Should I just leave it in SD????
06-08-2005, 05:41 AM
#1
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Should I just leave it in SD???? K guys... Is there any benefit to running a MAF if I live in Hawaii?? I live in the mountains and maybe at coldest in the winter my house will hit about mid to low 50's. Other than that the hottest it gets is like 90's but humid as hell. I was thinking about having a great SD tune and a great MAF as well and I could turn it on when I wanted. I can already see the difference in the LTFTs when I run my car during the day then at night. Dunno... whatcha guys think??
thanks.
thanks.
06-08-2005, 08:38 AM
#3
you could leave it in SD anywhere, as long as you watch your LTFT's, as one day they might change. the other day i went to dyno my car and it was so hot and humid that both MAF and SD mode were way off. strangely enough, the MAF mode was more off!
funny enough, the other day i had a conversation why would you stay SD, and i said 'only if you're on an island'. there really are no good reasons for it, unless you're using the 2bar SD mode, or the fast 90/90 combo and then the smaller MAF might actually be a bottleneck. if you got a more sane setup than that, just get your VE done, then MAF, and you should really not feel a difference. I don't. It's nice to have that extra ability to adjust parameters based on MAF information coming in though.
funny enough, the other day i had a conversation why would you stay SD, and i said 'only if you're on an island'. there really are no good reasons for it, unless you're using the 2bar SD mode, or the fast 90/90 combo and then the smaller MAF might actually be a bottleneck. if you got a more sane setup than that, just get your VE done, then MAF, and you should really not feel a difference. I don't. It's nice to have that extra ability to adjust parameters based on MAF information coming in though.
06-08-2005, 10:06 AM
#7
trust me, i wasn't thrilled going to a dyno with my tune that far off either.
but the next two days (just this past weekend) i went to a trackday, and got 100miles on that same tune i dynoed with, and the car was very strong. After one session, i got back to my spot and hooked up the laptop, my ECT was was 215F, and IAT was 158F, and it was probably 5-10 mins AFTER i stopped running it hard. so i went for a quick spin around the paddock, and my whole LTFT table was up to 8 points lean again. i left the car alone for an hour, took it for another spin, and the LTFTs were back to 0, once coolant was <190 and air was < 130. all of this on SD tune. so it's not only temperature (and it was super hot and super humid again) but also how much heat you got stored in your engine compartment.
but the next two days (just this past weekend) i went to a trackday, and got 100miles on that same tune i dynoed with, and the car was very strong. After one session, i got back to my spot and hooked up the laptop, my ECT was was 215F, and IAT was 158F, and it was probably 5-10 mins AFTER i stopped running it hard. so i went for a quick spin around the paddock, and my whole LTFT table was up to 8 points lean again. i left the car alone for an hour, took it for another spin, and the LTFTs were back to 0, once coolant was <190 and air was < 130. all of this on SD tune. so it's not only temperature (and it was super hot and super humid again) but also how much heat you got stored in your engine compartment.
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06-08-2005, 10:51 AM
#9
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Originally Posted by RedHardSupra
After one session, i got back to my spot and hooked up the laptop, my ECT was was 215F, and IAT was 158F, and it was probably 5-10 mins AFTER i stopped running it hard.
Damn! I've yet to break 95*F on my IAT. You might want to look into a SSRA to get some cooler air up in there. And then, when you figure out the best way to tune for a ram air kit, let me know.
I'm about to dive into HPT and I can't find anyone to respond to my question of tuning a ram air kit where I'm currently rich @ low mph's and lean @ high mph's. Even the C5 boys with the VaraRams have yet to say anything. 
06-08-2005, 11:24 AM
#10
Originally Posted by RedHardSupra
trust me, i wasn't thrilled going to a dyno with my tune that far off either.
but the next two days (just this past weekend) i went to a trackday, and got 100miles on that same tune i dynoed with, and the car was very strong. After one session, i got back to my spot and hooked up the laptop, my ECT was was 215F, and IAT was 158F, and it was probably 5-10 mins AFTER i stopped running it hard. so i went for a quick spin around the paddock, and my whole LTFT table was up to 8 points lean again. i left the car alone for an hour, took it for another spin, and the LTFTs were back to 0, once coolant was <190 and air was < 130. all of this on SD tune. so it's not only temperature (and it was super hot and super humid again) but also how much heat you got stored in your engine compartment.
but the next two days (just this past weekend) i went to a trackday, and got 100miles on that same tune i dynoed with, and the car was very strong. After one session, i got back to my spot and hooked up the laptop, my ECT was was 215F, and IAT was 158F, and it was probably 5-10 mins AFTER i stopped running it hard. so i went for a quick spin around the paddock, and my whole LTFT table was up to 8 points lean again. i left the car alone for an hour, took it for another spin, and the LTFTs were back to 0, once coolant was <190 and air was < 130. all of this on SD tune. so it's not only temperature (and it was super hot and super humid again) but also how much heat you got stored in your engine compartment.
06-08-2005, 11:33 AM
#11
To the original poster, there's really not a huge benefit between MAF and Speed Density for most cars. Some people say they get better throttle response in sd, some people say driveability is better with a maf. As long as you're not using a power adder it doesn't matter much. However, I am gonna try replacing my maf with a pcv coupler and see if that helps get me higher map at wide open throttle.
06-08-2005, 11:37 AM
#12
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Originally Posted by P Mack
You probably already know this, but the pcm doesn't use IAT directly in the speed density calculations, it adds in the effects of engine coolant temperature. In other words, the air picks up heat through the throttle body and intake manifold and the pcm attempts to correct for it. You can see the value in engine>airflow>charge temp bias vs ECT. Since your engine seems to be overcorrecting for the decreased density of the air on hot days, maybe you could try lowering the charge temp bias and see if it makes your trims swing less. I've been wanting to try this myself since I did the TB bypass.
I thought IAT was used directly in the SD calcs. That is what I got from this thread
https://ls1tech.com/forums/showpost....&postcount=133
Redhard surprising you dont have a 160* thermostat
06-08-2005, 11:41 AM
#13
i do have a 160deg thermostat see, this is the difference between drag and road racing--you do your 12 secs of madness and whine about 'heat soak' sitting in staging lanes. i do my 10-12secs of madness 3 times a lap, with lots of partial throttle (read: holding 5krpm+ in turns) that's definitely not helping temperatures. to me straights are where the car cools actually, not where it warms up 
generally speaking, i'm gonna spend the next month redoing cooling in every possible way.
see, this is the difference between drag and road racing--you do your 12 secs of madness and whine about 'heat soak' sitting in staging lanes. i do my 10-12secs of madness 3 times a lap, with lots of partial throttle (read: holding 5krpm+ in turns) that's definitely not helping temperatures. to me straights are where the car cools actually, not where it warms up generally speaking, i'm gonna spend the next month redoing cooling in every possible way.
06-08-2005, 12:06 PM
#16
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I dont complain either I have an SLP high capacity radiator on my car, car never sees abouve 180 (where both fans are running) sitting in traffic and the likes
06-08-2005, 12:29 PM
#17
Originally Posted by HumpinSS
I thought IAT was used directly in the SD calcs. That is what I got from this thread
Maybe one of the hptuners guys can chime in and tell us if the IAT pid is the raw value or the filtered value.
All you damn thread stealers!!!! 
I'm just joking lolol. Hey RHS.. I was planning on getting a 90/90 like you said, so I'd dump the MAF when I do get it??
06-08-2005, 04:10 PM
#19
i know a 9sec car that has a 90/90 with a 85mm maf and it eats up some massive amounts of air. so maf isn't exactly some sort of huge bottleneck. my primary concern would be how much you can afford/want to/need to screw with the settings. SD by nature needs more attention, although i gotta say living in chicago weather and driving in SD have not been a bad experience so far. if it is an occasional driver/mostly race car, i would go SD. If it is just more of a fun toy that you just wanna jump in and have fun without necessairly caring what kind of air you got this particular day, i'd stay with MAF. After de-mystifying MAF calibration this winter, there really is no reason to go permanent SD. I keep my MAF in for daily operations, and go into SD for track. this way i can drive around like a normal car, but i have less variables to deal with when i'm logging/experimenting/pushing the car's limits at the track.