Finally Intercooled

[AleroB888]

Originally Posted by Sprucegagt

An LS1 MAF will not restrict your airflow at low boost levels, meaning anything below 10 PSI. The only thing porting a MAF will do, is screw up it's readings.

At WOT in 1st gear (worst-case) I tested the ported LS1 MAF with no upsteam tubing and still measured about 0.5 peak in. Hg vacuum between the TB and MAF. I'm betting a stock LS1 MAF with screen is going to be twice that.

After connecting the tubing going into the fender, without the filter, I got just under 1 in. Hg vacuum, and the total CAI , filter + MAF was almost 2 in. Hg. This is almost a 6 % loss of flow, therefore power loss.

The filter is a K&N # 1796, 6 X 9.5 in., mounts horizontal, just under the headlight. And that is the biggest sucker I can fit in there. This might be the best I can do with the space available.

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[Sprucegagt]

How are you equating vacuum to flow? Both values are completely independant of the other. It also sounds like your intake tubing is undersized for your application.

[SpyhunteR]

Originally Posted by Sprucegagt

An LS1 MAF will not restrict your airflow at low boost levels, meaning anything below 10 PSI. The only thing porting a MAF will do, is screw up it's readings.

what he said. The LS1 MAF is NOT your bottle neck.

[AleroB888]

Originally Posted by Sprucegagt

How are you equating vacuum to flow? Both values are completely independant of the other. It also sounds like your intake tubing is undersized for your application.

Vacuum is a measure of pressure drop (below atmospheric), which is related to flow. If you increase pressure, as with a supercharger, you increase flow. If you decrease pressure into a partial vacuum, as with a restriction, you decrease flow.

Yes, the intake tubing is a big part of the restriction. Higher than 3.25 in. diameter will be hard to fit in there, but I'll give it a shot.

[AleroB888]

Originally Posted by SpyhunteR

what he said. The LS1 MAF is NOT your bottle neck.

I never said it was a bottleneck, and I did not test a stock LS1 MAF. I did say the ported LS1 MAF still dropped some pressure, and I expect the stock one would drop more. If I can find a stock one, I'll test it. I do need some ideas on the intake tubing and filter.

[lastyear4gt]

If you wanna talk about loss of flow, look into the rubber bellows tubing you have in the intake system.

[AleroB888]

Originally Posted by lastyear4gt

If you wanna talk about loss of flow, look into the rubber bellows tubing you have in the intake system.

Yeah, you're right. I need 3.25 or 3.5 in. mandrel-bent aluminum with a tight 90 deg. and 45 deg. radius, or make something out of carbon fiber.

[Sprucegagt]

Originally Posted by AleroB888

Vacuum is a measure of pressure drop (below atmospheric), which is related to flow. If you increase pressure, as with a supercharger, you increase flow. If you decrease pressure into a partial vacuum, as with a restriction, you decrease flow.

Yes, the intake tubing is a big part of the restriction. Higher than 3.25 in. diameter will be hard to fit in there, but I'll give it a shot.

Unless you show the equation relating vacuum with flow, then you only got half of it right. Vacuum is a measure of pressure, while flow is a measure of velocity.

[SpyhunteR]

under this logic, my 2.25 and 2.5 plumbing is FAR too small for the power I'm making and the flow i'm looking for.

[AleroB888]

Originally Posted by SpyhunteR

under this logic, my 2.25 and 2.5 plumbing is FAR too small for the power I'm making and the flow i'm looking for.

I was discussing what is upstream from the blower in my particular case. I have 2.5 in. tubing to and from the intercooler, which seems to do fine. What do you use ahead of your turbo when you race?

[SpyhunteR]

Originally Posted by AleroB888

I was discussing what is upstream from the blower in my particular case. I have 2.5 in. tubing to and from the intercooler, which seems to do fine. What do you use ahead of your turbo when you race?

a filter.

you should start cutting some of that fender out and get rid of that accordian looking black tube.

[lastyear4gt]

I managed to fit 3.5" tubing through my fender to the air filter, and that is WITH the battery still in it's stock location. Took some time and trimming, but it worked.

[AaronGTR]

On a normal NA car when you go WOT your vacuum drops from the 18-22 in/Hg range (depending on mods) to zero vacuum because you are opening everything in the intake up to atmospheric pressure. When you have a super or turbo charger you are pulling air in faster than the atmosphere can push it in by itself (this is the whole point). This means that there is always going to be some kind of vacuum in the intake since there is a pressure differential.

However, since you are normally at 0 in/Hg and an NA car, and only seeing 1-2 in/Hg on a boosted car, that is a very close number. If you were still seeing 10-14 in/Hg then I'd say you have a restriction. 1-2 in/Hg means it is very free flowing and there isn't enough restriction to even measure a power loss. Basically that little blower and a 3.4L v6 will not pull enough air thru a MAF designed for a 5.7L v8 to cause any kind of restriction. If you are going to do instrumented testing, at least do it on sound scientific principles and understand the meaning of what you are testing and the reason for it.

[aleroboy]

there is a reason the LS1 guys go to the larger truck style maf also used on the C5 zo6.
the stock ls1 maf became a restriction.


however I agree that 1-2 in is a very small restriction.
this could be caused by a number of things but basically anything in front of the tb to the sc will cause a restriction. this is why the race cars at the track trying to extract everything they can out of their engine hardly ever run even a filter before their turbo or supercharger.
obviously you have to keep some intake there to at least the maf

[AleroB888]

Originally Posted by Sprucegagt

Unless you show the equation relating vacuum with flow, then you only got half of it right. Vacuum is a measure of pressure, while flow is a measure of velocity.

We are not "relating vacuum with flow" which implies a reading at low rpm. The test is at WOT, full boost, worst case.

Keep in mind that a reading of 2 in. Hg of vacuum is still a measurement of pressure, just on a scale referenced to atmospheric, which is about 30 in. Hg. I don't have a gauge that measures on the absolute scale, so a vacuum/pressure gauge was used. We only needed to know the percentage drop in pressure, the scale used didn't matter, and we also don't need to find the actual velocities involved.

On the absolute scale, I measured 28 in. Hg, so delta-h is still 2, the percentage was 2 / 30 = 6.66 .

v2 = 2gh , Where v = velocity, g = acceleration of gravity, h = pressure

Here are other applications to find the actual velocity and flow rate:

"The Pitot tube measures flow velocity by converting the velocity to pressure at the stagnation point at a small entry to the manometer tube pointing into the flow. This works for air as well, with an appropriate pressure gauge, reminding us that air behaves as nearly incompressible at speeds well below the speed of sound."



"Another important example is the Venturi flow meter, where the fluid is made to pass through passages of different areas. The rate of flow is determined from the difference in pressures (heights of manometers) at the two sections. The difference in velocity is found from continuity, and then the difference in pressure from Bernoulli. The increase in velocity in the throat is accompanied by a decrease in pressure there. If r = A1/A2, then v1 = [2g(dH)/(r2 - 1)]1/2."[ dH = delta-h = change in pressure]



http://mysite.du.edu/~jcalvert/tech/fluids/bernoul.htm

[AleroB888]

Originally Posted by Sprucegagt

An LS1 MAF will not restrict your airflow at low boost levels, meaning anything below 10 PSI. The only thing porting a MAF will do, is screw up it's readings.

Well, so far it looks like you were right. I found a stock LS1-style MAF in a junkyard, and tested it on my car. I could measure no difference in airflow between it and the ported aftermarket one, even with the screen still in the stock unit. The test was done with the complete CAI installed.

The only trouble is (here we go again), I had to use the stock '99 Alero sensor element mounted in the LS1 outer pieces. So now, all I gotta do is design the ultimate tubing system, come up with a calibration, and call it a day.

[AaronGTR]

Mounting the stock LA1 center section inside the LS1 ends won't work very well. Heck, it shouldn't even be possible but I guess if the outside bolt holes have the same dimensions...

The inside diameter of the two are much different though and it would really screw up smooth airflow and a good reading. Why didn't you just use the complete LS1 maf? You have a tuner don't you? All you have to do is copy the LS1 maf table into your pcm. Very easy.

[Sprucegagt]

Originally Posted by AleroB888

Well, so far it looks like you were right. I found a stock LS1-style MAF in a junkyard, and tested it on my car. I could measure no difference in airflow between it and the ported aftermarket one, even with the screen still in the stock unit. The test was done with the complete CAI installed.

The only trouble is (here we go again), I had to use the stock '99 Alero sensor element mounted in the LS1 outer pieces. So now, all I gotta do is design the ultimate tubing system, come up with a calibration, and call it a day.

Like AaronGTR asked, Why couldn't you use a complete LSI MAF. If it's the connector being different, then you could of got an adapter from ZZP that splits it into separate MAF and IAT connectors.

[AleroB888]

Originally Posted by Sprucegagt

Like AaronGTR asked, Why couldn't you use a complete LSI MAF. If it's the connector being different, then you could of got an adapter from ZZP that splits it into separate MAF and IAT connectors.

The connector socket is broken on the junkyard one. The '99 center section's 2 locating tabs protrude into the outer rim of the assembly, each causing a 1/8" by 7/8" obstruction (restriction). Not too bad, really. I had to file off a ridge on the '99 center section to make it fit into the end piece on one side, and file a locator pin off one end piece.

I would be more concerned about them being electrically the same. I also don't know what car it was originally on.

[AaronGTR]

Most of the LS1 MAF's were the same and the connector is the same. No adapter needed, it's plug and play. Another question, why did you buy a maf from a junkyard that was broken? I got a brand new LS1 maf off ebay dirt cheap. And I'd call any kind of obstruction in the middle of a maf sensor "bad". Any kind of a lip sticking into the air stream is enough to cause turbulence.