Thinking about the future of my car. Has a MAF ever been used that is >73mm & <83mm?
04-09-2008, 05:35 PM
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Thinking about the future of my car. Has a MAF ever been used that is >73mm & <83mm?
I'm at altitude (6200ft) here in Colorado. When my K03s blow, I'd like to do K04 homebrew tuning. A guy or two here in Denver tried the RS4 83mm MAF and their MAF #s didn't get high enough to go into open loop. Quite a few people have used the stock MAF with success (73mm)with 38# injectors but have left a little on the table. I want to run 42# injectors and 3 Bar FPR with a MAF bigger than stock but smaller than the RS4. Any options out there? If not, I guess I could use an RS4 MAF with a sleeve.
04-09-2008, 06:11 PM
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I ran RS4 (83mm) with OEM RS4 airbox top and switched to ASP 85mm w/ OEM S4 airbox.
My MAF readings are higher with the ASP probabaly because it has a slight taper for teh stock airbox.
I go over 300g/s (307-315) w/ ASP at ~21psi.
IIRC I was around 260 @ 19-20 psi homebrew w/ RS4 MAF.
I am nearly sea level but do some more checking with ASP guys at altitude to see what kind of g/s they get.
You could probably use 42 lb @ 4 bar.
Besides, isn't 42 @ 3 bar lower flow than 38 @ 4 bar? When folks try to run 3 bar with a high flow pump, they have problems getting down to 3 @ idle which screws things up.
I go over 300g/s (307-315) w/ ASP at ~21psi.
IIRC I was around 260 @ 19-20 psi homebrew w/ RS4 MAF.
I am nearly sea level but do some more checking with ASP guys at altitude to see what kind of g/s they get.
You could probably use 42 lb @ 4 bar.
Besides, isn't 42 @ 3 bar lower flow than 38 @ 4 bar? When folks try to run 3 bar with a high flow pump, they have problems getting down to 3 @ idle which screws things up.
04-09-2008, 06:15 PM
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My guess is you have no idea what ASP does in terms of MAF scaling so that's a scary statement...
You don't need too much fuel at altitude because you don't flow nearly as much as you would at/near sea level. On stock injectors and stock maf, you can get ~20 PSI depending on how thin the air is.
04-09-2008, 06:23 PM
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You can't have too much injector (as long as you can idle nicely) but you can have too little.
I don't beleive the MAF values are scaled in my software but that is easy enough to find out.
I would NOT steer someone to use stock injectors on K04s Homebrewed (MBC). One trip down the mountains and BOOM go the pistons.
I would NOT steer someone to use stock injectors on K04s Homebrewed (MBC). One trip down the mountains and BOOM go the pistons.
04-09-2008, 06:25 PM
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i toyed with homebrew for a bit
im in utah, so 4500-8800ft depending on the day. i couldn't get things quite where i wanted them in terms of driveability and making cold starts a non-issue. what i went with was a mish-mash of software and parts. you can email me if you want more details, but my car runs great. i have never had it on a dyno but it is at least as fast, if not faster than, the AWE OTS cars that i worked on at my previous employer.
good luck!
good luck!
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04-09-2008, 06:27 PM
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That's easy for you to say, but you must match fuel flow and MAF housing close enough that Lemmi can
make up the difference. With the small MAF you must run at alitude, a lot of injectors is the last thing you want.
How is it so easy to find out if your MAF readings are scaled or not? If you mean by asking Mark, that's not conclusive IMO. There are probably plenty of tuners who say they don't scale, yet do.
How is it so easy to find out if your MAF readings are scaled or not? If you mean by asking Mark, that's not conclusive IMO. There are probably plenty of tuners who say they don't scale, yet do.
04-09-2008, 06:58 PM
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Matching fuel flow to a MAF housing is not altitude dependant. Its a fixed ratio.
Regarding scaling, he could ask Mark. Why not? He sells the MAFs ala cart to homebrewers, why would he lie?
Regarding your statement about what I know about the hardware/software I'm discussing. You know, I do own these things don't you? I have mixed em up over the years and tried different combinations. I stated my observations.
My whole point is that the ASP MAF "apparently" reads between RS4 and stock S4 MAF housings. Do you have any data or information that points to the contrary? You are welcome to post it.
Now back to your suggestion, stock injectors for a K04 car that is MBC'd at 20+psi is shortsighted and, well, stupid.
Regarding your statement about what I know about the hardware/software I'm discussing. You know, I do own these things don't you? I have mixed em up over the years and tried different combinations. I stated my observations.
My whole point is that the ASP MAF "apparently" reads between RS4 and stock S4 MAF housings. Do you have any data or information that points to the contrary? You are welcome to post it.
Now back to your suggestion, stock injectors for a K04 car that is MBC'd at 20+psi is shortsighted and, well, stupid.