SDI Intake on ALH with Dyno Data

VWBeamer

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Ya'll are so smart, wow. We all know physics work differently on VW engines.

Way to go, piss all over the guy trying to show you something. Big men.
 

X-Man

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Octavia mk2 BXE + hybrid @175bhp/400Nm
so is there a definite answer yet why is the SDI inlet performing worse than the stock ALH one? have anyone performed some further tests ? or did test some other manifolds to compare the with the stock ones ?
 

Seatman

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2014 Skoda rapid elegance 1.6 cr tdi
So to bring this thread back on track :rolleyes:

I was thinking of fitting this sdi manifold, but now I'm not so sure.









 

Rub87

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very good manifold imo.. good entry angle and relative ok plenum, I used this as a base and increased plenum volume with a better entry angle
 

Chris Coates

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Octavia TDI 90 ALH
I'm not convinced y'know.

The problem with the SDI mani is surely the effect of needing increased pressure through the system to fill up the manifold, and that in itself is going to introduce problems.

Now if the rest of the pipework to the manifold itself was replaced and made bigger... Then you may see a benefit of the SDI mani as the charged air going in would be at a higher pressure. But then you'd surely see the same with an ALH manifold as well up to a point.

The major benefit of the SDI manifold is that it would surely level out pressure between all 4 cylinders which would result in a cleaner burn... But pressure itself and cramming in air volume at pressure? I would have thought the ALH manifold may actually be better on smaller turbos because it drops the circumference of the pipes, therefore increasing the pressure that the air enters the head at and therefore the density - i'm not convinced the SDI would allow this without much bigger turbo and higher flowing pipes all the way to the manifold.

However at the higher end... I reckon the SDI mani would win out because of diminishing returns on the ALH manifold. Call it an air density saturation if you will, or the increase in back pressure caused by its design eventually hitting some sort of upper limit on the ALH manifold where the SDI manifold generates less back pressure so gives you more headroom on the upper limit.

Of course, I could be totally wrong here as well but it was just a thought.
 

ryanp

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Vac ASV is nice :)
 

Rub87

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Of course, I could be totally wrong here as well but it was just a thought.

I reckon the first one..

what counts is:

even air distribution
good flowing, good entry angle into the head, bellmount, ot at least radius transition between plenum and runner
plenum volume
runner lentgh (too a less extend, but every bit help at optimal rpm range)
 

Chris Coates

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Octavia TDI 90 ALH
Seatman - There are 2 different SDI manifolds? The snail one and the one you're using...?

On a seperate note - instead of the SDI manifold... The one pictured looks unbelieveably similar to the Mk2 8v GTI manifold does it not?

I take it that this has probably been discussed already and i've just not seen it but I thought i'd ask the question.
 

Seatman

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Vac ASV is nice :)

Bonus, that's what I thought when I seen that, it's the one thing that's put me off fitting an egr delete my egr is redundant anyway but I've kept the asv intact.



While I remember too, we all know what it's like when the intake manifold is dirty and we clean it then refit, the difference is pretty amazing especially up the revs so it makes sense to me that the sdi should help.
 
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flee

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- I would have thought the ALH manifold may actually be better on smaller turbos because it drops the circumference of the pipes, therefore increasing the pressure that the air enters the head at and therefore the density -
Of course, I could be totally wrong here as well but it was just a thought.
Remember that a decrease in pipe cross-section increases flow velocity not pressure.
 

Fix_Until_Broke

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The result I came up with was that the test variables (multiple times on the dyno) were greater than the effects of the manifolds.

My intuition is that any of the SDI intakes (snail or C shaped) are better than the ALH or PD variants.

I don't believe that the intake manifolds will make as much difference as nozzles or tuning, but are a part of the whole system where each component helps improve the effectiveness of the others.

I can still swap intake manifolds back/forth between the two so if I have the opportunity to swap them without unhooking from the dyno, I'll repeat the test (albeit with my current build, but the differences should still show up).

There's enough other before/after dyno comparisons on other products - someone else should be able to do a similar test and support/refute my findings.
 

brum

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Have anyone measured the airflow with stock intake and with the SDI intake? Just a log of the MAF readings with the same boost and the different intakes will be enough.
 

TDIMeister

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Alcaid

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Dave, I have this twin plenum long runner intake manifold in my "excess inventory" ;)

 

mirulu

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Octavia I, ASV(ASZ), S356V, Hflo-x, 6G, IC ...
Hi guys, what do you think abot my manifold I have made? Many hours of work. I hope that it made sense








 

nicklockard

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Aug 15, 2004
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Arizona
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I'm very late here, but nice work FUB. If I can summarize:

Background:

FUB modified a scroll-type SDI intake and fitted it to his modified ALH.
This ALH runs tunes that calculate theoretical air mass flow and ignore the MAF signal.
FUB then took his car to a dyno shop, and tested one intake against the other. He ran the car to pre-warm it and tried to keep engine coolant temps consistent by keeping the heater on full blast for all runs. First he tested the SDI. About 1.5 hours later he rolled onto the dyno again with stock setup.

The results appear to show SDI costing significant power and torque at every rpm.
Thread commenters analyzed various logged data and can't make sense of results.

2 notable questions thread commenters brought up though:

1. If the EDC15 ECU uses 'fuzzy logic' and gets more powerful the harder you beat on it (to my knowledge, this is true for stock tunes, but I don't know what effect the tuners have on this), then a most useful comparison is to switch the run order.

2. If the tune is ignoring air mass flow, and if the SDI has increased system volumetric efficiency, then the tune may actually be commanding too high of a boost, moving and compressing more air than is required for a given power output at a particular smoke opacity; thus the engine has more parasitic load. If there is merit to this hypothesis, then running the same dynometer test with MAF based tunes may provide for a most useful comparison.

IMO, FUB's data is an excellent discussion start to a new experimental design:

Repeat this test in reverse run order with MAF based tunes. Record smoke opacity. Compare dynometer power and torque data against smoke opacity. Perhaps smoke opacity can be gauged with something like this tool http://www.machinebuilding.net/p/p4197.htm although it would be best to plot power/smoke opacity at each rpm point.

What this data tells me is that TdiClub has some excellent engineers and scientists, and we are in need of an open-source designed, home made DIY dynometer that users can build for the $550-$750 range from easily-sourced materials. Is there any club interest in starting a thread to gauge and collect user knowledge for such a project?

I would request design requirements list starting with:
-frame built of easily weldable (using 110V welder) material like box section or round tubing.
-roller set sufficiently large for low drag, reliable bearing set with zerk fittings and sight windows
-chain or toothed belt driven fan load
-fan load has variable pitch blades or variable pitch obstructions for calibrating
-preference for off-the-shelf industrial fan or fans requiring minor modifications (+ off-the-shelf industrial fan will already have safety guards).
-fan load has keyed input shaft or universal coupling on backside so you can attach direct-drive motors of known power for calibration modes
-fan large enough to push volumes of air at velocities similar to what the car would actually experience on the open road to prevent over-heating, it also blows the smoke away.
-large rubber wheel chock integrated with physical safety INTERLOCKS such that fan load can not be driven unless safety chocks are properly deployed.
-bright mark and USB optical rpm sensor
-a non-skid shelf for laptop data capture: laptop logs USB rpm data and smoke opacity data using serial input logging. Laptop also connected to VCDS for capturing engine data. Raw text files can be merged in Excel.
-community written, open-sourced text data merging Excel macro.
-community written, open-sourced data analysis using Excel macros.
-A thread here for comparing data.
-community generated, open-source Excel file for temperature and pressure corrections.
-community based design plan, design FMEA risk assessment, warning stickers, and legal disclaimers
 
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Fix_Until_Broke

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Menomonee Falls, Wisconsin, USA
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More/less - a few things to clarify...

I ran both MAP and MAF based tunes on the dyno.

I have IMP/EMP data from these dyno runs and nothing stood out as significantly different between them.

I still think there was something with the re-hook on the dyno.
One was strapped tighter/looser than the other maybe.
RPM scaling was off (no direct engine RPM measurement so I told the operator what the RPM's were and they did a linear scaling off of that)

The data is just too much of an "offset" to make me think it's only the intake itself



I really like your fan load idea for a dyno - that's a great idea. I'm not sure it can be done for $750 though. I think the best thing for that price would be 3rd gear VCDS logs - Run 6 pulls - alternating direction each time (1 N-S, 1 S-N, 1 N-S, etc). Throw out any outliers and average the rest. Still a lot of variables.
 

nicklockard

Torque Dorque
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Aug 15, 2004
Location
Arizona
TDI
SOLD 2010 Touareg Tdi w/factory Tow PCKG
FUB,

I think if we put our heads together, we could get the cost of a DIY dyno down below $1000 for sure because of the open-source design, research, and development. Of course I'm conveniently ignoring the cost of welders, tools, etcetera. Alternatively, like you say, we could do an open-source 'butt dyno' method that would control for most variables, so long as everyone used the same brand of temperature/pressure sensor and Excel macros.

Edit: Oh, I'm not including cost of laptop, VCDS, or Excel license in my DIY dyno. Is there enough club interest to proceed?
 
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