pog0

iTrader: (17)

I've searched, but couldnt find too much info. All I really found was this:

https://www.evolutionm.net/forums/sh...=blowing+motor

I just installed my AEM wideband gauge and I have been going WOT til about 5-6K on the freeway from 3000-3200 in 5th and 6th gear. In 5th at 1 bar, my AFRs are from 10.4-10.9 in 5th and 6th. In 6th gear at 1.4 bar, it is about 10.9 - 11.3. 6th gear at 1.45 bar it went from 11.4 down to a solid 10.9. I am tuned for 1.4 bar with other basic mods, Al said 1.5 bar was too much boost during my tuning session.

I know I didnt give too much info and Im not able to log anything but my main question is... Is there any other way to blow my motor if I raise the boost and have good AFRs?

I plan to go to the 1/4 drags in two weeks and I am going to run 110. I dont want to crank up the boost too much if it is going to cause severe damage.

Ludikraut

iTrader: (17)

Yes, if you run too much timing advance, the grenade fairy will pay your engine a visit.

However, if you are going to run higher octane gas (hopefully unleaded), then you could turn up your boost a little bit. Personally I'm not a fan of simply upping the boost on racegas, though. IMNSHO, unless you _know_ that you have a good tune for whatever settings you're running, you're just inviting trouble.

l8r)

pog0

iTrader: (17)

I was wondering how much timing came into play with good AFRs... I guess it's two totally diff things. The gas is unfortunately leaded but I dont run it often. I plan to run 90-100% race gas, trying to get there as soon as the light comes on and dump in 5 gal. I dont plan on upping the boost too much, maybe around 25-26 psi max. Thanks for the response.

xenoturkey

yes, you can grenade your motor with good AFR's. Ask me how I know

Timing is very important, as are environmental factors, among other things. Also, you have to be careful that your AFR isn't right on the edge and slowly killing your motor over time.

nothere

iTrader: (23)

with an afr that fat the only thing you should worry about is your gas price. timing is where you need to worry. do you have your timing cut rigged up on the aem?
it wasn't to long ago a number of tuners were leaving it off and some motors went to heaven.

kjewer1

iTrader: (4)

I find that if I switch to race gas and don't lean out and add timing, I go slower. I run leaded 116-118 though, 110 may be a little better. In fact, I switched to 110 for a while because of this. I tried race gas last week on pump gas settings and I lost 2 mph. If you are not comfortable leaning out on the race gas, I would still add a couple degrees timing. And run as much boost as you want, assuming you are on the stock turbo. Monitor knock if you can though. I'm not sure what the AEM offers for options, but DSMlink turns my CEL on at over 2 degrees of timing retard due to knock, which makes me feel much better. Though I have lost motors with no knock, or at least not enough to show up on the sensor, due to excessively lean AFRs or excessively high timing (on different occassions, not at the same time ).

althemean

iTrader: (5)

As you can see you got your answer from a number of people already. But I will still chime in. Yes you can blow yor motor with good AFR's. My system went lean from a faulty fuel pump is all I can assume. The car was tuned and running great. Steady AFR's. A bit agressive on the timing I am told but I ran 100 octane most of the time. It went lean for whatever reason and blew the motor. My tuner left the knock control off I dont know if that wouldve helped any or not it happened so fast.

Rviscosi

To much timing also causes to much heat. Therefore a wideband AFR and EGT together are the best way to monitor. If you can do a pull and then check knock, thats even better.

pog0

iTrader: (17)

Thanks guys, I appreciate it.


Xeno,

How did it happen? What would you consider an on the edge AFR? 12:1 and up?

nothere,

Al tuned my car to around 11:1 AFR just to be on the safe side. What do you mean timing cut rigged on the AEM? I only have the gauge... wish I had the entire EMS though.

kjewer,

I would add timing thru ECU flash if I actually knew how to tune. I've been reading up on it but afraid to tweak my maps... It's running awesome right now, I want it to stay that way. Pretty cool feature with the DSMLink and the CEL with too much timing.

althemean,

Sucks to hear that a faultly fuel pump would cause that. Seems like you had a pretty aggressive tune if you were running 100 octane most of the time. I dont know why any tuner would turn knock control off but that might just be me.

SterlingEvo

iTrader: (5)

no oil would do it

Ludikraut

iTrader: (17)

Did you check to see if you are running different low octane vs high octane maps? Or are they set the same?

l8r)

blackevo110

youre running rich as it is, im at 10.9-11.3 myself because of fluctuating weather and my boost is 25psi on 93 pump. It was 26.5 but im not comfortable with that kinda boost on pump gas. You can, (possibly) turn up the boost safely, make sure your afr's arent going past 11.4 if you turn it up though. im not sure what gas/temp you run on/in. but turning it up with the higher octance is perfectly ok. you might not be "tuned" for it but as long as you stay reasonable it'll be ok.

btw...why does it matter leaded or not if its for track use w/ no cat? im not saying he has not cat i just think youre worried about cloggin injectors.. 1 tank wont do it and even after a few full tanks run some lucas injector cleaner and im positive you'll be quite all-right.

if hes got detonation, hows he gonna "check" it besides listening during a run? or even take off the plug cover and take the plugs out and look directly at the piston heads...

blackevo110

assuming he doesnt have a knock sensor***

Ludikraut

iTrader: (17)

Wow, 25 psi on 93 octane ... "ye pays yer money and takes yer chances"

Leaded gas will foul your O2 sensors, although you're right, limited usage won't do much harm. He's running on the stock ECU, therefore he can monitor actual knock counts (no need to guess at knock sensor voltage) via Evoscan.

l8r)

kjewer1

iTrader: (4)

Couple points.

With the stock ECU or something based on it, adding boost will either keep the same AFR, or it will go richer (higher load level map), assuming the fuel system is adequate. I adjust boost everywhere between 15 psi and 28 psi (spikes, drops to ~20) and AFR does not change. This is a bit of a misconception, but it does apply to MAP based cars like mazda, honda, and probably AEM EVO setups as well.

O2 sensors will usually survive leaded fuel if you put at least 1000 miles on them first with pump gas. The coating they get protects them. I usually go 2-3 years between sensor changes doing it this way. Earlier this season however I got greedy and only put ~350 miles on a new WBO2 sensor before going to leaded. It didn't last 2 weeks... This sensor got about 750, and it's still dead on with DSMlink AFratio after about 3-4 weeks. 1k is a good rule of thumb.

Also, if the AFR goes lean due to fuel system limitations, this thread no longer applies. This is why it pays to monitor AFR real time, not just when you are getting tuned. I know it's not in everyone's budget (though 300-400 for a WBO2 setup is less than what some people will pay for a BOV and some exterior modz), but it's a worthwhile investment. The sheer amount of data I've amassed over the last 5 years or so is unreal.