Dyno results.......Too lean?
Thread Starter
|
Cruiser
Joined: Feb 2008
Posts: 176
Likes: 0
From:
Dyno results.......Too lean?
So I got my dynonumbers back from my trip to the dealership.
They did 2 runs and plotted RPM vs. A/F ratio. First lets start with what I've installed
-Stage 1 A/C, SEII slip ons and I believe they mapped it for stage 1.
-Complete exhaust upgrade to Cobra Speedster Slashdowns
-Stock ECU and new O2 sensors (don't know if they are wideband or not).
Harley's baseline A/F ratio was 13.2:1 under loading.
Here are my numbers for the second run. First run was a bit leaner.
RPM Air/Fuel
1750 13.3
2000 13.4
250013.6
3000 13.5
3300 13.8
3500 13.7
400013.5
4500 13.7
5000 13.6
5500 13.2
AVG ~13.5
The curve had some peaks (3300 RPM being the leanest) and valleys but overall was consistent.
Is it a bit lean? Yes. Am I getting peak power? Probably not. Do I NEED a race tuner? I doubt it. The only thing I didn't get was a "cruise" test toget the A/F ratio at cruising speeds.A/F ratios at these speeds are around 14.7:1 (ideal).And, of course, the guy at the service desk said I needed a SERT but then again he couldn't tell me if I needed break pads or not. I say no thanks to the tune of another grand (parts,labor,dyno time). It's a money racket. Maybe at some point if I decide to go with it I may do it.
For those considering Exhaust/stage 1upgrades, before you shovel a boatload of money into a SERTor whatever put it on a dyno and get your ratios to know for sure.I will say that each bike is different and each dyno is different. It's not an EXACT science.
For your reading pleasure.....
http://www.drdyno.com/AIM_2006-08.html
They did 2 runs and plotted RPM vs. A/F ratio. First lets start with what I've installed
-Stage 1 A/C, SEII slip ons and I believe they mapped it for stage 1.
-Complete exhaust upgrade to Cobra Speedster Slashdowns
-Stock ECU and new O2 sensors (don't know if they are wideband or not).
Harley's baseline A/F ratio was 13.2:1 under loading.
Here are my numbers for the second run. First run was a bit leaner.
RPM Air/Fuel
1750 13.3
2000 13.4
250013.6
3000 13.5
3300 13.8
3500 13.7
400013.5
4500 13.7
5000 13.6
5500 13.2
AVG ~13.5
The curve had some peaks (3300 RPM being the leanest) and valleys but overall was consistent.
Is it a bit lean? Yes. Am I getting peak power? Probably not. Do I NEED a race tuner? I doubt it. The only thing I didn't get was a "cruise" test toget the A/F ratio at cruising speeds.A/F ratios at these speeds are around 14.7:1 (ideal).And, of course, the guy at the service desk said I needed a SERT but then again he couldn't tell me if I needed break pads or not. I say no thanks to the tune of another grand (parts,labor,dyno time). It's a money racket. Maybe at some point if I decide to go with it I may do it.
For those considering Exhaust/stage 1upgrades, before you shovel a boatload of money into a SERTor whatever put it on a dyno and get your ratios to know for sure.I will say that each bike is different and each dyno is different. It's not an EXACT science.
For your reading pleasure.....
http://www.drdyno.com/AIM_2006-08.html
Road Master
Joined: Apr 2006
Posts: 1,100
Likes: 1
From: Conway, SC
RE: Dyno results.......Too lean?
If 13.2 : 1 was a baseline that's pretty good. Installing wideband sensors you want 13.2 : 1 A/F
go here and watch the video http://video.google.com/videoplay?do...62040865858655
14.7 : 1 is lean as hell, not ideal.
go here and watch the video http://video.google.com/videoplay?do...62040865858655
14.7 : 1 is lean as hell, not ideal.
Thread Starter
|
Cruiser
Joined: Feb 2008
Posts: 176
Likes: 0
From:
RE: Dyno results.......Too lean?
14.7:1 is the most efficient Air/fuel ratio where you get the most complete burn and efficiency with low emissions. It's a HOT burn and it doesn't produce the most power but it's stoichiometrically ideal and recommended for cruising speeds. It's the benchmark. Anything less than that constantis rich, anything more than that is lean. Technically at 13.2:1 you're running rich based on the benchmark of 14.7:1.
This stoichiometricnumber isfor gasoline combustion engines with gas consisting of solely n-heptane and iso-octane. Fuels these days consist of a whole bunch of garbage so this stoichiometric constant changes (bringing it downward). For peak power output you're looking for an air/fuel ratio of around 13 or 13.1:1.
After watching the vid I don't think they put on wideband O2 sensors because I don't believe they put a module on with them. Funny though they're shooting for the same ratios I'm running.
This stoichiometricnumber isfor gasoline combustion engines with gas consisting of solely n-heptane and iso-octane. Fuels these days consist of a whole bunch of garbage so this stoichiometric constant changes (bringing it downward). For peak power output you're looking for an air/fuel ratio of around 13 or 13.1:1.
After watching the vid I don't think they put on wideband O2 sensors because I don't believe they put a module on with them. Funny though they're shooting for the same ratios I'm running.
Road Master
Joined: Apr 2006
Posts: 1,100
Likes: 1
From: Conway, SC
RE: Dyno results.......Too lean?
I have to ask, what "module" are you talking about?
They installed 2 modules, one per sensor.
I'ld rather run at 13.2:1 so my engine stays cooler than hotter.
They are wide band o2 sensors, try here: http://www.tuneyourharley.com/
They installed 2 modules, one per sensor.
I'ld rather run at 13.2:1 so my engine stays cooler than hotter.
They are wide band o2 sensors, try here: http://www.tuneyourharley.com/
Thread
Thread Starter
Forum
Replies
Last Post
Tampakingpin
General Harley Davidson Chat
15
Apr 30, 2013 06:55 PM
