Roland Kunz? - Volumetric Efficiency

[pbanders]

Roland,

Do any of those German references you have on the 914 discuss the volumetric effiency of the 2.0L 4-cylinder motor? I would be very interested in seeing the Ve vs. engine speed relationship.

thanks,

Brad Anders

[Roland Kunz]

Hello

No donīt have numbers but Porsche did focus on a maximum touqe curve.

Just some maybe helpfull links for not so deep inside the engine terminology:

For Beginners:
http://www.tpub.com/engine1/en1-105.htm

For Beginners or Hot roders:
http://www.ponycarburetors.com/calculating_cfm.htm

Expert mode:
http://eric.virginia.com/install_university/installu_articles/volumetric_efficiency/ve_computation_9.012000.htm

[pbanders]

Roland,

Thanks for the references. I have a web page on the analysis of the ECU:

http://members.rennlist.com/pbanders/ecu.htm

We've just finished analyzing the speed compensation circuit, which implements the Ve correction. I was looking for the Ve curve for the 2.0L engine to compare to the derived waveform from the ECU. I'd also like to have the Ve(engine speed) relationship for a spreadsheet that I have where I model the injection pulse duration of the 2.0L engine.

thanks,

Brad Anders

[mejulihn]

Hold on to your pocket protectors out there -- this one is not for average DIY!

[vw@micron.net]

If you have a dyno printout with horsepower numbers / RPM is it no possible to then calculate airflow needed to generate each horsepower. Compare those numbers to the theoretical numbers that a 2000cc engine should pump at each RPM, and you have VE. You could plot a curve of VE with those numbers.
Steve

[pbanders]

Originally posted by mejulihn:
Hold on to your pocket protectors out there -- this one is not for average DIY!

Yes, Toto, we're not in Kansas any more!

Brad Anders

[pbanders]

Originally posted by vw@micron.net:
If you have a dyno printout with horsepower numbers / RPM is it no possible to then calculate airflow needed to generate each horsepower. Compare those numbers to the theoretical numbers that a 2000cc engine should pump at each RPM, and you have VE. You could plot a curve of VE with those numbers.
Steve

Good idea. The third reference that Roland quotes provides a direct method for determining VE. On our cars w/o scan readouts it's more difficult, but I'd thought of the same method myself, and it should work. You need either a MF or AF sensor on the intake of the air box to do it.

Brad Anders

[John Rogers]

I think Roland's statement about the focus on torque is very correct. When I had my 2.8l four built, the shop said it will have lots of torque, meaning it will come out of a corner better than a six? I was a little curious, but at the time trial San Diego reigon just put on my "little four" could easily stay with most any six up to 100 MPH or so! Of course then they pull away but by then we have run out of room and have to brake so I was very happy! The head design is not the best and that is why all the aftermarket shops such as Pauter or Autocraft use a type 1 head design and domed pistons which is much more efficient.

[pbanders]

Originally posted by john rogers:
I think Roland's statement about the focus on torque is very correct. When I had my 2.8l four built, the shop said it will have lots of torque, meaning it will come out of a corner better than a six? I was a little curious, but at the time trial San Diego reigon just put on my "little four" could easily stay with most any six up to 100 MPH or so! Of course then they pull away but by then we have run out of room and have to brake so I was very happy! The head design is not the best and that is why all the aftermarket shops such as Pauter or Autocraft use a type 1 head design and domed pistons which is much more efficient.

John, is your 2.8L carb'ed or FI'ed?

From what I can tell about this stuff, the key factor here is the shape of the VE curve. Going for a high-lift, long duration cam probably increases the peak VE, but causes the low RPM VE to be quite low. Going for the milder cam with a big displacement, and good peak VE via head work and oversized valves probably produces a more useable torque band for most applications. Peak HP is mostly overrated in comparsion for engine flexibility - it's not like we're on a superspeedway or at Le Mans!

Brad Anders

[John Rogers]

The engine has Weber 48's and has a set of heads that are welded/flowed and have 48x38 valves, dual springs, etc. The cam is a Crower special grind that makes all the torque at about 4500 RPM but max power comes on at about 6500 RPM! The cam uses type 1 lifters, steel push rods and Pauter 1.5x1 roller rockers so the cam ramp up is mild in relation to the amout of lift/duration it has. As a side note, the lash is set HOT and is .004 intake/.006 exhaust to prevent uncontrolled clearance growth.

[Roland Kunz]

Hello

Sure I have seen your page and allready linked that.

I have some stuff about G-Jstr and just looking now if the University have some more and something in english.

Well there are to much things I come on my limits in terminology and descriptions.

I just think anout how to descripe the 72 on ECU change with lets say buffered runing injectors.

VE is direct relatet to the vacuum on the ports. A old sentence is that VE follows the middle pressure curve with is nearly equal to the torque curve. Now this is WOT under full load the partial throttle VE is also very interessting. VE max makes the power but VE/%load makes the drivability.

Well The D-Jetromic was used on the boxer becourse the lon runners gave now benefits versus the carb version. Normally the engines had to fit the flat variant version.

So VW coulnīt use high plenums to boost VE.

Now the 2,0 914 was intentet as Porsche only and Porsche made a new plenum with optimized runners and better flowing heads.

The 2,0 100 HP type 4 had more tourqe and on a wider peak then the 914/6.
The engine also had lower consumption and cleaner exhaust gases.


Well the background is very simple as the engie has comperable bigger combustion cgambers that will have nearly equal friction surface the drivetrain is much lowerr power demanding then the Dual OHC & with a oilsumppump that sucks more power then the complete type 4 gear.

If you look ate the 944 engines you will see the same again Compare the 944 S2 with the euro 204 HP 3,0 SC. And add the 986 in that row.

Ups off topic again but engeneering isnīt simple..

Now a other basic on the type 4 D-Jet is that the d-Jetronic will not like to peaky cams. The unit uses the vacuum in the plenum to run the ECU. the higher the total amount the finer the system can work. Tuned engines or worn engines have not enough vacuum to work in a satisfying range.

Tuning the ECU to a hot cam is very time robbing and you need to find the fiting Sensor.

I helped nyself by using a ventury jet booster from a 1,8 GTI but had not enough patience to make a 260° cam work perfect with the ECU, maybe on a 2,4 it would have worked ( Oettinger runed his 130 HP 2,4 kit on D-Jetronic ).

Using carbs is possible and a good setup with medium tall manifolds will keep the low end boom while adding some bricks at 4000/min. I prefered the Solex.

Now a other thing is interessting as Porsche didnīt have much time to develop that engine they used a old angine and copied it. They looked very sharp at the 2,0 547 Carrera 2.

If you ever worked on them you will be surprised how familar it looks. Same bore and lift and also similaritys on the valve size and the combustion chamber.

Mow the old 547 2,o had twin plug and other goodies and put 130 HP on the flywheel. If you follow the path you will end at usable 115 HP. 130 HP needs to rework the layout with higher compression and larger intake valves with harder springs andall the stuff that runs into further work.

The streeet usable limit for non Buses is around 160 HP. But this is motronic equiped and the rest stuff costs real money too.

Most go to the 2,4 Oettinger or the even higher displacement units.

Not to forget most run catalyc converters in germany.

O god, just an other long thread about a two letter word that will only be followed by rocket sience technicians.

Grüsse

[Bleyseng]

No, Great Post! These posts makes for some good reading. This helps me to understand some of the background of these 2.0l motors.

Geoff

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76 914 2.0L

[vw@micron.net]

Roland, have you heard of Power Tuning Parts? They are building most of the components for my T4 engine. 48x40 welded six stud heads, 39 gram lifters, 12 blade low mount Carrera cooling system, BAS merged exhaust, quad 48mm throttle bodies, Autronic SMC ECU with sequential injection, and more goodies. It is going in my 63 Ragtop beetle with 901 5 speed for gears!
Steve

[Roland Kunz]

Hello

No beeing in germany I only know FAT and SCAT. Now the german marked works an other way then the US marked.

Most cars are sleepers despite the bigger tires. Depending on the year we must also have catalyc converters. Also the beetle race Cup has rules restrict pollution ( catalyc and noise ).

Most germans are not to much interesstet into big power. They fetch a 130 HP 2,0 injectet and drive them hard.

Some 10 Years ago I met a american who had a tricked out ( Eurorace or stephens machining ) 2,7 type 4 in his bug.
with 48 mm Webers, polished dog hut, louverd stainless and all the thing that americans need to glow up there eyes. He said the thing pulled 200 HP on the dyno. One of my friends has a 2,4 oettinger back then ratet at 130 HP with the Porsche 356 40 mm Solex.
Well he build that engine himself and it was basically the Willibald layout.

We meet a weekend to drive up to Hanau for some Drag runs at the NHRA meeting. After 50 kms on the highway at some 200 km/h his car feel back and we slowed down and stoped at the next spot. He had a massive overheatet engine and backfiring carbs ( His head was distorded and the valves didnīt close complete ). I cooled it down with my fire extenguisher and jumped on to check the timing. After some fiddeling the engine came to life and we moved on at slow 120 km/h as he made the pace.

At the races he made two runs but didnīt feel comfortable. After some fideling we decided to have the car parked and fetch an other curved distributor and new sparks for the way home. I also needed a synchronizer, jets and tools to set the valves. So off they went, my friend in his 130 HP 1303 blasting down the highway at full load with the needle far in the red rev zone. They fetched the parts some tools refilled the gas and where back at the evening. He managed a 80 mph average with refueling.

Now the story is after we fixed and detuned the 2,7 he was on the next event, well prepared and on the first run his camshaft sheared off in the middle.

Now the background is you canīt sale here a "american" type engine that will run like hell and can cool down after a 1/4 mile. In germany the people somtimes trop the hammer untill they need a refill or someone blocks the fast lane.

If you donīt have a thermal balanced engine and did your homework the engine will be frolic and your reputation as engine builder goes down south.

Now reading your list shows good parts but you have to know what you want.

Six stud is important as the heads will blow off after a while if you cross some 130 HP.

You can manage to make a high reving type 4 good enough for 7000/min, but you better go to a more low rev puller.

Well that assortment reminds me of my favorite US Car Magazine "Autobuff" where the owner countet the parts down in one row and the claimed FP from the saler in the other and then after you countet all togehter they had a 289 with a 1050 cfm double pumper, redical ports, headers, Accel, Crane,,, you know, under the line the engines allways had 500 HP by adding the bolt ons togehter.

Grüsse

[Dave at Pelican Parts]

Yeah, the HP claims always make me laugh. Especially when someone just adds up the numbers in each ad to figure out how powerful their engine is. In the US, the biggest victims of that kind of selling seem to be the younger owners of Japanese cars. Some of them apparently think you can reduce a car's quarter-mile time simply by putting some stickers on the car, too...

Anyway, I had thought that Power Tuning Parts was a German firm. I never did really research them, so I don't know for sure.

There seem to be a good number of people running 2270cc motors (96x78), partly due to Jake Raby. I read a post on the Shoptalk Forums BBS by a customer of his that took his 2270-powered Bug to a chassis dyno. They ran off a 165 HP run--and that was at the rear wheels!! And the engines are (at least in theory) built to stay together for about 30K miles, from what I've read. Then the heads come off and everything gets checked and cleaned up.

I tell ya... If I didn't have to meet smog requirements and I didn't care about what autoX/time trial class I ran in, I'd probably have one of Jake's motors in my car right now!

--DD

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Pelican Parts 914 Tech Support

A few pics of my car: http://www.pelicanparts.com/gallery/Dave_Darling

[Roland Kunz]

Hello

Wups never heard about them. Not to much interesstet into that, can ask around.

I see I have to find some german links.

Try www.tafel.com they also have a shop in CA and therfore must have english support. Tafel has that 290 km/h beetle. I think they dynoed 260 HP. Thats a melt down engine.

No coment about badge engenieering as this will hit american fundamentals.

I know a company who makes sponsor stickers, parialy for F1. Those stikers do hurt topseed and so they have special technic.

Mc Laren Mercedes needs some 20 000 $ stickers over a race weekend. 95% for the race cars. The sponsors pay them. The body has some complete lowered area to mount them flush.

F1 is grazy