Draw through setup??

Hey guys,

I know this has been discussed in numerous threads, I have been doing some reading on this subject. Seems to be some debate out there, but for ease of setup and performance, I am thinking about using both safcII and MAFT.

I currently am running an safcII with EVO8 MAF. I personally feel this is limiting my performance. Kind of seems I cant achieve a perfect tune with this alone.

If I were to add the MAFT, could I just zero the MAFT unit out and basically tune with SAFCII?
Since I have the SAFCII, I wouldn't need to wire the MAFT RPM wire, correct?
Also, what size GM MAF/Part number do people generally run? I see there are multiple options out there (3", 3.5", and 3.75"). What works well for our cars?

Hoping that just adding a draw through GM MAF zeroed out will increase my turbo spool and yield more power.

Also, is there any thread out there that goes over draw through setup installation with pics?

Thanks in advance,
Rick

Im personally thinking about GM 3.5" MAF. Set mode switches to 1 On 2/3/4 Off. Set Aux to 9 and Base to 6 to account for my 550cc injectors.
Leave base/idle/mid/WOT zeroed out.
Zero out everything on my SAFCII.

This would give me basic settings to car can run. Then tune with SAFCII in car.

Is this logical thinking?

yes, your plan will work.

Hey guys, I got an air filter coming in Monday. I have received the MAFT unit and the GM 3.75" MAF. Waiting on the 3 plug to 5 plug harness from Ray. Anyway, I have decided to not splice the white wire as of yet. Since I will have SAFC, this will allow me to make more fine tune adjustments. Questions before I process (so I don't F anything up):
1.) for the mode, should I do the start up enrichment?
2.) Just to clarify SAFC settings. I will zero out all Ne point settings (both hi and lo settings), since my MAFT base/AUX settings are for 550cc injectors. However, I will leave the same hi and low throttle % positions on SAFC (as I am zeroing out idle/mid/WOT on MAFT unit). Car should start and I can adjust idle/mid range/WOT with wideband with SAFC.

Again, I am leaving purple AUX and white RPM wire disconnected from MAFT unit

Thanks in advance, hopefully this thread will help clarify things for other.
RK

You are over complicating all of this.

MAF-T *can* be used to tune fuel stuff, but really, it's best to use it as what it is... a signal converter. That's all it does. A lot of MAF's send a voltage signal, whereas the 3S reads in Hz. All the MAF-T does is convert the voltage to a Hz so the car can understand what is going on.

SAFCII is a great little tuning tool. All it is doing is taking that airflow signal from your (now) installed MAF-T and adjusting that signal so your engine doesn't flood itself every time you give it gas. The MAF-T can also do this, but it is in bigger increments and over a much more broad area (which is why you just use it to do the translation and tune with the SAFCII).

straight from Stealth 316: correction factor = [(stock injector size) / (new injector size)] - 1
Stealth 316 - A'PEXi S-AFCII Adjustment

So in your case:
Correction factor = (360/550) - 1
Correction factor = (.6545) -1
Correction factor = -34.5%

This tells you to remove 34.5% of your airflow reading across the board and your 550cc injectors *should* run like 360cc injectors. Pretty straight forward. However, engines are not that straight forward. Between volumetric efficiencies, heat expendature, the health of the engine, etc. you have to make some more changes.

I am not going to type up a giant list of how to tune the thing because the link that I posted is an incredibly helpful resource. But you are definitely over thinking the whole thing.

** AT LEAST** read from where it says "INITIAL SETTINGS BEFORE STARTING THE ENGINE" on that link. I think you should read the whole thing, but I do admit, it's a lengthy read.

And the RPM wire only needs to be connected if you plan to adjust things by RPM through the MAF-T. Which, as I've said, I do not recommend.

But with all of that established, doesn't the EVO8 MAF already send a Hz signal? You should be able to tune it out with the SAFCII alone I would think... but I don't know anything about the EVO8 MAF

Evo 8 Maf is more restrictive than stock, just because it reads higer doesn't make it a better choice..

oYes, the Evo 8 reads Hz. I realize this is not ideal for my setup, hence the purchase of the GM MAF. I totally understand the way the SAFCII works. I read that stealth316 guide about 5x after I installed the SAFCII years ago. I just wanted to confirm proper settings when combining it with the MAFT. I do not plan on running -35% correction on SAFCII since I will be setting base correction on MAF-T box. All I was asking is if this was appropriate. I dont think you set MAFT with base correction for 550s AND -35 across the board with SAFC. Its either one or the other, or so I think.

RK

You are correct. But a lot of people leave the MAF-T zero'd out and tune with only the SAFCII

I have done it both ways, personally.

Hey KeithMac,
why do you think that the Evo8 Maf is more restrictive than stock. According to several sources, the Evo Maf is flowing a maximum of ~62lbs/min with a pressure drop of ~.526 psi at 240 liters/second. The stock Maf is typically only good for about ~50lbs/min and the pressure drop is ~.75 psi at 210 liters/second. Do you have some practical comparison, or you are judging just by the looks ?

I am interested because I am just about to switch to the Evo Maf, but seeing the number of people switching to the 3.75 GM Maf makes me doubt my decision ... :dontknow2:

Just look at it compared to the 3s maf, unless it re-writes the laws of physics it (with much less cross sectional area) it can't flow as much for the same pressure drop surely?.

Can you post a picture of it next to a stock 3s maf and measure the depth?.

By all means try it but I can't see it being anything but a restriction personally.

When I went speed density and then blowthrough I found the turbos spooled much better and held boost better.

Any way to reduce restriction before the turbos is time well spent, they are far better at pushing than pulling.