Don't hurt me for asking, but...

Nigel

Well-Known Member
Sorry, I should have been more specific and said MAF sensor "attached" to the up pipe, not in it. Unless I understood you wrong? I understand the up pipe goes from the intercooler to the throttle body.

Ok, so what I've been learning, cold is better, but not at the expense of added tubing and bends, better off by bigger intercooler, or liquid cooled, or the other ways in the link Jerryl provided. Reducing the drive pressure, and if I understand that right, is to get the turbo as close to an ideal ratio of 1 to 1, every turn for exhaust equals a turn off intake air? so a more free flowing exhaust like I plan on getting should help, ease the exhaust side of the turbo.

Nigel the picture of the pipe flow chart I don't understand, but I understood most of what you wrote under it except for, "If there was no friction between the air and the pipe as long as the velocity remained roughly 40% of sonic". What does the "as long as the velocity remained roughly 40% if sonic" mean? I know Sonic velocity is the speed of sound, but I don't understand what that had to do with it? Also when you talk about not needing more then a 3" intake unless you're moving a shit ton of air. So a 3" pipe would be fine, since especially what I forgot about, even though an LS1 MAF sensor is 3.5" in diameter, its flow is still not equal to a 3" pipe, somewhere about 80% of it? I see some of the other guys are talking about their 4" pipe with the ls7 sensor, at what point do you know your moving a shit ton? I mean, I know you are correct, I'm far from anything they got going on, I'm just curious when a guy would know? Would it hurt if I was able to add a setup like Rodruckus had pictured?

Speaking of which, Rodruckus i think this is similar to what you were showing and describing, although there were several other versions on this site as well

JM, I do not, I am planning on getting the Scanmaster G along with the ALDLDROID app within a few weeks. I mistakenly thought I had not modified my car enough to get it.

My. Spool, you wrote "exactly!you can also make 9 sec passes on a stock maf with 1 screen removed." Just curious, but given that same vehicle, if it had a larger intake would it be running faster?

-Rob

I actually should have stated that if the pressure drop is 40% then the formula I posted it is not accurate for compressible flow(my mistake), what the fraction of sonic velocity is I don't know off the top of my head, but the point would be the same.
The formula is for incompressible flow, but remains accurate for pressure drops less than 10% for compressible flow and can be used to approximate up to 40% pressure drop for compressible flow.
So long as the pressure drop is reasonable, which in the case of a good aluminum maf pipe you would have to really be moving some air for that not to be the case, you will be able to recover a good amount of the velocity as pressure. I would be surprised if the pressure drop in a 3 in aluminum inlet pipe was more than 1/2 to 1 psi at flows up to 60 to 70 lb/min, and most of the velocity would be recoverable.
Once compressibility comes into play, at higher fractions of sonic velocity or a high friction factor you will start to dramatically increase your losses. The stock corrugated hose was definitely a restriction.
 

Grumpy

Thread killer
Nigel.. no offense BUT just because it should work on paper doesn't mean it will in the real world. We have tried so much stuff on theory an went backwards.
 

Rahob

Member
Thank you Nigel! I really appreciate all the explanations, I got to be honest, I really don't understand most of it, but I really want to learn.

Right, I fully understand why the stock corrugated is awful, and unfortunately I still have it and I've noticed it's in REALLY Bad shape (I was just changing out vacuum lines and check valves and took a close inspection of it) this is what caused my interest in the MAF pipes and sensors. I know I can just go get a 3" pipe now, but I figure if I'm going to possibly need something bigger in the future, why buy twice..
I really liked the setup Rodruckus has, and the way it looks. I had read some threads on here and other sites about people having issues like I explained about the 4" MAF sensors causing bad idle and low throttle issues, but I like the low restriction of the LS7 blade sensor over the LS1 and LT1. At least so far, I've narrowed out the cold air behind the headlight induction idea.

But again, thank you for the explanations, I like to challenge my brain to learn something I don't know much about.
 

Rahob

Member
I've been trying to search the web, about max flow rates for each of the MAF sensors available and learn about intake configurations. I read a few places about LS1 MAF sensor having about 80% flow of a 3" pipe, and the LT1 having 60% something %. But I haven't found where people are getting this from.
 

Mr.Spool

Well-Known Member
Nigel.. no offense BUT just because it should work on paper doesn't mean it will in the real world.
and thats the truth of it all.this is why guys should go out and test on there own cars,i think they would be very surprised ;)
 

Mr.Spool

Well-Known Member
My. Spool, you wrote "exactly!you can also make 9 sec passes on a stock maf with 1 screen removed." Just curious, but given that same vehicle, if it had a larger intake would it be running faster?
we upgraded the pipe to see,on that combo it went no faster.now i have the 4 inch on my nt car which goes alot faster than high 9s because it needs it.
 

Rahob

Member
I've been trying to search the web, about max flow rates for each of the MAF sensors available and learn about intake configurations. I read a few places about LS1 MAF sensor having about 80% flow of a 3" pipe, and the LT1 having 60% something %. But I haven't found where people are getting this from.

Just quoting myself in case anyone else tries a search like me with these words and comes across this. Flow rates for MAF sensors.
 

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Nigel

Well-Known Member
Just quoting myself in case anyone else tries a search like me with these words and comes across this. Flow rates for MAF sensors.

If those are flow bench numbers then presumably they were taken at 28 in WC. So those are not the limits, just what you can expect at 28 in WC, or 1 psi drop. They give a good picture though of how much the screen will cost.
 

Rahob

Member
If those are flow bench numbers then presumably they were taken at 28 in WC. So those are not the limits, just what you can expect at 28 in WC, or 1 psi drop. They give a good picture though of how much the screen will cost.
Would 1 psi drop equal to idle or low throttle?
 

Nigel

Well-Known Member
I would look at my combination and choose a MAF based on what I think I would flow at wide open throttle. 800 cfm is pretty big horsepower. I don't know exactly, but has to be getting close to 1000hp. So those numbers would be wide open throttle targets.
 

Gary Durden

Active Member
Rahob, I think you need to move past this or you will never figure it out, way overthinking. You are not building an all out race car where all of your 1/10 gains start to add up. You need to concentrate on what you are trying to accomplish and move towards your goal. Grumpy and some of the others have tried many different things with little to no improvement. Add your bolt ons and enjoy your car. If you overthink every thing like turbo, chip, downpipe, exhaust, alky kit, injectors, converter, uppipe, ect,ect it will overwhelm you and you will never finish your car or obtain your goal. There is a proven 12 second, 11 second, 10 second recipe. If you think you can take a 14 second car and make it run 12s by just changing the air flow you are sadly mistaken. Decide on your goal, work towards it and enjoy your Turbo Buick. Good luck with your build.
 

Rahob

Member
Thank you Gary, yYouare correct, I tend to overthink most things. I like to know as much possible about each item I change out. Yes, I've read all the different time recipes, and lots of threads on the forums, and I know I'm not going to get that time from changing out just the intake, it's just one piece in the puzzle for me. Honestly, I don't have a goal time, and I know that's going against what everyone preaches. I have goals on what I'd like to change out and just see where I end up with my own recipe of changes. Thank you for the wish of luck! I know I'll need it going against the grain of things.
-Rob
 

RUQWKNF

KEEPER OF SECRETS
Staff member
One more thing to remember is, a lot of people tend to follow the bigger is better train of thought with upgrades, when in reality they're no where near maxing out what they already have.

Just so you know, there have been a lot of cars that have gone really quick and fast with a simple 3" MAF pipe and stock MAF sensor with a 9" cone filter attached to it. Some do it for looks, others out of necessity, or knowing their future combo will benefit from it in the end. If this will mainly be a street driven, in any weather (including getting caught in a flash flood scenario) car, then keeping the air filter underhood with a standard 3" MAF pipe and K&N cone filter attached setup is perfect.

On the other hand, if you know your ultimate goals are quicker than mid 10's, and the car is a fair weather weekend cruiser, that sees the track a few times a month, then absolutely go for the true 4" CAI setup. But it's best upgraded when you upgrade the turbo to a 4" inlet compressor cover, vs slapping it onto a stock or stock appearing TA cover equipped turbo. (TA = stock appearing compressor cover)

On all of my cars in the past and on the one I have today, I've gone this route. 3" MAF pipe with stock MAF and K&N cone attached, to true, all 4" piping with either an upgraded MAF sensor, or no MAF sensor with aftermarket ECU. It's just what happens when you start chasing a goal. Whether it's hp/tq goal, or et/mph goal. It happens. I saw no downsides to running Mark's 4" Big Mouth kit on my blue T that was a low 11's combo.

Another history lesson is thinking back to the NHRA EFI stock eliminator class cars back in the day, running very low 11's with stock stuff. FFwd a bit to what Red accomplished with Jane's Limited and stock appearing mods. Red's results represent an extreme amount of R&D and combo test and tuning, to run what that car ran with stock appearing stuff. It just proves it can be done with stock appearing pieces. Another fine example is Brian Lorenz's amazing Butternut T.

With regards to 4" piping before the turbo and no ram air air-dam directing air to the filter, this is how my current combo is setup. I went from 3" underhood filter, to this setup and saw an immediate difference in IAT temps while crusing. Which is a big thing is this hot and humid MS weather. Do I take mine out when there's a threat of rain? Nope. Both types of tires I run are sketchy at best if I get caught in the rain. So I'm not worried about water logging mine, or getting caught in a flash flood or big water puddle.

It's definitely a lot of info to take in when figuring out your goals. Aka drinking from a firehose of knowledge with peoples replies on here and other sources of info. Your researching and planning will save you a ton of money and grief in the long run. The old saying is very true, "Plan your work, Work your plan." Then stick to that plan. Try to only spend once if you can. A perfect example of this is: skip the 38#, 42.5# and 50#, injectors and start with 60's and a good chip. TurboTweak has the tunes down perfect with 60#ers on mild to wild combo. The members that have shared their 2 cents in this thread, represents literally thousands of hours of testing and tuning combo after combo over many many years. Think, since these cars were new. Your zest for understanding, research and learning will definitely pay off and you're doing the absolute right thing by asking questions.
So hang in there and keep on asking.

Hope some of this helps.


-Patrick-
 

Nigel

Well-Known Member
I would look at my combination and choose a MAF based on what I think I would flow at wide open throttle. 800 cfm is pretty big horsepower. I don't know exactly, but has to be getting close to 1000hp. So those numbers would be wide open throttle targets.
I overstated that HP number, that cfm is probably closer to the 550 to 600 HP range.
 

~JM~

Wrinkled Member
I will not use K&N filters. I had them on several vehicles many years ago. Every one of them allowed fine dust passed the filter media & into the "clean" section of the intake tract. Granted, the SW desert has very fine dust, but still not acceptable. I have replaced K&N with filters by AFE: https://afepower.com/air-filter-media I use the Pro-GUARD 7 style. I have yet to find dust downstream of the filter.

Perhaps K&N may flow the best, but if the dirt isn't being filtered, might as well run without.
 

earlbrown

runs with scissors
Also, on top of that, I've read about adding the MAF in the up-pipe, but I don't believe that would effect flow? According to the article the vehicle performed better, I just feel leery putting the MAF sensor right before the intake.. It feels like with my luck the element would break off the sensor then get sucked into the engine and then I'd have to replace an entire engine instead of just a turbo, if it were to happen on the MAF tube. And while speaking of flow, I've read about turbulence in the MAF pipe after the filter which might cause issues for the MAF sensor.. So is it better not to mount a MAF sensor directly after a air filter, but to add a little tubing then the sensor? Or would it be fine after the air filter as long as the MAF screen is not removed? ALSO could be TOO BIG of an intake pipe???? From what I've read, since a larger pipe has less velocity (specifically idle and regular driving) it could give bad readings on the MAF sensor? Has anyone done any testing on this? I'm asking because I'd like to go from stock MAF to 4" pipe with LS1 sensor.

I'm amazed that this made it to page 3 and nobody mentioned the major physical difference between the stock POS MAF and the later LT1/LS1 MAFS.

Turbulence and/or removing screens will flip out a stock style MAF. It's a horizontal film type sensor that can ONLY measure nice smooth flow traveling across that huge sensor. It's ripe for getting ''doubletapped'' and throwing out false readings. It's made even worse with the aftermarket ones that neck down in the middle and have that flow cone around the sensor trying to avoid that. Basically it's full of corks. Turbulence is such a pain on these things, GM couldn't even use a wing nut on the air filter. The various angle of the ears will wreak havoc on the metering, even when brand new.

Not the newer LT1/LS1 MAFs on the other hand have small cylindrical sensors (plural) in there. If air flow hits them at an odd angle, they don't even notice. And if turbulence is bouncing all over the place, those sensors really won't notice because once the air is past the small sensors, they can't get doubletapped. Plus, they work just fine without screens.

Now on to size... I've measured the flow area of the LT1 and the LS1 MAFs... I don't recall the exact numbers, but the 3" LT1 sensor has 60 something percent of the flow area of a 3" pipe. The 3.5" LS1 MAF has 80 something percent of the flow area of a 3" pipe.

^notice that last part.... The 3.5" sensor is SMALLER than a 3" pipe. That being said, I've noticed a decrease in spool time on my powerlogger between a LT1 and a LS1 MAF. The much larger 3.5" sensor is worth it for decreasing pressure drop. AND that's sucking through a 3" K&N filter. The larger 3.5" MAF has another advantage. It can use a larger neck air filter. Some people like to get a 4" filter neck and squish it down the the 3.5 MAF. Then the filter exit can be thought of as a small velocity stack. Taper is ALWAYS better than a step.

Even if you have to get a tapered connector to hook the LS1 to a 3" pipe it's worth it. (and for some reason I've sold a bunch of those couplers the last week or so)


Now putting the MAF on the uppipe is better because pumps like to pump. A flow restriction on the outlet side doens't hurt near as much on the low pressure side (that's why we port oil pumps on the inlet side). I'm guessing the reason it's not more common is because most people can't burn their own chips. If the MAF is in the up pipe, it's dealing with hotter air (and it's compressed), so the chip will need to be re-calibrated to deal with the ''false'' readings from the MAF operating in the different environment. Doc1of7 did a lot of work with that before he died and it was very promising.

There are some things you'll want to be aware of. First, you'll need an IAC angle boss(purchased from RJC) to run any MAF pipe larger than 3".

That's actually not true. My 3.5" pipes clear the IAC plug (and up pipe, alternator stud, radiator hose, and A/C lines) just fine.


You're dead on with the Chinese MAFs and counterfit ones though. They're flat out garbage.
 

Rahob

Member
RUQWKNF and Earlbrown thank you both for the info. I've re-read this thread several times learning new information and making sure I am understanding everything. I knew I had read that somewhere about the MAF sensor flow area, it's nice to have that confirmed.

So like I've said, and based on what I've learned from this thread, I've ruled out cold air kit, just like previously mentioned, I don't want to be cleaning the streets, and the extra restrictions with the bends. I am thinking of going with the 3.5" pipe with the LS1 sensor. According to what's been posted, it should be more then enough flow for at least how I have things envisioned for now.
 

1986 Buick GX1

GX1 #001 [The One and Only]
I would like comments on the 85mm Z06 MAF as well.
If I recall the inlet is closer to 3 3/4” for clamping on a 4” filter.
The outlet is around 3 5/8” so it’s a stretch to get a 3 1/2” hose on.
I’m not sure the inside diameter and flow rate.
 

Rahob

Member
I would like comments on the 85mm Z06 MAF as well.
If I recall the inlet is closer to 3 3/4” for clamping on a 4” filter.
The outlet is around 3 5/8” so it’s a stretch to get a 3 1/2” hose on.
I’m not sure the inside diameter and flow rate.
From what I've learned so far, the LS7 style is 100mm which is 4". Rodruckus was talking about his setup on page 1 of this thread. But heck, knowing the flow area for both of those would be great added to this, just to have it all in one place so at least I can go back and re-read it all until I have it memorized. I'd have to imagine those are easily 100% of at least the 3" MAF pipe.
 
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