MIVEC disassembly notes
Nov 28, 2007, 10:31 PM
#46
I meant the part about there actually being a difference in how the feedback controller sees an input of 28.8 vs 30. If the output is a 1-5V signal and the scaling is set so that 28.8 in the ECU is 5V then it won't make any difference either way. It was my way of saying that I'm making a WAG.
Nov 28, 2007, 10:55 PM
#48
Found out this evening that while 28.8 deg looks for certain to be the upper limit on MIVEC, 0 deg is not the lower limit. I was able to push the MIVEC as far as -1.6 deg by altering the lower limit and adding negative values to the MIVEC table. So, it looks like the total range is around 30-31 deg, with it spanning from around -1.6 deg (logged) to around 28.4 deg (also logged).
Not sure how much value there is to be able to go negative by -1.6 deg. I suppose the place to use it would be at higher rpms.
Not sure how much value there is to be able to go negative by -1.6 deg. I suppose the place to use it would be at higher rpms.
Nov 29, 2007, 10:09 AM
#50
What values should they read in Ecuflash?
Any ideas for rom 88570008?
SK
Any ideas for rom 88570008?
SK
Found out this evening that while 28.8 deg looks for certain to be the upper limit on MIVEC, 0 deg is not the lower limit. I was able to push the MIVEC as far as -1.6 deg by altering the lower limit and adding negative values to the MIVEC table. So, it looks like the total range is around 30-31 deg, with it spanning from around -1.6 deg (logged) to around 28.4 deg (also logged).
Not sure how much value there is to be able to go negative by -1.6 deg. I suppose the place to use it would be at higher rpms.
If you want to see the MIVEC upper lower limits, add the following two entries to your 88590015 xml file:
---
<table name="MIVEC Bounding Minimum" category="Timing" address="293A" type="1D" level="1" scaling="ValveTiming16"/>
<table name="MIVEC Bounding Maximum" category="Timing" address="293C" type="1D" level="1" scaling="ValveTiming16"/>
---
Then add the following entry to your evo9base.xml file (if you're using post 1.29 version of ECUFlash, use "big" instead of "little" endian):
---
<scaling name="ValveTiming16" units="degrees" toexpr="72-x*0.6/32" frexpr="(72-x)*32/0.6" format="%.1f" min="-1.8" max="28.8" inc="0.1" storagetype="uint16" endian="little"/>
---
Not sure how much value there is to be able to go negative by -1.6 deg. I suppose the place to use it would be at higher rpms.
If you want to see the MIVEC upper lower limits, add the following two entries to your 88590015 xml file:
---
<table name="MIVEC Bounding Minimum" category="Timing" address="293A" type="1D" level="1" scaling="ValveTiming16"/>
<table name="MIVEC Bounding Maximum" category="Timing" address="293C" type="1D" level="1" scaling="ValveTiming16"/>
---
Then add the following entry to your evo9base.xml file (if you're using post 1.29 version of ECUFlash, use "big" instead of "little" endian):
---
<scaling name="ValveTiming16" units="degrees" toexpr="72-x*0.6/32" frexpr="(72-x)*32/0.6" format="%.1f" min="-1.8" max="28.8" inc="0.1" storagetype="uint16" endian="little"/>
---
Nov 29, 2007, 10:51 PM
#52
So I tried out -1.6 (which actually you can't input into ecuflash, it just snaps to -1.8) on the dyno today. Was interested in seeing what it would do as I usually run 0 up top on the 9's. Didn't really do anything power wise but this Evo was a un-standard case 9, using a exhaust adjustable cam gear.
I'll try it out on some more 9's and report back.
I'll try it out on some more 9's and report back.
Nov 30, 2007, 10:18 AM
#54
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So I tried out -1.6 (which actually you can't input into ecuflash, it just snaps to -1.8) on the dyno today. Was interested in seeing what it would do as I usually run 0 up top on the 9's. Didn't really do anything power wise but this Evo was a un-standard case 9, using a exhaust adjustable cam gear.
I'll try it out on some more 9's and report back.
I'll try it out on some more 9's and report back.
Nov 30, 2007, 10:54 AM
#55
Now I've pretty much convinced myself that approx 28-29 deg is the max advance. I grabbed a drawing of the MIVEC assembly from the FSM and measured the amount of rotation possible. Assuming the drawing proportions are reasonably correct, then it looks like there is room for up to 50 deg of advance. However, there is a nub on one of the MIVEC arms that limits the MIVEC advance to 28.8 deg. Seems like that nub would have to sawed off get more than 28.8 deg.
It was pointed out earlier that the 4G63 is an interference motor, but the piston is moving away from the intake valve so there isnt really a chance of interference unless it was extremely over advanced BTDC. As far this is concerned you could look at the specs for the biggest MIVEC cam now available and see how much advance BTDC it has taking into account it has the safety margin for 28.8*. Add the 2 numbers together and you should come up with a reasonable idea of what the max limit is. I will look at the cam engineering for the Cossies again and then see what we have for a rough idea. I would assume its only in the 45-50* range though (total max advance).
Nov 30, 2007, 11:10 AM
#56
mrfred- One other question about the "nub" on the MIVEC gear. I am thinking this is behind the plastic cover and IN the spool valve assembly yes? Once my car is back from getting the transmission rebuilt or replaced I am gonna do this just because I have to know whether it helps or not.
Bryan- Without having to disclose the actual cam gear setting has this helped spool at all? Optimum MIVEC changes with the lobecenter so altering the effective engineering requires a little time with a dynosim and then you can see what will help or not. I can run it on my lappy later if you want some ideas (unless you already got it in the bag), just PM if you want it done.
Bryan- Without having to disclose the actual cam gear setting has this helped spool at all? Optimum MIVEC changes with the lobecenter so altering the effective engineering requires a little time with a dynosim and then you can see what will help or not. I can run it on my lappy later if you want some ideas (unless you already got it in the bag), just PM if you want it done.
Nov 30, 2007, 02:02 PM
#57
mrfred- One other question about the "nub" on the MIVEC gear. I am thinking this is behind the plastic cover and IN the spool valve assembly yes? Once my car is back from getting the transmission rebuilt or replaced I am gonna do this just because I have to know whether it helps or not.
...
...
Dec 3, 2007, 10:28 AM
#59
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Bryan- Without having to disclose the actual cam gear setting has this helped spool at all? Optimum MIVEC changes with the lobecenter so altering the effective engineering requires a little time with a dynosim and then you can see what will help or not. I can run it on my lappy later if you want some ideas (unless you already got it in the bag), just PM if you want it done.
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