Intake Manifolds

Alright.. something to ponder while I move back to the NE and the car is locked away in its trailer... Intake manifolds for TDI engines (guess for any engine really but thats my focus)

There is a problem with the stock intake that came on the ALH VW TDI's in that they are restrictive and they don't equally share the air to each cylinder (some say its cylinder 3 that gets jipped)


Sure the PD150 manifolds fit and can be found for $150 or so... but can I gain anything over them?

Are there any good resources i should read before I delve into designing my own.. I was thinking a reverse header with no plenum, but what the fark do I know... The engine is a 1.9 that will spin to a whopping 5k with about 20psi of the boost ;-)

Thanks
Dave



Edited 1 time(s). Last edit at 01/23/2013 11:24AM by DexterVW.

The stock manifold is fine for quite a bit of power. What are you trying to accomplish?

One of the advantages to the PD manifold is the seperate EGR valve. Most people don't really care about their EGR valve.

Tdiclub should be your first resource.

Tim.

This is a good site with many people making their own stuff, inlet manifolds, turbo upgrades, even compound turbos.

http://www.vwdiesel.net/forum/

---

Disappointingly not yet a Jackass

Not sure if you have room but I think the ALH has a low mounted VNT turbo fitted.
Any room for the manifold from a non turbo application like this. Has runners and everything.
You can still see the coal running out of number 4 from the EGR.

---

Disappointingly not yet a Jackass

Sweet thanks guys... so how does one register for vwdiesel.net.. its currently disabled.

Quote
DexterVW
Sweet thanks guys... so how does one register for vwdiesel.net.. its currently disabled.

Ahh, yeah, the site had been hit by alot of spam recently, so it is a bit of an involved process to sign up.
I helped someone just a few weeks ago get through the process. But basically it involves sending an email to the owner, this email must have the word diesel in the title to get through his email spam filter.

This page here I think explains it.
http://www.vwdiesel.net/forum/index.php?topic=30622.0

I also got this instruction from a moderator on the site.

He has to go to the general section and send Redrotors an email to the website there. It may take a few days for him to get to it. The code word is diesel...it is in that general section page to register. If you do not put diesel in your email then he will not activate the account.

If you get stuck let me know and can chase it up for you.

---

Disappointingly not yet a Jackass

I've seen people talking about dual plenum intake manifolds for the diesel VW's.



I have no experience with them but it seems like every turbo rally car has one and other low revving boosted stuff like the Audi R8 Le Mans:



Skoda Fabia WRC



EVO WRC:



206 WRC:



Audi S1 Group B:



Cosworth EVO X:



Cosworth Mis YB:



Fiesta WRC:



Focus Zetec WRC:



Duratec WRC:



The strategy is to equalize airflow to each cylinder, first plenum starts the size of the throttle body then tapers down to ~1" and has a "slot" to the second plenum which is 100-110% the area of the Throttle body, the second plenum is about the same volume as the engine displacement.

They all have velocity stacks on each runner in the second plenum, but runner design seems to vary and the more recent designs seem to feature individual roller style throttle bodies.

Anybody have ACTUAL REAL LIFE experience with these or hearsay and opinions?

The "Trend" seems to be tapered side feed intake manifolds,

Citroen Xsara WRC:



The "Motorsports" versions all seem to have ITB's and the "Tuner" versions don't. Some of the "Tuner" versions are made by successful companies but inevitably the focus seems to be the highest dyno numbers which causes me to quickly lose interest and while close to equal airflow to each cylinder can be achieved it seems to take more development.

I used to have some of the formulae for calculating runner-length and plenum volume in a word file, all culled from SAE empirical testing (not by me - someone gave it to me). All the calcs were based on rpm and VE of the engine, and where you wanted the peak power in the rpm-range for a give bore/stroke ratio. But that's all long-gone, several computers ago.

The only thing that really sticks in my head from all the diy_efi discussion group threads was to "start" with the rule-of-thumb for peak-power as having each runner (including inside head and in the bowl) to be at-least the same volume as the individual cylinder-displacement, and the plenum volume at least the same as all the cylinders combined. Increasing runner-length without altering displacement moves the power-peak lower in the rpms, and vice-versa.

This was all from before dual-plenums became "commonplace", of course - so is really of limited/no help, and is mainly anecdotal anyway - I gave up on my engine-design hobby years ago due to time constraints and loss of a place to experiment and fabricate.

---

Parfois, on fait pas semblant!

I am:
I know:
I am from:

Nobody.
Nothing.
Nowhere.

BTW, that first pic looks The Shit - I believe I could fabricate something like that with a bit of work. (the modifications to the stock manifold)

---

Parfois, on fait pas semblant!

I am:
I know:
I am from:

Nobody.
Nothing.
Nowhere.



Edited 1 time(s). Last edit at 01/24/2013 11:35PM by Creech.

This is the kind of stuff I love to learn about. How does the length of the runner effect the engine? If all the cylinders don't get the same amount of air, does the engine run rough?

---

Kirk Coughlin
Woodbury, MN and River Falls, WI

Quemadmodum gladius neminem occidit, occidentis telum est.

Quote
sidewaez
The strategy is to equalize airflow to each cylinder, first plenum starts the size of the throttle body then tapers down to ~1" and has a "slot" to the second plenum which is 100-110% the area of the Throttle body, the second plenum is about the same volume as the engine displacement.

just to clarify that I'm understanding correctly:
You've got the somewhat conical plenum #1, and the cylindrical plenum #2.
The 'slot' between them runs the length of both plenums?
Looks like the slot (and plenum #1) are oriented such that the slot is off to the side of the velocity stacks?

---

KF7RWG
http://www.utahrallygroup.com

Quote
Aaron Luptak

Quote
sidewaez
The strategy is to equalize airflow to each cylinder, first plenum starts the size of the throttle body then tapers down to ~1" and has a "slot" to the second plenum which is 100-110% the area of the Throttle body, the second plenum is about the same volume as the engine displacement.

just to clarify that I'm understanding correctly:
You've got the somewhat conical plenum #1, and the cylindrical plenum #2.
The 'slot' between them runs the length of both plenums?
Looks like the slot (and plenum #1) are oriented such that the slot is off to the side of the velocity stacks?

Yeah. The idea is that theoretically the air velocity through the slot is even across the whole length of the slot, because the conical plenum narrows down to keep pressure in it more constant as air goes into the cylindrical plenum, so the pressure distribution in the cylindrical plenum is even across all the runners.

As for runner length and whatnot, that's related to trying to acoustically tune things and mostly varies with where you want the powerband. Some OEM and racing engines actually have variable length intake tracts to broaden the torque curve. The math there is googleable.

With cylinders getting the same amount of air, the big issue is that unless you have the ability to map the ECU on a per-cylinder basis and do so very carefully, some cylinders are going to be leaner or richer than others, and will need more or less spark timing because they'll have more or less intake charge in them to get squished. So you have to make the tune safe for the worst case, which means that some cylinders will be rich, and won't be running as much spark timing as they could. The more even the intake tract flows, the less difference between the best and worst cylinders.

Word on the street is the std PD TDI inlet manifold is good for over 200hp, even though it looks like shit.
So unless you are going tractor pulling it will probably suffice.
Blocking off the EGR may require a ECU flash to work correctly depending on what model, but it will save a port or two (it does not distribute the soot evenly over all runners) filling up with gunge and restricting port size, thus makes worrying about equal pressure and flow on all runners a little ocd.

Unfortunately the EGR system is also used to assist the engines heating up quicker from cold as those TDIs take an age to heat up even with a good thermostat.

Not to do with turbos but an interesting read on intake runner length here.
http://www.emeraldm3d.com/articles/cat/projects/post/emr-adj-length-intake/

---

Disappointingly not yet a Jackass

Quote
danster
Not to do with turbos but an interesting read on intake runner length here.
http://www.emeraldm3d.com/articles/cat/projects/post/emr-adj-length-intake/

Ooooh! Thank you!

---

Kirk Coughlin
Woodbury, MN and River Falls, WI

Quemadmodum gladius neminem occidit, occidentis telum est.