Supra Forums banner
1 - 15 of 15 Posts

·
Registered
Joined
·
1,526 Posts
Discussion Starter · #1 ·
Suppose a car runs smoothly but excessively rich at WOT/under boost. Would tuning the A/F to be correct instead of too rich result in more power, or would there be no benefit other than better fuel economy?

Would running correct instead of too rich have any effect on the car being less likely to knock or pull timing and benefit power indirectly that way?

TIA, Brian
 

·
Follow the white rabbit
Joined
·
1,659 Posts
Aim for like 11.5:1 on pump gas and 12.5:1 on e85 and it'll feel like a different car.
Yes you can rich knock, yes it will definitely improve fuel economy and yes you will definitely gain hp and better throttle response.
 

·
Premium Member
Joined
·
3,148 Posts
The car will typically gain power as you lean it out, but not always.

Basically you need to go to the dyno. Start leaning the car out to 11.8:1. If you continue to gain power, than keep leaning out the A/F ratio until you get to 11.8:1.

If you stop gaining power as you lean it out to 11.8:1, than leave it a little rich. This of course assumes your A/F is not in the 9's. :)

Later, Steve
 

·
Premium Member
Joined
·
3,148 Posts
I would say that is borderline. I have seen cars in the low to mid 11's not make anymore power at mid to high 11's.

Later, Steve
 

·
Registered
Joined
·
13,581 Posts
...too rich have any effect on the car being less likely to knock or pull timing and benefit power indirectly that way?...
Running a bit rich under high load helps cylinder cooling which supresses detonation to some extent. Running rich under no load or light load is a waste of fuel.
 

·
Registered
Joined
·
358 Posts
pump gas vs pump gas with meth vs race gas vs e85 <---- Four totally different strategies and everyone will have their own preferred method. I'd rather be slightly more rich so there's more of a buffer than trying to run on the edge of my tune just to shell out another 10whp.
 

·
Premium Member
Joined
·
3,148 Posts
I believe on our engines, you're dumping fuel unnecessarily at high 10's. 11.8:1 still has buffer built in.

I have run my old Supra at 12.5:1 on the roadcourse with 93 octane pump gas without an issue. Was I asking for an issue? YES, but 11.5 to 11.8:1 is plenty rich.

Of course I would recommend a little richer than 11.8:1 for the roadcourse, as exhaust temps get very high at that point.

Later, Steve
 

·
Registered
Joined
·
1,526 Posts
Discussion Starter · #13 ·
Thanks for the tips. I'm putting a WB O2 on in about a week, and will be very interested to see if my OBD II BPU car and high elevation adds up to running rich. kind of hoping it does so I can try to wring a little extra HP out.
 

·
Premium Member
Joined
·
3,148 Posts
Al,

Long time no talk. I don't see any new fast times in your sig, do you still go to Rockingham?

BTW I was running approximately 17psi on the roadcourse and I run 18-19psi on the street.

Later, Steve
 
1 - 15 of 15 Posts
Top