REDRX3RX8

Soaring Eagle,
OK, you go first!
I can top out my 6spd AT RX8 on a very steep hill in 4th gear, while holding approx 6500rpm @107 mph. on my 6spd AT RX8.
Keep in mind that I'm holding the throttle to the floor for at least 2 minutes.
Your turn; HOLD TO FLOOR IN NEUTRAL FOR 2 MINUTES!
Who flowed more air?

Soaring Eagle

I know exactly what you're getting at: logic would tell you that of course there is going to be air ramming into the intake at over 100 mph, and so of course there would be more air than if the car were standing still. But, I don't really know if that is the case, and that is what I'm trying to figure out. If more air is going into the chamber, than more gas would also have to be injected in, or else the air/fuel mixture would run very lean. But, if you add more fuel and air mixture, then I would think then the RPM's would have to increase in proportion, and so your 6500 rpm's would go up beyond that. My car at a standstill, with no ram induction, would maintain the 6500 rpm's. But if I raise my rpm's in neutral to match yours, won't I need the same amount of air/fuel to do that? Am I making sense here? I'm honestly trying to figure this out - not trying to be a pain the butt!

REDRX3RX8

Soaring Eagle,
I think you're serious so here we go.
First of all, we are mostly concerned about lubricating the 3 apex seals on each rotor by the injection pump that seeps a little motor oil on them (mine 1/2 quart in 2000miles). Motor oil is known to cause hard carbon, and some cars (even piston engines) that are never reved up much can carbon up, lock seals, and/or chunk off destroying the seals and or rotary.

When I keep reading your understanding of the manifold throtte plate, I don't think you can visualize mechanical issues. Of course you won't need the same amount of fuel air mixture to idle at 6500rpm.

YOU DIDN'T SEEM TO CATCH MY SARCASM. YOU CAN'T HOLD THROTTLE TO FLOOR IN NEUTRAL FOR MORE THAN 1-2 SECONDS OR YOU'LL BANG OUT ON THE REV LIMITER. Then, you'll pull back your foot (partially closing throttle) to cut off some of that air to hold 6500. That might be like me coming back down that steep hill at 6500rpm in 4th gear with my foot not touching gas pedal. When you put it to the floor going up a hill you can hear the air and noise coming out of your exhaust, but way less coming down.

Just get a scan gaugeII and you can program the air flow (MAF). When I track the RX8 I get 175cfm @ 7000rpm when it shifts to third. At idle I get about 7cfm, and there is no way you can get over 40 or 50 cfm by reving in neutral.

Hope this helped, but IMO you shouldn't get into tuning your car.

JinDesu

iTrader: (2)

Just to jump in - I did the test yesterday using my AP

@7500 rpm, 100% load, 2nd gear - 180 grams of air flowing into the engine
@7500 rpm, 10% load, neutral - 80 grams of air flowing into the engine

So basically, that's the effect of that mechanical plate, I guess. To understand the numbers, my idle is 4 grams of air and the max I can get is probably 220 grams of air.

If airflow is equal to power, and power generates heat and exhaust strength, then while I am under load the car will burn more carbon and exhaust more of it.

Does it keep happening, or did it just happen once?

Soaring Eagle

[QUOTE=JinDesu;3433740]Just to jump in - I did the test yesterday using my AP

@7500 rpm, 100% load, 2nd gear - 180 grams of air flowing into the engine
@7500 rpm, 10% load, neutral - 80 grams of air flowing into the engine

So basically, that's the effect of that mechanical plate, I guess. To understand the numbers, my idle is 4 grams of air and the max I can get is probably 220 grams of air.

If airflow is equal to power, and power generates heat and exhaust strength, then while I am under load the car will burn more carbon and exhaust more of it.


Okay - this is the info that finally convinces me! I'm one of those people who has sort of a scientific mind who needs "proof" for what someone says is "fact"! I appreciate your patience andd responses!

Incidently, I do have a very mechanical and electrical mind. Starting at age 12, I did complete house wiring and plumbing, and have driven and rebuilt engines (not rotaries) for 50 years!

JinDesu

iTrader: (2)

^no problem. I really wanted to do the above test for a long time, but the snow storm recently kept me from taking the car out. I was finally able to go out for a short stint yesterday to record the values. I was just a little behind REDRX3RX8 though, he put up the CFM information prior to mine lol.

Easy_E1

iTrader: (2)

I think you might be in for a dealer visit. I wish you luck. I mean the issue could be anything electrically related. Bad connection on an electrical connector Faulty PCM/ECU which is warrantied to 80,000 miles thanks to the EPA. But like I say I think your in for a dealer visit. Just try and find a good one.

Easy_E1

iTrader: (2)

It's all relative to engine Load.

Josh.miller

damn i hate going to the mazda dealers.. they are ********.. and dont even know what they are talking about.. i know its something simple...

JinDesu

iTrader: (2)

You tested the battery, but did you check the connections? Are the connections tight and secure? Clean?

Jim Sanderbeck

What is the best oil pre-mix ratio for a 2007 RX 8 manual?

JinDesu

iTrader: (2)

Swing... and a miss! Wrong forum, buddy. Find your answers in this thread:

https://www.rx8club.com/series-i-tech-garage-22/gas-oil-premix-thread-99636/

quicksilver34

iTrader: (10)

i red line my auto rx8 everyday to clear the carbon inside the engine, i feel better reponsce and better rev responces,

bren5279

iTrader: (15)

Ahhh Crap!!! I bought my car about 4 weeks ago and it had just had a new engine put in bout 600 miles ago.

I didnt even stop to think that it could still need to be burned in.....


My engine seems to be quite boggy and if I had to estimate the hp Id put it at upper 120's


Is it possible Ive f%$ed up my engine by not letting it burn in?

(I usually shift at 3-4k and occasionally hit 5-6 once or twice a week)

socompro

iTrader: (1)

Quick question i dont know when i should change my spark plugs im at 37k and i do what your saying about the red-line almost everyday but i want to know when i should be changing it. thank you

ShellDude

iTrader: (12)

37,000 miles would be a good time to change your plugs. A number of other things are due at around that time including coils, transmission fluid, and differential gear oil.

socompro

iTrader: (1)

ooh ok i should go to mazda for this then

ShellDude

iTrader: (12)

um, no

socompro

iTrader: (1)

what do you mean i dont know how to do

Jedi54

iTrader: (7)

changing spark plugs is very easy.
do a search on this forum using the search feature for spark plug and you'll find the instructions

socompro

iTrader: (1)

what are a good brand for spark plugs?

Jedi54

iTrader: (7)

use OEM.
also known as NGK.

socompro: you really need to do a few searches and find this information on your own, EVERYTHING you'd ever want to know about your car can be found on this forum.

szjalo

quick question: I live in an area very close to school and my daily driving is all around the campus(damn speed limit is 30 on most roads). Seems 2nd gear 6k rev is still too fast to be neglected by police. Heard some ppl mentioned used gas additive (redline SI-1) can make this situation better, reduce the need for revving the engine? how do you think?

mdw1000

I just do mine in first gear. Not sure about the redline SI-1 - I haven't been following the forums much the last couple years. But Redline usually makes good stuff. I personally use Idemitsu premix with every tank, and I started running a can of BG-44k through it once a year. Read good reviews about it here and elsewhere for removing/preventing carbon buildup. But I only put roughly 5000 miles a year on my car since I got my Miata - use the Miata for daily driving sometimes when it is nice top down weather (plus it gets a heck of a lot better gas mileage

Red_lineRX-8

So i have owned my first rotory car for about 4 hours now lol. but this is a good thing to know! hope to keep learning about these cars!