Type IV upgrades and FI, Where's the cut-off to carbs? Options

[ClayPerrine]

Anyone know if the chip in the stock 914 ecu is soldered in?

Anyone had a look at the content on the chip?

Shouldn't be that hard to change the fuel table...I have mapped VW Digifant earlier, and the 914 ecu cant be any harder?

The 914 fuel injection box is not really a computer. The D-Jet is a bunch of 1960s era big assed transistors. The L-Jet is a little more refined, but there is no real "processor" and there is no such thing as a programmed fuel map. It has a bunch of transistors, resistors, and capacitors that control the fuel map. Changing the fuel map involves replacing resistors to change the mixture curve.

Welcome to the 1970s. (IMG:style_emoticons/default/biggrin.gif)

[914_teener]

Yep.....transistors...no integrated chip in there. (IMG:style_emoticons/default/shades.gif)

[seanpaulmc]

Hello World -

I hope you don't mind me bringing up an old tread. I'm interested in the conventional wisdom of how far the D-jet can stretch to larger T4 builds.

I saw these youtube videos and it got me wondering if D-jet would work up to larger displacement T4 engines say up to 2270. These videos say 2.4L but I wanted to know what the experience here is.

Porsche 914, 2.4 with Bosch D-jetronic - It lives!

Porsche 914 2.4 with D-jetronic

The other relevant 914World thread I found was...
What is the largest displacement engine - FI

It seems the 2056 with D-jet is very typical.
Can the D-jet be made to work with the 2270? What modifications would be needed?

Know that I am a ways off from getting this sorted. Just dropped the engine yesterday - thanks Ian - and have some serious body repairs to make before getting to the motor. I certainly don't want a built motor sitting around with nothing to put it in. As I stated at the onset, would like to hear the current consensus about the D-jet on the bigger 4's as I have some time to ponder FI vs Carbs as I work to put this body back together.

Since we all love pictures...
















Thanks in advance.
Sean

[Bleyseng]

The 2056 with Djet is the best of both worlds as that's why most go with it. It can be in the 110 to 125hp range with the right combo of cam and heads. Its easy to build and runs cool.
The bigger 2270 means more work on everything to get it to run right and cool. Anywhere from 150-175hp...

My question to you is how big do you think you need to go as 125hp is alot in these little cars. Especially if you haven't addressed the suspension, brakes, rust etc.....

[JamesM]

Even D-jet on a totally stock car can be frustrating these days with the age of the system and the lack of parts. I used to be a d-jet purest but dealing with that system has become much, much more difficult and more expensive over the years.

If "upgrade" is your ultimate goal I would forget about d-jet, at least all the electronic pieces of it (the actual intake, throttle body, etc work great with a Megasquirt setup) even if you get d-jet working "well" you are still going to be limited in what you can do with it engine wise.

Ditch the d-jet and go modern injection and a 2056 properly built to take advantage of it is looking more like 140hp + much nicer manners.

[JamesM]

https://www.youtube.com/watch?v=gINH-EDVKdM

https://www.youtube.com/watch?v=xtsmebEX25k

[ClayPerrine]

If you want a stock looking FI system, but have some money to spend, think about this:

Take a D-Jet system, and replace the insides of the "computer" with an MS3-Pro module. Replace the trigger points with a trigger wheel, the injectors with more modern ones, hide a modern TPS inside the D-Jet throttle switch and hide a modern MAP sensor inside the MPS. Lastly, gut the aux air regulator and put in a IAC. Optionally, use a wide band O2 sensor to run the auto-tune, and fire the coil from the ECU.

Fully programmable FI, and it would look dead stock. And it would work with any displacement motor you could bolt it onto.

[scottthephotog]

Just some thoughts. I've recently been tuning my 2056cc with D-Jet. I was running rich and with an AFR meter I discovered I was running about 10:1 AFR across the entire throttle range. I have since leaned it out.

I've seen people say D-Jet was used on up to 2.4L engines and with how rich I was able to get the mixture, I'd imagine you could actually get it to work with a 2270 engine. As others have said, it will take more to keep that larger engine cooler.

[seanpaulmc]

Thanks for the replies. Let me add some input for the questions so far.

The motor pulled from the car is a 2.0L with Italian Weber 44s on it. It ran. Just not well. However, I didn’t drive it much due to the (unsafe) rust issues. Which means I have a set of 44’s that I could use (if rebuildable) on a 2270 and I am told are too big to get tuned well for 2056 let alone the engine coming out of the car.

I also have a full D-jet system for a ’74 and most of the makings for a second D-jet system also for a ‘74. One FI harness is a core for sure and the other is known to be working but should be replaced for reliability because of its age.

A stock set up isn’t my concern. In some sense having the right package is. I want the injection system to work well for the engine configuration. Just trying to size up what that might be which has led me to this thread and my questioning the D-jet capabilities. I very much appreciate the feedback thus far. 140 hp with a modern FI system on a 2056 is a very good argument. However, by the time I get through the body there may not be additional funds to lay into a modern FI system.

[thelogo]

If you wanna step up the performance

Djet isnt your friend.

You have to decide between the daily type driving ( djet)
Or balls to the fire wall Aryton Senna style driving
( carbs) (IMG:style_emoticons/default/smile.gif)

There is no life in between

[GregAmy]

There is no life in between

That's not necessarily true...

(IMG:http://www.914world.com/bbs2/uploads_offsite/cdn11.bigcommerce.com-15565-1594085638.1.jpg)

(IMG:http://www.914world.com/bbs2/uploads_offsite/1.bp.blogspot.com-15565-1594085638.2.jpg)