SD vs. GM MAF. Which would be better?

[v8s_are_slow]

So I plan to run a BW S366 turbo with 3 inch intercooler piping all the way. Plan to ditch the 2g maf and wanna go with either a GM maf or SD. I've used both, but really don't what advantage or disadvantage one may have over the other. If I use a GM maf, I'm thinking of going with a 3.5" or 3.75". Not sure if one MAF would allow more airflow than the other to where it reaches it's limits. I don't really see any threads comparing the two different systems.

I posted about this on the Link forums but I don't really get many replies so thought I'd ask over here. I have V3 Lite just for an fyi. Opinions?

 

[LandoAWD]

Any MAF is a restriction, of sorts. I'm not SD literate, but SD cars often report improved drivability. No surprise as I feel like I'm always tuning around my MAF.

I'll stop being lazy someday and just take the plunge.

 

[v8s_are_slow]

Well, my piping will be 3 inches in diameter. The maf I'll be using will be a 3.5 or 3.75, so if the inside is at least 3 inches, I don't see how it'd be a restriction. So if there's no restriction, I'm wondering why I'd need to pick one over the other.

 

[pboglio]

Only drawback I see with a Speed density is throttle lag. Supposedly if you hard mount the MAP sensor to the intake manifold, it can be tuned out. Other problem I see is a potential for MAP failure, which would take out the motor. I've experience both conditions on my HKS VPC, but ECMLink V3 has come a long way and guys are reporting very good driveability results.

 

[v8s_are_slow]

What is it that happens? Does the map sensor go bad and runs lean, destroying the motor?

 

[toofast82]

Only drawback I see with a Speed density is throttle lag. Supposedly if you hard mount the MAP sensor to the intake manifold, it can be tuned out.

I'm guessing this must be the reason that most modern cars that run MAP sensors do have them mounted in the intake manifold usually.

When I was running SD, I had mine mounted on the firewall and if there was any throttle lag, it wasn't noticeable to me.

Other problem I see is a potential for MAP failure, which would take out the motor.

I always worried about this when I was running SD,

I ran SD off a burnt chip, and the car ran great.
It was dead consistent whether it was 0* out or 100*.
Also keep in mind I was using a file from 2005-6, so I would assume today's Jackal and V3 versions of SD are much more refined.

Plus the GM maf is known for the "wandering tune" and really isn't intended to be ran in blow-through configuration. Many have success with it though.

 

[v8s_are_slow]

Having a consistant tune would be nice. I remember when I had my GM Maf and translator, I was ALWAYS having to click a knob to keep things in check. But is this necessary if it's being used with ecmlink??? The translator wouldn't be used but I guess it's the maf itself that'd cause the problem. Wondering if they're both about the same difficulty level to tune. I'll probably be using some 1550cc injectors so I'm sure I'll be having to lock it into openloop. So somewhat nervous about that since I won't have closed loop to keep things in check for me. It'll be all up to me to make sure things work like they should and not burn up my motor.

 

[1997_GSX]

SD for sure, my car is about to be tuned in about a week! I'm very excited, I hope I get to take it to the track soon to see what kind of numbers the new setup lays down!

 

[lAsErfWd]

If you have your stock boost gauge setup to read knock and a good wide band you would be able to see the problem and should be able to shut the car down and avoid major engine damage. Also am map sensor may fail and a maf may fail so there is no differece there.

 

[v8s_are_slow]

Okay, but why do you feel this way? I need educated answered on this. No offense. Just don't want opinions on this. I want the facts, cause I don't wanna screw around and buy something, just to be unhappy with it. Trying to do everything ONCE on this setup this time around.

My last "fully built" Talon was a nightmare that cost me thousands. This build has to be right.

Sorry, reply was meant to 1997 gsx.

 

[donniekak]

I use a gm maf, it sucks. For the longest time, it was the only option, beside aem, that could meter enough air for a big power car. I would go sd. The cool thing about link, is you can get a good ve table by just driving around with a calibrated maf.

 

[1997_GSX]

I'm just tired of the drivabilty issues of the MAF. Venting isn't possible, without running rich, not that I'm a ricer, my setup is not able to recirculate right now.

The only problem I can see is a boostleak messing with SD but thats minor.

Plus the restriction of the MAF in front of the turbo. Plus all the big power cars are running SD, I don't see the need to waste money on a gm maf which the sensors vary greatly. A Omni Map sensor and GM IAT will run you less than $75 so if you have V3 its cheap. To run a GM Maf in v3 you need the maf, couplers, tbolt clamps, $75 wiring harness.

I just think it is pointless.

 

[v8s_are_slow]

Guess I should reword the question. When using a GM Maf with Ecmlink, is the tune consistant or does it have to be adjusted a lot? One of the guys on Link says he never had to adjust his with V2, but wanna see if that's true for everyone or not. I know that when I used a gm maf and translator alone, I was constantly adjusting. But with Ecmlink, I dunno if that'd be the case or not.

I'm just tired of the drivabilty issues of the MAF. Venting isn't possible, without running rich, not that I'm a ricer, my setup is not able to recirculate right now.

The only problem I can see is a boostleak messing with SD but thats minor.

Plus the restriction of the MAF in front of the turbo. Plus all the big power cars are running SD, I don't see the need to waste money on a gm maf which the sensors vary greatly. A Omni Map sensor and GM IAT will run you less than $75 so if you have V3 its cheap. To run a GM Maf in v3 you need the maf, couplers, tbolt clamps, $75 wiring harness.

I just think it is pointless.

It sounds to me like you're hating the stock maf. I'm ditching the stock maf and going with either SD or GM Maf, which can vent the bov to atmosphere.

 

[Killa_dsm]

I am running a v2.5 and a gm maf, and do not have a problems with having to re-adjust the translator. The translator is basically zero'ed out and all the adjustments are made with link. I have not used or messed with SD so I can not comment on that.

 

[4g63awdhonda]

if you do research all of it says maf reads more accurate sd goes off of a bunch of calculations but if you want a clean look sd is the way to go

hey luke dont use the gm as a suck threw use it as a blow threw then venting is possable and the closer the mass is to the throttle body any type of boost leak from the turbo to the mass dosent account as lost air because only the air that is read can be accounted as lost air so put ## mass at the trottle body and your bov between the turbo and mass

 

[govproperty]

I am currently running a Gm maf in blow thru with dsmlink v2 and a maf translator. I am saving up to get v3 upgrade solely to get SD. I have had the coupler on the maf blow off too many times and SD is a chance to eliminate 2 couplers from the path. Also, the maf may not be a restriction but any change in pipe size or direction can effect air flow. Maybe not a lot but some. There was a discussion somewhere, I'll try an look it up, that having a 90 degree bend before a blow thru maf would cause abnormal reading due to the air favoring the outside of the bend. It cleans up the engine bay too, no big honking square thing stuck in my piping.

 

[LiquidX]

if you do research all of it says maf reads more accurate sd goes off of a bunch of calculations but if you want a clean look sd is the way to go

Going SD on V3 of Link is usually ran off of MAF estimates to start and then fine tuned so you would be getting a more accurate reading. Also most people who use a GM MAF have it in blow through which is actually less accurate of a reading than using it in draw through.

If you don't have ECMLink v3 then use the MAF+translator if you want to vent. Otherwise if you have v3 then go speed density as it's cheaper, cleaner and boost leaks *won't matter*.

 

[Scientist]

or if you don't have V3 give jackal a try to go Speed density

 

[1997_GSX]

if you do research all of it says maf reads more accurate sd goes off of a bunch of calculations but if you want a clean look sd is the way to go

hey luke dont use the gm as a suck threw use it as a blow threw then venting is possable and the closer the mass is to the throttle body any type of boost leak from the turbo to the mass dosent account as lost air because only the air that is read can be accounted as lost air so put ## mass at the trottle body and your bov between the turbo and mass

Thanks for the advice Gabe, but I am going speed density for sure!

Ricky and the guys on link talked me into it. Ricky is actually going to tune it for me. He tuned my car the last time and with the car pushing coolant we were flowing around 47lbs a minute. We are hoping for 50+ lbs a minute out of this 54 trim . The internal gate is hating its life at 34 psi right now. I want to see if we can get 40 psi out of this baby.

 

[Calan]

The only problem I can see is a boostleak messing with SD but thats minor.

Actually, SD is much LESS sensitive to boost leaks, since it is based on absolute manifold pressure.

 

[v8s_are_slow]

I'm looking at SD and may go that route mainly because it'd be cheaper to convert to, I'm basically doing the same thing (getting rid of the drawthru setup), and a cleaner install. Tuning it is all I'm worried about being able to do really.

 

[delta448]

SD Pros:
*Less airflow restriction; quicker spool and higher max airflow
*More accurate at lower airflow and idle airflow metering when running large valve overlap
*With the right MAP sensor installed, you won't overrun it
*Boost leaks won't affect your tune
*No need to recirculate the hotter than ambient air from the BOV discharge

SD Cons:
*Can be tricky to tune well if starting from scratch without a MAF based VE estimation
*Properly tuning temperature compensation tables can be time consuming due to IAT mounting hardware heat soak on boosted vehicles
*Does not measure airflow directly, but computes it
*Likely will need re-tuned with every change in engine bolt-ons due to the resulting changed VE
*Less resolution in tuning for each increase in MAP sensor range

 

[v8s_are_slow]

A buddy of mine hooked me up with a GM Maf for free so all I really need to do is upgrade from Ecmlink V3 Lite to full (cause I wanna use the cable and not have the translator) and buy the cable. Figure the tuning may be easier and forgot about having to change the tune with every mod. Thanks for all the replies though.

 

[dsm-onster]

If you're running an s3** turbo, I'm sure you plan on getting to airflows where the gm maf has been known to drop counts. I know you can just use 'fake maf/use map'. But that's pseudo-speeddensity then. And every alteration to your setup will mean that you will still have to retune your VE table. Unless you want to take a gamble with using the maf alone (at such airflows dropping hertz counts spells absolute certain disaster).

*Less resolution in tuning for each increase in MAP sensor range

This is the ONE real issue I have with sd. But others have been successful with 40psi boost and V3 sd. So That's why I'm running it. I've not tuned in that range yet. But i've been fooling around with lower boost with the 4 bar sensor. So far so good. No nuances that I've seen. Yet, I've never even toyed with a 3 bar sensor. So I have no clear back to back review of drivability with the lower MAP output resolution.

 

[ramsack]

does the sensor actually have a resolution or could it be the resolution of the input on the ecu?