Originally Posted by 8_is_enuf

This "engineer" must have been a wind tunnel guy or something. Deginately didn't work on motors.

I think Gordon was too nice to Maolin. Gordon was dead on and Maolin was dead wrong and trying to change his arguement as he went along and confuse the actual arguement with a bunch of garbage. All while he never admitted that oil got thinner when it got hot. (Opposite of his original post)

BTW -- it is a year later, where is my 250 HP?

This thred sucks.

Originally Posted by zoom44

this has holes that others have pointed. but there is one other point to make. why is 5w20 recommened in the USA but not in other countries? simple answer- CAFE which stands for corporate average fuel economy. this is a US federal standard that each auto maker has to meet a certain product line wide avg mpg. Ford companies as well others have started shifting to thinner oils because they get better fuel economy during the EPA testing than heavier oils. now the answer to why 5w20 and dino oil is recommended and why does every Mazda employee stick to the company line. because whatever oil that is used when the car is undergoing epa testing HAS to be USED AND RECOMMENED FOR USE TO THE CONSUMER. they cant use one oil for testing and then have you use another. its against epa regs. That is the main reason they keep saying dino only. the other reason is that they just do not want to spend the time , money and personnell resources to test the efficacy of synthetic oils. the dino works fine so why bother? its a bottom line bean counter decision.



that's pure nonsense. during city driving you normally stay at lower rpms. if you stay under 3750rpms then you arent opening anymore of the s-dais tracks or injectors. then what you have when open when you start the car.if that is the reason for for alot of people getting 10-11 mpg then that is saying those people never shift out of 2nd gear and its all user error. which we know its not.



true if you go up to 4k and then shift some of those first few squirts of gas may be swept around adding to the rich a/f. but the sensors after will note this a/f and change injector and igniton maps to try to bring it back to stoich in closed loop.



oxygenated fuel does decrease the mpg. but they are use donly during a short period in teh winter in some states. this does not acount for the people who have extremely low mpg all year round. and as i stated before oil that has been in the combustion chamber DOES NOT go back to the sump. nor does any fuel. if either is happening there a more problems with your engine than the mpg. you need a rebuild at least and at most anew engine.


i was going to try to chop this up for clarity but ill do my best. a) no horsepower was lost as a result of the port flash campaign. it was never there. b) the flash at port was done to lower the exhaust gas temps to promote cat longevity. Mazda is nopt the only company to use this method. the coflict comes from different standards between US epa regs and california emissons regs. california rules say the cat must reach operational temp in less than 5 minutes. in order to meet this requirement all car manufacturers started to move the cats closer to the engine to get them heated up faster. then the feds brought a new reg for 2004 and newer cars that says your cat must live to 110k miles and if your cat reaches x degrees it wont so lower the cat temp. the richening at port was done to pass this new req. c)there have been no zero nada flashes designed to increase power. every flash so far has been to deal with flooding issues related to rich a/f and oil metering, while trying to stay within the requirements. there not been 2 flashes since M. the 1st he is thinking of was a change in the nomenclature. this file had a bug which caused a cel. the 2nd he is talking about was the de-bugged file that replaced the 1st. there is no difference in performance between M and these. that is why the updated bulletins say if a car is at M ther eis no need to flash it with this "newer"(differently named) file. there is no memo that says "We are trying to get the horsepower back to those that do not reside in green states." they arent trying and wont because there never was 250hp. now when you go for your reflash on monday find out if he updated his WDS between today and monday. if he did not there is not any flash to be had because his WDS is not on the correct level. there is however a new flash name on a tsb out today. ill have more on that once i get a chance to digest teh tsb.


there was no change to the throttle body, intake or intake manifold for 2005. if any of those parts were changed on future models no flash would help 2004 models because the programmign would include parameters for the new parts that the 2004s wouldnt have.


just plain ludicrous and already answered by others



right and wrong. there is no fuel in the oil as i have stated before. but there is moisture(water) that is condensing out of the oil in the dipstick tube. betting the oil hotter wouldnt help because it woul djust boil the water out faster and with no place to go but up the dipstick its still going to condense there. i cant imagine what their "fix" will be.

Originally Posted by rotarygod

Let me get this straight, a worse flowing air filter will help you get better gas mileage? Which part off all of that sounds wrong? I'm not going to choke myself while I'm running a marathon because it will help me conserve my breath and go farther. That makes no sense. Less air and less fuel is less power. It takes a certain amount of power to hold a certain speed.

Holy crap, Mazda please hire me! I'm a genious by comparison to this "engineer".

Originally Posted by Maolin34

I think that the best way is to use a similar situation as an example. One would think that a free flowing exhaust system will always yield more power, but that is not always true. In many instances removing the backpressure that a stock exhaust may create will have an adverse reaction on hp and torque. It is so often that people by high performance exhaust systems without the big picture in mind.

Higher flow is typically needed when you have modified the engine that will use that exhaust system. If you add forced induction, you will definately need to free up the exhaust. Once you find a way to get more air in, you have to get it the hell out....or the performance will be lost. In this situtation, it is a similar issue. The entire system was designed together. The intake, engine, exhaust....and the fuel system that runs it. When the fuel system was forced to change outside of the predesigned configuration or specs, the entire system was affected.

So, the intake system may be supplying too much air for the fuel map. It's just not in the correct range anymore. Hopefully Mazda will fix the PCM flash for us, and we can have our horsepower back.

Originally Posted by rx7speed

the whole backpressure thing right there screams at me.


backpressure doesn't create power. doesn't create torque.

exhaust goes out the which creates a low perssure zone behind it hopefully hitting a peak of low pressure right as the exhaust valve opens creating a very big pressure differential sucking the exhuast out more efficiently. why would you want to ruin that by creating backpressure to help keep the exhaust inside the combustion area? that spent gas isn't going to improve power

Originally Posted by PeteC

So close, you're so close to understanding his point RX7Speed. The point is that it's designed as a system. You're right that backpressure alone, like a banana, would do nothing for the system. But sticking a 6 inch diameter coffee can on as an exhaust doesn't mean that you'll automatically pick up power. Exhaust tuning is about pressure waves and exacuating the cylinder (again, you're so close) as efficiently as possible. Skewing the variables to one extreme or the other normally doesn't work.

Originally Posted by rx7speed

I understand fairly well just choose not to go in depth anymore unless I need to being over at thirdgen.org I have done so many times already.


but since I'm being told I'm so close to understanding I will try to see for sure if my understanding there.


exhaust systems work to scavange the exhaust through the high/low pressure zones in the exhuast. when the exhaust port opens it allows a fairly high pressure wave to enter the exhaust system followed behind it by a low pressure zone. backpressure is bad exhaust velocity is good.

most people think though by going larger is better. sometimes it is but not always. you go too large and it creates a few problems.
the higher surface area of the exhaust itself will help to absorb heat energy from the exhuast slowing it down at which point it is not able to create as strong of a low pressure zone. also the larger volume tends to dampen the exhaust pulses creating a much weaker negative pulse as well. you also have an issue of a small volume gas objet going into a high volume object which is going t oslow the exhuast down as well. while some of these might sound the same they are going to be a little different from one another. all these lead to low exhaust velocity causing lack of scavenging.

with an exhuast that is too small you create a new set of problems.
first an most obvious is your going to choke the living hell out of your motor. it just can't manage to breath through that little straw. and while it might create a higher exhaust velocity and the pulses hit higher peaks but it comes at that price. first is higher overall avg pressure inside the exhaust stream which also leads to reduce overall exhaust efficieny. generally the higher avg pressure and the fact that it just doesn't flow enough both outweigh the pluses of such an exhaust.


or if your board you can see a long thread on this involving me and many other people from I think 4 years ago
http://www.thirdgen.org/techboard/ex...als-daily.html


that good enough peteC :p

Originally Posted by PeteC

lol sure man, that's cool. I didn't mean any offense, and I'm not saying you are, but I'm tired of seeing all these ricers in my area with huge exhausts because they think "bigger is always better". That and I'm doped up on some pain medication right now.

As long as we are talking exhausts though....does anyone know if anybody's ever tried a two-stroke expansion chamber style exhaust on a rotary motor? They are tuned specifically to remove exhaust gas and suck in more fresh charge. Much more so than 4 strokes. Not saying it would work, just wondering....

No hard feelings eh?

Originally Posted by rx7speed

thats just caust you drive a rotary

Originally Posted by rx7speed

yes you do and don'to you know to go any place with one you have to rev to 4587287374768762387648759rpms
oh wait that is the rx7 you have the rx8 with the renesis motor right? that different you go up to 65406468406840654687687460451564654365446456462354 654086.11 rpms

Originally Posted by StealthTL

An expansion chamber type exhaust won't work on a Renesis because of the type of effect it has.

On a 2-stroke, the exhaust AND intake ports are open at the same time. If you time the exhaust pulses right, you can get some fresh charge to flow out of the exhaust port, then compress it back into the chamber using the exhaust pulse energy.

If you look at the rotary cycle you will see that there would never be any use for exhaust back pressure pulses.


S

Originally Posted by Mugatu

if your goal was to sound like a friggin' moron, congrats. you did it with flying colors.