yes you wanna see it? call me rice thats fine with me.

10-11:1: Very rich. Some supercharged engines run in this range at full power to control detonation.

12-13:1: Rich. This slightly rich mixture produces the best power for unsupercharged engines. When you read engine dyno charts for performance engines particularly, maximum power will usually be found in this A/F range.

14-15:1: A 14.6:1 A/F ratio is considered stoichiometric, which is chemically ideal. Theoretically, there's no excess fuel or oxygen remaining after combustion. This is the A/F ratio that the ECU in an EFI equipped car is trying to maintain. Overall, this range is best for part throttle cruise.

16-17:1: This lean mixture is the best A/F ratio for economy. It can be borderline for part throttle, since this lean mixture is unstable and prone to detonation. THis ratio is worse if EGR is used.

18-19:1: Very lean ratio. It's considered the upper limit of drivelability. If the ratio is any leaner, detonation will occur, if it hasn't already!!


the audi runs at about 14-16 approx 18:1 when nitrous is on

the gn runs about 11-12 but its needed for 28 psi of boost

the 300zx runs a steadt 13-14

th omni runs 16-18

 

Oh yes what a very mature come back. Just like a little kid.."well my car is faster than yours!!". It must be that BOV that makes it so fast!!!!

I'm interested to see your "scientific research". I'm sure you can provide all the needed data and A/F plots from before and after.

Yeah I can copy and paste too!

http://www.westsidemustang.com/air_fuel.htm

 

thats wher i got my info but i didnt get my fuel charts from them

 

like i said i used a venom a/f meter and its the bov that keeps it running fast.

 

That's like saying "My timing belt makes my car fast!". BOV/DV's do not increase HP.

 

Why Rich is Better
by Klaus Allmendinger, VP of Engineering, Innovate Motorsports

Many people with turbochargers believe that they need to run at very rich mixtures. The theory is that the excess fuel cools the intake charge and therefore reduces the probability of knock. It does work in reducing knock, but not because of charge cooling. The following little article shows why.

First let’s look at the science. Specific heat is the amount of energy required to raise 1 kg of material by one degree K (Kelvin, same as Celsius but with 0 point at absolute zero). Different materials have different specific heats. The energy is measured in kJ or kilojoules:

Air ~ 1 kJ/( kg * deg K)
Gasoline 2.02 kJ/( kg * deg K)
Water 4.18 kJ/( kg * deg K)
Ethanol 2.43 kJ/( kg * deg K)
Methanol 2.51 kJ/( kg * deg K)

Fuel and other liquids also have what's called latent heat. This is the heat energy required to vaporize 1 kg of the liquid. The fuel in an internal combustion engine has to be vaporized and mixed thoroughly with the incoming air to produce power. Liquid gasoline does not burn. The energy to vaporize the fuel comes partially from the incoming air, cooling it. The latent heat energy required is actually much larger than the specific heat. That the energy comes from the incoming air can be easily seen on older carbureted cars, where frost can actually form on the intake manifold from the cooling of the charge.

The latent heat values of different liquids are shown here:

Gasoline 350 kJ/kg
Water 2256 kJ/kg
Ethanol 904 kJ/kg
Methanol 1109 kJ/kg

Most engines produce maximum power (with optimized ignition timing) at an air-fuel-ratio between 12 and 13. Let's assume the optimum is in the middle at 12.5. This means that for every kg of air, 0.08 kg of fuel is mixed in and vaporized. The vaporization of the fuel extracts 28 kJ of energy from the air charge. If the mixture has an air-fuel-ratio of 11 instead, the vaporization extracts 31.8 kJ instead. A difference of 3.8 kJ. Because air has a specific heat of about 1 kJ/kg*deg K, the air charge is only 3.8 C (or K) degrees cooler for the rich mixture compared to the optimum power mixture. This small difference has very little effect on knock or power output.

If instead of the richer mixture about 10% (by mass) of water would be injected in the intake charge (0.008 kg Water/kg air), the high latent heat of the water would cool the charge by 18 degrees, about 4 times the cooling effect of the richer mixture. The added fuel for the rich mixture can't burn because there is just not enough oxygen available. So it does not matter if fuel or water is added.

So where does the knock suppression of richer mixtures come from?

If the mixture gets ignited by the spark, a flame front spreads out from the spark plug. This burning mixture increases the pressure and temperature in the cylinder. At some time in the process the pressures and temperatures peak. The speed of the flame front is dependent on mixture density and AFR. A richer or leaner AFR than about 12-13 AFR burns slower. A denser mixture burns faster.

So with a turbo under boost the mixture density raises and results in a faster burning mixture. The closer the peak pressure is to TDC, the higher that peak pressure is, resulting in a high knock probability. Also there is less leverage on the crankshaft for the pressure to produce torque, and, therefore, less power.

Richening up the mixture results in a slower burn, moving the pressure peak later where there is more leverage, hence more torque. Also the pressure peak is lower at a later crank angle and the knock probability is reduced. The same effect can be achieved with an optimum power mixture and more ignition retard.



I rest my case. No more will I post in this forum

 

Well you really didn't prove much to me. That article fails to mention fouled plugs, clogged cats and extra carbon soot.

 

thank god

 

thats cuz thats the result of a combination of things.

 

I just use a screw driver to tune my car.[sm=happybounce.gif]