Please don't tackle me with all the "search" replys please. I've searched and seen topics dealing with a/f ratios, but mostly problems with them.
Im soon to be boosted, with the HAHN stage 2 kit. And i just wanted to know what A/F ratio numbers should be. Whats lean, ideal, and whats rich.
What should they be just driving?
What they should be Idol?
What they should be under boost?
I just wanted an early jump on all this information for when im ready.
Thanks in advance
2004 Turbo cavalier 11PSI and blown!
Driving will bounce back and forth between 14 and 15.5 or so, this is computer controlled. It will be the same at idle.
Under boost you want around 12.5:1 for a safe tune.
The richer the smaller the numbers, 12:1 is richer than 13:1 and so on.
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Ron, what about boost without WOT. I have boost at part throttle so should it be around 14 or 12?!?!?
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I read somewhere, i don't remember where. I think it was somewhere on the internet while i was surfing it for some stuff. That under boost the a/f ratio should be more around 11.5 is this so or is it to rich?
2004 Turbo cavalier 11PSI and blown!
OK. If you are tuning it yourself, there's nothing wrong with a 14:1 AFR. Some cars with a more minimal tune tend to run around a 21:1 AFR at idle, which... not so good, but it happens. Under WOT, your AFR's should be anywhere from 12:5:1 while still in vacum, and in to boost, adding timing, you want it to get down to no more than 11.5:1. We try to tune for a 11.2 - 11.5:1 WOT AFR in full boost. As for partial throttle, it's really tricky to tune. But depending on how quickly you make boost with partial throttle, you should still try to keep it around a 12.5:1 AFR. I hope that helps you out. In tuning, you want to address your AFR's FIRST. Then timing and others, and then go back and adjust your AFR's again for the final touches.
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Now is it necessary to change timing to get right a/f ratios. I read that alot of people don't change there timing, all the way up to 10-11 psi. Granted im not gonna be running that much psi, im gonna run more round 8psi. to start..
2004 Turbo cavalier 11PSI and blown!
MetallicCavy wrote:Now is it necessary to change timing to get right a/f ratios. I read that alot of people don't change there timing, all the way up to 10-11 psi. Granted im not gonna be running that much psi, im gonna run more round 8psi. to start..
Well... for 8 psi you shouldn't have to adjust timing too much. I would pull it back a few degrees from stock at high boost in higher RPM's. Just to be safe.
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The one thing you have to remember about pulling timing is that your EGTs can skyrocket. So, you need to make sure all the components can handle that.
fortune cookie say:
better a delay than a disaster.
So if i was to run higher psi i should chage timing? How would i do this?
But for low psi i should be fine for getting the correct a/f ratios w/o timing change.
Sorry if this has already been posted somewhere else. Im just trying to get all this stuff understood for when i am boosted...
2004 Turbo cavalier 11PSI and blown!
MetallicCavy wrote:So if i was to run higher psi i should chage timing? How would i do this?
But for low psi i should be fine for getting the correct a/f ratios w/o timing change.
Sorry if this has already been posted somewhere else. Im just trying to get all this stuff understood for when i am boosted...
Yes. Typically on these cars, you're fine on stock timing numbers up to about 9 or 10 psi. Now... that's with stock bottom end. More boost, with higher timing, yields more power. But naturally, you can't make too much on stock bottom end. Your EGT's will get higher with pulled timing, but they won't be too terrible.
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Thanks
2004 Turbo cavalier 11PSI and blown!
