Increasing ECM Displacement to drop VE's from 127.5

[ColoSpgsMark]

I'm curious what the consensus is regarding how far you can increase displacement in your tune before you start introducing other problems?

This is my second 103" motor (not stock) and each one has required that I bump displacement to around 108" in order to keep my peaks below the ECM limit of 127.5.  I'm currently tuning a new 2:1 exhaust from FuelMoto and it's wanting to scale displacement to 113" right in my power range (3500 rpm and 60Kpa).  Some have said to work CDE/EGR first in the peak area as taking displacement too high will cause problems.  I am using Powervision for tuning.

Appreciate any input on the matter and what others do in similar situations.

Mark

[hrdtail78]

Best bet is to work it out with EGR.  Then engine displacement.  But I have added 20-30% to it, and just reworked the other tables it affects.

[rbabos]

I've run into problems with the TTS MT8 with increasing the CI. Way rich. MT7 on the other hand seemed fine. Since that experience I would tend to leave that as a last effort fix to the 127 ve areas.
Ron

[FLTRI]

I've run into problems with the TTS MT8 with increasing the CI. Way rich. MT7 on the other hand seemed fine. Since that experience I would tend to leave that as a last effort fix to the 127 ve areas.
Ron

Ron,
Are you saying you cannot increase the engine size without it ending up way rich?
I see small AFR changes with minor changes to engine size.

I haven't seen the need for large ci/injector changes to these constants with MT8 cals as often as necessary with MT7 cals.
Bob

[rbabos]

I've run into problems with the TTS MT8 with increasing the CI. Way rich. MT7 on the other hand seemed fine. Since that experience I would tend to leave that as a last effort fix to the 127 ve areas.
Ron

Ron,
Are you saying you cannot increase the engine size without it ending up way rich?
I see small AFR changes with minor changes to engine size.

I haven't seen the need for large ci/injector changes to these constants with MT8 cals as often as necessary with MT7 cals.
Bob

My experience only, your milage will vary.
On the 113 I had , I had to run about 120+ci to keep from maxing the ve's. Same engine, I put the equivilent MT8 cal in at the same 120 CI constant. It was washing my O2s at idle and could not vtune the idle area. Dropped the CI back to actual displacement and the O2s lit up and away I went. No hint of maxing the ve's even with actual displacement in the MT8. Something within the two cals is different even though they looked identical with the exception of the egr tables. I believe some others found this as well at first load setup based on MT7 experience and then dropped the CI back. Lonewolf, I think was one.
Ron

[flatfifth2003]

I am in the same dilemma I have a 103 mild build, (s&s 510) flattops, some head work, PV and increased my displacement by 7% but it's throwing codes front o2 rich, rear o2 lean, how do I address this? Using Pv autotune basic btw bike doesn't really run too bad at this point, highest ve's are 120, but only 4 or 5 cells, sorry not trying to highjack thread any help is appreciated

[joe_lyons]

I am in the same dilemma I have a 103 mild build, (s&s 510) flattops, some head work, PV and increased my displacement by 7% but it's throwing codes front o2 rich, rear o2 lean, how do I address this? Using Pv autotune basic btw bike doesn't really run too bad at this point, highest ve's are 120, but only 4 or 5 cells, sorry not trying to highjack thread any help is appreciated

What year is your bike?  And if its 10 or newer make sure you have the black o2 sensor in the rear headpipe.

[FLTRI]

...And if its 10 or newer make sure you have the black o2 sensor in the rear headpipe.

Probably the most common error/source of "Potty mouth"ty running bikes after exhaust changes.
Bob

[flatfifth2003]

it's an 08 Flhx with V&h propipe, thought about maybe bungs being the problem, I was planning on checking them out and trimming them down when I take them off for a cam change next month going with s&s 585ce, and .030 head gasket.

[FLTRI]

it's an 08 Flhx with V&h propipe, thought about maybe bungs being the problem, I was planning on checking them out and trimming them down when I take them off for a cam change next month going with s&s 585ce, and .030 head gasket.

V&H definitely had O2 bung issues in the first couple years of their "bunged" pipes.
Thanks to SC and a couple tuners calling most exhaust mfgs complaining about their bung hole locations (now that just doesn't sound right) the mfgs have, for the most part, corrected their errors.
So identify if the bung is too long and trim if necessary.
Bob

[hrdtail78]

Names on that page were on the WB math excel sheet that you posted. The first time. It is a head scratcher.  Just figured it was you.