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Replying to Topic '6 dyno plots are up'

Does anyone know if our VVT is continuously variable, or a step?

Cuz it looks like the A/F ratio drop coincides by 500 RPM (meter delay?) with a sudden jump in the torque at 2750 RPM.

thanks for the plots!
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Replying to Topic '6 dyno plots are up'

PS, it really looks like you could unlock a healthy dose of power with a fuel computer...

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Replying to Topic '6 dyno plots are up'

Thanks for posting the charts, thats very interesting. past 2750 RPM our torque curve is pretty flat, as I would expect and feel in my car given its a V6. Could a CAI smooth out the torque from 2000-~2700 RPM? Why the ~17lb decrease? I thought our VVT was continuous, which is why you don't see a major drop and then gain in the 5000 RPM range.....maybe I'm to use to looking at 4 bangers....
 

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Replying to Topic '6 dyno plots are up'

I'd think that the 2750 rpm jump is due to the opening of the shorter set of intake runners. The torque curve is fairly flat up to that point, and fairly flat after that.

Thanks for posting the plots. I was currious how the variable valve timing handled the changes caused by the opening of the short intake runners...
 

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Replying to Topic '6 dyno plots are up'

Ahhh yes, thanks I forgot about the variable intake runners... that makes far more sense than valve timing (the RPMs are too low!)

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Replying to Topic '6 dyno plots are up'

Those seem a bit low. 174 wheel means a 20% loss, that is a bit much for a FWD 5 Spd. My current car is RWD auto and only loses around that. Shouldn;t it be more like 15-18%?
 

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Replying to Topic '6 dyno plots are up'

The things you could do with an S-AFC. If you could keep that A/F ratio to a flatter line you'd have a nice pull for sure.
 

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Replying to Topic '6 dyno plots are up'

Thanks for posting these up!


I'll drop them into CarTest2000 and then do some playing :)
 

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Replying to Topic '6 dyno plots are up'

I wasn't even aware that the 6s had variable runners. Are you guys sure about that? 2750rpm looks awfully low for runners to be switching over.

Are you sure it's not like a tumble or swirl control valve that helps with emissions and fuel economy at cruise RPM's, because that's what it looks like to me. I know the WRX has something like this. Tumbler valves, they're called. It's like a half-moon flap that interrupts the flow in the runners. It induces more turbulence and swirl which helps with the emissions, but it also drops the power off a lot. At around 3000rpm or so is when it closes (IIRC); and returns the runners to their full capacity.

Something like this would explain the torque jump at 2750.

If it is in fact variable runners, then they're very clearly designed for economy/emissions, and not performance. If true, locking them to only the top-end profile (if possible) might help the low-end by deleting the economy stage :D

Forgive me if I'm wrong. Just trying to learn as much about this car as I can ;)


QUOTE
Originally posted by mpulse1
I'd think that the 2750 rpm jump is due to the opening of the shorter set of intake runners.  The torque curve is fairly flat up to that point, and fairly flat after that.  

Thanks for posting the plots.  I was currious how the variable valve timing handled the changes caused by the opening of the short intake runners...[/b]
 

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Replying to Topic '6 dyno plots are up'

I do believe they are tumble flaps and not variable length intake runners....

On the 2.5L Duratecs, we have long and short length intake runners. The short runners are blocked off at less than ~3300 rpm to force the air into the long runners for low end torque.... then the valves open and the air naturally follows the shorter runners which provides a kick in HP..

I also think the intake manifold on the Mazda6 V6 has swirl vains built into them....


Nikolas
 

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Replying to Topic '6 dyno plots are up'

So does that mean something can be done about the torque dip from 2000-2750 RPM? I don't want to screw up the emissions, but is there a way to get around that problem with a CPU mod?
 

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Replying to Topic '6 dyno plots are up'

QUOTE
Originally posted by DuratecPerformance


            I do believe they are tumble flaps and not variable length intake runners....[/b]
Yup.

QUOTE
I also think the intake manifold on the Mazda6 V6 has swirl vains built into them....

Nikolas[/b]
Yup.

I'm feeling long winded today.
 

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We wont know until we have a way to tune these engines. I am trying to convince Diablo to move the Mazda6 up on their development list. I think this car is going to be very popular and Diablo will have all of the market share for engine tuning until companies like Apex'i Come out with their products. Only so much can be accomplished though through air/fuel tuning. Timing advancement or retard can do good as well. Control over when the tumble flaps open and close would be nice, but we havent even arrived there yet.


Nikolas
 

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Replying to Topic '6 dyno plots are up'

Yeah, i didn't think the 6s had variable length runners. ;)

Disabling the tumblers isn't really going to help you performance wise, since you're not below 2750rpm much during racing, but it would help the low-end torque and driveability around town. But disabling them will almost certainly throw a check engine light.

Back when I was considering getting a WRX (a year ago) I was reading extensively on their boards, and the trick was to remove the half-moon flaps in the intake manifold, but leave the actuators in place. That way it would operate normally and you wouldn't get a CEL, but the half-moon flap was no longer there, effectively deactivating them. I think doing this helped the turbo spool up quicker as well.

This is all from memory, from a LONG while ago though, so it's pretty foggy. Probably not worthwhile to even bother with.
 

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Replying to Topic '6 dyno plots are up'

The tip-off was the suddeness of the jump in the torque curve. When you have variable runners, there's usually a little dip in the torque curve as the airflow realigns itself and starts flowing through the other runners on the dyno. Like in this Altima dyno. Look at 3800rpm

http://mywebpages.comcast.net/stevtecv6/dy...manceMagcom.jpg


The jump in the 6s curve at 2750 is much too sudden to be variable runners. It's almost like a VTEC torque curve jump, or, in this case, tumblers closing.
 
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