great work subscribed

 

Very good job...However be careful for the turbo not to such fluid...a meter should be safer...rep for you...

 

IMO there will always be SOME vac registered. Even on NA cars you tend to see some but you shouldn't be seeing very much. I seem to recall 5inches or less on the last NA motor I tested but it was no more than 5liters making less than 300HP and this was a long time ago. The closer you can get to zero at WOT the better! Turns and curves will not produce additional vac unless they're a restriction, it has nothing to do with the fact that the air is being forced to turn. Try sucking air through a thin straw used to stir c0cktail drinks, try the same with a soda straw, now use one of those most awesome straws McDonalds provides for a large sweet tea. Noticing the differences?

Your engine is nothing more than an air pump and the easier it can inhale through the straw the better. Even the super kewl McDonalds straws, if long enough, would be a restriction.

Using some other device like a vac to measure this would indeed be a great idea! However these cars inhale 3liters of air on every revolution. So you'd need something that could move 3liters of air times oh say 7400 to match what one of these cars can move... without boost! Okay we're only measuring one side so divide that in half! If the turbo is pushing 1BAR of boost double that number back again... and I still don't think you will have matched how much air goes through one of these motors at redline! These motors are 4 strokes, does that play into this too?

1BAR on the gauge is how much air the engine wasn't capable of consuming and backed up in the intake to be measured by a boost gauge. How much it actually flows through the pipe leading to the turbo that moves all that air I'm not totally clear on - it's fuzzy to me - but I think it's safe to say it's a metric crap ton Things like BSFC, intercooler efficiency, and other things all come into play too - mostly to lower the amount of air consumed. You might be able to use readings off the MAF to figure this out but I guess my point is that there's no way a shop vac is going to be good enough or even a standard flow bench IMO.

As for variables on the car, I think that's okay. We live in the real world and so does this test. Even if it isn't lab rated scientific I think we'll get some good benchmarks from it which is really what we need to draw some rough conclusions. Depending on how crazy Earl gets and how much money he's willing to spend we can find out how much resistance the air filter is, whether the MAF is a restriction, and if he has a GT2 style tail with intakes sealed to his air box he could maybe even find out if there's any ram air effect.

It's great when someone puts on a part like an intake and picks up say 10HP on a dyno. But what if they left another 20 on the table because the part wasn't as optimized as it could be? Measurements done like this is how you know, the dyno doesn't tell you everything....

Anyway Chad, please don't take this as an attack on your posting. Your reactions and questions are perfectly normal and this is a subject I get enthused about. The more efficient an engine is, intake and exhaust, the more power it will make more easily. On these cars the intake leading to the turbos seems to be a prime candidate for improvement!

P.S. Earl that was an interesting article you linked. I'm also finding this one of interest -> http://www.avweb.com/news/pelican/182102-1.html

P.P.S. Not a huge concern if water had gotten sucked into the turbo so long as it wasn't a huge volume or an extended period of time. Some folks have actually injected water\meth into turbo intakes intentionally searching for power! It DOES eat up the compressor blades if done long enough (!) but for a short burst it's probably not going to hurt anything. I completely agree a gauge is better and i'm sure the wife would appreciate that too! (lol)

 

No offense BLKMGK. I think we are on the same page, you just said it clearer than I did!

The test bench idea would make it easier to swap parts IMO. Changing the intake pipes on these cars is not an easy job! That was the only point in my idea... Otherwise would have to count on other people doing it to their car, but may have different turbos, intakes, filters, etc...

 

I'm with BLKMGK... Let me know if you want some cash for support of developing the testing of this...

The fact that the vaious vendors haven't done this, doesn't surprise me. They're worried about moving product, not developing and validating products to prove they actually "work"!

Mike

 

Honestly if there was some way to setup a system to do this I think it would be great! But the amount of airflow is sick! I once watched a kid who was trying to develop an "electric blower" dyno his car. He used one of those stupid bilge blowers like you find on eBay and obviously saw a performance drop - this on a 5liter Mustang. He then strapped on a leaf blower with like a 5HP rating and STILL didn't see a boost. That's how much air that 5liter was moving. Frankly I was impressed he was willing to dyno and experiment - I and the shop owner were all curious but the failure was expected.

We have 3liter turbo engines. At 1BAR of boost we're running roughly two atmos of air into the engine. That 3liter has just become a 6liter! That pressure measurement is how much air couldn't make it into the engine too. Free up the intake of the engine (not turbo intake) and it will ingest more air. Due to the wastegate it will still read 1BAR though - but the turbo will be spinning harder and passing less exhaust through the W/G. This is pretty awesome if you drive up into the mountains too - NA cars are left gasping for air but turbo cars keep right on going up to the point the turbo runs out of it's effeciency range or the intake side of the turbo becomes way inefficient. Neat stuff! I would LOVE to know just how much air would be needed to do a test like this - and we'd probably need to do it with suction rather than blowing too....

Anyway my, long winded, point is that while testing off the car would be great it would take some serious wind to do it - more than a 5hp leaf blower for sure. Multiple gas powered leaf blowers? I dunno. Not sure how consistent that would be. I sort of tried to figure out how much air but gave up - something close to 1K CFM I think.

Honestly I'm betting that if Earl has been willing to go so far as to test this he's got an engineer's mind set and is looking for bottlenecks like I've wanted to. He's probably doing this with an eye for efficiency and I'll be surprised if once he figures out just how bad those pipes are that he doesn't try to find a way to "fix" this issue and retest. If I were a vendor unwilling to do this sort of testing for myself but wanting to show just how big an improvement my parts made I would be considering offering him something at a serious discount just to get the test results out there from someone independent. If Earl also backs this up with a dyno test before and after then we will ALL as a community have benefited! Depending upon how willing Earl is to be guinea pig and if any vendors are willing to help him out I'd be willing to toss in some cash to make it happen too - seems fair since he's doing the work.

To be clear, as a consumer this information is valuable to me in choosing parts for my car. Knowing where the issues are and how to fix them, with the resulting HP measurements, can save me and others money on parts I don't need. Looking at a part and trying to judge it's merit is tough - we might even find out those vac cleaner hose looking intakes some of us have laughed at are "good enough" for decent amounts of power! This kind of testing used to be done in the Supra world by both vendors and individuals, very happy to see guys doing data gathering here and sharing it too! CJV and a very few others have done this and shared, we need more of it and I applaud (and rep!) Earl for doing it.

 

I agree, results will be very interesting no matter how they are gotten. I just lean to the analytical side on reducing variables and getting solid repeatable numbers, etc. If that cannot be easily done, then I guess on the car would be the only option. Too bad nobody has a turbo engine setup on an engine dyno where parts can be swapped easily!

 

Even on different cars we'd learn something. One of these guys running 7-900HP doing a test like this would be VERY interesting too. If say Markski's setup on one of those cars had minimal pressure drop then sure as heck it would flow fine for guys making 600HP or so. Even he saw HP differences with different filters at his power levels with fender intakes, pressure testing would have shown this like a neon sign I'm sure. I'd love to see a vac test on that car with the two different filters to see how much restriction it took to rob 30WHP...

 

You can't cramp more than 3 liters into a 3 liter engine. Actually probably not more than 90% of 3 liters for an efficient engine. Boost just changes the density of the air but the volume is still the same.

 

Okay... I see where you're coming from. Correct that efficiency means not 100% cylinder filling. However can we agree that at 90% efficiency (high actually) and say 1BAR of boost pressure measured in the intake that the INLET to the turbo is consuming more than 3liters of air volume per stroke? Air can be compressed unlike a liquid, it just gets more dense as you've stated. If I have more than 3liters of air per stroke coming in the inlet to the turbo(s) then I'd argue that the engine is consuming more than 3liters even if the semantics say it's not but that it's just more dense... Not arguing that you're wrong, just trying to get a handle on this.

Does that make sense or have gone off track somewhere?

 

The volume stays the same boosted or not but the air is denser, i.e. has more molecules and will make more power. I guess you can call it semantics....Lets take an na car. If you at 5000 feet elevation you suck in 3 liters. Coming down to sea level you still suck in 3 liters, correct? Even though I just gained 3 or so pounds of boost from atmospheric pressure.

 

May be BLKMGK tries to say these,

Normal Aspiration: 90% efficiency of engine 3 liters, outside pressure 1 atmosphere
= 0.9eff x 3L x 1 = 2.7 comparable liters of air at atm. (Air sucked in.)

90% eff of 3 liters boost 1 bar( 1 atm above outside pressure. double pressure makes twice of mass per volume. Absolute pressure=2) Unfortunately, there is heat generated, so say 80% mass left.
= 0.9eff x 3L x 2 x 0.8 = 4.32 comparables liters of air at atm.

So 3 liters Force Induction engine at 1 bar cramps 4.32 liters of outside air compares to NA engine that puts 2.7 liters of outside air in.

Hope this help. My English is not that good. and try not to put PV/T Thermodynamic thing in here.

 

You might want to do a little research into fluid dynamics and flow of compressible fluids.

Begin by looking into the definition of static, velocity, and total pressure.

Your proceedure measures only a portion of the total pressure loss. Additionally measurements at discontinuites & turns can provide erroneous results.

Those that are willing to make mistakes are the ones, maybe the only ones, to accomplish anything. Good luck to you and have fun in your experiments.

 

Understand that there are many factors at play here. We've got viscous effects, changing Re#s, flow that probably isn't always incompressible (pre-turbo), and changing diameters. The idea here is to get a good baseline and some before & after numbers measuring at the same spot. Short of jamming a pitot tube in front of the compressor, this is probably as good as it going to get. Hopefully future results and AMS's dyno test will help folks make a more informed decision.

Edit: A few more thoughts... Did a hypothetical, but probably typical K16 inlet pipe dynamic pressure look. Starting with a K16 compressor map http://www.not2fast.com/turbo/maps/k16_2467.gif , the highest mass flow without going too overboard is around 0.2 kg/s (note that at my 0.7bar, I'm probably barely touching 0.15kg/s). If mass flow = density*cross sectional area of a tube*velocity, and, for now, assuming density is a sea level ish 1.225 kg/m^3 and the inlet pipe radius where I'm measuring static pressure is 1.25", we end up with 0.2kg/s=1.225kg/m^3*(0.0318m)^2*pi*V => V=50.3m/s (incompressible flow, bueno). P_dynamic=0.5*density*V^2 => P_dynamic = 1589 Pascals = 6.4" of H2O
(someone check my math)

In this case the dynamic pressure contribution to total pressure is a good bit smaller than the delta in static pressure and will likely stay fairly stable as changes are made upstream (so long a mass flow doesn't change dramatically). Now, this is a hypothetical case with some assumptions, but I can log mass flow rate from the MAF, measure the inlet pipe diameter exactly where I'm tapping for static pressure and get local density from a weather station. So now we can back out velocity from mass flow, density, and a given pipe area, then find the dynamic pressure at various points in the rev range from the velocity and density. Yes/no? Maybe?

For my stockish tests now, if my math checks, I think the dynamic pressure contribution to total pressure is almost negligible (probably 3-4" H2O).

 

YES! My point, without going into a pile of math, is that the engine ingests MORE than 3liters of air via the turbo inlet. Yes technically it's still 3liters of dense air with some fudge for effeciency but you have the idea. The inlets to the turbos flow a BUNCH of air and a measurable pressure drop in the piping tells you there's a restriction. You will probably never get that reading to zero but the closer you come to zero the freer flowing that pipe is.

It would be interesting to get a reading from someone running one of the freer flowing intakes with fenderwell inlets just to see the difference - I'm betting it's significant!

P.S. Nothing at all wrong with your English, I understood you just fine!