@norbs I hope these two quotes from this thread clear things up for you.
Originally Posted by BenFenner 
I'm going to explain why I tune fuel to 12.0:1 (high boosted applications) and why I recommend you do the same.
Originally Posted by BenFenner
For me, 12.0:1 is the ratio to use when you're in the good parts of the compressor map. This is regardless of turbo size, power output, or boost level. If you're in the efficient islands of the map, you belong at 12.0:1. Once you start pushing off of the normal efficient range of the turbo and/or losing efficiency for other reasons (poor flow in intake or exhaust) then it can make sense to go richer (although really I'd rather see a more efficient setup instead). I think 11.5:1 is tolerable in those situations. If you're going past 11.0:1 then for me you're off the reservation.
Basically, 12.0:1 even for high boosted applications. However, if you're not running a turbo designed for those high pressure ratios and instead are just cranking up the boost on a turbo that puts you well outside of the efficiency range then while I'd like to see a more efficient setup, I wouldn't blame you if you went a bit richer to band-aid the situation. @kevwal this meshes with your advice, yes?
And then Vadim asked a question.
Originally Posted by BenFenner
Originally Posted by Vadim
Any reason you like richer outside of turbo efficiency map? I would figure it is better to go leaner in those spots?When you're out of the efficient areas, intake temps rise quickly. The extra fuel is the easiest (obviously not best) way to cool things down a bit and slow the combustion.
A better way to deal with the situation is to retard ignition with high intake temps, and add only a little bit of fuel if you have to.
The best way is to avoid this situation altogether by using a correctly sized turbo and intercooler setup for your goals.
Originally Posted by BenFenner I'm going to explain why I tune fuel to 12.0:1 (high boosted applications) and why I recommend you do the same.
Originally Posted by BenFenner For me, 12.0:1 is the ratio to use when you're in the good parts of the compressor map. This is regardless of turbo size, power output, or boost level. If you're in the efficient islands of the map, you belong at 12.0:1. Once you start pushing off of the normal efficient range of the turbo and/or losing efficiency for other reasons (poor flow in intake or exhaust) then it can make sense to go richer (although really I'd rather see a more efficient setup instead). I think 11.5:1 is tolerable in those situations. If you're going past 11.0:1 then for me you're off the reservation.
Basically, 12.0:1 even for high boosted applications. However, if you're not running a turbo designed for those high pressure ratios and instead are just cranking up the boost on a turbo that puts you well outside of the efficiency range then while I'd like to see a more efficient setup, I wouldn't blame you if you went a bit richer to band-aid the situation. @kevwal this meshes with your advice, yes?
And then Vadim asked a question.
Originally Posted by BenFenner Originally Posted by Vadim Any reason you like richer outside of turbo efficiency map? I would figure it is better to go leaner in those spots?
A better way to deal with the situation is to retard ignition with high intake temps, and add only a little bit of fuel if you have to.
The best way is to avoid this situation altogether by using a correctly sized turbo and intercooler setup for your goals.
Last edited by BenFenner
on 2013-06-18
at 03-56-51.
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