Air/Fuel ratio question on 103"
#1
03-19-2009 | 08:58 PM
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From: Sandy, UT
Air/Fuel ratio question on 103"
So I've got a SE 103" with Head Quarters heads and cams. Have it installed and dynoed with a SERT and it comes back with 103hp and 107 lbs tq. Not bad numbers but I was looking for a little more. Anyway, what I'm concerned about is the graph from the dyno shows an almost perfectly flat air/fuel ratio of about 13.2 through the whole range. Is this normal? The bike is running great but I don't know if that was just the setting they used for the dyno tune or if my bike is really running that rich.
#2
03-19-2009 | 09:30 PM
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From: TX
Alex,
I saw your post on another board and it was a bit unclear as to exactly what your build is.
As I recall, it said something about S/E103 (minus cams?).
Does this mean you have off the shelf S/E jugs, pistons, & rings? If so, there is no telling what your actual compression ratio is, if the deck height is set properly, which pistons you have, what the squish is, etc, etc.....
ASSuming, you have a decent tune.... I would agree that the "numbers" might be a bit on the low side. However, dyno "numbers" don't mean DICK. "Rideability" is what REALLY matters.
Do you know if it was fully tuned, or just had a MAP thrown on with minor tuning for WFO dyno print purposes?
13.1 (from the other site) is ok for WFO conditions, as long as the rest of the MAP is properly tuned, you may be fine.
As was noted, if it's truly 13.1 or 13.2 "across the board", you will soon be smelling gasoline in your oil and the result is contaminated oil that will not properly lubricate your engine.
I think if I were you, I'd try to clarify some of those things & provide Doug & KB with a more complete set of working data so they might be better equipped to provide you an informed & complete response.
I saw your post on another board and it was a bit unclear as to exactly what your build is.
As I recall, it said something about S/E103 (minus cams?).
Does this mean you have off the shelf S/E jugs, pistons, & rings? If so, there is no telling what your actual compression ratio is, if the deck height is set properly, which pistons you have, what the squish is, etc, etc.....
ASSuming, you have a decent tune.... I would agree that the "numbers" might be a bit on the low side. However, dyno "numbers" don't mean DICK. "Rideability" is what REALLY matters.
Do you know if it was fully tuned, or just had a MAP thrown on with minor tuning for WFO dyno print purposes?
13.1 (from the other site) is ok for WFO conditions, as long as the rest of the MAP is properly tuned, you may be fine.
As was noted, if it's truly 13.1 or 13.2 "across the board", you will soon be smelling gasoline in your oil and the result is contaminated oil that will not properly lubricate your engine.
I think if I were you, I'd try to clarify some of those things & provide Doug & KB with a more complete set of working data so they might be better equipped to provide you an informed & complete response.
Last edited by PhilM; 03-20-2009 at 06:27 AM. Reason: Edit to clarify what I was trying to say....
#3
03-19-2009 | 10:11 PM
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So I've got a SE 103" with Head Quarters heads and cams. Have it installed and dynoed with a SERT and it comes back with 103hp and 107 lbs tq. Not bad numbers but I was looking for a little more. Anyway, what I'm concerned about is the graph from the dyno shows an almost perfectly flat air/fuel ratio of about 13.2 through the whole range. Is this normal? The bike is running great but I don't know if that was just the setting they used for the dyno tune or if my bike is really running that rich.
#4
03-19-2009 | 11:06 PM
Stellar HDF Member
Joined: Sep 2007
Posts: 2,079
Likes: 382
From: Vancouver Island B.C.
Alex,
I saw your post on another board and it was a bit unclear as to exactly what your build is.
As I recall, it said something about S/E103 (minus cams?).
Does this mean you have off the shelf S/E jugs, pistons, & rings? If so, there is no telling what your actual compression ratio is, if the deck height is set properly, which pistons you have, what the squish is, etc, etc.....
ASSuming, you have a decent tune.... I would agree that the "numbers" might be a bit on the low side. However, dyno "numbers" don't mean DICK. "Rideability" is what REALLY matters.
Do you know if it was fully tuned, or just had a MAP thrown on with minor tuning for WFO dyno print purposes?
13.1 (from the other site) is a little fatter than I shoot for in WFO conditions, but as long as the rest of the MAP is properly tuned, you may be fine.
As Doug noted, if it's truly 13.1 "across the board", you will soon be smelling gasoline in your oil and the result is contaminated oil that will not properly lubricate your engine.
I think if I were you, I'd try to clarify some of those things & provide Doug & KB with a more complete set of working data so they might be better equipped to provide you an informed & complete response.
I saw your post on another board and it was a bit unclear as to exactly what your build is.
As I recall, it said something about S/E103 (minus cams?).
Does this mean you have off the shelf S/E jugs, pistons, & rings? If so, there is no telling what your actual compression ratio is, if the deck height is set properly, which pistons you have, what the squish is, etc, etc.....
ASSuming, you have a decent tune.... I would agree that the "numbers" might be a bit on the low side. However, dyno "numbers" don't mean DICK. "Rideability" is what REALLY matters.
Do you know if it was fully tuned, or just had a MAP thrown on with minor tuning for WFO dyno print purposes?
13.1 (from the other site) is a little fatter than I shoot for in WFO conditions, but as long as the rest of the MAP is properly tuned, you may be fine.
As Doug noted, if it's truly 13.1 "across the board", you will soon be smelling gasoline in your oil and the result is contaminated oil that will not properly lubricate your engine.
I think if I were you, I'd try to clarify some of those things & provide Doug & KB with a more complete set of working data so they might be better equipped to provide you an informed & complete response.
#6
03-20-2009 | 07:38 AM
Sounds like your tuner knows his stuff. When we tune bikes, we set the AF in the ECM to 13.2, I.E. that is what we tell the ECM to aim for, then we calibrate the the bike as cose to 13.2 as we can, when we are all finished with the tune, we set the AF tables back to Harley specs and the bike is calibrated. When we are done with this, I always run some cruising speed passes to check the A/F with a 20%, 25% and 30% load on the bike to simulate solo and 2-up riding, the bike should cruise at about 14.2 to 14.6 A/F which is probably about where your's really is at. Hope this helps, if not, PM me and i'll get into it further with you if you'd like.
#7
03-20-2009 | 09:22 AM
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From: Sandy, UT
Thanks for all the help everyone. Harleytuner, you are correct. I was able to speak to the shop this morning to verify the 13.2 AFR was a WOT reading and the cruise AFR is in the mid 14s. Just to explain the build a bit more, I had the 103" SE kit done when I bought the bike in '07 so it was the exact SE 103" kit with V&H exhaust. I went back and looked and the AFR was set at 13.2 when that was done and the bike has run fine since then so that pretty much alleviated the concerns about the 13.2 from the tune this week before I could confirm with the shop. If I could do it all over again I would have just bought Head Quarters entire 103" or bigger but since I already had the SE kit I just went with a set of heads and the HQ-TC-575-HC cams. As far as the numbers go, I'm not concerned with the bike being a dyno queen. It rides great I was just wondering about them though because the numbers were a little outside the 10% dyno variation HQ mentions when evaluating the final dyno numbers compared to the numbers they post on their page and just wanted to be sure there isn't a glaring oversight on my part as to why the numbers were a little low.
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#8
03-21-2009 | 12:42 PM
#9
03-22-2009 | 09:59 AM
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Joined: Mar 2008
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One thing is your fuel economy. Some tuners drop the afr in the cruise range and if they do so then you take a big hit on fuel economy. Personally, that's a gimmack to make the dyno tune seem to have done more than it should though there are arguements for doing it. If the fuel economy is pretty much the same cruising on the highway then there's no reason to think they dropped the afr in the cruise range.
#10
03-23-2009 | 09:48 AM
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From: Sandy, UT