a/f ratio question...
07-12-12, 09:15 AM
#1
snap crackle brap
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a/f ratio question...
With my 6 port stock tii conversion, what is a good air to fuel ratio reading for my wideband? I am going to start tuning it this weekend and would like to know what a good safe zone would be. Thanks in advance to those helpful rotorheads.
07-12-12, 09:27 AM
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Engine, Not Motor
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Well, that's a loaded question. Are we talking cruise? Boost? Idle?
And ask 5 different tuners and you'll get 5 different answers. For example, I like to tune boost similar to the following:
0-5 PSI: 12:1
5-10 PSI: high 11s
10 - 15 PSI: mid 11s
15 PSI +: high 10s
Yet I've been lambasted on the other forums (where I don't post) by another experienced member that my ratios are excessively rich...Of course this after that member has blown through several engines and I've never lost one.
So yeah, it depends. And if you are running unsafe or crappy timing, no AFR is going to be ideal.
It may help you to read the Basic Tuning page from my Megasquirt writeup:
How To Megasquirt Your 2nd Gen RX-7: Basic Tuning
Should give you some ideas and really, applies to any standalone.
And ask 5 different tuners and you'll get 5 different answers. For example, I like to tune boost similar to the following:
0-5 PSI: 12:1
5-10 PSI: high 11s
10 - 15 PSI: mid 11s
15 PSI +: high 10s
Yet I've been lambasted on the other forums (where I don't post) by another experienced member that my ratios are excessively rich...Of course this after that member has blown through several engines and I've never lost one.
So yeah, it depends. And if you are running unsafe or crappy timing, no AFR is going to be ideal.
It may help you to read the Basic Tuning page from my Megasquirt writeup:
How To Megasquirt Your 2nd Gen RX-7: Basic Tuning
Should give you some ideas and really, applies to any standalone.
07-12-12, 11:17 AM
#4
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those numbers are good ballparks. i usually tune a little richer in the 5-10psi zone.
since detonation/pre-ignition is the killer of these engines, you need to be able to run a rich mixture for safety. if you cannot run something around 11:1 or richer, the correct fix is a stronger ignition. leaning the mixture is a bandaid, its easier to ignite, but it doesn't have the detonation resistance of a rich mixture.
you will also find with a strong ignition that power doesn't change much with AFR, so you can run richer and not loose power like you do with the stock setup.
the things to start with are the plug wires, they need to be low resistance. the race plugs also take less power to fire than the stockers.
for upgrades the HKS twin power seems to work really well.
since detonation/pre-ignition is the killer of these engines, you need to be able to run a rich mixture for safety. if you cannot run something around 11:1 or richer, the correct fix is a stronger ignition. leaning the mixture is a bandaid, its easier to ignite, but it doesn't have the detonation resistance of a rich mixture.
you will also find with a strong ignition that power doesn't change much with AFR, so you can run richer and not loose power like you do with the stock setup.
the things to start with are the plug wires, they need to be low resistance. the race plugs also take less power to fire than the stockers.
for upgrades the HKS twin power seems to work really well.
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