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Does anyone have some sources of information on the efficiency of low rpm wot (vs higher rpm and not wot) and associated (IF ANY) mechanical considerations (issues with bearings, rods, other).

Several good articles on support of WOT and low RPM for best efficiency.

http://autospeed.com/cms/A_110216/article.html
http://www3.fs.cvut.cz/web/fileadmin/documents/12241-BOZEK/publikace/2007/2007_108_01.pdf

are there other definitive papers that you are aware on durability concerns with WOT low RPM? With or withour turbos such as MS3.

THANKS!
 

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Okay, I'm not an engineer and I did not attempt to read and fully comprehend all the info in the links. But I'll take a crack at it on an inexpert level.

By going to WOT at a low RPM with turbocharged engine you're putting a lot of force per power stroke on the internals, at least in higher gears. Presumably, Mazda has taken precautions against people doing this when they decided to mass market this engine, but in the short term there has to be an significantly increased chance of cracking something. And long term you're almost certainly reducing the longevity of the internals.

I think you would eventually encounter many of the same problems as people who push the envelope on manual boost control.
 

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You also might want to consider that some people, mostly 07 MS3's as far as I can tell have issues with WOT in 5 or 6th at low revs. This is because our High pressure direct injection fuel pump is mechanically driven, off of the camshafts. This can cause too low of fuel pressure if the engine goes into boost. This results in a lean mixture, which results in predetonation. This is very bad both for the engine's life, and the efficiency, as the engine will respond by retarding timing.

I have not felt this problem, but its pretty widespread as far as I can tell.
 

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I'm not sure exactly what you are asking? Please elaborate on your question.
 

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I didn't read the article mostly because of reasons that we know this engine should not be loaded like this at low RPM's, but technically an engine is most efficient at WOT @ the rpm peak torque is produced. Note efficiency and fuel efficiency can be two different things. in terms of accelerating habits that produce the best mileage results, you dont want to drive like grandma and you definitely don't want to do all of your accelerating @ WOT. I definitely don't like trying to accelerate below 2000 RPM's in this car in any gear above 3rd, and if I am below 1800~1900RPM I will most certainly downshift if I need to do any serious accelerating, I would only apply light throttle @ that low of an RPM to accelerate a few kph.

For best results, accelerate briskly and shift @ around 3000RPM, or lower if you are already @ desired cruising speed. 2000RPM or so @ cruising speeds is about perfect in really any gear if you are not sure. But if you are in 5th or 6th gear @ 2000RPM and need to accelerate I would go down a gear, if you need to accelerate quickly and need to go relatively heavy on the throttle than maybe go down 2 gears to avoid over loading the engine.
 

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^+1

when i'm accelerating i usually go to 3-3.5 rpm, if i need to accelerate a little quicker then 4k. if i'm driving around base, then going to 3k would be almost over speed limit, lol, and there's a lot of slow driving involved on base, so 2500 rpm would be shift point, cruise at 2k (4th gear usually).
 

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You aren't hurting your engine by driving like that. It is a good fuel efficient profile. If you aren't opening up your throttle enough to get you turbo involved then you are losing a bit of fuel efficiency but you make up for it with your low rpm at cruise speeds. WOT maximises your volumetric efficiency, which has virtually nothing to do with fuel efficiency.

There are lots of "efficiencies" associated with engines so its good to name which one we are talking about.
 

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[quote author=jarry link=topic=134387.msg2894375#msg2894375 date=1233096301]
You aren't hurting your engine by driving like that. It is a good fuel efficient profile. If you aren't opening up your throttle enough to get you turbo involved then you are losing a bit of fuel efficiency but you make up for it with your low rpm at cruise speeds. WOT maximises your volumetric efficiency, which has virtually nothing to do with fuel efficiency.

There are lots of "efficiencies" associated with engines so its good to name which one we are talking about.
[/quote]

you think you arent hurting the engine by going WOT at low RPM's? im sure all the people with dash hawks that log massive amounts of knock by doing that would disagree.
 

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Your engine management shouldn't allow your engine to start pre-igniting. Lugging doesn't really hurt engines like it used to. Most of the "problems" associate with low RPM driving are leftover stories from carbs.
and besides what i got from his post was 2k-3.5k. Rpm.
 

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he isnt talking about going WOT at those RPM's though. but I am sorry I thought you were referring to the original post, which seems to imply WOT at the lowest possible RPM is best, which is just crazy.
 

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[quote author=jarry link=topic=134387.msg2894412#msg2894412 date=1233097739]
Your engine management shouldn't allow your engine to start pre-igniting. Lugging doesn't really hurt engines like it used to. Most of the "problems" associate with low RPM driving are leftover stories from carbs.
and besides what i got from his post was 2k-3.5k. Rpm.
[/quote]Lugging per se is not the issue. The issue is high boost at low RPM.
 
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