2into1 vs Stock; EFI AFR? : V-Twin Forum: Harley Davidson Forums

Sleeps In Trees · 07-21-2006, 06:18 PM

In theory, what effect does going from stock pipes w/slip ons to a hi perf. 2 into 1 exhaust have on AFR? Am I figuring wrong, or wouldn't the added scavenging of the 2 into 1 tend to make the existing mix richer?

Thanks,

VicW.

GRock · 07-21-2006, 06:42 PM

Quote:

Originally Posted by Sleeps In Trees

In theory, what effect does going from stock pipes w/slip ons to a hi perf. 2 into 1 exhaust have on AFR? Am I figuring wrong, or wouldn't the added scavenging of the 2 into 1 tend to make the existing mix richer?

Thanks,

VicW.

You have it backwards. The scavenge rate will pull more air thru the chambers, however the fuel load will be the same. You tend to get leaner with added scavenge rates.

Sleeps In Trees · 07-21-2006, 07:18 PM

Thanks GRock! I was hoping I had it backwards, that's good news for me. Since my scoot is tuned a bit rich in a couple of key areas, I'm hoping to run good (or at least ok) w/the new pipes for the remainder of the riding season & get one last GOOD dyno-tune after getting headwork done & attempting to do a 95" build over the winter. It'd go against my usual run of luck, but maybe this'll work out according to plan.....

VicW.

slo_kid78 · 07-21-2006, 09:51 PM

Which would be a better starting point for this setup, a touring base map or a dual map like the softails run??????

ohiomotoxer · 07-24-2006, 06:07 PM

Since I work in the exhaust industry AND do carb EFI recalibration I might be able to shed some light on this question.

AFR is just that, air to fuel ratio. It cannot change unless temperature or humidity change.. in theory.

Let's have some examples:
A fuel system is mapped to a certain AFR from the factory, it has the ability to adjust (+/-) a few points AFR for conditions, that is basically it.

The airbox, intake manifold, intake runners, velve size, cam profile, ignition, fuel system and exhaust are all designed to work within this "window" of AFR.

Changing just one of the above will throw off the "balance" built into the original FEI map OR carburetor for that matter. Typically, changing ANY of the above items will increase the machines ability to flow either more air or exhaust. This increased flow will be outside of the stock map perameter to the point where the AFR would need to be recalibrated to match the increased flow.

Adding compression (to a point) should not really require a big AFR change.

The NICE thing about EFI is that anyone can make the needed adjustments whenever a mod is done.

Take the time to understand your stock fuel map (say a power commander or SERT) know which throttle position you are having a problem in and break down the % of throttle position to engine RPM and make cell adjustments, DO NOT bother to use the buttons on a PC, not accurate enough.

MY best advice: get a wideband O2 datalogger like one from Innovate, it will END ANY BS that anyone will tell you or try to sell you on when it comes to tuning.

So to answer the original question adding free flowing components will increase flow, which typically leans to the lean point of AFR.

Sleeps In Trees · 07-24-2006, 08:45 PM

Quote:

adding free flowing components will increase flow, which typically leans to the lean point of AFR

Yes, but the increased scavenging & (possibly) backpressure of the 2into1 system over the stock cross-over would introduce another dimension to the formula wouldn't it?

VicW.

Rock · 07-24-2006, 08:49 PM

Why yes it would. It's called power and torque.

Sleeps In Trees · 07-24-2006, 10:20 PM

Quote:

Why yes it would. It's called power and torque

Now THAT'S what I'm talkin' about! >grin<

VicW.

Totenkopf · 07-26-2006, 12:45 AM

ohiomotoxer will have more to say about this but tuning an exhaust for a certain need is a real science. There is short pipe formula for high rpm peak power, then there is long pipe formula for lower end performance and combinations there of. It has to do with getting the pulses down the pipe and in unison with what is going on in the intake and the timing of these events.

Just going through this now with the Pro Mod dragbike and a new custom designed Burns 2-1 with tuned length and stepped header pipes that go into a merge collector and then the megaphone.

Paniolo · 07-26-2006, 12:53 AM

"My best advice: get a wideband O2 datalogger like one from Innovate, it will END ANY BS that anyone will tell you or try to sell you on when it comes to tuning."

Ohiomotoxer,

Is that the system that basically "tells how to write a MAP" for your SERT? I may be mistaken, but I heard somewhere that there is an O2 system that you plug in, ride, and when you come back it tells you which cells to adjust in which rpm range to tune the bike. It reads the O2, and all the other sensors, and actually shows you which fuel and timing cells to adjust, and by how much.

I this true, or am I mistaken as usual?

Thanks

bedemonster · 07-26-2006, 03:32 AM

Quote:

Originally Posted by Paniolo

"My best advice: get a wideband O2 datalogger like one from Innovate, it will END ANY BS that anyone will tell you or try to sell you on when it comes to tuning."

Ohiomotoxer,

Is that the system that basically "tells how to write a MAP" for your SERT? I may be mistaken, but I heard somewhere that there is an O2 system that you plug in, ride, and when you come back it tells you which cells to adjust in which rpm range to tune the bike. It reads the O2, and all the other sensors, and actually shows you which fuel and timing cells to adjust, and by how much.

I this true, or am I mistaken as usual?

Thanks

What you are reffering to is the Daytona Twintec "Twin Scan+ w/wego"

ohiomotoxer · 07-26-2006, 09:46 AM

Quote:

Originally Posted by Paniolo

"My best advice: get a wideband O2 datalogger like one from Innovate, it will END ANY BS that anyone will tell you or try to sell you on when it comes to tuning."

Ohiomotoxer,

Is that the system that basically "tells how to write a MAP" for your SERT? I may be mistaken, but I heard somewhere that there is an O2 system that you plug in, ride, and when you come back it tells you which cells to adjust in which rpm range to tune the bike. It reads the O2, and all the other sensors, and actually shows you which fuel and timing cells to adjust, and by how much.

I this true, or am I mistaken as usual?

Thanks

The Innovate LM1 is a portable wideband data logger, everyone should have one, check out their forum, I go there when I think I know everything, the information on their forum is priceless.
http://www.innovatemotorsports.com/index.html

Paniolo · 07-26-2006, 09:58 AM

Quote:

Originally Posted by bedemonster

What you are reffering to is the Daytona Twintec "Twin Scan+ w/wego"

I just checked it out, and TwinScan does not work with the M&M system I have. I'm not sure, but it looks like I can use the WEGO to get AFR, and maybe figure out a way to translate that to use with my M&M SERT.

Mark

ohiomotoxer · 07-26-2006, 10:10 AM

Quote:

Originally Posted by Totenkopf

ohiomotoxer will have more to say about this but tuning an exhaust for a certain need is a real science. There is short pipe formula for high rpm peak power, then there is long pipe formula for lower end performance and combinations there of. It has to do with getting the pulses down the pipe and in unison with what is going on in the intake and the timing of these events.

Just going through this now with the Pro Mod dragbike and a new custom designed Burns 2-1 with tuned length and stepped header pipes that go into a merge collector and then the megaphone.

Yeah, I hear ya. I have all those calculations from my old Kerker days, they were actually George Kerkers, how cool is that?

Check out this exhaust flange and system we made for a fuel bike, grrrrrrrrrrrrr
There is a ton of stuff you can do to taylor the pulse to specific needs...how much time do you have......