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Discussion Starter · #1 ·
Hi guys,
Check out this video of my laps at Combe the other day.


If you look closely at my AFR gauge (in the middle of the 3 gauges) you can see I am around 10.1/10.2 AFR at full power down the main straight

I was also told the car was spitting flames when easing off for the Braking zones. Also, it just doesn’t feel as fast as I think it should do - I would guess it’s around 260/270 fly wheel hp when a lot of rev3 turbos with my mods are + 300.

the car is boosting about 16psi at initial full power and then tails off to 14 ish at redline. Manual boost controller and CT20b.

any thoughts or suggestions to improve my tune?

I was told 11.5 is the perfect AFR at full power. So am I down on power due to running too rich do you think?
 

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10 is really rich, on the border of washing oil off the cylinder walls. 12.5 is generally the sweet spot for turbo.
 

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12.5:1 is as lean as I would ever run a port injected turbo engine. You really want to be about 11.5-12.0 as a fairly safe range where you're getting maximum cooling of fuel without reducing power. Low 10's is very rich, and you are probably losing a decent bit of power running it that fat.
 

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Discussion Starter · #4 ·
Thanks guys

How would I go about tuning the AFR?

I am on the stock ECU so I guess the only way to lean it up is to increase the boost using the manual boost controller?

my only concern is it’s already peaking at 17psi when I first apply full power, then it tapers off to around 15psi at redline. And I’m pretty happy with the boost level, just feel like it should be making more power. And as you say, this is probs because it’s pig rich!

I suppose all this would be resolved with a stand alone ecu?
 

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Yes a standalone could be programmed to run as lean or as rich as you would want.

Is your fuel system stock? Injectors, fuel pump, pressure regulator? What's the part number on your MAP sensor?

The stock ecu doesnt know how rich or lean it is under boost and cant correct for it.
 

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Discussion Starter · #6 ·
Yeh sounds like I need to go stand alone then
Seems strange it’s running so rich as all the post of easy mods on a rev3 for 300+ Bhp never mention needing a stand-alone ecu.

maybe it’s because I am only around 15 psi at redline instead of 17.

yes fuel system/ injectors all completely stock
 

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I had the same issues on my gen3. Wanted to get to 300whp but not above a safe boost of 17psi. Leaned out mix by adding some methanol to the tank but that just changed my exhaust flames from yellow to blue. Think I was below 10afr sitting in mid 9’s.

I ended up installing an aftermarket ECU and never looked back. Quite a learning curve but huge step forward with engine monitoring and control.

Jimb
 

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Discussion Starter · #8 ·
Ah interesting thanks.

did you notice a big power increase after you went standalone and got the AFR sorted?

also, is there anything really dangerous about running low 10s AFR full throttle? I see it was posted above that I could be washing oil off the cylinder walls, should I immediately look to resolve this or would it be ok for another few track days?
 

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No I didn’t have big power gains as I was conservative in my approach to the tuning never have done before. My aim was to make more drivable with better response at lower revs. Over time I’ve pushed my limits a bit more with changes to ignition and fuel tables. Having installed a larger turbo I have been trying to get most from lower down power band. Reliability has been paramount taking into account such things as sequential fueling by adding fuel to centre two cylinders during high boost. Without such changes I’m sure engine would have died as I’ve unintentionally boosted to 26psi on the track when my wastegate stuck closed.
 

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I don't know much about your setup, but since you are running on the track I assume for longer periods of time, you are most likely heat soaking your intercooler, thus running up your intake temperatures. The car is dumping fuel to compensate for the high intake temperatures and keep your engine safe.

I ran my car bone stock on Laguna Seca and had exactly the same result, though I didn't have the gauge to verify, but I did calculate my miles per gallon which was extremely low.

Maybe watch the ratios on the first lap and compare it to your last lap to see if there is a difference.
 

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Discussion Starter · #11 ·

watch from the 3:00 min mark to see some lovely flames proving again I am running very rich
 
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