More timing and fuel vs less timing and fuel

[HPLouis]

I've seen tunes set up two different ways:
1. Timing at 22-23 and A/F ratio at 11.2-11.4, so more timing on a richer mixture
2. Timing at 18-20 and A/F ratio at 11.8, so less timing on a leaner mixture

Why does one choose one way or the other? Does one give more power, is safer....etc.

Is there a rhyme, reason or science behind it?

Thanks

 

[robvas]

This is gonna be good

 

[papajoewill]

Tuned in for the answers as well. Also curious.

 

[MG0h3]

I’m at 11.8 and 22* or 23*. Can’t recall.

20psi

Tuned by Kevin


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[q6543]

Maybe gas scale E85 vs 93 ??

Sometimes E85 likes to run fatter with more timing.

The 93 cars you'd see a few degrees less and run it at a more normal AFR.

Just speculating for op

 

[2003RedfireVert]

Are you assuming the same fuel between both tunes? I would think the correct answer to this question is…whichever one makes the most power, in the safest manner, for the fuel being used, on that particular vehicle.

 

[01yellercobra]

For pump gas I aim for 11.5. With the eaton I ran 18 degrees, but I was only at 12psi. With the Whipple it's the same 11.5, but only 14 degrees of timing. Mostly to stay on the conservative side.

For E85 it's around 11.0. It just seems to pull better around there. 21 degrees of timing on that tune.

 

[HPLouis]

This is for gas.

My prior tunes on my older cars have always been around 18 degrees and 11.5.

This new car and tune is around 11.0 (Lambda .72 to .75) and 23 degrees. It runs very well, no knock or anything. I emailed Greg about the timing and he said that he runs this tune on 91 octane so it will be plenty safe for 93. I haven’t heard any knock and the plugs don’t show any signs of detonation or running lean.

Another thing, the plugs are TR6IX iridium and they’re gapped at .044 with 13 lbs of boost and there’s no spark blowout. I was surprised that it pulled cleanly over 6000rpms.


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[robvas]

My vast knowledge gained from watching 3-4 YouTube videos tells me that running 2-3 degrees more timing is going to be capable of making way more power than being 0.4 leaner ever would

 

[HPLouis]

My vast knowledge gained from watching 3-4 YouTube videos tells me that running 2-3 degrees more timing is going to be capable of making way more power than being 0.4 leaner ever would

I’ve always been scared of running more timing because I’m always hearing about too much timing blowing up motors. That’s why I was worried about seeing 23 degrees and it was 23 degrees at 132, 138 and even 148 degrees IAT’s.

One of my friends said that maybe this car has more timing tuned into it because it has a head cooling mod but I never heard of that making a difference.


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[2003RedfireVert]

For reference…on my ported Eaton 2.76 pulley, my tune was 11.5afr, 18-19 degrees on 15-16lbs of boost for 93 octane.

With my octane booster tune it had 21 degrees.

 

[HPLouis]

For reference…on my ported Eaton 2.76 pulley, my tune was 11.5afr, 18-19 degrees on 15-16lbs of boost for 93 octane.

With my octane booster tune it had 21 degrees.

That’s the other thing I found weird with this car. I was expecting 15-16lbs of boost so when my datalogger showed 12.8, I was surprised. Maybe it’s the long tubes and off road pipe that lowered the boost. My older Terminators showed 15lbs on a 2.76 and 16lbs on a 2.7 pulley. Both those cars were non ported and the usual bolt ons (pulley, intake, catted mid pipe, exhaust and tune). They both were tuned to 11.5 A/F and 18 degrees of timing.


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[01yellercobra]

I only saw about 12psi with my stock eaton. But that was with a 2.8 upper, stock lower, bassani catted mid, and stingers. I still had the stock manifolds at the time.

 

[Bdubbs]

My E85 tunes on 21psi is:

Peak timing is 23*. It's not at 23* throughout the whole RPM range. It peaks at 23* around 6500.

My A/F is set around 11.6-11.8 range. Just depends on the ethanol. Right now I have some E75 mixed with E80. So I have it set on my E85 tune which means it's running a tad on the rich side. Better than lean.

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[gt347mustang]

Put the car on the dyno and see what it likes.

 

[HPLouis]

Put the car on the dyno and see what it likes.

The car’s already been dynotuned and there are no issues and it made good power and drives very well.

I’m just asking a question about the different styles of tuning and why. While doing some research before posting this question, I found post # 12 in this thread and that brought up the question in my mind:

2003 cobra timing map?

How many folks in here tune their own cobra, or tune cobras with SCT PRP? I'm going to start tuning my stock one, and am looking for suggestions for how much the stock timing map can be adjusted. Any help would be appreciated. --Matt

www.svtperformance.com

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[HPLouis]

I only saw about 12psi with my stock eaton. But that was with a 2.8 upper, stock lower, bassani catted mid, and stingers. I still had the stock manifolds at the time.

So mine is OK. I just remember seeing 15 on 2.76 and 16 on 2.7 on my old cars and was expecting to see close to that with a 2.8 on this one.

 

[gt347mustang]

The car’s already been dynotuned and there are no issues and it made good power and drives very well.

View attachment 1758327

I’m just asking a question about the different styles of tuning and why. While doing some research before posting this question, I found post # 12 in this thread and that brought up the question in my mind:

2003 cobra timing map?

How many folks in here tune their own cobra, or tune cobras with SCT PRP? I'm going to start tuning my stock one, and am looking for suggestions for how much the stock timing map can be adjusted. Any help would be appreciated. --Matt

www.svtperformance.com

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Did your tuner swing the a/f back and forth? Did they also do the same with timing? Is the a/f bump around 4100 rpm followed by the torque sag intentional or is that a lazy tune? I try to avoid having the leanest part of a wot run at or near peak torque because that's where cylinder pressure is highest.

Simply aiming for an arbitrary target isn't tuning. Tuning is putting the car on the dyno(or track) and tuning it by changing air fuel and timing to see what it actually likes.

Judging by the dyno count your tuner only made 4 pulls, so it likely wasn't optimized as I suggested above. It may or may not have another 5-10hp in it by optimizing every little bit of power. Is that worth the $500+ dyno time to figure out for you? Most people would say no.

 

[HPLouis]

Did your tuner swing the a/f back and forth? Did they also do the same with timing? Is the a/f bump around 4100 rpm followed by the torque sag intentional or is that a lazy tune? I try to avoid having the leanest part of a wot run at or near peak torque because that's where cylinder pressure is highest.

Simply aiming for an arbitrary target isn't tuning. Tuning is putting the car on the dyno(or track) and tuning it by changing air fuel and timing to see what it actually likes.

Judging by the dyno count your tuner only made 4 pulls, so it likely wasn't optimized as I suggested above. It may or may not have another 5-10hp in it by optimizing every little bit of power. Is that worth the $500+ dyno time to figure out for you? Most people would say no.

This was done by the prior owner in 2014 so I'm not sure how he did it. I was considering a new tune and after reading your post, I might just do that. The one reason why is that I have the SCT software and my tuner would give me the MTF file after tuning.

Thanks for the explanation. It really helped me in my decision making.