I know this is a bit offtopic, with all the *****ing going on around here, but i have a question/discussed to start.

With all the variables around, intake manifold flow, injector precision, fuel quality, do you run your car richer then usual to compensate... Im talking about daily driven/beaten, stock engines which cant really take much abuse.

Now im going to post a plot of my car, 8000km's since install;



Now, i was a little skeptical at first with the tune. *Too rich* uptop i thought. But the tuner has convinced me that running any leaner, i just dont have the buffer or reliablity i want. AF/power was consistant over 4 runs. His argument was;

"I dont want to run it any leaner uptop, because if i do, i just cant know for sure, that a cylinder is not leaning out."

Mangement is unichip, so individual cylinder trims cannot be adjusted. Well that and i dont have a wideband on each cylinder.

The tuner isnt a n00b. He has a track record of 1 motor, from 30cars (most have upwards of 50,000km's on the clock). The one motor which did blow, was inspected and rod failure was determined to be the cause.

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For arguments sake, this is the original dyno i got with the car.



The goal of the tune is maximum reliablity, which decent amount of power. This is only stock boost levels on an APS kit. Engine checks out good compression on all cylinders.

 

What's that translate to in hp?

 

1.25hp per 1kw.

Beyond that I'm keeping my opinion out of this thread

 

I believe 1 KW = 1.34 HP, so 288 kw should be around 386 hp

edit: lol - you beat me to it. I think I'm right though

In regards to the tuning question, there are so many other variables: octane, ambient temp variation, cylinder temps, timing, cooling, detectable detonation (knock) that it's hard to say just by looking at dynos as to which is better for your car. I'd say trust your tuner, particularly if they are recommending a more conservative tune.

It looks like you have more low end power in the 1st plot. Your total power under the curve is probably very similar. You'd have to add up all the little squares to be sure though

 

The main reason i started this thread is because all i ever see plotted around here is 11.5-8:1 AF. The above tune is much like a stock turbo car.

PS. Google converts hp to kW

 

I think your tuner has a valid point. Unforunately, without attaching an EGT probe to each exhaust outlet runner, it would be impossible to determine exactly which cylinders are running leaner or richer. If we use the imperical data that shows more airflow to the air cylinders (refering to the Cosworth flow bench charts we viewed at SEMA), that it would be prudent to run more fuel in those rear cylinders. This is what we do with the FCON, since it offers individual cylinder trims. Listening for knock is probably the best way to determine how rich you should go, assuming your timing values are spot on. What I've noticed, is some threshold knock can be eliminated just by richening those rear cylinders.

 

+1 Not bad for the afr you are running!

 

Hey Sharif, is that flow data published anywhere on the 'net? I wonder if that data holds true if a spacer and/or modified lower collector are installed...

 

I havent been able to locate it online. It was some proprietary Cosworth data comparing the OEM plenum to their new plenum. Even with the new plenum, they could not get equal distribution, but it did help quite a bit.

 

IMO your tuner is still a little sketchy, else he should've been able to plot the dyno vs. RPM not speed...

does he do Z's often or primarily other cars?
P.S. I'm not telling you he's wrong, but I've seen many a dyno with leaner AFR up top tuned by some of the reputable tuners on this forum

 

That's just a default setting for DD Shootout mode. It could very easily be switched to read over rpm. 2 keystrokes.

Now the tuner is a bit suspect due to the a/f running off the chart rich.
Will the car run like this... yes. Is it optimum... nowhere close.

 

But if you are actually tuning the car, wouldn't it make 1000000x more sense to plot vs RPM?

this wasn't exactly a "dyno day" right? This was a tuning session I thought?

 

That only the OP can answer.
Tuning wise, yes graph over rpm.
But... there are some other reasons to graph over speed especially in a competitive setting, which is what shootout mode was created for.

 

Good points above..I didnt notice that the AF was going off the charts sub 10's....I think that's too rich under any conditions, IMHO.

 

The A/F plotted dyno was at a dyno day.

RPM is not used due to tach signal needing to be wired in, otherwise its just a guestimate anyway.

Sharrif, your points on airflow distribution was exactly what i was after. thanks!

Personally im not about power, im about reliablity. I beat the hell out of my motor daily. But i did question his tactics of sub 10.5 richness. Hence this thread.

 

Maybe its super hot over there in Australia and he was getting knock going leaner? Maybe he should've pulled timing and brought the A/F back leaner? All good questions to pose to him and see what he has to say... Must admit I've never seen a dyno on these forums from the pros run that rich.

 

is it just me or does that AFR look like the one from an APS base tune?

I would guess that like the previous post said it does get faily hot in AUS and hense the extra fuel up top to substitute for in cylinder cooling and maybe they are getting a bit more det purely due to heat factors.

 

are u able to post a link to this plot?

 

Easy way to do that comparison is to cut along the curve with a pair of scissors, and weigh the paper.

 

sorry no link to the plot,

I am basing it on what we saw when tuning my APS TT 350.

we are also about 1500m above sea level in JHB.