Whats the LEANEST A/F you should go with higher compression?
Thread Starter
Honda-Tech Member
Joined: Dec 2001
Posts: 18,151
Likes: 2
From: Hollywood Babylon
Whats the LEANEST A/F you should go with higher compression?
Id like to know the LEANEST(safely) you guys are running on your higher compression motors? My car seems to respond nicely when I lean out the A/F but my tuner doesnt want to go any leaner than 14.X:1 I know that 14.7:1 is usually considered optimal, but I know Ive seen A/F and dyno charts of guys leaner than that. Im particularly interested in the mid to high rpm range, where currently Im running around 13-12:1 A/F.
New User
Joined: Jul 2001
Posts: 4,521
Likes: 1
From: Extraordinary Machine
Re: Whats the LEANEST A/F you should go with higher compression? (Haunt)
You're not talking about octane on high compression, but PSI and fuel volume. Right?
I wish I could answer the question, but basicly you DON'T want lean. Never lean with a high compression engine.
Fuel pressure and volume or to different subjects. If you raise pressure you might not have adiquate volume. Just for your information.
I would recommend a dyno session.
I wish I could answer the question, but basicly you DON'T want lean. Never lean with a high compression engine.
Fuel pressure and volume or to different subjects. If you raise pressure you might not have adiquate volume. Just for your information.
I would recommend a dyno session.
Thread Starter
Honda-Tech Member
Joined: Dec 2001
Posts: 18,151
Likes: 2
From: Hollywood Babylon
Re: Whats the LEANEST A/F you should go with higher compression? (976)
Thanks for the info but Im not really worried about volume or fuel pressure. Im just wondering about the AFR itself and how lean its safe to run with a higher compression motor. My car has seen many dyno sessions so I know exactly what my AFR is through the entire RPM band. However at around 9-9500rpm, Im at about 12:1 AFR and Im wondering if it would safe to lean that out some since my car seems to like it when I make it less rich.
Honda-Tech Member
Joined: Jan 2000
Posts: 4,968
Likes: 0
From: Chattanooga, TN, USA
Re: Whats the LEANEST A/F you should go with higher compression? (RTW DC2)
14.7:1 AFR is optimal at partial throttle. I woudl say all motor you are looking about 13.2-13.7 depending on the car. Someone like Steve will have to weigh in on compression changes and their effects on AFR but I would not think you would change the AFR much. I'd say about 13.5:1 as a best guess.
Trending Topics
INSERT TITLE HERE
Joined: Jan 2000
Posts: 1,600
Likes: 0
From: Littleton, CO, USA
Re: Whats the LEANEST A/F you should go with higher compression? (976)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote »</TD></TR><TR><TD CLASS="quote">I would recommend a dyno session.</TD></TR></TABLE>
It sounds to me like the reason he's asking is to know what to shoot for when he goes to the dyno.....
All I know is what to shoot for for F/I. 11.8:1 for a turbo or JRSC on 8+psi, and 12.5:1 for a JRSC on stock boost.
The best thing to do (if you're running a standalone with datalogging anyway) is to push the AF ratio until you start to get a little bit of knock, and then back it off a few tenths of a point to provide yourself some room in case of heat build up or bad gas or something. If you have no way of reading your knock sensor logs though, that may be difficult.
It sounds to me like the reason he's asking is to know what to shoot for when he goes to the dyno.....
All I know is what to shoot for for F/I. 11.8:1 for a turbo or JRSC on 8+psi, and 12.5:1 for a JRSC on stock boost.
The best thing to do (if you're running a standalone with datalogging anyway) is to push the AF ratio until you start to get a little bit of knock, and then back it off a few tenths of a point to provide yourself some room in case of heat build up or bad gas or something. If you have no way of reading your knock sensor logs though, that may be difficult.
Thread
Thread Starter
Forum
Replies
Last Post