ProtoConVert

reading the HP controversy... it got me curious as to why exactly a rich A/F will be better for break-in... can anyone explain exactly why?

ggreen29

The extra fuel keeps the engine a little cooler.

TurboSE

Rotary engines like to run richer anyway. The renesis can run a little leaner but under throttle all engines should run a little on the rich side. 12.5 ~13 :1 is not uncommon.

neit_jnf

Lower temperatures and better lubrication would be my guess

86rx7

The extra fuel that doesnt burn evaporates, and keeps things nice and cool. Which is why you can see rich/lean mixture on an EGT gauge, rich = too cool of exaust temp, lean= to hot. NA rotaries dont like 12-13:1 that is a myth derived from turbo rotaries that need rich mixtures to keep form detonating. NA's like 13.5-14.2 for best power.

P00Man

the 8 has been running very rich, you can see the large amounts of soot on the tail pipes
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VAPIR VAPORMATIC DELUXE VAPORIZER

TurboSE

14.2? At full throttle?

wildwhl

Hello group. Been lurking for a while. Picked up my black 6MT with 1GT package about two weeks ago. Been breaking her in somewhat nicely, have 800+ miles now, and found something discouraging last night.

I have a repeatable but not consistent problem that may have something to do with the additional ports opening. What happens is that just pass 6K on part to full throttle acceleration the thing goes flat - reminds me of a motorcyle that has been jetted too rich - like fowling plugs. Doesn't happen all the time - but about half the time, in any gear, DSC on or off, etc. Slow back down, accelerate again, and it may or may not happen. It stays flat, by the way, and refuses to accelerate much beyond 7K when this does occur. For what it is worth, when it doesn't happen, the cars a blast :-)

So, this will certainly warrant a trip to service come Monday...but thought I might post it here in case anyone else wanted to comment or has noticed anything similar. Don't know if this could tie into the dyno thread in any way...but I'm certain something is not functioning properly with my vehicle at least. My guess is that one portion of the variable intake volume stuff (hey, don't know the correct terminology here) is not funcitoning properly. Conditions were great last night for building horsepower as many of the hot rodders attending Hot August Nights can attest to...just not for me.

Mind you, I haven't driven this fine handling machine like a raped ape just yet...but was seriously disappointed to discover the aforementioned problem. Otherwise, I love the car and hope this little "quirk" goes away and/or is fixed promptly by my local dealer. I'll keep you posted.

brothervoodoo

Everybody seems to indicate that the 8 is running rich, probably due to the ECU not kicking over. I would wait and see what happens after a couple 1000 miles (4-6) and then see. Time well tell.

86rx7

Ive seen a few people tunning that lean, one of which was Jimmy325i, which i posted in a previous thread, i dont think mazda will go that lean though, id be looking for 13.4-13.7 if i had to guess.

P00Man

thats still A LOT leaner than 12.2ish though
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Squirting Squirter

86rx7

on the up side, if it isnt the ecu detunning for break in, and mazda fixes it somehow, you all can gain an easy 20 or so HP from leaning it out alot. I wonder is a S-AFC would work on an 8....

Lensman

Sounds like a stuck port surely?

TurboSE

I doubt mazda would honor their warranty if you changed a/f ratios particularly if you run on the leaner side with 10:1 compression.

86rx7

Mazda wouldn't have to know, just uninstall it when you go for service. Actually if a S-AFC would work we could settle this whole low on HP thing if someone would just dyno tune it, and check somehow that the butterflys are opening all the way. I still believe very much that it is a detuned break in thing. And i dont think its a stuck 6-port, as you can see them open on all the dyno graphs.

P00Man

"dont think its a stuck 6-port, as you can see them open on all the dyno graphs" - 86

exactly, its gotta be the ratios, no car should have fuel coming out of the tailpipes when running "normal" or "proper" AFR's

also any theorized problems with the engine can be set aside because we know the engine can put down the power as seen in the C&T #'s as well as the recent Aussie numbers, not to mention the star mazda series.

anyway, as boostd7 said, its the stuff surrounding the engine that is questionable, but then that guy (forget his name) that posted the thing about a special sort of Plunum and acoustical tuning the 8 uses so id say that stuff is sound (HA HA! get it?!?) which leads me to beleive that it is definately the air/fuel ratios and overall "tightness" of the engines, though i think that the bigger culprit, maybe even by a considerable margin, is the AF ratios
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