Still trying to understand how everthing works. I believe the rear cyl should run a little richer than the front. On map #27 and others, it has lower VE numbers in the 2000- 3000 rpm range, by 4-9 points. Isn't this way leaner ? Or am i missing something ??

 

The flow characteristics of the pipe have a great deal to do with where the VE tables end up at a given throttle percentage and rpm, some shotgun style pipes for example having a longer front pipe will generally have higher VE's than the rear.

 

BVBOB is correct and I will add this, every engine is an air pump....if you built two identical motors side by side they would breathe differently taking on their own flow characteristic plus ignition timing would also be different in each motor to optimize the performance. VE in these engines is an indication of Air movement through the motor so if the identical motors had their own flow characteristics the VE would be different. They might put out the same hp and tq but, at a given rpm and throttle position the engines will differ. Now if this is true we can break it down even further, if every engine is an air pump then each cylinder is it's own air pump too....so the flow characteristic (VE) of the front cylinder is going to be different than the (VE) of the rear cylinder. ie the rear cylinder is going to breathe differently from the front. A lot of this comes from the firing order of 315 degrees for the rear and 405 degrees for the front....the rear has less time to fill with air than the front as you can see so the air movement through the same motor differs.Cams, like pipes will make a big difference in the airmovement through the motor too...a cam that comes in late will have better airflow numbers in the higher rpms and throttle positions, like wise a cam that gives more torque and power on the bottom end will havelarger VE numbers in the lower rpm area and lower throttle position or vice versa. This air movement from camsand pipescan be seen on the VE tablesand their effect on the motor. (Is this making sinceto you yet...I hope so.) Ant time the motor has something installed like pipes, cams, air filter, and such the VEs increase and they move up or down the rpm and throttle position range. So for a good example; a set of SE pipes are installed...the VE tables are altered by the tuner to fit the flow characteristics of these pipes (we do thisthrough a process of Syncronization which takes up to four to five hours some times).....now the guy wants to put on Rienhart Tru Duals.....do you think the VE is going to be the same of these pipes....absoulotly not. Like cams pipes flow differently so the VE changes again and again with ever change. Now how many times have you seen questions out there like " Do I need to remap just because I installed my new Fat Cats'?If you understand what I just explained what would your answer be? Yes he does need to remap. Better yet...whatch this. If you notice all the down loads (canned maps) on the Race Tuner are for Screamin'Eagle parts....if you had all SE parts but decided to install aV&H Pro Pipe will that down load work? ........NO !!!!!..... Because the Pro Pipe has different flow charcteristics...... So how many times have you heard dealers just installing a down load in bikes that don't have all, or any, SE parts on them and out the door they go?Bottom Line....any timeyou change the air movement in an engine configurationthe ECM needs to know so a remap is necessary for the bike to have optimum performance.

In my opinion the Race Tuner is by far the best tool to manage the ECM out there if you have the knowledge of the program and how to use it correctly....it doesn't get any better or more complete Gentleman.

Sorry for getting carriedaway....I'll quit now.
Doc

 

Thanks guys.

Going from a 85 to a 88 , how much will that change the AFR ? Thats how much i changed the rear cyl in the 2250 to 3500 rpm at 60 to 100 throttle. Plug looks better. At a 60mph chop , it was pretty white before.

06 Ultra SEAC and SE Pro pipe 64924-99