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Discussion Starter #1
It seems many of you are getting around 175 hp to the wheels. My question is, don't you feel this is extroidinarily low? I mean that is a 20% loss in a FWD car with a manual tranny. I just dont see that as being possible. I was all for getting the 6 until i heard those numbers. Seems like it is not making the advertised 220hp. What are Jag X-Types and Lincoln LS's putting down in comparrison? Unless this 175 was for an auto, and even then its seems a bit low. Do you guys think Mazda will answer to this?
 

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Reading Topic: Questions for guys that have dynoed...

Not really. People just seem to beat around the bush about it. I would be genuinely concerned and demand an explanation.
 

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Reading Topic: Questions for guys that have dynoed...

I don't know that you can demand much without ripping your engine out and testing for hp at the crank. Now we can all whine and moan about the low numbers, and make statements about typical power losses, but you can't really demand a whole lot about power output at the wheels except for an explanation, vague as it may end up being, about reasons for power loss. Someone in another thread made mention of a different way to dyno cars that hooks up to the wheel hubs. Then you could eliminate one variable.
 

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Reading Topic: Questions for guys that have dynoed...

well, I dyno'd my 6s MT (see photo album for pic of dyno sheet); I had a 19% HP loss, BUT a 11% TQ loss. Now since we tend to drive torque, it may be that mazda decided to give up HP for TQ, I'm not an engineer so I don't know if thats possible, but bottom line, HP is alot easier to make up with Mods than TQ, so I'm not complaining.
 

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Reading Topic: Questions for guys that have dynoed...

well, I dyno'd my 6s MT (see photo album for pic of dyno sheet); I had a 19% HP loss, BUT a 11% TQ loss. Now since we tend to drive torque, it may be that mazda decided to give up HP for TQ, I'm not an engineer so I don't know if thats possible, but bottom line, HP is alot easier to make up with Mods than TQ, so I'm not complaining.
 

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Reading Topic: Questions for guys that have dynoed...

Brillo, how did they get the A/F ratio info on that dyno chart? Did they read that from the ECU?
 

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Replying to Topic 'Questions for guys that have dynoed...'

QUOTE
Originally posted by kyler13


            Brillo, how did they get the A/F ratio info on that dyno chart?  Did they read that from the ECU?[/b]
Nope. stuck a little O2 sensor up the tail pipe, added like $5 cost of the dyno.
 

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Replying to Topic 'Questions for guys that have dynoed...'

I have a theory about the engine's power production (V6 only). I will go over some hardware in the engine and how I 'think' it all works together.

The engine has a 10:1 static compression ratio. Which is not extremely high by today's standards but to run on 87-octane gas, it is very extreme.

The engine also has variable valve timing. Which as we all know, trys to keep the cam timing in the sweet spot throughout the rpm range of the engine. Meaning that a certain cam timing will allow an engine to breathe better at lower rpm than higher and the reverse is true. Certain cam timing will breathe better at higher rpm than lower. VVT allows engine to breath better through the entire rpm range.

When the engine is breathing better means that the engine is consuming more air. More air in the combustion chamber means a higher dynamic compression. More compression means more power, which is what we see in the dyno plots, until about 5000 rpm.

I 'think' that the V6 is tuned right on the edge of what the 87-octane fuel can provide. And at 5000 rpm detonation is probably a problem. So the Mazda engineers tried to work around the problem. They 'may' have reduced torque output at these engine speeds by changing the cam timing (I hope not). That may explain the dramatic drop in torque after 5000 rpm. Another 'trick' in reducing detonation is to richen A/F ratio. This allows the fuel to cool the combustion chamber. This is shown on the dyno plots.

So what I’m getting at here is that if the engine were retuned for 91/93 or even 89 octane fuel, a lot of torque can probably be made above 5000 rpm. If you flat line the torque curve (which would probably not be possible) out to redline you would have over 205 hp at the wheels. That would be a strong 220 hp engine. However with rising fuel costs I doubt I would ever do this, unless I could switch between high-octane tune and factory tune.

And as a side note, if you think that you are missing out on hp now. Wait until its hot outside, 90+. Then you will be able to tell if the engine is riding on the detonation threshold.
 

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Replying to Topic 'Questions for guys that have dynoed...'

QUOTE
Originally posted by jackalvt

So what I’m getting at here is that if the engine were retuned for 91/93 or even 89 octane fuel, a lot of torque can probably be made above 5000 rpm.  If you flat line the torque curve (which would probably not be possible) out to redline you would have over 205 hp at the wheels.  That would be a strong 220 hp engine.  However with rising fuel costs I doubt I would ever do this, unless I could switch between high-octane tune and factory tune.[/b]
Has anyone talked about doing this? I remember seeing Nikolas post something saying he planned on working with Ford to tune the ECU, but I didn't know if tuning the car for premium was part of that or not.

I'd gladly pay the 15-20 cents extra for premium if it bought me an extra 15-20 horsepower at the wheels.
 

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Replying to Topic 'Questions for guys that have dynoed...'

QUOTE
Originally posted by fly4aday
 I remember seeing Nikolas post something saying he planned on working with Ford to tune the ECU,[/b]
I think his statement was that he is trying to work "with an established Ford computer tuner ". Any attempt to work directy with FORD would result in a meeting with a brick wall.
 

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Replying to Topic 'Questions for guys that have dynoed...'

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Originally posted by LBJay

I think his statement was that he is trying to work "with an established Ford computer tuner ". Any attempt to work directy with FORD would result in a meeting with a brick wall.[/b]
Oh yeah...oops.

Thanks for the correction. You're right, doing anything with a manufacturer when they don't stand to make a zillion dollars would be just about impossible I'd think.
 

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Reading Topic: Questions for guys that have dynoed...

I've written before that I believe the tuning is DOWN in this engine due to Mazda's attempt to market this car with "regular" octane fuel as a selling point. I also think the marketed numbers come from a better state of tune using higher octane fuel. Thus, I wonder if the program for this is already out there?

As far as the more torque less hp theory, I don't accept it. I like more torque in proportion to hp, however, if Mazda claims the engine puts out 220hp then it should put out 220hp. Also, there are accepted parameters even on real world dyno's in regard to what is an acceptable drivetrain loss.
The 6 appears to have a much greater than acceptable loss even in manual mode. At some point I want Mazda to address this and now is as good a time as any. :)

"When the engine is breathing better means that the engine is consuming more air. More air in the combustion chamber means a higher dynamic compression. More compression means more power, which is what we see in the dyno plots, until about 5000 rpm."
****

Yes, more compression can get you more power. However, the compression in this car is set not variable. You can try and get more air in, but it will be compressed at the same rate. Without a way to further increase or "force" air into the combustion chamber the compression will remain and never increase in a normally aspirated engine. Superchargers and turbo's are "compressors" which "force" air into the combustion chamber.

Advancing timing can increase power but it increases the risk of detonation thus with low octane fuel timing has to be kept back. Frankly, with such a modern and variable engine, I'm surprised Mazda choose to keep tuning to low octane levels. This needs to be corrected asap.

Tome
 

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Discussion Starter #14
Reading Topic: Questions for guys that have dynoed...

That was my point exactly 20% IS NOT acceptable drivetrain loss for a FWD manual car with no LSD.
 

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Replying to Topic 'Questions for guys that have dynoed...'

QUOTE
Originally posted by M-006

Yes, more compression can get you more power. However, the compression in this car is set not variable.   You can try and get more air in, but it will be compressed at the same rate.  Without a way to further increase or "force" air into the combustion chamber the compression will remain and never increase in a normally aspirated engine.   Superchargers and turbo's are "compressors" which "force" air into the combustion chamber.

Tome[/b]
I don't want to get in a debate over dynamic compression vs. static compression, because I think you miss understood what I am trying to say. My only point to this was that the engineers 'may' have changed the cam timing to reduce detonation, and in so making it harder for us to tune the engine for higher-octane fuel.


I found this on another forum that can sorta explain what I mean by dynamic compression.


http://www.eng-tips.com/gviewthread.cfm/le...id/78/qid/16213

near the bottom of the page:


kjb2002 (Mechanical) Jan 29, 2003
The max compression ratio for 100 octane fuel is around 10.5:1 . That figure is calculated by taking the intake valve closing point to tdc as the engine's stroke. That is the "dynamic" compression ratio of the engine, not the mechanical compression ratio. For example if a v-8 engine had a 4 inch bore and a 4 inch stroke each cylinder would have 50.27 cu in or 824 cc's. Now if the total volume of the combustion chamber, deck space, gasket and piston dome or dish = 70cc then the mechanical compression of that engine is 12.77:1. Now we can make that engine run on 100 octane fuel by reducing the dynamic compression ratio with a late intake valve closing point. In this case, we chose an intake closing point of 70 degrees after bottom dead centre (ABDC) and at that point the piston had risen one inch on it's compression stroke. From that point to TDC is 3 inches. Caculate your new dynamic displacement with a 4 inch bore and a 3 inch stroke (618cc). With the same 70cc chamber volume and you end up with a compression ratio of 9.8:1. Increasing the lobe seperation of a camshaft will decrease dynamic compression and increase piston to valve clearance at TDC during the overlap period. For example if your cam specs at .050" is 286/292 ground on a 109 degree lobe seperation the timing will be I: 34/72 E: 75/37. If the cam's rate of lift is .005 per degree X your rocker ratio of 1.7, minus the valve lash of .030" then the intake valve at tdc will be 34X .005X 1.7 -.030 = .26" The exhaust valve is .015 more. ( Watch fo piston dwell as tdc is not always the location where the closest piston to valve occures and that is why engine builders use putty between the valves and pistons then measure it's thickness when "mocking-up an engine) Now let us take the same cam ground on a 116 degree lobe seperation (crank) using 1.5 ratio rockers and .025 lash. The valve timing is now I: 27/79 E: 82/30 The intake valve is now .18" off of it's seat at tdc and the exhaust valve is open .015 more. With the old 1.7 rockers and .030" lash the valve lifts at tdc is now .200 and .215 . Lift has remained the same with the 2 cams, but piston to valve clearance has increased by 7X.005X1.7 or .060" simply by increasing the lobe seperation by 7 degrees from 109 to 116.
 

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Reading Topic: Questions for guys that have dynoed...

Since some of you guys are much more knowlegable on the subject, what makes the Accord so special that switching from 87 octane to 92/93 octane buys you 10 more hp than the 240 quoted as stock? What's different about the Accord engine vs. the 6 engine?
 

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Reading Topic: Reading Topic: Questions for guys that have dynoed...

All this discussion is rather puzzling due to one thing... the dynos show peak power below 6300rpm, which is where Mazda claims it to make 220hp at.
 

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Replying to Topic 'Questions for guys that have dynoed...'

QUOTE
Originally posted by stretchsje


            All this discussion is rather puzzling due to one thing... the dynos show peak power below 6300rpm, which is where Mazda claims it to make 220hp at.[/b]
my dyno peaks right at 6300...it spikes 5900-6000 then spikes back up for peak hp at about 6300

http://www.massimoperformance.com/images/e.../withairbox.JPG
 

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Replying to Topic 'Questions for guys that have dynoed...'

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Originally posted by kyler13
Since some of you guys are much more knowlegable on the subject, what makes the Accord so special that switching from 87 octane to 92/93 octane buys you 10 more hp than the 240 quoted as stock?  What's different about the Accord engine vs. the 6 engine?[/b]
Simple. Engine management.


In the new Accord V6, the engine's power specifications have been "de-rated" for 87 octane fuel. When 87 octane fuel is in the engine, the knock sensor detects knock (same 10.0:1 CR as the Mazda 6s); sends feedback to the computer, and the computer retards the timing to prevent the knocking from occuring. This is 240HP and 212TQ.

When higher octane fuel is in the engine, the knock sensor will no longer pickup knocking because the higher octane fuel (more resistant to knock) is now taking care of this. With no knock being detected, the computer is now free to advance the ignition timing to more optimal levels that will give better performance. This is 250HP and 222TQ.

A bunch of other Honda V6's are supposedly like this also such as the Honda Pilot and the Odyessy minivan.


I haven't posted here in a long while so I've forgotten what all was covered in the previous discussions. But just search for octane in this sub-forum and you'll find some lengthy and informative discussions. Also look for posts by DuratecPerformance.
 

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Reading Topic: Reading Topic: Questions for guys that have dynoed...

Which leads me back to the question of tuning in the Mazda 6 (sorry to be cyclical). What do you have to lose in tuning the car for more performance with higher octane and letting the ECU handle the situation of using lower octane. You'd still get the 220hp, which they could *still* rate the car at, but you'd have the opportunity for an additional 10 or so hp if you chose to move to 93 octane. Seems like a money issue again with Mazda development. Aye chihuahua!
 
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