VE influence on wot
11-10-2004, 02:10 PM
#1
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VE influence on wot Does having a correct VE table at wot really matter when you have the maf plugged in? If it does, how would I get it nailed down without a wideband? Say for example i have my pe at 1.17 but my 02s still read 940 or something, does that mean the ve table is set up to high? I've done ve tuning up to 4000 rpm but quit there since i don't have a wideband and i thought maf took over at that point anyways.
11-11-2004, 04:17 PM
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The MAF does take over -when MAP is steady-.
But, having a good VE table at the top end will
improve your tip-in performance, get rid of tip-in
KR, etc. so it's not a waste of time to tweak up
the top end too.
But, having a good VE table at the top end will
improve your tip-in performance, get rid of tip-in
KR, etc. so it's not a waste of time to tweak up
the top end too.
11-11-2004, 04:26 PM
#3
You really do need a wideband to safely calculate your high rpm/load ve table. You could always use the ve formulas posted in the sticky to calculate those cells as an alternative. Even though you normally can't trust your maf enough to use the equation, the maf error would be lower at the higher maf readings so it wouldn't be that bad if you trust your maf tables.
Gameover said above 4000 rpm the pcm trusts the maf completely regardless of throttle transients.
Gameover said above 4000 rpm the pcm trusts the maf completely regardless of throttle transients.
11-11-2004, 04:49 PM
#4
Originally Posted by jimmyblue
The MAF does take over -when MAP is steady-.
But, having a good VE table at the top end will
improve your tip-in performance, get rid of tip-in
KR, etc. so it's not a waste of time to tweak up
the top end too.
But, having a good VE table at the top end will
improve your tip-in performance, get rid of tip-in
KR, etc. so it's not a waste of time to tweak up
the top end too.
Take the 1st question on this thread, MAF goes out at 4200 RPM because you maxed out the frequency. Besides using the MAP SD tune, what would your solution be?
11-11-2004, 05:32 PM
#5
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That must be a monster motor; I don't see much
over 10KHz at 6000 (this on a straight Delphi
85mm).
I do know that the regular 75mm, if you use the
Holden table that properly populates the upper end,
takes you out to 511 g/sec at 12KHz while the
85mm Delphis only hit about 450g/sec there.
I think if you are over 12KHz by 4200RPM, even
porting out the MAF grossly would not get you the
range you need. I guess my favorite idea would be
the twin-MAF way, either going with an electronic
averaging or just using one as a "dummy" (though
the latter might have some unknown fidelity issue).
I guess it would not be too bad a job to take a pair
of F-V chips, sum and scale and put that to a V-F
to regenerate a MAF-like signal. Then have to scale
the injectors to fake fueling, scale all the load based
trans, spark, etc.
But I'd also think on this extreme a motor, you'd almost
have to be boosted, be looking for a 2-bar or 3-bar
MAP sensor capable PCM and then why not just go
speed density? Is there such a thing as an 800HP,
smoggable motor?
over 10KHz at 6000 (this on a straight Delphi
85mm).
I do know that the regular 75mm, if you use the
Holden table that properly populates the upper end,
takes you out to 511 g/sec at 12KHz while the
85mm Delphis only hit about 450g/sec there.
I think if you are over 12KHz by 4200RPM, even
porting out the MAF grossly would not get you the
range you need. I guess my favorite idea would be
the twin-MAF way, either going with an electronic
averaging or just using one as a "dummy" (though
the latter might have some unknown fidelity issue).
I guess it would not be too bad a job to take a pair
of F-V chips, sum and scale and put that to a V-F
to regenerate a MAF-like signal. Then have to scale
the injectors to fake fueling, scale all the load based
trans, spark, etc.
But I'd also think on this extreme a motor, you'd almost
have to be boosted, be looking for a 2-bar or 3-bar
MAP sensor capable PCM and then why not just go
speed density? Is there such a thing as an 800HP,
smoggable motor?
11-11-2004, 05:46 PM
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Jimmy- What are my options for setting up the upper end of my ve. I got the <4000 rpm cells nailed using the stfts. What do you recommend me to do for the higher rpm cells. Keep in mind I don't have a wideband. If they are wrong, would it make it hard to achieve a flat afr when i hit the dyno and use pe to adjust fuel?
11-11-2004, 05:48 PM
#7
Bryan, you could
-get a dual maf or pro-m maf like jimmy said and trick your pcm into fueling right
-go speed density with a 2 bar map sensor and cut your ifr tables in half to trick your pcm into fueling right
-go with fast or big stuff 3
-wait and see what hptuners is working on, i saw a screen shot with a ve table that went up to 200 kpa but i don't know anything else about it
-you could get a pro-m maf to keep the sensor from maxing out and reprogram your pcm operating system to get rid of the maf limit in the software (I think I heard lingenfelter does this, try calling them)
-get a dual maf or pro-m maf like jimmy said and trick your pcm into fueling right
-go speed density with a 2 bar map sensor and cut your ifr tables in half to trick your pcm into fueling right
-go with fast or big stuff 3
-wait and see what hptuners is working on, i saw a screen shot with a ve table that went up to 200 kpa but i don't know anything else about it
-you could get a pro-m maf to keep the sensor from maxing out and reprogram your pcm operating system to get rid of the maf limit in the software (I think I heard lingenfelter does this, try calling them)
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11-11-2004, 06:31 PM
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The only time I've done this, I just did it by eyeball
and educated guess. I took the stock table, pushed
its "fade" off to the right, raised the peak for the cam,
headers etc., and made it all smooth so it "looked right".
If the MAF is trustworthy and not maxing out, I believe
at the high end you could use the VE spreadsheets, or
make your own, and see a pretty good result. The MAF
is really a pretty good instrument, at higher flows and
continuous operation; its weakness is at low flow and
dynamic conditions. An unmolested Delphi MAF (75mm
or 85mm) is a couple-% or better accuracy from what
I've been told (even talked to a cal lab that had done
a batch of Delphis once).
Even if you only get as far as "doesn't suck" that would
be a big improvement over sticking with the table residue
from the stock tune.
As a rule of thumb, or a sanity check, I believe your VE
should peak where your torque peaks, and your peak VE
(presuming similar MAP values, no boost etc.) should
increase by the same ratio that your peak torque did,
relative to same-RPM stock. Of course if you didn't have
that baseline this might be not so helpful but you might
take a dyno curve that represents your combo, one for
stock (your model) and check that out. I think the
similarity between the shape of the VE curve (at WOT
MAP value) and the torque curve, is not coincidental.
Here's the table I ended with (not that I claim it's right
for anybody elses car, but the guy I did it for found it
an improvement). This is the Primary, it was an '00 so
I made the Secondary too as a "strip-out")
27 31 34 37 40 42 44 46 48 50 52 54 55 56 57 57 56 56 55 55
30 34 37 41 45 48 52 54 57 60 62 64 66 68 69 69 68 68 67 67
32 36 40 44 48 53 57 60 63 67 70 73 74 76 77 77 77 76 76 75
34 38 42 46 50 55 60 64 67 71 75 78 80 82 83 83 82 82 81 81
36 40 44 48 52 57 62 66 70 74 77 80 83 85 86 86 85 85 84 84
38 42 46 50 54 59 64 68 72 76 79 82 85 87 88 88 87 87 86 86
40 44 48 52 56 61 66 70 74 78 81 84 87 89 90 90 89 89 88 88
41 45 49 54 58 63 67 71 75 79 83 86 89 91 91 91 90 90 89 89
42 46 50 55 60 64 68 73 76 80 84 88 90 92 92 92 91 91 90 89
43 47 51 56 61 65 69 74 77 81 85 89 91 93 93 93 92 92 91 90
44 48 52 57 62 66 70 74 78 82 86 89 92 93 93 93 93 92 91 90
45 49 53 59 64 68 71 75 79 83 87 90 93 94 94 94 94 93 92 91
46 50 55 60 65 70 73 76 80 84 88 91 93 95 95 95 95 94 93 92
47 52 56 61 67 71 74 78 81 85 88 91 94 96 96 96 95 95 94 93
48 53 57 62 68 72 75 79 82 86 89 92 95 96 96 96 96 95 94 93
50 54 58 63 69 73 76 80 83 87 90 93 96 97 97 97 96 96 95 94
51 55 59 64 70 74 77 81 84 88 91 94 97 99 99 99 97 97 96 95
52 56 60 65 71 75 78 82 85 89 92 95 98 100 100 100 98 97 96 96
53 57 61 66 72 76 79 82 85 89 93 95 98 100 101 100 98 97 96 96
and educated guess. I took the stock table, pushed
its "fade" off to the right, raised the peak for the cam,
headers etc., and made it all smooth so it "looked right".
If the MAF is trustworthy and not maxing out, I believe
at the high end you could use the VE spreadsheets, or
make your own, and see a pretty good result. The MAF
is really a pretty good instrument, at higher flows and
continuous operation; its weakness is at low flow and
dynamic conditions. An unmolested Delphi MAF (75mm
or 85mm) is a couple-% or better accuracy from what
I've been told (even talked to a cal lab that had done
a batch of Delphis once).
Even if you only get as far as "doesn't suck" that would
be a big improvement over sticking with the table residue
from the stock tune.
As a rule of thumb, or a sanity check, I believe your VE
should peak where your torque peaks, and your peak VE
(presuming similar MAP values, no boost etc.) should
increase by the same ratio that your peak torque did,
relative to same-RPM stock. Of course if you didn't have
that baseline this might be not so helpful but you might
take a dyno curve that represents your combo, one for
stock (your model) and check that out. I think the
similarity between the shape of the VE curve (at WOT
MAP value) and the torque curve, is not coincidental.
Here's the table I ended with (not that I claim it's right
for anybody elses car, but the guy I did it for found it
an improvement). This is the Primary, it was an '00 so
I made the Secondary too as a "strip-out")
27 31 34 37 40 42 44 46 48 50 52 54 55 56 57 57 56 56 55 55
30 34 37 41 45 48 52 54 57 60 62 64 66 68 69 69 68 68 67 67
32 36 40 44 48 53 57 60 63 67 70 73 74 76 77 77 77 76 76 75
34 38 42 46 50 55 60 64 67 71 75 78 80 82 83 83 82 82 81 81
36 40 44 48 52 57 62 66 70 74 77 80 83 85 86 86 85 85 84 84
38 42 46 50 54 59 64 68 72 76 79 82 85 87 88 88 87 87 86 86
40 44 48 52 56 61 66 70 74 78 81 84 87 89 90 90 89 89 88 88
41 45 49 54 58 63 67 71 75 79 83 86 89 91 91 91 90 90 89 89
42 46 50 55 60 64 68 73 76 80 84 88 90 92 92 92 91 91 90 89
43 47 51 56 61 65 69 74 77 81 85 89 91 93 93 93 92 92 91 90
44 48 52 57 62 66 70 74 78 82 86 89 92 93 93 93 93 92 91 90
45 49 53 59 64 68 71 75 79 83 87 90 93 94 94 94 94 93 92 91
46 50 55 60 65 70 73 76 80 84 88 91 93 95 95 95 95 94 93 92
47 52 56 61 67 71 74 78 81 85 88 91 94 96 96 96 95 95 94 93
48 53 57 62 68 72 75 79 82 86 89 92 95 96 96 96 96 95 94 93
50 54 58 63 69 73 76 80 83 87 90 93 96 97 97 97 96 96 95 94
51 55 59 64 70 74 77 81 84 88 91 94 97 99 99 99 97 97 96 95
52 56 60 65 71 75 78 82 85 89 92 95 98 100 100 100 98 97 96 96
53 57 61 66 72 76 79 82 85 89 93 95 98 100 101 100 98 97 96 96
11-11-2004, 07:28 PM
#9
Originally Posted by jimmyblue
Is there such a thing as an 800HP,
smoggable motor?
smoggable motor?
I originally asked the question because I wanted to know if you had another thought to the problem. I took a friends of mines car, a 2000 Corvette and got a Pro-M MAF and it is working up to 800 Hertz. Car is making about 700 RWHP. I will be doing mine in SD mode.
