What are the Benifits of Running - RICH / LEAN? - what would it do.. more power.. less power? I know my gas milage would be worse but other than that?

 

If you run it lean, you stand a chance of blowing your rings or, worse case, pistons. Rich will not give you more power and, if too rich, can flood the engine. My advise, work on your airflow. Add an intake (fastest, easiest way to get more power), Y-pipe, cat-back exhaust, and, if you have a M/T, get the computer programmed. I added an Injen CAI and saw a decent boost in power for $250. According to Injen, the intake on an '02 increases power by 20 hp and torque by a couple of pounds, if you believe them. I haven't had my Dyno'd yet, but it definitly pulls harder now, especially in the higher RPM's.

 

interesting because my darn A/F gauge constantly reads lean all the damn time except when I start it up cold

 

it runs lean even at open throttle?!?! hey man your greatest amount of power is actually achieved at a slightly rich mixture.......not incredibly rich just "slightly" rich. remember stoichiometry is 14.7:1 but if you run it that lean under a load its prolly not that great of an idea. where as 18:1 would be lean and 10:1 would be rich just to clarify that because alot of people get it confused........it is the ratio of air to fuel not fuel to air, thus the greater the number the more air and the lower the number the less air. i find it kind of odd that you say your car runs lean all the time, if im not mistaken there was a thread a while back that said the maxima runs really rich in the upper rpms almost the exact time that the vais opens up.

 

excuse me in the previous post i meant to put .......it runs lean even at wide open throttle?!?!?

 

here is another little tid-bit of information, the level of co2 in the exhaust gas should peak at optimum mixture, co2 is a gas that represents complete combustion. the gasses that you dont want to see alot of in your exhaust is carbon monoxide which is partially burnt fuel, hydrocarbons which is unburnt fuel, and excessive amounts of oxygen which is usually a sign of a misfire when accompanied by HC's. there is one other gas that is involved with combustion which is NOx or oxides of nitrogen, these occur when there are extrememly hot combustion temperatures, in reality NOx emissions increase with the efficiency of the engine but they are harmful the the atmosphere which is why there are catalytic converters and EGR valves to control the tailpipe emissions.

 

I was under the impression that very few modern cars run at stoich these days because the cats need a slightly loaded mixture for them to light off and operate properly.

With stock intake/exhaust the engine might be short of air in the mix at high RPMs, especially when it gets up on the cams. AFR meter should tell you at high RPMs whether you need to add air (bigger intake, throttle body) or add fuel (bigger injectors or longer pulse)

 

How sure are you of those numbers that Injen claims? Just curious... I've heard mixed things about it...

Bottom line, IMO, I don't think an Injen intake for $250 is worth it when consider what a cheaper Frankencar or Berk intake will do for ya...

 

20hp? Hah, more like 5-6hp at most.

 

Yeah, that's more around what I was thinking... just didn't wanna throw it in his face like that...

 

Rich will wash down your engine oil, which will no longer lubricate the low end of the engine (crank, rod bearings, main bearings, oil pump) and cause internal engine damage. You would have to run very rich in order to get to that point, and you would get **** for gas mileage. I personally run 12.4:1 on my DE-K, and found over 12WHP in some parts of the powerband, especially around 3500-4K and then once again from 5500-redline. By runing leaner you can gain power, but there is a point where you will stop gaining power (HP and TQ) with going to lean, and you will induce detonation- pinging. I found that for max power on my car 12.6:1 is the most I could run on 93 octane with no detonation, and timing advanced to 18 deg (up from 15 stock). Since not all fuels are always going to be 93 octane ( even thou I never put anything else in there) I chose to back off to 12.4:1 to sacrifice like 2WHP here n there. Engine throttle reponse is much much more snappy and gas mileage has never been better. 100K miles and shes still ticking strong. Hopefully TS ECU will come out soon with higher redline so I can pop some cams in her ( Tomei ) before the turbo goes on.

 

yes this is true except maybe for the ULEV emission vehicles that would definitely sacrifice the performance for the emissions standpoint most cars are run around 12.?:1 for optimum performance. in reality 14.7:1 is just way too lean.