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How can we trick the car into running richer?

7804 Views 22 Replies 8 Participants Last post by  marlinspike
Let's pretend that with cold air intakes, and/or performance exhaust systems, that the air/fuel ratio leans out - perhaps even leaner than ideal. How would I trick the car into running richer?
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Perhaps you could replace the air intake temp sensor with a high resistance resistor? Though this would also retard the timing.
I could be wrong, but I thought that on these newer cars air intake temp sensors control both mixture and timing. Guess not. I'm a bit confused by that mixture control write up. Why would tricking it into thinking it's cooler make it richer? Shouldn't it do the opposite? I understand colder = more O2, but I know from my own tuning on my mechanical injection car that when it gets colder I dial in lean for more power.

Edited to add: just realized, we are talking about different types of timing. I'm talking about injection timing.
Bugszrt, it's cause he's got aftermarket headers on.
Speaking of getting the 6.1 flowing, musn't Hennessey have been able to mess with the computer in order for his 392 stroker to work? Is he holding out on us on the computer front?
14.7:1 is stoichiometric so how can leaner than 13:1 be problematic? Besides, leaner gives you more upper end as long as you are still burning all the O2. This engine is what 10.5:1 compression? I don't think you'll gain anything going from 13.5:1 to 12:1, maybe down low but you'd lose enough to more than counter that up top. Max power is typically around 13.7:1, leaner if you have the octane to support it.
John Hennessey said:
most fuel injectors are rated at 3 bar or 43.5 psi.
Is that all? I have a mechanical injection car that runs at 45psi, I would have thought by now they'd be much higher pressure, especially in these high hp engines.
Now your making me wonder if I should go out and richen my car, but then I'm running an 8:1 compression ratio so I should be safe running my 14:1 at idle.
Well, if on my car according to the service manuals if I have 14:1 at idle I have 14:1 at 2000rpm. It's funny actually, the only reason I'm lean (mechanic says their standard for this car is 13:1 at idle) is because of the richening at WOT. If I richen my idle to like 13.3:1 then I get better throttle response, but the WOT richening richens it too much and slows down my times. I can get better and better ET's by running so lean that it idles rough, but obviously that's not a viable option.
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