Are MAF g/sec readings a good indicator of airflow efficiency?
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Are MAF g/sec readings a good indicator of airflow efficiency? For example, when scanning say WOT g/sec airflow peak is 18x g/sec with a filter system and 24x g/sec without one, would this be a significant restriction of airflow that a larger/ more efficient intake system should be considered?
Just curious because the filter I got for free is so tiny both being short and having a small outlet diameter that I've wondered if it was holding back top end power, but forgot to remove it on my second dyno pull to check.
I was just wondering if these scanner readings could be a useful tool in tuning things like this.
Just curious because the filter I got for free is so tiny both being short and having a small outlet diameter that I've wondered if it was holding back top end power, but forgot to remove it on my second dyno pull to check.
I was just wondering if these scanner readings could be a useful tool in tuning things like this.
18x g/sec & 24x g/sec??? What does that mean? Do you mean 180 g/sec & 240 g/sec?
There is a big difference from 180 g/sec & 240 g/sec. However, these numbers are low even for a stock LS1. Makes me think that your MAF table is not scaled correctly. What are your mods & how high do you rev during WOT?
There is a big difference from 180 g/sec & 240 g/sec. However, these numbers are low even for a stock LS1. Makes me think that your MAF table is not scaled correctly. What are your mods & how high do you rev during WOT?
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Hey thanks for the PM, yes I mean like 180 g/s but put an x because I dunno exactly what the last number is...I can't easily watch both the road and the scanner.
My transmission has started short shifting itself a bit so those flow numbers are on the 2-3 shift at 6000rpm. On the 1-2 is has started shifting at 5800rpm. Computer is supposed to be set at 6200 and used to shift there consistantly.
I haven't cleaned the MAF yet as yesterday the search function was not working and I didn't know if carb cleaner would work since they don't sell MAF cleaner locally and I haven't been anywhere to pick some up.
Mods are:
comp 230/224 111+3 cam on XE lobes
ls1 intake
ported throttle body
stock MAF on a 4"-3" 90 tube, 3"-3" tube about 4" long, small cone filter I got for free, the outlet on the filter is small and goes inside the 3" tube so its smaller than 3" (2.75" maybe?)
stock 2000 heads
1 3/4 long tubes (IIRC)
2.25" dual exhaust with good free flowing mufflers (not the best I know but I seriously doubt its any worse than a stock type ypipe setup with an aftermarket catback at my power level)
mail order tune
I have cutouts but they are manual, these reading were with them closed. Car dynoed 325rwhp/339tq with open cutouts, with the filter in place. Converter unlocked and both cooling fans on. HP peaked at 5600 then began falling off faster than I'd like.
I had a serious backfire problem while trying to get the car running so I'm starting to wonder if it might have damaged compression rings on the pass side of the engine. Cars runs great but just listening it sounds like the driver side exhaust note hits harder (this could be 100% in my head and paranoia, so I'm gonna check compression today)
EDIT: power was 325/339 sorry about that
My transmission has started short shifting itself a bit so those flow numbers are on the 2-3 shift at 6000rpm. On the 1-2 is has started shifting at 5800rpm. Computer is supposed to be set at 6200 and used to shift there consistantly.
I haven't cleaned the MAF yet as yesterday the search function was not working and I didn't know if carb cleaner would work since they don't sell MAF cleaner locally and I haven't been anywhere to pick some up.
Mods are:
comp 230/224 111+3 cam on XE lobes
ls1 intake
ported throttle body
stock MAF on a 4"-3" 90 tube, 3"-3" tube about 4" long, small cone filter I got for free, the outlet on the filter is small and goes inside the 3" tube so its smaller than 3" (2.75" maybe?)
stock 2000 heads
1 3/4 long tubes (IIRC)
2.25" dual exhaust with good free flowing mufflers (not the best I know but I seriously doubt its any worse than a stock type ypipe setup with an aftermarket catback at my power level)
mail order tune
I have cutouts but they are manual, these reading were with them closed. Car dynoed 325rwhp/339tq with open cutouts, with the filter in place. Converter unlocked and both cooling fans on. HP peaked at 5600 then began falling off faster than I'd like.
I had a serious backfire problem while trying to get the car running so I'm starting to wonder if it might have damaged compression rings on the pass side of the engine. Cars runs great but just listening it sounds like the driver side exhaust note hits harder (this could be 100% in my head and paranoia, so I'm gonna check compression today)
EDIT: power was 325/339 sorry about that
Last edited by thunderstruck507; Dec 23, 2008 at 01:16 PM.
225/239 is about 100 HP low. Your airflow is also low. So, something is wrong.
You need:
-a bigger filter
-an LS6 intake
-find the compression problem
-clean MAF w/ die-electric cleaner. Be careful of the resistor wires.
I would expect you to be making in the 340-360 RWHP locked through an Auto w/ those mods & an LS6 intake. Although, you're gonna need a tune & MAF table calibration once you find the engine problem. Would expect the airflow to yield around 310-340 g/s @ 5800 RPM, as well.
Anytime you make an intake related change, it effects the tune.
You need:
-a bigger filter
-an LS6 intake
-find the compression problem
-clean MAF w/ die-electric cleaner. Be careful of the resistor wires.
I would expect you to be making in the 340-360 RWHP locked through an Auto w/ those mods & an LS6 intake. Although, you're gonna need a tune & MAF table calibration once you find the engine problem. Would expect the airflow to yield around 310-340 g/s @ 5800 RPM, as well.
Anytime you make an intake related change, it effects the tune.
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From: Northwest AR
edited because power is 325/339
I cannot use a f body style setup here...this is a chevelle. I am going to get some cleaner today and try that. I expected to dyno at least 350rwhp even with the ls1 intake. A gto with nothing but a lid, exhaust, and longtubes put down 330rwhp right after me.
I cannot use a f body style setup here...this is a chevelle. I am going to get some cleaner today and try that. I expected to dyno at least 350rwhp even with the ls1 intake. A gto with nothing but a lid, exhaust, and longtubes put down 330rwhp right after me.
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From: Northwest AR
Checked my compression and cranking compression is between 175-180 on the ones I could get to easy.
Cleaned the MAF sensor too so I'll see if that helped if it stops raining
Cleaned the MAF sensor too so I'll see if that helped if it stops raining
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GTO could have been a 6.0L, if it's a late model & if was a manual, it would put down more power to the wheels than your auto. 325/339 is a whole lot different than 225/239. From this, I'd say your filter is the main trouble. However, 240g/s still isn't where it should be. Maybe dirty MAF, but doubt that that's the whole issue. As far as a filter, there are many different cone filters made that will work for you.
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From: Northwest AR
I cleaned the MAF today even though it didn't look too bad. But the roads are wet and foggy so I didn't want to go jump WOT in it while trying to look down at a scanner.
I did just get my driver o2 fixed so the car will go closed loop but I doubt that has anything to do with it at all
the gto was a manual 5.7 with lid, longtubes, and cutout (but only made 2-3 hp more with that open)
I did just get my driver o2 fixed so the car will go closed loop but I doubt that has anything to do with it at all
the gto was a manual 5.7 with lid, longtubes, and cutout (but only made 2-3 hp more with that open)
I cleaned the MAF today even though it didn't look too bad. But the roads are wet and foggy so I didn't want to go jump WOT in it while trying to look down at a scanner.
I did just get my driver o2 fixed so the car will go closed loop but I doubt that has anything to do with it at all
the gto was a manual 5.7 with lid, longtubes, and cutout (but only made 2-3 hp more with that open)
I did just get my driver o2 fixed so the car will go closed loop but I doubt that has anything to do with it at all
the gto was a manual 5.7 with lid, longtubes, and cutout (but only made 2-3 hp more with that open)
The manual transmission in the GTO makes a difference, as does rear end gearing. Anyway, that's not important.
The 02 is important for idle & normal driving. WOT uses the PE table based on RPM, once the PE enablers are met.
The 325/339 is great news. There is likely not a major engine issue. At the very least, a new appropriate cone filter is needed.
In the future, grab an LS6 intake if you can. It is a missing component to your otherwise free flowing set-up.
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its at the top of the list, but being unemployed my car is low on the bigger list, I'm just trying to do what I can for free or cheap because it's stress relief for me to work on my car
I actually noticed tonight that with the filter off and the car idling, if I quickly press the filter into the intake tube where it goes the idle drops for a second...I can only imagine what kind of hell that's causing at 6000rpm where it really matters
I want to get a much larger filter and preferably box it down low to pull cold air from under the car with a "ram air" type scoop
I actually noticed tonight that with the filter off and the car idling, if I quickly press the filter into the intake tube where it goes the idle drops for a second...I can only imagine what kind of hell that's causing at 6000rpm where it really matters
I want to get a much larger filter and preferably box it down low to pull cold air from under the car with a "ram air" type scoop
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ignore the second pull's falloff, that was me letting out because the tailhousing snapped on the transmission and fluid hit the exhaust causing a smoke storm
also during these pulls I hadn't realized the car wasn't seeing 100% throttle, usually it would max at 92% (just enough to get a first gear kickdown on the street, pedal was bottoming out)
ever since then the car shifts early though at WOT and I can't figure that out either...used to/ supposed to shift at 6200, but short shifts at just a hair under 5800 1-2 and 6000 2-3
OK, form the information that you have been able to provide, I'd say that the graph is smooth & the powere is close to about right considering only 92% open throttle, stock heads (2000) & an LS1 intake. I also think that the MAF table is off due to the exhaust mods & the slight intake mods. Don't worry about where the transmission is shifting because it isn't gonna improve anything by shifting higher in the RPM range. For now, she's about where she's gonna be until you can get your hands on an LS6 intake. At that time, you'll need a tune including a MAF table re-calibration, in order to get the improvement out of your exhaust related mods & the LS6 intake.
At the time of the new tune, I'd expect the tuner to have to increase the MAF table anywhere from 10-20% & possibly reduce WOT timing a bit. A/F ratio should be 12.5-12.8 (12.5 if the 02 sensor is bung mounted, 12.8 if the sensor is shoved into the tail pipe during tune) during WOT in order to provide good engine protection from pre-detonation. Also, make sure he tunes for normal driving. If you don't ask him to, he may not even look @ the normal driving tune.
So, confirm no vacuum leaks & she's good 'till then. Good-luck
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thanks again very much for all the help and advice
the guy I was going to take it to does street and dyno tuning in his tunes
what is the best way to look for vacuum leaks on these motors without making a mess? I have the bay cleaned pretty decent so I really didn't want to start hosing down the intake and stuff with WD40 and stuff that evaporates like brake cleaner or carb cleaner might mess up the paint on the intake, fuel rails, and stuff (I just spray painted them nicely while everything was apart)
thanks again!
the guy I was going to take it to does street and dyno tuning in his tunes
what is the best way to look for vacuum leaks on these motors without making a mess? I have the bay cleaned pretty decent so I really didn't want to start hosing down the intake and stuff with WD40 and stuff that evaporates like brake cleaner or carb cleaner might mess up the paint on the intake, fuel rails, and stuff (I just spray painted them nicely while everything was apart)
thanks again!
Just check that any un-used intake connections are sealed & then listen near the base of the intake where it meets the heads for a leak. Could also use a spray bottle w/ a water/rubbing alcohol mix (shouldn't hurt the paint).
Tell me about your PCV piping. How is it routed? Any breathers mounted in the heads?
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Its all done like stock. Even used the stock brake booster hose since it fit perfect.
There is 1 connection on the pass side behind the throttle body that's small we didn't use. I put a plastic cap on it. Then there's the brake connection, the PCV connection, and 1 running inside for my a/c heater flapper door under the dash.
I don't get any kind of vacuum code, and the car idles perfect in neutral or park, but when put into drive it goes up to 1000rpm and tries to pull the car. I just assumed that had to do with cam and stock stall.
There is 1 connection on the pass side behind the throttle body that's small we didn't use. I put a plastic cap on it. Then there's the brake connection, the PCV connection, and 1 running inside for my a/c heater flapper door under the dash.
I don't get any kind of vacuum code, and the car idles perfect in neutral or park, but when put into drive it goes up to 1000rpm and tries to pull the car. I just assumed that had to do with cam and stock stall.
It is possible to have a leak without throwing a code. Although, it sounds like everything is sealed correctly & that there are no leaks.
The going up to 1000 RPM in drive is programmed in the tune.