I think the maf I.D. is 2-3/4". That is 69mm and the GM throttle body has twin 48mm blades(48x2=96mm). Anything before the throttle body that's of smaller diameter is a restriction. The factory throttle body is way bigger than a maf. There is a 27mm (1"+) difference. If you have a 58mm TB the difference is 47 mm!!!. You might as well block one of the blades off. Imagine flowing water in a pipe that has a I.D. of 116mm, half way down it tapers off to 69mm. I can't find a reason anyone would keep one of these in the intake tract. Sure the engine might run good but it's exactly like having 1-7/8 headers and 2" exhaust. WHY

 

Long story made short.

That *choke point* is in part what sets the tuned lenght of the intake tract. One thing to try and figure out is the Peak Manifold Pressure readings. These are what allow for over 100% VE in a N/A engine. The intake tract/plenum volume, and shapes all play a role in when you can max out your VE.

It can't be over emphasized, that looks can be misleading.

A quick glance at Lingenfelter's ole Turbo Cavalier (?, or what ever the 4 cylinder compact he got hurt in), shows that they refined, or found out how much in fact anything post Intercooler was in fact Plenum volume. That I/C to TB is some fine piece of metal working.

Years ago, I posted that for every 1% reduction in Intake tract resistance needed a 2% gain in HP, and it seems to be more and more borne out in what you see in manifold tract design here lately.

There's alot to be done in that reguard, that just seems to escape alot of people. Further evidence is the new Pro Stocker scoop look. While some folks glance at it and look for an aero advantage, the advantage is what that shape does to the air above the air horns. Angles of convergence, divergence, difusion, and volumes all play pivotal roles in getting the best out of an engine.

 

BTW, your calculations completely ignore the boundary layer.

 

You can't compare a large single diameter with two smaller diameters like that. You need to compare the "area" - Pi x r x r
(or PI R square ... I don't have any fancy keyboard to show the 2nd power). My calculator does not have the true value for pi, so I am using 22/7, so the calc is slightly off, but the single 69mm = 3741 sq mm and dual 48mm = 3621 sq mm.

This is why a single 3" exhaust can flow more than dual 2" exhaust. Actually a single 3" approximates dual 2 1/4.

 

hey guys

iam not trying to start **** . but you guy need to go to the corvette forum and do a search on ski_dwn_it and corkvette1.

they built a 434 with 23deg heads this past winter and they both used the MAF on there cars .

ski_dwn_it changed to SD and proved to us all that there both the same . corkvette1 is still running the mass air and the stock computer, and his car is holding the better time between them 2 . its only by .06 but that good to prove that the mass air can still kick *** .

both cars are still running the IRS , 700r4 and the 3.07 gears. i bet if they had a 9inch with a break the would get a 9 sec pass out of there motors .

thanks guys

 

Sorry Jesse, they are not the same.

 

sorry to break your heart but im not jesse . and what i mean

that they preform the same . and switching to SD is wast of time

and money

 

Maf here with a 870 ECM. 383, 219, AFR Super ram. Ran a 11.8 On the brakes at 100mph. No cage rule is the reason for the brakes. Still got booted that night. That was on drag radials to. I will be able to run 11.50 Next year and I should be in the ball park. No cage now till you hit 11.49

 

He may have proved it to you, but by no means *ALL* of us.

Did he go back to a stock MAF?.
Are you absolutely and totally sure that he's tuned both to their max?.
Is he back to running gasoline?, or is he still using concoction he used?.

I'll leave it at that as far as SDI goes.

As far as the MAF vs SD, the stock GM MAF cars have run 9s. And one of the cars that was running 9s with a MAF, picked up several tents by going MAFless. Look around for the name Mark Jackson, and Buick GN, for further evidence of this. Another name of note to search on about MAFless GN systems is Steve Yaklin, and his co. ME (Maxeffort).

 

F.A.S.T., Motec, BS3, and all the aftermarket ecms will be heartbroken when they find out.

Again, please reseach the matter before making claims that are easily disproven.

 

Nick, are you also in Pennsylvania? I ask that because I know a number of other guys in that area and have come across Jesse and Corky.

This spring my buddy and I will also be doing our own experiments seeing what he can do with an optimally tuned MAF and SD system. He's supplying the car and I'm supplying the tuning. We plan to do the runs at a drag strip at sea level and then another about 1500'.

Frankly, I am not expecting much of a difference. Except the elevation factor may throw an interesting curve ball.

 

no bud im from michigan . i never came across jesse or cork in person . but they did all they can do to prove to us all that its true . they posted time slips , films and lots of members meet them in person .

 

im not saying that the stock computer and the mass air is better than all the aftermarket computers out there . all im trying to say is that you can go 10 or even 9 with a mass air car and thats it .

 

****************
and what i mean
that they preform the same . and switching to SD is wast of time
and money
****************

Your words, *switching to SD is wast of time and money*.

And I see you've ignored the facts about what SD is worth, and ignored anwering any of my questions. If he's running a gutted MAF, then your ignoring one of the original posting, about flow area.

Not to mention that I posted that the stock GM MAFs have gone 9's, and even at that stage of tune they still picked up by going to SD.

 

it is a wast of time and money .. for people with heads and cam or any mild set up .

How many people on this forum are running in the 9s or 10 with an all motor set up ??

what im saying is that you can go fast with a massair and its not a big restriction for air flow .

see im not a tuner or an expert on this stuff but my point is that the mass air is just as good as a SD until your in the low to mid 9s and its been proven my members like ski_dwn_it and cork ..

and please don let me bring up the fact the cork is still running the 24lbs injectors ....

 

That's not what you said or even implied originally.

Why is that relavent?

No your original claim that I took issue with was your claim that
SD is a waste of time and money, again your words.

have you done your own testing?, and why do you refuse to answer any of my questions?

Now your mixing up street vs strip. For street the MAP offers better response transistional fueling and spark, if in doubt try the archives and look up the OBDII strategies. Unless of course you think you know more then the design teams at GM.

 

no bud i didnt do any testing . my car has the BIG STuFF system, i didnt miss around with the mass air or SD . and im not saying that i know better or more than the design team at GM .

and im sure you know more than me about any of the tuning stuff out there . but dont mean you have a faster car ..

your question is why do i think it a wast of money or time ????

my answer is you dont need to switch if you have a mild set up or if your car is only in the 10s ...

 

I and others don't advocate people to switch from a perfectly good working MAF system on a N/A motor either. If your MAF is shot or your ECM is shot, then it may be cost beneficial to go to SD. In fact, if I see someone asking about switching to SD, I will ask them why, to understand their reasons and make sure they are valid reasons other than "the sake of change".

Also, thanks to Grumpy and others, there has been a big stride in the $58 (and Grumpy's version $60) SD systems for people with a superchargers/turbochargers. One area where the 165 MAF system does fall short.

In the "old days" when more was known about the SD system than the MAF, there was a number of people that switched due to the assistance available. But today, there is plenty of knowledge on the MAF system (and not just the 1989 $6E). Heck, one time, before there was knowledge on the V6s, running the V8 code was considered.

Whoever told you or wherever you read that "TGO advocates switching from MAF to SD for the sake of switching" is wrong and obviously not a regular member/reader of this Board. They're about 3 years behind the times.

 

Wonderful, your not even running the system your trying to support, yet feel necessary to express an opinion. And in the course of expressing that opinion flip flopped/ tried spinning what it was you said.

Not to mention you completely left out the details that would have even made your post relevent to the original subject, if you'd have answered the questions I posed to you.

 

I'll tell ya, with the some of the patchs done to the 60 code, there's nothing like it (other then possibly some other custom code). Period, none, nada. It's kind of a shame so few have been interested in actually doing much in that reguard. There are huge rewards in driving a car with the perfect code.
And yes, MAFs do have there place, just not the 3rd Gen one, IMO.
Like I said GM has it right with the dual sensor useage of the OBDII stuff.
And like you said, for T/C, S/C setups the 165 MAF falls wayyyyy short.

 

1. My maf took a dump. It cost $160+ to replace. Swapping to SD cost about $100 less. You are not going to convince me it's a waste of time or money.

2. Jesse has not proved anything. I would like to see the track data. Not just that but the weather conditions at the time of each test. Need to see both bins,data logs, wideband logs. Then he might get some respect. All talk and nothing to back it up. I don't mean that in a derogatory way. I'm saying that if he has the HARD data to prove maf is better then let's see it.....

 

What about the boundary layer around the maf electronics

So was you originally trying to say a reduction in the intake track I.D. can increase VE. Example: 4" inch intake tract might create less VE than a 4" pipe with a 3.X taper to it.???