04 cooper S,
I have an 04 Mini S, with Cold-air, 15% Pulley, Alta Cat-back, and Shark Injector from Mini Mania. I dyno'd it this morning and max power was 175hp and 160 torque at wheels. The problem is Air Fuel ratio is like 9-10. From what I underdstand is It needs to be around 13. Is this correct? If so, any recommendations?

Also, I'm new to the forum, and definitely appreciate any advice. Here is a pic of my car,

I also, have 1" alta springs, rear control arms, short shifter, and wheels.

 

You may want to check into a Apexi SAFC Select. Ive seen some real nice HP gains with the controlling of the Air/Fuel ratio. You can check it out here:
http://www.apexi-usa.com/product_ele...=225&pageNum=1

 

You should strive for a number around 12.5 . I have seen quite a few at 10 which is bad , 9 is WAY too rich.

Randy
M7 Tuning

 

Peak torque for N/A engines is between 12.8 to 13.2:1, however this isn't recommended for boosted engines. Typical recommendations for boosted engines is 11.8, leaner if you have cold IAT's, awesome quench, or like to live closer to the edge of detonation. 10:1 is not "bad", just a bit rich. Of note is most current production cars that are boosted [super or turbo] have factory AFR's near 10:1. This is to minimize any chance of detonation even when the owner puts in crappy or low octane fuel. 9:1 is pig rich, but it's not "WAY too rich" if you're trying to cool off the combustion temps.

 

Based on the mods listed - the culprit has to the the shark ? strange

 

From where did the dyno operator pull the a/f numbers? I don't see a header (with a precat bung) in your mod list. If he was pulling a/f's from the end of the exhaust pipe, the number isn't accurate.

 

The a/f was from the tailpipe. I am going to uninstall the shark and re-dyno to see the differece. The strange thing is that I did see a noticible increase in response as well as what seemed to be better acceleration after the shark. Then again, they only advertise about 10 hp from the shark, It's not going to be a significant increase.

 

Accuracy is all relative. A measurement, provided it's error isn't absurd, is better than none at all. Tailpipe sniffers, while usually not as accurate as a pre-cat bung, is still useful. Keep in mind the cat is in bypass mode during WOT, as it can't process the airflow, so the sniffer isn't being too corrupted by the cat. If the measurement system is in doubt, a quick 'on-the-dyno' check is to run the car part-throttle, where closed loop has the AFR at 14.7:1.

 

"the cat is in bypass mode during WOT...so the sniffer isn't being too corrupted by the cat."
???

 

Certainly you've heard of catalytic converter blow-by, jlm.

 

I am going to a different dyno tomorrow at 1pm for a comparison. I haven't changed anything from the first pulls on Friday. I'm curious to see the difference if there is any. I will post tomorrow with the results Just curious, does anyone know the formula to calculate the crank horse power, I'm running 17 in wheels with 45/17's. as mentioned before, The previous max was 175 whp

 

Not that I am any kind of expert, but if IATs are high, doesn't the ECU start dumping fuel to cool the cyclinders down to prevent detonation? If the dyno was run with poor air flow and the engine was already hot, could that explain the rich readings?

 

nope; I'm a cat converter moron. I would assume "bypass mode" to mean the cat is bypassed, but all the gas still does goes through it. re-reading, I take it your point is that more gas is going through the cat at WOT than can be "converted" by the cat. therefore, the post-sniff is similar to the pre-sniff, at least as far as the influence of the converter is concerned?

 

13 is a bit high...I would say 11:1 would be good...with the tuning I have done in the last few months....I have take MINIs like yours and made 25 WHP with an AFC and some ECU mods...so just think...add another 25 WHP....that's 200 WHP which is about right for the tune of those mods...and LOTS OF FUN TOO!!

 

I'm back! I took my car to a different dyno this afternoon, What a difference. There is no doubt that the first guy didn't know what he was doing. I pulled 188 whp and 166 torque, but the craziest thing is the a/f was right at 11. I didn't change anything. I had even left the shark installed. I was looking for a straight comparison. I only wish I could post both of the sheets for all to see, Like 2 different cars. The point Somwon made about the heat I believe was right on. The first guy only had a small fan where today we Ran 2 huge 4 1/2' fans and engine temp was much lower, we also let cool down a lot longer between pulls.

All that said, Thank you all for you input, it was all excellent info. Does anyone know how to convert WHP to Crank, I know stock crank is 168, I'm guessing approx 205-210 w/ 188 at wheels, any input?

 

The mini's do run rich from the factory, 10-1 at WOT from about 4000 RPM on up isn't surprising. I have a wide-band O2 before the cat.

The heat thing is very real. If you have access to any data logging that can get to the coolant temp, it's good to run it. Also IATs. Randy says the ECU starts to dump more fuel when the IATs exced a bit below 80 C. If there isn't much areflow through the intercooler during a dyno run, you may read even lower AFRs than you would see on the road.

Matt

 

I read a thread here that stated that there was a 11% hp loss from crank to wheels.

 

but most are using 12%-15% loss for driveline. But what does it matter? Since most of us won't ever pull a motor to put it on an engine dyno, seems WHP is the relevant number. The advertised HP number is just a marketing item....

Matt