Port swirl & flow measurements

I have just been reading a few threads regarding cam choices for 8v PD 1.9 engines, and it appears to be a well known fact that the TDI intake ports are very restrictive mostly due to cam lift and duration, but my educated guess is its also partly due to the restrictive helical/snail shape nature of the intake ports, this is what generates the swirl effect inside the comustion chamber.

my question is, has anyone conducted any type of swirl measurements on a flow bench using a swirl meter like this:

http://www.performancetrends.com/swirl.htm

It seems that the 1.9 8v engines respond well to cam changes with more lift and duration, I think one of the side benefits of upgrading the cam, is less swirl.......but thats just an educated guess.

Also, has anyone got any flow-bench results from any standard or modified 1.9 PD 8v heads???.....someone mentioned the standard cams and heads are limited to about 240bhp, which is actually not too shabby to be honest.

You couldn't be more incorrect. The swirl port design is extremely complicated and required hundreds of hours of research and testing to insure the optimal flow into the cylinders.

The Swirl ports I am pretty sure are a subject discussed about 15 years ago when the engine was first designed. I have personally seen the original casting blanks of various shapes that were used to verify the computer aided design in the engine test cell.

The newer engines use a variable valve to provide an optimum swirl at varying rpm ranges.

As far as these aspects of the motor being as you call it "restrictive" is simply unfounded and far from well known fact in fact it's more urban legend than anything else with it's basis in uneducated guessing.

DB

Drivbiwire said:

You couldn't be more incorrect. The swirl port design is extremely complicated and required hundreds of hours of research and testing to insure the optimal flow into the cylinders.

The Swirl ports I am pretty sure are a subject discussed about 15 years ago when the engine was first designed. I have personally seen the original casting blanks of various shapes that were used to verify the computer aided design in the engine test cell.

The newer engines use a variable valve to provide an optimum swirl at varying rpm ranges.

As far as these aspects of the motor being as you call it "restrictive" is simply unfounded and far from well known fact in fact it's more urban legend than anything else with it's basis in uneducated guessing.

DB

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ahem.......no actually I'm quite correct, I design diesel engines for a living, I have done a lot of swirl port development on 2v and 4v engines, and feel quite happy saying what I have said above .....2-valve heads are notoriously restrictive to mass-airflow and feature a very high amount of swirl due to helical ports.......I'm only trawling through this forum to extract knowledge about the PD injection system, as its so antiquated and unknown to myself.

the old VW 1.9 8v swirl system operates just like any other 2-valve per cylinder system, swirl increases as engine RPM increases........this is exactly NOT what is required from a high performance diesel, as it blows the fuel out of the re-entrant combustion bowl and causes lots of black smoke........ this is why on latter day 4-valve per cylinder engines, one port is termed the charge port, and the other port is termed the swirl port, at low to mid RPM the charge port is closed, which increases swirl........at higher RPM, the flap is opened which creates a low swirl condition for max power.

My gut feel is that camming an engine increases flow, therefore marginally reduces swirl, which is all good.......but I'm speculating on that particular one, but peoples dyno results seem to suggest camming a 1.9 8v head works very well if you have the supporting mods like more boost and high flow injectors.

Camming helps in a few ways. Compression reduction, increased shrouded area and velocity reduction(less swirl). A cam in these engines helps a bunch because the valves are too small. I find that porting greatly improves power and driveability as well as reducing smoke. A cam, or larger valves would be icing. Both...orgasmic.

Hi and welcome!!

Quote...........by Knighty
ahem.......no actually I'm quite correct, I design diesel engines for a living.

Can you tell us which type/s of diesel engines you have had a hand in disigning and which types of fuel injection systems did/do they run.

And how come you havn't don't know much about the PD system being in the game so to speak plus why are you not more interested in the newer CR system which has even more scope!!.

knighty said:

the old VW 1.9 8v swirl system operates just like any other 2-valve per cylinder system, swirl increases as engine RPM increases........this is exactly NOT what is required from a high performance diesel, as it blows the fuel out of the re-entrant combustion bowl and causes lots of black smoke........

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Which leads to why the TDI pistons are designed the way they are. The engines components are designed to work together. VW didn't just slap a head on a block and call it a diesel.

My point is if you modify the swirl ports you must modify the piston bowl design along with a few other key components (injectors and fuel pressure).

VW proved with the older ALH and AHU engines that reliable 200+hp was possible in racing applications. This pre-dates the high pressure PD and CR systems.

The newer CR systems are already producing in excess of 140hp per liter (in the lab) but you won't see those for another 4-5 years.

LOL Drivbiwire..................i'm thinking this chap is really wanting some info on which way to go on porting the PD head.........if so just ask!!

mojogoes said:

Hi and welcome!!

Quote...........by Knighty
ahem.......no actually I'm quite correct, I design diesel engines for a living.

Can you tell us which type/s of diesel engines you have had a hand in disigning and which types of fuel injection systems did/do they run.

And how come you havn't don't know much about the PD system being in the game so to speak plus why are you not more interested in the newer CR system which has even more scope!!.

Click to expand...

no problem........I have worked on a series of contracts mainly for Ford, Iveco and Cummins.......on the smaller engines for Ford I have worked on the 4cyl 8v 1.8 Lynx.......then the 2.0, 2.2 and 2.4 Puma these are 16v diesels.......more recently i just did a load of work of the new 4.4 V8 destined for the new F150 in 2012........prior to that lot I did a lot of work of 4 cyl 4 Litre, and 6 cyl 6 litre engines on a joint venture for Cummins and Iveco.........half of tha above engines for Iveco and Cummins are CR with 7 or 8 hole nozzles.......the rest were 2-valve mechanical injection with 5 holes per nozzle and a lot of swirl!

believe me, the PD system is completley unknown to me, as VW are the only people who have stuck with it. I need to know more as I'm consulting on a PD based racing project.

mojogoes said:

LOL Drivbiwire..................i'm thinking this chap is really wanting some info on which way to go on porting the PD head.........if so just ask!!

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correct!........ I will be interested to hear what people have done regarding 8v 1.9 porting, I have a pretty good idea what direction I wopuld like to take, but I will be interested to hear of other peoples results

A cam does not change swirl that much imo.
You can take out a bit of swirl with porting to improve flow, but imo it's not a good way.
TDI engine efficience and fuel economy is largly based on swirl.
Exhaust side of the head is the main problem.
And you need big injectors for high power, not only for amount of fuel, but mostly for injecting fuel in a short time.

Johan

Quote...........
believe me, the PD system is completley unknown to me, as VW are the only people who have stuck with it. I need to know more as I'm consulting on a PD based racing project

Do tell more! what type of racing at what level (VW CUP!!) vw have dropped the PD injection system some time ago in faver for the cr system........mybe you could invite me along to consult along side you!.........lol.

thanks Johan, I keep hearing the exhaust is very restrictive on several posts, sure enough, the piper cam specs I have just been looking at seem to indicate this too, piper introduced a lot more lift and duration on the exhaust side......more so than the inlet........I must admit, hacking out the swirl ports sounds quite a serious modification to reccomend straight away, so its probably left till later on........it just seems that camming an engines fixes so many things at once, reducing the dynamic compression ratio is a particular bonus.

Knighty what aspect of diesel engine design do you specialise in and what have your colleagues voiced on the various points your bringing up here!

A good cam really shows lower oil temp and lower egt.
Engine breaths way better on high rpm.
More exhaust gasses get out of the engine and results in lower dynamic compression and more cold air into cilinder.
This also helps reliability of the engine during racing.
So camming is really good start, but best in combo with lager valves and porting.

Johan

mojogoes said:

Knighty what aspect of diesel engine design do you specialise in and what have your colleagues voiced on the various points your bringing up here!

Click to expand...

there are 2 general areas of engine work, base design & development, or calibration, which to you and me is mapping, but calibration is more associated with emissions legislation & conformity, not necessarily all out power tuning!........my specialist area is base engine design, I have done it all, blocks, heads, cranks, ports, rods, pistons, valves, lube systems you name it.

all of what I have quoted are well established trends used on all latterday high power diesels.........in short they are a mile away from the PD system & base engine design, which was never intended to produce any where near 100bhp/litre!

turbo johan said:

A good cam really shows lower oil temp and lower egt.
Engine breaths way better on high rpm.
More exhaust gasses get out of the engine and results in lower dynamic compression and more cold air into cilinder.
This also helps reliability of the engine during racing.
So camming is really good start, but best in combo with lager valves and porting.

Johan

Click to expand...

Johan - I just noticed you are running Race783 nozzles........how many holes are there in these nozzles???

turbo johan said:

A good cam really shows lower oil temp and lower egt.
Engine breaths way better on high rpm.
More exhaust gasses get out of the engine and results in lower dynamic compression and more cold air into cilinder.
This also helps reliability of the engine during racing.
So camming is really good start, but best in combo with lager valves and porting.

Johan

Click to expand...

One thing I noticed with my (tdimeister) race cam besides more horsepower/torque, is the drivability improved at low rpms, and tip-in. It is amazingly smooth at 1500 rpms with race nozzles, and 17/52, and snaps to life at any rpm. The oem cam would complain with shutter and smoke at low rpms below 2000.

Jeff

knighty said:

no problem........I have worked on a series of contracts mainly for Ford, Iveco and Cummins.......on the smaller engines for Ford I have worked on the 4cyl 8v 1.8 Lynx.......then the 2.0, 2.2 and 2.4 Puma these are 16v diesels.......more recently i just did a load of work of the new 4.4 V8 destined for the new F150 in 2012........prior to that lot I did a lot of work of 4 cyl 4 Litre, and 6 cyl 6 litre engines on a joint venture for Cummins and Iveco.........half of tha above engines for Iveco and Cummins are CR with 7 or 8 hole nozzles.......the rest were 2-valve mechanical injection with 5 holes per nozzle and a lot of swirl!

believe me, the PD system is completley unknown to me, as VW are the only people who have stuck with it. I need to know more as I'm consulting on a PD based racing project.

Click to expand...

believe me, the PD system is completley unknown to me, as VW are the only people who have stuck with it. I need to know more as I'm consulting on a PD based racing project.[/QUOTE]

Hmmm are u sure with this? May be you are a new in diesel? PD injectors has to be mainly used in truck - VOLVO, SCANIA.....so what kind of research you´ll do?

knighty said:

Johan - I just noticed you are running Race783 nozzles........how many holes are there in these nozzles???

Click to expand...

5 holes.

Johan

jsrmonster said:

One thing I noticed with my (tdimeister) race cam besides more horsepower/torque, is the drivability improved at low rpms, and tip-in. It is amazingly smooth at 1500 rpms with race nozzles, and 17/52, and snaps to life at any rpm. The oem cam would complain with shutter and smoke at low rpms below 2000.

Jeff

Click to expand...

This is exactly what my old performance cam gave my setup , even running the W/G unit and i'm hopeing the sports 260 will give me the same if not even further improvements in the low end tip-in region and possibly more at wot though this will depend on how much my last cam really had in lft compared to the 260 unit.

StingrayRT said:

believe me, the PD system is completley unknown to me, as VW are the only people who have stuck with it. I need to know more as I'm consulting on a PD based racing project.

Click to expand...

Hmmm are u sure with this? May be you are a new in diesel? PD injectors has to be mainly used in truck - VOLVO, SCANIA.....so what kind of research you´ll do?[/QUOTE]

UUmm me's thinking the exacly the same thing!!

mojogoes said:

Hmmm are u sure with this? May be you are a new in diesel? PD injectors has to be mainly used in truck - VOLVO, SCANIA.....so what kind of research you´ll do?

Click to expand...

UUmm me's thinking the exacly the same thing!![/quote]

guys, I have told you my background, if you want to speculate otherwise I'm not going to lose any sleep......new to diesel LMFAO.....I have not worked for VW, Volvo or Scania, so its quite obvious I know nowt about PD!

anyways, thanks for the comments about cams and the restrictive exhaust.........all very helpful stuff.

Quote
Quote...........
believe me, the PD system is completley unknown to me, as VW are the only people who have stuck with it. I need to know more as I'm consulting on a PD based racing project

Do tell more! what type of racing at what level (VW CUP!!) vw have dropped the PD injection system some time ago in faver for the cr system........mybe you could invite me along to consult along side you!.........lol.


Have you any more info on the type of "diesel based racing project" your woking on.........what type of racing etc will this car be running in.

mrchill said:

Camming helps in a few ways. Compression reduction, increased shrouded area and velocity reduction(less swirl). A cam in these engines helps a bunch because the valves are too small. I find that porting greatly improves power and driveability as well as reducing smoke. A cam, or larger valves would be icing. Both...orgasmic.

Click to expand...

Well, I have both. I'm still waiting...

shadowmaker said:

Well, I have both. I'm still waiting...

Click to expand...

SNAP!!...............no i'm having a look now and there's nothing happening down here at the mo ..........but that could be down to not having my cam at the moment.

mojogoes said:

Quote
Quote...........
believe me, the PD system is completley unknown to me, as VW are the only people who have stuck with it. I need to know more as I'm consulting on a PD based racing project

Do tell more! what type of racing at what level (VW CUP!!) vw have dropped the PD injection system some time ago in faver for the cr system........mybe you could invite me along to consult along side you!.........lol.


Have you any more info on the type of "diesel based racing project" your woking on.........what type of racing etc will this car be running in.

Click to expand...

you have mail

I would have guessed that increased valve lift would increase the swirl in combustion chamber.
I have not yet seen any 16v diesel head that would have been desingned so that it would create low swirl values al higher engine speeds.. actually vice versa, so that mass flow of secondary valve is reduced to maintain good swirl characterics.
Though I am not a head designer.

Increasing the amount of burnt gasses in combustion chamber will actually reduce combustion pressure by degreasing the amount of fresh air to be heated and expanded in burning process.

shadowmaker said:

Well, I have both. I'm still waiting...

Click to expand...

+1

@ Marko

Indeed the 4 valve per cilinder racing engines have imo huge mounts of swirl, the audi le mans engine has no flapper in the intake, as it has it's powerband between 3000-5000rpm, one port goes straight in like a gas engine, so thus creating a some rotational movement in the cilinder, while the other port makes a 180° turn (also contributiing to the rotational movement).. the runner starts actually (lets say left) next to the valve and then goes right an then starts the known swirl 180° turn, 8v tdi head also has this a bit, but much less.. the outer wall of the first right turn goes down too..

What also is noticable that the lobes on the intake cam are separated by lets say 10-15° (cam degrees)

So hard to explain, but we weren't allowed to take pics at Neckersulm

knighty said:

thanks Johan, I keep hearing the exhaust is very restrictive on several posts, sure enough, the piper cam specs I have just been looking at seem to indicate this too, piper introduced a lot more lift and duration on the exhaust side......more so than the inlet........I must admit, hacking out the swirl ports sounds quite a serious modification to reccomend straight away, so its probably left till later on........it just seems that camming an engines fixes so many things at once, reducing the dynamic compression ratio is a particular bonus.

Click to expand...

What has been said is true. There is no small amount of CFD computer time that has gone into designing the re-entrant combustion bowl and swirl/tumble port combination (air enters bowl and travels toroidal donut path inside bowl at optimum air velocities.) Additionally, the flapper valve in the EGR port of the PD's intake is there to broaden the rpm range over which good swirl/tumble characteristics are present for achieving emissions goals.

Without CFD super computer time or specific knowledge--and you probably know more than any of us here except Dave/TdiMeister--one would be very hard pressed to re-engineer things, IMHO.

knighty said:

ahem.......no actually I'm quite correct, I design diesel engines for a living, I have done a lot of swirl port development on 2v and 4v engines, and feel quite happy saying what I have said above .....2-valve heads are notoriously restrictive to mass-airflow and feature a very high amount of swirl due to helical ports.......I'm only trawling through this forum to extract knowledge about the PD injection system, as its so antiquated and unknown to myself.

the old VW 1.9 8v swirl system operates just like any other 2-valve per cylinder system, swirl increases as engine RPM increases........this is exactly NOT what is required from a high performance diesel, as it blows the fuel out of the re-entrant combustion bowl and causes lots of black smoke........ this is why on latter day 4-valve per cylinder engines, one port is termed the charge port, and the other port is termed the swirl port, at low to mid RPM the charge port is closed, which increases swirl........at higher RPM, the flap is opened which creates a low swirl condition for max power.

My gut feel is that camming an engine increases flow, therefore marginally reduces swirl, which is all good.......but I'm speculating on that particular one, but peoples dyno results seem to suggest camming a 1.9 8v head works very well if you have the supporting mods like more boost and high flow injectors.

Click to expand...

Would a more pronounced omega bowl lip help keep the gases from being blown out of the bowl?