[E82tt6]

Originally Posted by shiv@vishnu

Not when you only run rich under boost. Washdown is only an issue if it runs excessively rich at idle, cruise, etc,.

Shiv

My concern with running that rich in a DI engine would be:

A. Fuel Dilution, especially for your average non-forum Dinan user on 15,000 mile intervals.

B. Carbon despoits on Intake valves, seeing as their is no fuel to clean them.

C. Damage to cats? Guess it's hard to tell how the AFR is while crusing, but the car adds A LOT of fuel very, very fast under load.

IMHO, a fuel curve like that shows sloppy/lazy tuning in general, and I wouldn't be comfortable with it.

[OpenFlash]

Originally Posted by 335e92tx

There still is being raw gas dumped into the oil system. Fuel dilution in Oil will serverly reduce its lubrication ability... increasing wear especially if extended oil change intervals are used.

Absolutely, but we're talking about 10-11:1 AFR in this case. And only under max boost when being control/monitored in a closed loop system. Washdown wouldn't even begin to be a concern to me in this situation.

Don't get me wrong. That AFR trace is pretty ridiculous. But no more ridiculous than other stock tune DI and nonDI cars I've seen.

Shiv

[smartys]

Originally Posted by Winston Wolf

http://www.e90post.com/forums/showthread.php?t=133625

here.

thanks!

I remember that now, i did view it a while back....

Hmm, I wonder why the difference in gains....again, My HPFP? can't be THAT much of a diff in gains for i vs xi?

I wunder............

[smartys]

Originally Posted by shiv@vishnu

Absolutely, but we're talking about 10-11:1 AFR in this case. And only under max boost when being control/monitored in a closed loop system. Washdown wouldn't even begin to be a concern to me in this situation.

Don't get me wrong. That AFR trace is pretty ridiculous. But no more ridiculous than other stock tune DI and nonDI cars I've seen.

Shiv

Interesting....Wondering Shiv on your thoughts about how the AFR measurement was taken, ie. tailpipe vs right behind O2 sensor, and only ONE at that....?

[RynoDyno312]

Originally Posted by shiv@vishnu

Don't get me wrong. That AFR trace is pretty ridiculous. But no more ridiculous than other stock tune DI and nonDI cars I've seen.

Shiv

I've heard that stock EVO X AFR is 9:1 at full boost/wot. The huge gains from a reflash make a lot of sense if that is the case.

[smartys]

So I spoke to Dinan's Engineering Dept and forwarded them my Dyno results and this is what he wrote back:

The dip at 2500 rpm might be due to the knock sensors. This rpm range is where the boost dramatically ramps up, and because the engine is turning so slowly, it allows more time for detonation to develop. When the knock sensors go off, the computer will alter the fuel delivery & ignition timing to decrease power, to protect the engine. The tuning changes depending on the severity of the knock sensor signal.



On the dyno, this is usually caused by inadequate cooling. You’re probably doing the dyno run in 5th gear, where the transmission is 1:1, which means the car is going well over 100mph. On our dyno, we use a fan that’s taller than the car, and it can still only get 70-80mph of airflow, even with ducting that directs the air right at the radiator (see the second picture at http://www.dinancars.com/bmw/technia...ern-bmw-engine). If the fan you were using is smaller (which is very likely), then the radiator & intercooler would be heating up excessively, which leads to a hotter engine and intake air, which raises the likelihood of detonation. So what you see on the dyno may not be a true representation of what happens on the road. What was the setup used during the dyno test?



Also, fuel quality will have an effect too. If available, you should try a higher octane (or at least a different brand of fuel), and see if this “dip” goes away.



Please feel free to contact us if you have further questions. Thank you!

James Leong
Dinan Engineering Inc.

With regards to the AFRs, he also stated that tailpipe measurements of AFRs are essentially useless and inaccurate.....

So what's your verdict guys? Seems plausible, but what about others' Dyno results that DON'T have that dip?

I wonder if I should try Sunoco 94......I just don't want to take a chance with that friggin Ethanol in their gas......

[E82tt6]

Why did he state that tailpipe AFR measurements are useless and inaccurate?

[ElliottP]

Just to clarify. What do the terms 'rich' and AFR mean in this context?

[smartys]

AFR = Air Fuel Ratio
"Rich" means its running with relatively high amounts of fuel (ie. Air:Fuel ratio is low)