Jenko
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| posted on 12/6/14 at 02:52 PM |
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quote:
Originally posted by johnH20
Thanks for the above. I would only add that ,in theory at least, you could be anywhere in the speed range at less than 30% ( or what ever your chosen
value ) of throttle opening hence you would need a full VCT 'off' map to cover this. Only likely to be a transient condition outside of
cruise though.
If you take speed out of the equation as the ecu has no idea of car speed or gear. The fuel and ignition map are plotted by rpm vs throttle load. So
simplistically, any part of the table that is under the 30% throttle load is mapped accordingly to account for the fact that the vct is off. Still
just one fuel and ignition map required. If you wanted to change the throttle load point that the vct kicks in then yes, you would need to do some
fuel map optimisation. But around 30% seemed about right during the rolling road session.
If you think about it, that only covers a fairly small part of the fuel / ignition map, but means when you are off throttle or driving gently, the
advanced cam is not needed. I suspect even the standard ford ecu has some algorithm that backs of the cam advance on light throttle loads, but I would
still think that it only uses one map.
MY BLOG - http://westfieldv8.blogspot.co.uk/
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Ugg10
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| posted on 12/6/14 at 03:21 PM |
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I've no evidence for this but I suspect the Ford map just rounds off/angles the edges of your table top "on" portion of your map
i.e. that bit above 30% TPS value and between 2k and 6k RPM approx. giving a slightly smoother lead in and lead out to those boundaries. This is
probably what you would do if you were controlling the VCT via a PWM map which is avalable in the Omex 710 ECU and what the
Triggerwheels/motorsportselectronics VCT controller does.
Intersting on the Triggerwheels site it shows a power map for their VCT controller that looks almost identifical to Jenko's map graphs he has
added to his blog - http://trigger-wheels.com/store/contents/en-uk/d68.html - which sort of prooved that the simple off/on/off method is pretty good.
---------------------------------------------------------------
1968 Ford Anglia 105e, 1.7 Zetec SE, Mk2 Escort Workd Cup front end, 5 link rear
Build Blog - http://Anglia1968.weebly.com
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Jenko
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| posted on 12/6/14 at 06:16 PM |
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Re the vvt pro and the graphs on the trigger wheel website.....this is what frustrates me and I believe is misleading to the customer.
First off....I've had stuff from Trigger wheels before, and found them brill so this is no reflection on them. But, as per the previous thread
with the company who developed the VVT pro, I think the claims are a little confusing. No problem with the product, and reality is a full on
controller that also looks at the cam sensor and is constantly variable has to be a good thing. I just wish they show a real like for like. You cant
compare the with vvt pro without showing what a correctly mapped on / off system loks liket....plus, why do they compare the vvt controler with a
permantly on cam..of course this will hold back power at the top end.
I still agree that the variable control is no doubt better than on / off, but we are yet to see by how much....
MY BLOG - http://westfieldv8.blogspot.co.uk/
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johnH20
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| posted on 12/6/14 at 06:34 PM |
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Not wishing to set myself up as an expert which I am not I have seen 3D cam maps. An important dimension of OEM stuff is fuel economy and emissions
which may or may not concern us performance types at your choice. The cam map has a significant influence here. My interest, as I suspect with most
enthusiasts, is best performance within the practical limits of affordable mapping. For an OEM this takes thousands of man hours including validation
( 50k miles durability remember ). I admire what has been done here, just want to understand fully what that is so that someday maybe I can emulate
it. Well done Jenko/NMS.
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Jenko
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| posted on 12/6/14 at 08:38 PM |
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quote:
Originally posted by johnH20
Not wishing to set myself up as an expert which I am not I have seen 3D cam maps. An important dimension of OEM stuff is fuel economy and emissions
which may or may not concern us performance types at your choice. The cam map has a significant influence here. My interest, as I suspect with most
enthusiasts, is best performance within the practical limits of affordable mapping. For an OEM this takes thousands of man hours including validation
( 50k miles durability remember ). I admire what has been done here, just want to understand fully what that is so that someday maybe I can emulate
it. Well done Jenko/NMS.
Spot on....I can't begin to think how complex the OEM mapping is to allow for all the variables (including selling the cars in other countries).
And it could well be on a full throttle run, the VCT system basically works like the on/off. Hence why the graph on the trigger wheels site looks not
to disimilar to the one I ended up with (although it's on an ST170).
MY BLOG - http://westfieldv8.blogspot.co.uk/
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