...........

Flashwing

Sorry Phil. I was bored and never thought anyone would actually bite...

Guess I was wrong!

The truth is (with regards to auto vs. manual), in the words of the great Charles Hill, "it doesn't even f***'in matter!"

dmac1961

Just my two cents. I owned an A/T before someone wrecked it, and own a M/T now, and there is really no comparison as far as performance. As far as gas mileage, they were fairly comparable as well. The thing I noticed most however, was the strain that the A/T put on the coolant system. I was driving from SC to FL and got stuck in Atlanta traffic, and have never seen a temp gauge peg out to H without letting the steam out.

PeteInLongBeach

Your cooling system, perhaps. I regularly drive mine in Palm Springs during the summer months and have never seen my ScanGauge display an engine temperature above 210 F in any type of driving, and the dash gauge never moves from its normal reading.

pistonhater

With all respect, I don't trust the readings from the Scangauge 2 to be totally accurate. I have one in my truck (still debating whether or not I want to use it in the RX-8) and from experience I know the Scangauge 2 is not as accurate as they advertise when it comes to calculating MPG.

Manual or auto, getting close to 30 MPG on the RX-8 is closer to a miracle!!!

9krpmrx8

iTrader: (46)

This thread sucks.

Jedi54

iTrader: (7)

must....not.....post.....



Nah, changed my mind.

LifeAfterRx8

iTrader: (17)

Wow,
how is this thread still alive?

Am I reading this correctly or are people trying to say an advantage of the auto is the better gas mileage?

The better gas mileage is due to the lack of horsepower, the lack of extra RPM band, typically autos are just driven like Buicks.

That's almost as stupid as me going to a 3rotor Rx-8 and saying HAHA my cars better because I get better gas mileage than you...

KDispel

This thread is sustained by the tears of small children.


The winner is whatever you drive, because I'm sure you bought one or the other for a reason.

REDRX3RX8

You mean 4spd auto that was slow?

Yeah, I agree that the water and atf temps move a lot just by driving hard for a few minutes, and I got 229 f once on a 95 deg track day.

I fixed that by putting a good size tube and fin cooler in front of the radiators, and it cools both the trans and the engine.

I like flat chested chicks with black hair, too, so it's all apples or oranges.

Less is more!

PeteInLongBeach

Have you calibrated it during fill-ups? This needs to be done for the device to calculate fuel consumption accurately. I check the calibration of my Scangauge at each fill-up, and the displayed average fuel consumption per tank equals the manually calculated consumption.

PeteInLongBeach

Apparently you did not read comprehensively. The fuel consumption is affected by the higher gear ratios in 5th and 6th, as the A/T engine turns slower in these gears than the M/T. It has little to do with the upper RPM range, unless you are consistently cruising between 7500-9000 RPM (which I doubt you do).

You don't know how I "typically" drive my car, and there is nothing "stupid" about comparing various performance aspects of each drivetrain.

viilee206

Agreed

Pico

iTrader: (2)

Simple fix to a simple problem. No biggie

Now let this pointless thread die