whats the volumetric efficiency of a tdi engine

getting some progress done today, im off from school and trying to pick a turbo. im looking at the compressor maps. whats the aproximative VE for our engines?? im thinking 75% tops. anyone have a idea?

If you want to do the math

“Volumetric efficiency. The volumetric efficiency of an engine is the ratio of the volume that would be occupied by the air charge at atmospheric temperature and pressure to the cylinder displacement (the product of the area of the bore times the stroke of the piston). The volumetric efficiency determines the amount of air available for combustion of the fuel, and hence influences the maximum power output of the engine.
Volumetric efficiency is actually the completeness of filling of the cylinder with fresh air at atmospheric pressure. The volumetric efficiency of an engine may be increased by enlarging the areas of intake and exhaust valves or ports, and by having all valves properly timed so that as much air as possible will enter the cylinders. Since any burned gases will reduce the charge of fresh air, the supercharging effect gained by early closing of the exhaust valves or ports will reduce the volumetric efficiency.”
If you want to work the math, the Bently manual lists the stroke for the BEW engine as 95.5mm, and the bore as 79.5mm with a compression ratio of 19.0:1.

At what rpm?? At 2K you could assume 90% falling to 80% at 4K....

i have a bit of trouble accepting 80% for some reason. if it is ill be happy but these heads are horrible. i wanna know VE for 2000rpm, 5000, 55000

im getting good progress done all the math is done now i have 7 maps to pick a turbo LOL

i used .75 at 5000 rpm in the formula

It can be tricky to work out , you have to do flow testing to find out the restrictions eg valve size , valve timing , intake tract size ect , the list goes on and on .

Since our cars are cars are forced induction we can over come a lot of restrictions .

With out the turbo , 75% max at 2k , i recon with 2 bar boost it could be around 85% anyway at 4500

from the compressor maps that i have from the garrett site half the gt20s shouldnt even be running at 25psi thats what im looking for. i wonder what the compressor maps for the vnt17 and vnt20 are. i have a fealing u guys are running wayyyyy out of the maps. from the maps the best choice should be the gt2259 ( its to bad they only provice the map for the .41 AR tho)

For purposes of selecting a turbocharger, just use 75%. It will be close enough. You do not need to split hairs with the numbers in order to do that.

cant figure out what would spool up faster the gt20 with a smaller wheel and larger ar or the gt22 with bigger wheel but way smaller ar (gt 20 ar is around 50-56, gt 22 ar is .41. i should ask my friend he knows a bit more then i do

I always thought that when you have a pressurised intake system that volumetric efficiency was close to 100%. Valve overlap will help rid the chamber of burned gas. Gil

What valve overlap. None on a tdi....

The presence or absence of any forced induction has absolutely no bearing whatsoever on the true value of volumetric efficiency of an engine by definition.

It is my understanding that an increase in intake pressure will increase VE.
Many engines use valve overlap to increase VE. (not ours)
The trick to getting power out of any engine is to make sure the cylinder is fully charged at high RPM where VE decreases.
Events happen so fast in an engine that the gasses don't have enough time to fully charge the cylinder without help at high RPM.
If you are talking about the engine on a test stand and powered by an electric motor the VE of the base engine can be measured. The higher the RPM the amount of air will drop off a lot.
I think the biggest problem for power is in the injectors not being able to operate in the high RPM area. Spark ignition in a gas engine used to be a big limiting factor. Valve float is another problem as the cams won't be able to open and close properly due to the springs design. (There are always limits)
SuperCHARGING or turboCHARGING are a great way to increse VE IMHO.
...........Gil

ok boys ill explain why i need the VE u put VE in a formula for a engine to be able to find the proper turbo to mate with that engine. thats all lol. the head sucks automaticly VE on this engine would be wayyyyy lower then say a aeb 1.8t or a b18 from honda. u guys might not realise but our cars probably have the worst head on any car on the planet right now

BlakGolf said:

ok boys ill explain why i need the VE u put VE in a formula for a engine to be able to find the proper turbo to mate with that engine. thats all lol. the head sucks automaticly VE on this engine would be wayyyyy lower then say a aeb 1.8t or a b18 from honda. u guys might not realise but our cars probably have the worst head on any car on the planet right now

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Apples and Oranges. In this case, Gassers and Diesels. I almost forgot,
Mountains out of Molehills.

You are making this much harder than it needs to be.


Bill

its cuz im a perfectionist im very picky about what goes onto my toys

Dude, you're overanalyzing this.

Yes, the TDI cylinder head looks restrictive, but we are talking about an engine that has peak power at 4000 rpm. It does not NEED big ports. And, the shape and size of the ports is critical for swirling the intake air, and this is *essential* for a direct-injection diesel engine.

Just plug in 75% for the volumetric efficiency and your turbo selection will come out fine. Whether it's 70% or 80% won't change the selection you make by anything that's enough to matter.

Where swirl becomes less of a critical factor and moves the importance factor by at least -50% for an Di engine is 1/ in a fuel system that boasts 1700bar + pressure 2/ a more central positioning of the injectors in conjunction with the piston and 3/ the use of multi holed nozzles and a multi staged injection event......

I didn't know your name was John. B. Heywood.

LoL!!!!

GoFaster said:

Dude, you're overanalyzing this.

Yes, the TDI cylinder head looks restrictive, but we are talking about an engine that has peak power at 4000 rpm. It does not NEED big ports. And, the shape and size of the ports is critical for swirling the intake air, and this is *essential* for a direct-injection diesel engine.

Just plug in 75% for the volumetric efficiency and your turbo selection will come out fine. Whether it's 70% or 80% won't change the selection you make by anything that's enough to matter.

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Actually swirl is not essential for DI engine. I have been experimenting with getting rid of most of the material in TDI heads that create the swirl, it seems that the swirl effect is really only effective at engine speeds under 2500rpm, that said I havent had luck with completey deleting the swirl port and mainting good low end revability, but man does it flow up top! The swirl port is a restriction in the head no doubt, and there is a line, but I wouldn't say it is a fine one, were decreasing the swirl effect is desirable.

The big power cummins guys with big ported heads have virtually no traits of a swirl port left.

Hi P Performance........i see your on a slight mission tonight.........Can you do me a cam and one of these style heads.......................................................................................ooooops sorry my mistake i already have them .

mojogoes said:

Hi P Performance........i see your on a slight mission tonight.........Can you do me a cam and one of these style heads.......................................................................................ooooops sorry my mistake i already have them .

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Yep on a mission to educate, I'm sick of hearing all this crap based on theory or what they read or heard here or there. Whats been done to your head MOJO?

Passenger Performance said:

Yep on a mission to educate, I'm sick of hearing all this crap based on theory or what they read or heard here or there.

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Hi Dave,
I keep meaning to ask you a few questions:
1) What is your formal education - training regarding VW products?
2) Where have you received/gained your experience?
3) What dealers/tuning shops have you worked for and in what capacity?
4) What certification/ government tickets do you have and from where?
5) How many years of formal experience do you have in regards to tuning VW's, specifically TDI's?
6) Where are your tuned/completed VW TDI project cars competing in, on the 1/4 mile, track ect.?
I gladly welcome another experienced tuner to the market - but you do need to prove your credentials to be taken seriously in this cut throat market.
Leigh-Anne

LA@JSPerformance.ca said:

Hi Dave,
I keep meaning to ask you a few questions:
1) What is your formal education - training regarding VW products?
2) Where have you received/gained your experience?
3) What dealers/tuning shops have you worked for and in what capacity?
4) What certification/ government tickets do you have and from where?
5) How many years of formal experience do you have in regards to tuning VW's, specifically TDI's?
6) Where are your tuned/completed VW TDI project cars competing in, on the 1/4 mile, track ect.?
I gladly welcome another experienced tuner to the market - but you do need to prove your credentials to be taken seriously in this cut throat market.
Leigh-Anne

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Its a shame you have become so hateful but I will answer your questions anyways.
1. I am not really sure how to answer this one, is there a training course for learning about vw parts?? I've built and repaired plenty of mk1-4 cars and am generally familiar with vw's, I don't particularily like vw's but their diesel engines are much more affordable than mercedesbenz(way better engines) so they are my play car of choice.
2. I have gained my experience from a head porter thats been in the industry for 20 years, he's flowed heads for everyone from porsche, to subaru, to honda, to toyota. Hes extremely gifted and I am very grateful he has taken a liking to me and has been pacient and kind enough to share his work with me.
3. I haven't worked for many shops, I was a mechanic at goldstar mercedes benz, but mostly my jobs have been in welding and fabrication, both for performance engines and industrial applications, I work as a private contractor.
4. Currently none, I just recieved my testing date to challenge my welding C ticket, so in january I should be C ticket certified, if I can get in (long wait times) I will be going to school for my B and A tickets as well. I have no current interests in becoming certified at anything else at the moment. Unless a manifold design or performance diesel class opens soon
5. Specifically tdi's and vw diesels, 2, gassers 5.
6. I havent completed a TDI project yet, not that it matters, diesels are just air pumps, I have had plenty experience with vw idi. I hope to have my personal mechanical tdi featuring my new manifolds, custom cam, ported head, 14mm pump etc done by the end of the year. As for IDI's there are a lot more of those floating around. I don't specialize in or advertise to building cars, it happens but I am more interested in flowing head, making manifolds, downpipes, charge piping, and welding and machining.

I've got a health & safety certificate plus a basic and advanced food and hygiene certificate's.................do these count.

Quote...."Whats been done to your head MOJO?"................most of what you describe to a certain degree!!

mojogoes said:

I've got a health & safety certificate plus a basic and advanced food and hygiene certificate's.................do these count.
Quote...."Whats been done to your head MOJO?"................most of what you describe to a certain degree!!

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Yeah obviously they just want to make me look bad because I don't have government certifications, pretty lame and childish but whatever, its not like any certification is gonna make you a certified manifold builder anyways.

Mojo I would like to heard more about your engine.

Oh yeah I also have my forklift operator ticket and first aid This is actually getting pretty funny. You (js performance) sure are acting pretty threatened by someone who you think doesn't have a clue what he is talking about.

Passenger Performance said:

Oh yeah I also have my forklift operator ticket and first aid This is actually getting pretty funny. You (js performance) sure are acting pretty threatened by someone who you think doesn't have a clue what he is talking about.

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Sorry Dave, my questions were not meant to be offensive, I just wanted you to clear up a few facts for me - which you have done. I find it very disturbing that you think me asking what your credentials are, are ‘hateful’. Jose, Ian and I have customers that have asked the exact same questions that I have asked of you - I have never found these questions offensive as a well informed customer is a happy customer. For you to find my query 'hateful' more than answers my question as to your knowledge of the product.

By the way I do find it insulting when you bash innovators and reputable tuners such as Charlie@Kerma, Jose@JSP and others - these men and companies have proven themselves in this industry and have the credentials to back up there claims - YOU DO NOT.

Dave you are like a parasite in the tuner market and we are in no way threatened by you or your back yard operation - I am just tired of you giving people the impression you know more than you actually do. A little knowledge in the wrong hands is a dangerous thing and you keep proving this point time and time again.

We would have more respect for you, your ideas and operation if you stopped criticizing other reputable companies and started producing something tangible. You might also find that these companies may be of assistance to you in the future – but due to your attitude, I think most of these companies would not give you the time of day. No matter how much you think you know there is always someone out there that is more knowledgeable. You always get more with honey than you do with vinegar.

Please take this advice seriously, as it is given for free and with no ill intent.

Leigh-Anne

Oh I'm not offended, I just think its funny, because no one can prove the theoiry is wrong your guys have to start grappling for small things that make me look unreputable, I agree experience is good, but it doesn't actually mean you know anything. Ok So I have only been tuning vw diesels for 2 years, but you know what, I started playing with ported heads, custom camshafts, manifolds, custom intercooler setups in the first month. I havent bashed jose or js performance before so I still do not know what the you guys are so bent outa shape for, just chill out I have said it many times I don't have a problem with you guys, but now I am starting too. The reason I spoke up about charlies manifold is probably pretty damn clear with the evidence I used to back it up. If I came in here selling performance bricks, put in your passenger seat and gain 10WHP, people would be all over my ass because obviously its a load crap. I am fortunate to be able to tell poor flow and good flow, apparently not a lot of other people do so I have been explaining myself every step. I mean good grief the people that are reading that thread are learning so much so quickly, it doesn't get better than that. I was never bashing charlie, I still have nothing against him, I was giving very helpful advice and truly want to see him make a better manifold, he turned into a pissing match by name calling. Its that simple.