double maf g/sec how to?
01-18-2003, 06:38 PM
#1
double maf g/sec how to? what maf parameters to check for correct halving/doubling to get the most out of a stock 85mm uncal'd maf and stock 98 ls1 computer.
something like this. in the maf table, double all the g/sec numbers
then half all of the tables that are vs grams/second. (timing table etc.) provide the etc.
and half the displacement size.
anything else before i go try this?
i need to make 600rwhp without flatlining on the ls1m turbo kit.
am i leaving anything out? testimonies?
THanks! david C.
something like this. in the maf table, double all the g/sec numbers
then half all of the tables that are vs grams/second. (timing table etc.) provide the etc.
and half the displacement size.
anything else before i go try this?
i need to make 600rwhp without flatlining on the ls1m turbo kit.
am i leaving anything out? testimonies?
THanks! david C.
01-18-2003, 07:43 PM
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Re: double maf g/sec how to? You could half the MAF table and half the injector constant - problem would be you will still run into the max frequency input wall - the pcm will only use MAF input frequencies so high - then it just carries over the final value.
What you need is an external way to reduce the MAF signal - what you could do now is buy a MAF translator, set it to full lean base (what, -20%) - now scale the injector table by 80 percent also. This will give you a 20% incease in your dynamic range.
The best solution would be a dual MAF in parallel setup with a chip that read both MAF's, averaged the airflows, then output that frequency (you would meter exactly half the air). Now divide your injector constant and engine size by 2. (This procedure would keep the MAF in it's calibrated range even at high airflow). I am working on a setup for this right now - don't know when it will be done. If you can interest one of the electronics guru's in it (harlan, etc.) I am sure they could turn out one easily - I emailed a few people but got no real response, so am working on it myself.
Chris
What you need is an external way to reduce the MAF signal - what you could do now is buy a MAF translator, set it to full lean base (what, -20%) - now scale the injector table by 80 percent also. This will give you a 20% incease in your dynamic range.
The best solution would be a dual MAF in parallel setup with a chip that read both MAF's, averaged the airflows, then output that frequency (you would meter exactly half the air). Now divide your injector constant and engine size by 2. (This procedure would keep the MAF in it's calibrated range even at high airflow). I am working on a setup for this right now - don't know when it will be done. If you can interest one of the electronics guru's in it (harlan, etc.) I am sure they could turn out one easily - I emailed a few people but got no real response, so am working on it myself.
Chris
01-18-2003, 10:07 PM
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Re: double maf g/sec how to? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">What you need is an external way to reduce the MAF signal - </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">exactly!
You can NOT do this with ls1edit alone.
First off you can not just double the maf grams sec in ls1edit.
Otherwise we would all do this if it was possible.
511.99 gms/sec is the max you can go.
From what I understand it's a pcm limit of some type.
You need to recalibrate the raw maf flow data reported to the pcm though.
There are ways of doing this with huge ported meters or much larger housings and then using stock unmodified electronics.
That's fine if you need a larger housing but you will lose some accuracy with very large housings IMO.But if you are on a shoe string budget and have plenty of time, then go make some different size housings for the electronics and have at it.
There are ways to change the frequency with devices that "intercept" like the translator.Although 20-25% is the max it can go I think. But I am sure that was there self imposed limit and not a limit of the design of the device.
Me and partner in crime JAS, change the flow by altering the maf electronics and use no interceptor device or different housings.
We could easily make 50% reported flow meters if there was enough interest.We did that a while ago when using stock programming with large injectors.
Chris, I like your idea also.
Pretty radical.
Packaging concerns me with the plumbing needed for 2 meters though.You are going to need merge pipes before and aft of the meters don't you think?
Steve
You can NOT do this with ls1edit alone.
First off you can not just double the maf grams sec in ls1edit.
Otherwise we would all do this if it was possible.
511.99 gms/sec is the max you can go.
From what I understand it's a pcm limit of some type.
You need to recalibrate the raw maf flow data reported to the pcm though.
There are ways of doing this with huge ported meters or much larger housings and then using stock unmodified electronics.
That's fine if you need a larger housing but you will lose some accuracy with very large housings IMO.But if you are on a shoe string budget and have plenty of time, then go make some different size housings for the electronics and have at it.
There are ways to change the frequency with devices that "intercept" like the translator.Although 20-25% is the max it can go I think. But I am sure that was there self imposed limit and not a limit of the design of the device.
Me and partner in crime JAS, change the flow by altering the maf electronics and use no interceptor device or different housings.
We could easily make 50% reported flow meters if there was enough interest.We did that a while ago when using stock programming with large injectors.
Chris, I like your idea also.
Pretty radical.
Packaging concerns me with the plumbing needed for 2 meters though.You are going to need merge pipes before and aft of the meters don't you think?
Steve
01-19-2003, 01:17 AM
#5
Re: double maf g/sec how to? Not really <img border="0" title="" alt="[Frown]" src="gr_sad.gif" />
That's why i went to a specifically cal'ed aftermarket MAF.
Max frequency at a very high airflow, scale down the MAF table and injector constant. It does throw off the rest of the tables.
But if you halve the air, the rest of the tables will halve accordingly.
That's why i went to a specifically cal'ed aftermarket MAF.
Max frequency at a very high airflow, scale down the MAF table and injector constant. It does throw off the rest of the tables.
But if you halve the air, the rest of the tables will halve accordingly.
01-19-2003, 09:11 AM
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Re: double maf g/sec how to? Steve:
A 50% re-scaled MAF would be the perfect solution as far as packaging, etc. are concerned - and for Dave would probably be his ideal solution. My only concern would be the precision/accuracy of the meter itself at high airflow levels - do you all have the ability to put the meter on a flowbench and datalog the frequency/flow from the flowbench? A few repeat measurements across the board (so we could construct a calibration slope and get some statistics on the repeatability) would be phenomenal.
The packaging is the main issue - on the intake side it isn't to bad, but I would rather have the MAF on the boost side (we tried the theory on a D1 LT1 with 2 parallel maf's on the intake side - we only hooked up on and assumed equal flow through equal path-lenths. It worked to an extent, but part throttle was not good as our pathlenghts were not perfectly equal (about impossible for this applicaion, imo). The advantage would be that you can remain in the factory calibrated flowrange (~450g/sec) for each sensor - taking your total flow up to 900g/sec (more than enough air).
Since the ls1 scales by grams/cylinder you can also effectively scale your timing vs boost - and since 1/2 the maf would 1/2 the g/cyl value also you will loose granularity in your timing table, but you will be able to scale up to an actual 2 or 2.4 g/cyl - which is scaling for a decent amount of boost. This would be tremendous, esp. with a turbo motor with a boost controller.
Chris
Dave:
If you want to stay out of the PCM then you could purchase a 50% re-scaled MAF and install injectors that are exactly 2x as large as whatever your pcm is programmed for.
A 50% re-scaled MAF would be the perfect solution as far as packaging, etc. are concerned - and for Dave would probably be his ideal solution. My only concern would be the precision/accuracy of the meter itself at high airflow levels - do you all have the ability to put the meter on a flowbench and datalog the frequency/flow from the flowbench? A few repeat measurements across the board (so we could construct a calibration slope and get some statistics on the repeatability) would be phenomenal.
The packaging is the main issue - on the intake side it isn't to bad, but I would rather have the MAF on the boost side (we tried the theory on a D1 LT1 with 2 parallel maf's on the intake side - we only hooked up on and assumed equal flow through equal path-lenths. It worked to an extent, but part throttle was not good as our pathlenghts were not perfectly equal (about impossible for this applicaion, imo). The advantage would be that you can remain in the factory calibrated flowrange (~450g/sec) for each sensor - taking your total flow up to 900g/sec (more than enough air).
Since the ls1 scales by grams/cylinder you can also effectively scale your timing vs boost - and since 1/2 the maf would 1/2 the g/cyl value also you will loose granularity in your timing table, but you will be able to scale up to an actual 2 or 2.4 g/cyl - which is scaling for a decent amount of boost. This would be tremendous, esp. with a turbo motor with a boost controller.
Chris
Dave:
If you want to stay out of the PCM then you could purchase a 50% re-scaled MAF and install injectors that are exactly 2x as large as whatever your pcm is programmed for.
01-19-2003, 10:07 AM
#7
Re: double maf g/sec how to? allright, somebody sell me a 50% maf.. pro-m (Harlan) or retuned 85mm (SJH) I got money, who wants it?
I'll be using msd 50# injectors so I would work out the flowrate that they are at, and input 1/2 that.
I agree that a not rediculously costly retuned or aftermarket maf and simple instructions on halfing/doubling in edit would be a huge step forward for ls1 technology.
btw the ls1m kit is pull through maf if it matters.
I'll be using msd 50# injectors so I would work out the flowrate that they are at, and input 1/2 that.
I agree that a not rediculously costly retuned or aftermarket maf and simple instructions on halfing/doubling in edit would be a huge step forward for ls1 technology.
btw the ls1m kit is pull through maf if it matters.
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01-19-2003, 10:17 AM
#8
Re: double maf g/sec how to? this is a kind of stupid idea, but what if i bought 3 maf translators and hooked them end to end.. put them all at -20% then i would have roughly double the airflow capability as stock..
yea thats a silly idea... nevermind
yea thats a silly idea... nevermind
01-19-2003, 10:44 AM
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Re: double maf g/sec how to? Cant you just call the people who make the MAFT and ask how much it would cost to be able to have one that goes to 50% instead of 20%? Or maybe someone could hack the maft and provide the extra adjustment?
01-19-2003, 11:17 AM
#10
Re: double maf g/sec how to? simplify, what part of the maft is cutting down the frequency signal to 80%
and what would i buy at radio shack to cut the frequency by 50% at what voltage and stuff that you could splice in where the maft would go.
and what would i buy at radio shack to cut the frequency by 50% at what voltage and stuff that you could splice in where the maft would go.
01-19-2003, 01:19 PM
#11
Re: double maf g/sec how to? hmm, hard to guess, i would assume 700#tq at 4k and 600hp at 5.5k.. thats the goal anyways. I could use a stock table and stock maf if thats what it took but i have an uncalibrated stock 85mm maf and stock maf table *90%
injector constant at 5.51 and ltrims are -4%
injector constant at 5.51 and ltrims are -4%
01-19-2003, 02:39 PM
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Re: double maf g/sec how to? Some how the LPE TT427 vette is able to run 8.95@153.6 with a reprogrammed stock computer. This has to be at least 850 rwhp, which should result in some very high MAF flow numbers. I asked about this before but never found out how they get the stock computer to do this.
LPE 427TT
Any ideas?
LPE 427TT
Any ideas?
01-19-2003, 08:21 PM
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Re: double maf g/sec how to? </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> hmm, hard to guess, i would assume 700#tq at 4k and 600hp at 5.5k.. thats the goal anyways. I could use a stock table and stock maf if thats what it took but i have an uncalibrated stock 85mm maf and stock maf table *90%
injector constant at 5.51 and ltrims are -4% </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">David, you are using a stock 85mm LS6 MAF with a stock LS6 MAF table for the LS1 on the pressure side of a boosted car?
On a 98, with the stock LS6 table *90%, it only goes up to about 328g/sec of MAF flow. Something a mild heads and cam car can peg easily.
Second, the LS6 MAF's are pressed together (metal & plastic). Didn't Rob Raymer blow a few apart a few years ago by putting them on the pressure side?
Yes, at this time you are better off using a stock LS1 MAF with stock LS1 table on the pressure side on a 98.
<strong> hmm, hard to guess, i would assume 700#tq at 4k and 600hp at 5.5k.. thats the goal anyways. I could use a stock table and stock maf if thats what it took but i have an uncalibrated stock 85mm maf and stock maf table *90%
injector constant at 5.51 and ltrims are -4% </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">David, you are using a stock 85mm LS6 MAF with a stock LS6 MAF table for the LS1 on the pressure side of a boosted car?
On a 98, with the stock LS6 table *90%, it only goes up to about 328g/sec of MAF flow. Something a mild heads and cam car can peg easily.
Second, the LS6 MAF's are pressed together (metal & plastic). Didn't Rob Raymer blow a few apart a few years ago by putting them on the pressure side?
Yes, at this time you are better off using a stock LS1 MAF with stock LS1 table on the pressure side on a 98.
01-19-2003, 08:55 PM
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Re: double maf g/sec how to? Ok I admit this can be a bit strange looking but I think the theory is sound.
This was my plan before deciding to leave the stock PCM for my engine management.
Create a dual tube. Meaning have two MAF's each in a seperate tube. Both tubes would then merge into a single tube that attaches to the throttle body. This would cause half the airflow to travel through each of the tubes. The MAF that you take your measurements from will be effectively halved.
I thought about air reversing or traveling at a different rate from one tube to the other causing measuring issues. But I just can't seem to see a flaw in doing this. Other than it looking a bit strange.
This was my plan before deciding to leave the stock PCM for my engine management.
Create a dual tube. Meaning have two MAF's each in a seperate tube. Both tubes would then merge into a single tube that attaches to the throttle body. This would cause half the airflow to travel through each of the tubes. The MAF that you take your measurements from will be effectively halved.
I thought about air reversing or traveling at a different rate from one tube to the other causing measuring issues. But I just can't seem to see a flaw in doing this. Other than it looking a bit strange.
01-19-2003, 09:12 PM
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Re: double maf g/sec how to? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by chasgiv3:
<strong> Ok I admit this can be a bit strange looking but I think the theory is sound.
This was my plan before deciding to leave the stock PCM for my engine management.
Create a dual tube. Meaning have two MAF's each in a seperate tube. Both tubes would then merge into a single tube that attaches to the throttle body. This would cause half the airflow to travel through each of the tubes. The MAF that you take your measurements from will be effectively halved.
I thought about air reversing or traveling at a different rate from one tube to the other causing measuring issues. But I just can't seem to see a flaw in doing this. Other than it looking a bit strange. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I've seen something like this on a ford and a supra application...
<strong> Ok I admit this can be a bit strange looking but I think the theory is sound.
This was my plan before deciding to leave the stock PCM for my engine management.
Create a dual tube. Meaning have two MAF's each in a seperate tube. Both tubes would then merge into a single tube that attaches to the throttle body. This would cause half the airflow to travel through each of the tubes. The MAF that you take your measurements from will be effectively halved.
I thought about air reversing or traveling at a different rate from one tube to the other causing measuring issues. But I just can't seem to see a flaw in doing this. Other than it looking a bit strange. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I've seen something like this on a ford and a supra application...
01-19-2003, 09:45 PM
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Re: double maf g/sec how to? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by chasgiv3:
<strong> Ok I admit this can be a bit strange looking but I think the theory is sound.
This was my plan before deciding to leave the stock PCM for my engine management.
Create a dual tube. Meaning have two MAF's each in a seperate tube. Both tubes would then merge into a single tube that attaches to the throttle body. This would cause half the airflow to travel through each of the tubes. The MAF that you take your measurements from will be effectively halved.
I thought about air reversing or traveling at a different rate from one tube to the other causing measuring issues. But I just can't seem to see a flaw in doing this. Other than it looking a bit strange. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I wouldn't trust that. Like Chris said, meter both and average the readings...
<strong> Ok I admit this can be a bit strange looking but I think the theory is sound.
This was my plan before deciding to leave the stock PCM for my engine management.
Create a dual tube. Meaning have two MAF's each in a seperate tube. Both tubes would then merge into a single tube that attaches to the throttle body. This would cause half the airflow to travel through each of the tubes. The MAF that you take your measurements from will be effectively halved.
I thought about air reversing or traveling at a different rate from one tube to the other causing measuring issues. But I just can't seem to see a flaw in doing this. Other than it looking a bit strange. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I wouldn't trust that. Like Chris said, meter both and average the readings...
01-19-2003, 09:58 PM
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Re: double maf g/sec how to? If you have the room, etc.
Easier way and probably more accurate way is to use a HUGE Ford MAF with conversion electronics and edit the PCM like Matt is doing.
I think they go to 117mm in size. Is this the size you are using Matt?
Easier way and probably more accurate way is to use a HUGE Ford MAF with conversion electronics and edit the PCM like Matt is doing.
I think they go to 117mm in size. Is this the size you are using Matt?
01-19-2003, 10:25 PM
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Re: double maf g/sec how to? re lingenfelter vette: The problem isn't making full boost/max power - you can do that with pe vs rpm if you have enough fuel; the problem is maintaining good part throttle drivability with high boost, especially if a boost controller is used (so boost vs load isn't even always constant) - and also about the ease of tuning.
re only metering one tube: I tried that on a friends D1 LT1 - a dual path intake with 2 maf's, but only metering one. It worked to a certain extent - it proved the viability of the 1/2 injector size trick, etc. - part throttle drivability wasn't good, and logging the other maf with a oscilloscope showed the flow through both was not perfectly equal. That is going to be the problem - getting them matched. It's much better to meter both and average it.
Re ford vs. GM maf's: The ford meters use a sampling tube type setup, and that scales very well to higher ranges - our meters use a heated wire setup - which is much more precise for it's range. The problem is as the range goes up the meter doesn't scale as well - when you start flowing more air through the same size ortifice you are greatly extending the range of the meter - the heat carried away from the wire will be much greater. Enlarging the meter and recalibrating would be a little better - but that will only help by a few percent - you really need a physically larger electronics piece.
Chris
re only metering one tube: I tried that on a friends D1 LT1 - a dual path intake with 2 maf's, but only metering one. It worked to a certain extent - it proved the viability of the 1/2 injector size trick, etc. - part throttle drivability wasn't good, and logging the other maf with a oscilloscope showed the flow through both was not perfectly equal. That is going to be the problem - getting them matched. It's much better to meter both and average it.
Re ford vs. GM maf's: The ford meters use a sampling tube type setup, and that scales very well to higher ranges - our meters use a heated wire setup - which is much more precise for it's range. The problem is as the range goes up the meter doesn't scale as well - when you start flowing more air through the same size ortifice you are greatly extending the range of the meter - the heat carried away from the wire will be much greater. Enlarging the meter and recalibrating would be a little better - but that will only help by a few percent - you really need a physically larger electronics piece.
Chris
01-19-2003, 10:26 PM
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Re: double maf g/sec how to? I think Matt said in one of his post it was a 3.5" Pro-M unit, ~90mm.
I was checking out Pro-M's website and I think your right about the 117mm being the biggest they make.
I'm guessing they output a different type of signal that requires a signal conversion box? Where would one get something like this? I didn't see anything on the Pro-M website and not being an electronics guru I wouldn't attempt making one. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
A recal'd MAF or aftermarket unit(with appropriate electronics) and computer tuning instructions(for LS1edit) would really be a big seller and boost <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> in the LS1 FI world.
John
I was checking out Pro-M's website and I think your right about the 117mm being the biggest they make.
I'm guessing they output a different type of signal that requires a signal conversion box? Where would one get something like this? I didn't see anything on the Pro-M website and not being an electronics guru I wouldn't attempt making one. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
A recal'd MAF or aftermarket unit(with appropriate electronics) and computer tuning instructions(for LS1edit) would really be a big seller and boost <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> in the LS1 FI world.
John
01-19-2003, 11:04 PM
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Re: double maf g/sec how to? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">re only metering one tube: I tried that on a friends D1 LT1 - a dual path intake with 2 maf's, but only metering one. It worked to a certain extent - it proved the viability of the 1/2 injector size trick, etc. - part throttle drivability wasn't good, and logging the other maf with a oscilloscope showed the flow through both was not perfectly equal. That is going to be the problem - getting them matched. It's much better to meter both and average it.</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Well that's another theory down the train...lol