VTEC Optimum AF Ratio

[integramania]

Guys are your vtecs running at 13:1 AF Ratio?

I read that this is the best and also saves fuel...but Honda stes it at 12:1 AF which is on the rich side....

Can anyone share their experience on this?

Thanks:regular_smile:

 

[udengfahlawi]

not 14.7 kah?

 

[sasuke]

Someone told me is 14.2...

 

[hattech-v]

someone oso told me 2.14... kekkekeke
but now i'm running 13+

 

[integramania]

14 plus so lean?

 

[J101]

13.6 should be fine. get it run on a dyno or use some wide-band tool like Innovate. but then again if this is a question of "how-to-save-fuel" i think it depends more on the engine setup and driver's foot :p

 

[chris2000]

I was told that in the lower revs we can run leaner like 14 to 15 (fuel economy city and cruising) and in the midrange 13.5 and then in the upper rev 12.5 to be safer and cylinder cooling..

My friend have seen DC5-R, running Mugen ECU 8600rpm cut and dyno A/F was almost flat 12.5 throughout rev and another DC5-R with the Mugen ECU 9200rpm cut was almost flat 13.0 thorughout rev.

 

[udengfahlawi]

what's the best A/F meter around?...the Apexi TT not that accurate lah...

 

[hattech-v]

I was told that in the lower revs we can run leaner like 14 to 15 (fuel economy city and cruising) and in the midrange 13.5 and then in the upper rev 12.5 to be safer and cylinder cooling..

My friend have seen DC5-R, running Mugen ECU 8600rpm cut and dyno A/F was almost flat 12.5 throughout rev and another DC5-R with the Mugen ECU 9200rpm cut was almost flat 13.0 thorughout rev.

agree on this.. this is the important of the management.
u can tune the fueling for any rpm range...
another option is using FPR but its all the way rpm increment.. sighh...

 

[hattech-v]

what's the best A/F meter around?...the Apexi TT not that accurate lah...

wideband... ekekeke... then i can pinjam....

 

[J101]

yeah true chris. but do take note on the driving application (daily driven or race)whether its running on day time or night time. it does affect the performance when heat starts to boil.

I was told that in the lower revs we can run leaner like 14 to 15 (fuel economy city and cruising) and in the midrange 13.5 and then in the upper rev 12.5 to be safer and cylinder cooling..

 

[semutapi]

I was told that in the lower revs we can run leaner like 14 to 15 (fuel economy city and cruising) and in the midrange 13.5 and then in the upper rev 12.5 to be safer and cylinder cooling..

My friend have seen DC5-R, running Mugen ECU 8600rpm cut and dyno A/F was almost flat 12.5 throughout rev and another DC5-R with the Mugen ECU 9200rpm cut was almost flat 13.0 thorughout rev.

Ooo.. this explain why my AF meter show diff reading when Im drive slow or fast.I tought my car tuning problem.
Chris2000, sometime my car AF show 20.0 during long distance driving are it ok?

 

[integramania]

guys so 14/15 low rev..mid 13 and high rev 12....

this one sure engine will be safe?

reason i am asking is I'm running about 12 throughout and was told that its hsould be tuned to 13....i didn't think that 14/15 would be ok

I want it to be as fuel economical as possible and also when the power is needed it comes in properly as its a daily driven ride

thanks guys....any other suggestions please free to post

 

[WalBro(Apexi)]

13 like tat
14 2 lean

 

[integramania]

tats wat i think to...even 13 i also a bit

 

[J101]

hello there integramania
im answering based on the topic asked, your optimum would be between 12-13.5 at WOT. you didnt list any specs on your engine and what type of a/f ratio toy are you using at the moment. so it is impossible to even guess at a WOT your air/fuel spread although what people have said in the thread are pretty close.

well basically the optimal ratio differs slightly from engine to engine, especially concerning whether the engine is naturally aspirated or turbo. but since it is a vtec, slightly rich around 12 is so you reduce the risk of detonation by vaporising the excess fuel. it draws heat out of the air/fuel mixture.

for your statement "i want it to be as fuel economical as possible and also when the power is needed it comes in properly as its a daily driven ride". you know and i know you have 2 types of power before and after vtec. it cant be too economical if you start to lean out whatever is in the stock factory ecu(i assume its stock with no chip, no safc and no mods). probably with stock airbox, stock exhaust system..u might save fuel at this moment of time :) the term daily-driven is very intriguing nowadays..haha

guys so 14/15 low rev..mid 13 and high rev 12....

this one sure engine will be safe?

reason i am asking is I'm running about 12 throughout and was told that its hsould be tuned to 13....i didn't think that 14/15 would be ok

I want it to be as fuel economical as possible and also when the power is needed it comes in properly as its a daily driven ride

thanks guys....any other suggestions please free to post

 

[ken12292703]

Hello brothers, sorry to interupt. How to check the AF ratio on a carbie engine? Thank you.

 

[integramania]

Hi thereJ101....thanks for sharing your thoughts

hello there integramania
im answering based on the topic asked, your optimum would be between 12-13.5 at WOT. you didnt list any specs on your engine and what type of a/f ratio toy are you using at the moment. so it is impossible to even guess at a WOT your air/fuel spread although what people have said in the thread are pretty close.

has been tuned to have about 12 or 12.5 throughout...so i think i wanna retune to about 13 on the lower revs

well basically the optimal ratio differs slightly from engine to engine, especially concerning whether the engine is naturally aspirated or turbo. but since it is a vtec, slightly rich around 12 is so you reduce the risk of detonation by vaporising the excess fuel. it draws heat out of the air/fuel mixture.

yeah tats wat i was told but i wanted to know if it was ok to go to 13 instead of 12...

for your statement "i want it to be as fuel economical as possible and also when the power is needed it comes in properly as its a daily driven ride". you know and i know you have 2 types of power before and after vtec. it cant be too economical if you start to lean out whatever is in the stock factory ecu(i assume its stock with no chip, no safc and no mods). probably with stock airbox, stock exhaust system..u might save fuel at this moment of time :) the term daily-driven is very intriguing nowadays..haha

yah i agree with you...can't get power without more fuel...anyway i'm not running stock so i plan to retune it on the dyno again....who would you suggest?:regular_smile:

 

[hattech-v]

if u need power then have to sacrify fuel...n vice versa...

 

[chris2000]

agree on this.. this is the important of the management.
u can tune the fueling for any rpm range...
another option is using FPR but its all the way rpm increment.. sighh...

FPR is the cheapest and fastest way to increase fuel though, but personally i don't really like to use them as i have had bad experience with them. need more fuel? Upgrade fuel pump 1st then look into simple management at least when can afford.