FI HP Mods?

Thorkhild · Post by **Thorkhild** » Sat Apr 28, 2001 3:47 pm

http://www.914fan.net/djet.html most of your answers are there. other than replacing everything

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Thorkhild
1968 VW Blue Fastback
My Car Page

Bleyseng · Post by **Bleyseng** » Sat Apr 28, 2001 5:01 pm

Yes, I have read/used that article alot to adjust the FI. I was hoping to hear some of the "tricks" tuners use....

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76 914 2.0L

Bleyseng · Post by **Bleyseng** » Sun Apr 29, 2001 12:30 am

What are some of the everybody's tricks to get the most HP out of a 2.0l w/DJet?
MSD? Throttle body mods? Carbon fiber intake cover? cool Type R stickers? ChromeMoly pushrods?
Geoff

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76 914 2.0L

pbanders · Post by **pbanders** » Wed Jul 11, 2001 8:07 pm

Other than modifications, you're not going to get more power out of a totally stock D-Jet setup by simply tuning it. Check the Q&A part of my ECU article at the URL below for some things you can do and still retain the stock D-Jet.
http://members.rennlist.com/pbanders/ecu.htm

Brad Anders

Roland Kunz · Post by **Roland Kunz** » Thu Jul 12, 2001 5:56 pm

Hello

Well in 1990 I had been at Haltech and they showed a prototype to replace the 914 ECU.

The base thing was that the ECU could run every tuning stage by reding out the inputs and calculating the injector triggering. To get optimal results they would have added a lambda probe on each bank for optimal fuel ratio under all loads and circumstances. This would have allowed to use the D-jetronic vacuum sensor as a additional correction input but you also could have delete it.

I for myself did a 115 HP engine but after many hours fiddeling with D-jet I swaped to a Digifant/L Jetronic mixup developed basically by Holzapfel. Other tuners offered CIS conversions. I also had the luck to get some suport by Mr. Merkle junior ( Son from Mr. Bosch and also Porsche race ignition/injection developer and Beetle tuner )

My last stage was having weber throttle bodys and using a Alfa Romeo 33 1,7 QV aircleaner/barndoor setup. Never dynoed that setup but it run very fine trough the band and redline was strictly 6500.

Grüsse

Va914 · Post by **Va914** » Wed Jul 25, 2001 11:20 pm

So...did you end up with a L-jet F.I.? I have a 914 engine with the L-jet and have been thinking about going the d-Jet to get more out of the F.I

Thanks

Roland Kunz · Post by **Roland Kunz** » Fri Jul 27, 2001 12:20 am

Hello

The L-Jetronic is basically the better FI but the VW-parts have to much restrictions and you have to redesign the system. There is no solution out off the box and you just have to learn a lot and try different parts or use parts that have been known to work.

The D-Jetronic is eayser to adopt as long you have a mild cam and therfore stable and smoth (non pulsating ) underpressure.

The CIS also has a similar restriction. L-Jet and follow ups can be adoptet to higher HP/Liter rates.

In germany the tuners where working with CIS and L-Jetronic, even Motronic. I startet with D-Jet, was feed up inbetween and runed on Solexes. The later design was basically a adoptet Alfa Romeo 1,7 QV Injection with a modified Siemens digifant brain from a 2,1 Boxer. ( it just came cheap too swaped it against some old carbs as that engine went into a beetle )
The digifant is much simpler and easyer to manipulate the the Bosch LE-Jet or LH-jetronic brain. The lowside is it doesn´t have to much memory.
Fairchild DLS was sperate ( but not needed I just thought it would be better as I had a sharper cam ). Ignition used a Bus hall trigger with TSZ H module.
Smoth and responsive, good tourqe and good milage. Maybe with Haltech this coud have been improved but coudn´t afford that. Next step was to move a 2,4L into the car. Sold it to buy a 914/6 with a 2,7 RS engine.

I think I was hooked by the sound

Now your way is to adopt the L-Jetronic to your power. First is to find better runners, manifold and throttlebody ( 2,0 are larger ).
Then you need a suiting barndoor. Try it with your old brain and wireloom.

If you go for a smaller HP upgrade you can leave it for testing and adopt the fuelpressure. The barndoor can be modified to run richer too. To diagnose that you need a lambda probe and a A/F readout.

Grüsse

Va914 · Post by **Va914** » Fri Jul 27, 2001 11:41 pm

Thanks for the info.

I am going to use a web cam #73 and 96mm P&C's.

I have the A/F gauge and just need to buy a 3-wire O2 sensor.

I Have heard of guys adding resisters to change the readings from various sensors to the FI.

I'll look at new Fuel rails and TB's.

Thanks again

Roland Kunz · Post by **Roland Kunz** » Sun Jul 29, 2001 9:12 am

Hello

Yes the first step is to make a interface and run a the wires to a box in the interiour. The box has a set off potentiometers for fine tuning. So you can adjust the engine while you drive. But to have enough range you have to start with the lowest or highest senders ( NTC or PTC ), you only have your feeling to determine the mixture and you will hit on limitationas.

Then you try combinations with all possible EFI components get a 12V gas analyzer and after some days off work you have a nice compromisse fix the potis with hot glue and store it away ( there is neat space behind the passenger seat.

But if you go to wild the ECU and the sensors will run into there limits then you need a faster ECU and a better metering system. My goal wasn´t to make a EFI for the power seekers I wantet a bolt on replacment for the D-Jetronic that will also be capable for Tuning and for modern 3 way catalyc converters.

I found out that it was very hard to boost the power from the 2,0 euro D-Jetronic setup. That thing is very close to optimum in the range power to tourqe to feuel economy.

The Haltech solution would had been very nice but Haltech decided to distribut there system themself in germany and get themself the bleeding nose and I wasn´t to much interesstet for the price they where asking.

But in the last 10 years the price droped very fast and those things are now much better and easyer then before so I wouldn´t waist anymore time with hanging around and fiddeling.

Get a Haltech or other programable ECU and then try to get the best out off your system. If you hit on limits then just work out to remove them.

Don´t focus to much on the power search as any good carb setup will deliver the same peak power for less money.

Best TB for money is the 944 or the Audi/VW two throat units. But you still have the long runners with are very good for midrange power and are needed for the D-jetronic.

With a wild cam you need large ports to flow and small long runners to boost low end drivabilyti and take off tourqe.

I once had the idear to copy the Toyota system with dual runners and one shut off at low load demands. The good thing is that you can make them with cheap steel tubes. I startet a set but quitet it after the Weber throttle bodys and all other stuff worked real nice and smoth. There would have been some benefits but after several 100 hours you just like to drive and enjoy and the marked didn´t show up as most beetle tuners couldn´t use the specific 914 setup and most 914 drivers swaped to the Willibald CIS or EFI setup. If not they sticked to cheap Solex or Weber carbs. And the Oberland Mangold system makes the 3 way catalytic possible with normal carbs.

Grüsse

ray greenwood · Post by **ray greenwood** » Wed Aug 08, 2001 8:34 pm

I have a lot of agreements and disagreements here. I agree with pbanders to a point...about tuning d-jet. Yes... the mechanical part of the engine will take some mods...yes..there is little or nothing you can do to the ECU...BUT...there is a whole lot you can do with the information that is gathered by the sensors and sent to the ECU for processing. Modifying the sensors themselves is difficult, because of their design, but not impossible and usually not necessary. The sensor you can do a lot of tuning with...such as modify the response time and range...is the pressure sensor. It has three individual range settings inside(1) outer stroke length stop (2) inner chamber tension stop (3)inner diaphram depth stop. The throttle valve switch can me modified slightly for better sensitivity and smoother operation. You can use the later 5mm larger throttle body off of L-jet...bolts right up and has a better seal system (enlarge the inatke opening sheet metal) you can modify the vacume and PCV system (you will have to) to get smoother pulse response out of the pressure sensor. You can vary the fuel pressure to a degree, and add a fuel accumulator (huge difference) like CIS...but mainly for keeping the fuel pressure constant during acceleration....by the way the was one of the single largest acceleration power losses. Also when extreme heat or extreme cold affect power range...you can modify the resistance of the intake air temp sensor with a variable resistor...but I usually leave it unplugged (this makes a huge difference depending on how tightly controlled your fuel mixture is already). I have also modified the angle at which the injectors fire into the manifold...also a noticable difference. Trigger contacts...slot the screws...experiment with placement. This made a large difference in smoothness and response using the grind #73 cam..because it allowed the out of sync pair of injectors to inject a little closer to correct valve opening point. Also relocating by a few degrees the other stationary contact...and correspondingly modifying the wiper bridge on the moving contact...allowed the opposite pair of injectors to stay pretty close to where they need to be...a few other little things here and there made for quite a bit of tuning on the injection. Add that with a large number of tests on the ignition, plugs, valves, timing ,advance rate, retard rate, the excellent cam, a good port job, a good balancing job. I was able to extract 102 hp at about 4100 RPM on a 1.7 D-jet. Stock 8.2:1 domes (these little domes are more important for correct mixing than the increase in compression they create) 42x39 valves, grind #73 web cam and solid lifters ( by using a better closer method of adjusting the valves, I gained noticable response and HP...and it will be necessary with the exhaust overlap created by this cam) solid rocker spacers, 10mm valve adjusting screws, stock stroke, stock crank,stock..but carefully blueprinted oil pump, J series heads with PCV ports (these help to keep the rocker area cleaner and it runs cooler) Stock distributor P series (this has a better injection timing location than the more common B, G and H series)with a pertronix system and nology plug wires, #917 adjustable advance unit (very noticable tuning differnce) a modified mechanical advance underneath, Bosch W7DTC triple electrode plugs. I have found over time that D-Jet is superior in its tunability to L-jet, just because of the available adjustments in the pressure sensor and the trigger points. L-jet has very few adjustments. Ray

regis101 · Post by **regis101** » Wed Oct 24, 2001 9:01 pm

Very admirable, Ray

bowlsby · Post by **bowlsby** » Thu Oct 25, 2001 1:14 pm

So tell us more about the distributor/vacuum advance/reard modifications...

<<Stock distributor P series (this has a better injection timing location than the more common B, G and H series)with a pertronix system and nology plug wires, #917 adjustable advance unit (very noticable tuning differnce) a modified mechanical advance underneath>>

The dashpot on the dizzy has an adjustment screw...what does that do, set the upper or lower advance limits, advance rate or...?

How are the mechanical weights modified...weight removed or added and any significance as to where and how to modify?

Thanks for the good insight...maybe you could create a list of specific adjustments or procedures to follow of tuning tricks that worked/didn't work...

ray greenwood · Post by **ray greenwood** » Thu Oct 25, 2001 4:11 pm

The advance weights in the type 4 dist. are not very different at all compared to others and are easily interchangable. I have found some models that use an asymmetrical weight combination. Almost all of them have an assymetrical spring combination. The reason behind this is to get modest advances in two stages. Or else it acts like a 009. I have only seen one manual that listed the actual rpms that each weight "breaks loose" at with the factory springs. I made the smaller weight a little smaller by grinding. It is best to weigh them to keep track of what you are doing. There is a lot of slack/loosness in most weight sets that have more than normal amount of milage. Performance suffers from this. In the bottom of late water cooled dists. you find the wights pivoting on nylon bearings on their pins. This helps sensitivity a lot. You can also buy similar at a good hardware or parts store...especially electronic shops. They are used as insulators. You will have to clearance the holes in the weights. You should take all slack out of the loops on the springs, or else advance is happening without control. The #917 advance unit has a set screw that limits the total advance. This unit without screw will give up to 46 degrees advance depending on what idle timing is. In all dual advance units...you will notice a stop pin inside the bracket that corresponds to the notch in the arm. This is the retard stop. You can either bend that post one way or the other, or add to the diameter to adjust the stroke on the retard. Rteard is necessary to D-type on over-run at high speed. I set it to just retard ignition back to idle time...or else it retards back to about 10 deg. ATDC...this makes a big flat spot on fast throttle transitions, as the advance has to go a long way to kick in. You can add a set screw to a single or any other advance unit. Get a very fine thread metric 4mm screw and nut. Carefully drill a hole in the dimple in the center of the can. Fill it with cold water, hold it lightly with a c-clamp or vice grips and put it in a dish of water to keep it cool. Use a mig-welder to tack it to the can on three sides, let it cool, do the other sides. Spread a fine bead of J-B weld around edge...and file to make it pretty. You will need a lock nut. There are panel fasteners you can buy...but they have dificulties cause the metal is thin. As far as trigger mods, first get it even before you change anything. Most trigger points are set at factory. The real setting is slightly different for each engine. You will need to clean and polish the trigger contacts carefully. The resistance should ideally be around .8 ohms. Less is fine, but both points have to read within .1-.2 ohms to each other. Get an old plug to hook the VOM to. With the dist. out hook up one side and the middle contact, set on continuity...and slowly turn the rotor. Put an exact mark where each side injection begins..and ends. Measure their locations in reference to the #1 mark on the dist. make sure both sides start and end in the same length of range. Each trigger cycle is about 165 degrees. If one is longer than the other, which is rare, it is usually because the rubbing block is worn. Usually the right contact is worse. You can bend the fixed contact inward one or two degrees to make up the difference. I usually reinstall the distributor in the car, hook up the volt meter, turn the engine over by hand, until the VOM beeps. The #1 exhaust valve should just be at the point of opening. Not actually lifting the valve...but rocker is tight. This will tell you that the #1 and #4 pair of triggers is set in the right place. Use this reference with the before mentioned method, out of the car to set up the left hand trigger to have a mirror image start point, duration and end point. I have found an average of 20 degrees of difference in the average point setting...in relation to crank position, from where it should be. This is only about two degrees of deviation at the fixed contact in the trigger points, so it doesn't take much to be out of wack. It runs much smoother. If you use a web #73, you will find it runs better to slot the mounting screws on the trigger plate to be able to advance the injection timing a little to better balance with the lift and duration of the new cam. I am working on a twin cam experiment, that gives a little less potential injection duration...about twenty degrees, in exchange for being able to move the left trigger set into better range with the valve opening. They are 90 degrees out from factory on #2 and #3.There can be no overlap opening of the triggers. Each injection trigger must complete its cycle before the other is capable of actuating. More later on this. Most of this is really just blueprinting the advance system to clean up its operation. There are a few tweaks that need to be done to the breaker plate also...but more later. Ray

ray greenwood · Post by **ray greenwood** » Fri Oct 26, 2001 12:41 am

Thanks....I try to give away what I find for free...so more people will start using this injection again...so parts will become cheaper and more plentiful..for me! Hee hee...Also look at Paul anders web site...he is sharp and actually knows a lot more about the electronic workings and design parameters in the components than I do. Ray

JP Noonan · Post by **JP Noonan** » Sun Nov 04, 2001 11:20 pm

Uhhhhhhhh...

WOW!!!!!

Question: What else needs to be modified on a stock 75 2.0L, besides the manifold, if I put on the L-jet throttle body? Also would I benifit from retrofiting the pre 75 PCV system to my car which has no rocker vents.

Have you found a good, new, replacement for the PCV valve?

Thanks