the ls1m kit is draw through, and a 85mm ucal'd maf is supplied in all of the kits.

i left an email with both pro m and ramchargers on making a divider box for the maf.

jas you're right the way i have it set up now, but the maf reports frequency and the computer converts it to g/sec correct?

i could just as easily multiply the table by 120 or even "200%" and tune it out in the injector table.. but that doesnt get me anywhere either

like i said, i got money if you want to send me one of those half maf's to try.
David

 

David, at what RPM do you think you would hit 68lb's on a MAF? Are you using 100% stock table and LS1 MAF right now?

 

David, dropped you a note.

 

David give me a phone number to call you at (free ld) and I'll give you my input since your goal is only 600rwhp......LOL...ONLY 600rwhp...can't believe I just typed that. Harlan and Rob made me say it <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

 

David give me a phone number to call you at (free ld) and I'll give you my input since your goal is only 600rwhp......LOL...ONLY 600rwhp...can't believe I just typed that. Harlan and Rob made me say it <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

 

ok i got a test file going..

i multiplied a stock 85mm maf table by 140.x% to get 512 max at 11250hz

then i reduced the injector flowrate by the same 40.x%

also reduced the cylinder size by the same 40.x%


now i just need a electrical change in the maf right?

 

If you are changing the electronics externally then you do not want to touch the MAF table - assuming a stock MAF then leave the MAF table stock. If the maf was a 40 percent reduction, then scale your injector table and engine size by 60% - but leave the MAF alone.


Chris

 

but if i dont run the maf table to 512, then i'm stuck at the stock ls6 maf's max of 37X.

or are you saying that 37X will equal 512 when the frequency comming from the maf is only 60% or original.. ah, that makes sense.

so then what good dose it do anybody to scale the maf table to 512 max? from the above reading i thought this was required to get the full range.

yes thats what i did, reduced by 40% or multiplied by 60% =same numbers

 

how much more cfm does the 85mm flow?

im hoping for a % right at 16 or right at 40.


if the 85 flowed 40% more ( i doubt) then i would get 40% more unmetered air in which would work perfectly with my new maf/injector scaling/cyl size. thats the goal

if it was 16% more then i could use the stock maf table (which goes up higher in g/sec) and get 16% more unmetered air in, then multiply the higher g/sec number from the stock maf to still reach 512 g/sec after that i'd just have to do some more monkey time to get the ltrims back in line that moving away from the appropriate maf scale caused by using the injector table again afterwards.

comments? as accurate results as possible please!

cablebandit, still waiting for that call..

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by MIGHTYMOUSE:
<strong> but if i dont run the maf table to 512, then i'm stuck at the stock ls6 maf's max of 37X.

or are you saying that 37X will equal 512 when the frequency comming from the maf is only 60% or original.. ah, that makes sense.</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif"></strong>

yep, you pretty much got it - when you do this trick the absolute value of the numbers in the MAF table is not that meaningfull (though their relationship still of course is) - the actual relationship depends a bit on the scaling method - for it to work properly you really need soemthing that scales the AIRFLOW by a factor of 1/2 - I don't know if the MAF translator does this or not (it would have to convert the frequency via a lookup table, half it, then output the frequency for the halved airflow) - this will mean at each airflow value you are getting twice as much as indicated - so your 370g/sec will actually be 740 g/sec.

If the device simply halves the frequency then you will need to re-scale the MAF table appropriatley also - see

http://www.slowcar.net/shared/maf.htm for an example of what both methods do (and re-scaling if you are doing a frequency/2 divider)

If the airflow is halved then you don't need to touch the maf table.


</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">
so then what good dose it do anybody to scale the maf table to 512 max? from the above reading i thought this was required to get the full range.
</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">

When you continue to use one maf basically the scaling allows you to get around the frequency input limit of the pcm, and the injector change allows you to get around the 512g/sec value limit. For it to work you are assuming that the maf is accurate and precise above it's rated flow levels. This is what I am not sure of - but it stands to reason you would at least have some lee-way.


</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">
how much more cfm does the 85mm flow?

im hoping for a % right at 16 or right at 40.


if the 85 flowed 40% more ( i doubt) then i would get 40% more unmetered air in which would work perfectly with my new maf/injector scaling/cyl size. thats the goal</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">

If you switch to the 85mm MAF then you should start out with stock MAF tables for the 85mm (z06) - you can't calculate extended flow based on area because the response characteristics of the MAF itself are different.

Also a nitpicky point, but none of the air is "unmetered" - it is still all metered, we are just adjusting how the pcm handles the values.


Chris

 

It does no good to raise your max without changing anything else unless you are maxingout your PE vs RPM tables. It will also make tuning more difficult. You will increase the fueling past a certain actual airflow, but will still max out the meter at just the same actual point - regardless of what g/sec value the pcm declares for that point. You would just end up with more base fueling - and making it an abrubt switch (like you suggest at 8000hz) will just making tuning that much more difficult.

Chris

 

If it was as easy as messing with the table, then we would of been done with years ago and not messed with the electronics.

Even with modified MAF the MAF table isn't just a linear change by %.

 

I called Granatelli about making a MAF sensor that output 1/2 the frequency of a stock one, and JR said they have a unit that plugs between the MAF and stock harness that can cut the frequency in half, and I think 40% and 20%.

BUT, he also said that the stock MAF can only generate 15k hz, so if you half that you have only 7.5k hz, where I believe you would want to have around 11k hz from the 'halved' sensor.

 

wow sweet, the 40% setting would work just as well!

links, prices any other info would be super duper!


this would sucessfully meter you over 512 up to as high as around 900g/sec, just at half the resolution.. i knew the box thing had to be too easy for some place (like granitelli) to make.

i bet they want 300 bux for the thing though <img border="0" alt="[bang head]" title="" src="graemlins/gr_banghead.gif" />

 

i agree.. no need to loose accuracy to gain flow that i cant make.

im emailing back and forth with pro-m at this time.

 

so for that you would just need a housing that flowed precisely double stock. then place stock electronics inside.

for now im just going to move my max to 511.99 and leave 0-8000hz stock so my driveability wont change, then swoop up from there to the max.

then adjust any part throttle issues out with the inj. flowrate and adjust wot fueling with pe/rpm.

i still wanna know when the above is going to be a viable option though.

 

Just do what I did and install the fast system <img border="0" alt="[gruffy cottonball]" title="" src="graemlins/gr_gruffy.gif" />

 

you write another check for it and i'm there
<img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />

 

my realization:

at 11250 my maf is maxed out no matter what number i put under it.

so i am actually BETTER off leaving the 85mm maf table ending at 360 than pulling up to 512.. pulling it up would just make my maf inaccurate and overrichen up until the 11250 point.. then start leaning. unless i change the pe table.

so now i have a file with the stock maf table, and when it gets to 11250 i just have to note what rpm that happens and switch over to the pe table and take over from there.. because it will be leaning out linearly with rpm.. i will need to richen it back linearly with rpm in the pe table. (assuming constant boost level)

that would not work with a supercharger just fyi cus boost goes up and rpm goes up so that ones exponential or somethin'

if the car runs rich overall, im going to move the maf table up until its all good, that will bring my maf table up, which will make my airflow range a little bigger which isn't a bad thing... cuz my pe table wouldnt come in until later rpm then.


on the other hand, pro m is working up a maf setup for me, if the price is right i wont be able to turn that down.. i think a 800 g/sec capability at 11250hz would cover any hp i could ever hope to make with this engine.

if g'telli comes up off of their frequency reduction box for cheap (and the pro m falls through) then i'll grab that and do a 40% reduction or so with that.


thanks everybody for your help! i've learned a ton!

 

Keep us updated on the PRO-M meter.

Just FYI, Granatelli said their box would split the maf hz by 50%.