Bosch K-Jetronic Injection

[zukirider21]

Also known as CIS (continuous injection system). Used on many Porsche's, Volvo's and Volkswagen/Audi vehicles. I was just looking around and stumbled upon this system, and I'm absolutely amazed at what a simple, elegant, foolproof setup this is. For those who are unfamiliar, here's a nice little overview- http://www.volvoclub.org.uk/tech/fuel_injection/k_jetronic2.shtml

Next, I got to thinking. Wouldn't this be a fairly universal system? shouldnt it feed ANY engine (roughly the same size as the injection system was originally intended for) a mixture of fuel and air at the stoichiometric ratio, without any fussing with adjustments or anything? Regardless of where the air's going, it measures it, and pumps out the necessary amount of fuel, right? Sounds good so far, right? Now what if one of those little AFM's isnt enough for what i want? Seems like i should be able to run two afm's, with two sets of injectors (right next to each other). Just think, injection even timing doesnt matter (continuous injection), and the airflow meters would either work in unison (equilibrium), or even if they didnt, with one actuated farther than the other, it should still work out, no?

Okay so now that my confusing fuel injection theory has probably got you thinking, here's what I'm really wondering about. If i were to rig up this system on a ford 2.3t, would it work under boost?? i dont wanna be messing with efi, and finicky blow-thru carbs are out of the question.

I'm really interested because i love simple things, and i think it would be sooo badass to build a lowered 2.3 street ranger with this ingenious system, and a turbo.

 

[martin]

That's an interesting question. The last time I worked on one of those systems was years ago and it was on a n/a application, never thought at the time what would happen if you blew it. Wish I could remember how the pressure regulator is handled on these systems as that would be a key factor in what happens to the mixture when boost is applied.

 

[zukirider21]

well the fuel is at a constant regulated pressure of i think around 75 psi. so i dont think boost should inhibit fuel delivery too much.

oh and apparently this system was used on some oem turbo cars so this might just work out...

 

[zukirider21]

i went and read this great overview:

http://www.scribd.com/doc/3299223/Bosch-KJetronic-Fuel-Injection-Manual-

and found this to sound pretty promising:

"The intake air quantity serves as the main actuating variable for determining the basic injection quantity. It is the appropriate physical quantity for deriving the fuel requirement, and changes in the induction characteristics of the engine have no effect upon the formation of the

air-fuel mixture. Since the air drawn in by the engine must pass through the air-flow sensor before it reaches the engine, this means that it has been measured and the control signal generated before it actually enters the engine cylinders. The result is that, in addition to other measures described below, the correct mixture adaptation takes place at all times."

 

[martin]

I do remember that there is some degree of adjustability for mixture but if memory serves correctly it normally runs around 15:1 (this was on a volvo I4) and the adjustment was quite limited. If you turbo it you need to aim closer to twelve. If the fuel pressure remains constant it will deliver more fuel under a high vacuum situation than it will when pushing into a pressurised manifold. The later electronic systems can easily correct for this but are helped by the manifold connected fpr that reduces pressure when under vacuum and goes up to full fuel delivery pressure when pushed by boost pressure. This is going to bother me now so I guess I'll go searching through my old books to find out how they did it on the factory installations.

 

[WNY964x4]

this system was also used on the Ford 2.8 V6 , it was used in some British sports car whose name escapes me right now , we had one in the senior shop at school for a few weeks

the car was a TVR 280i , it used a K-Jetronic injected 2.8

 

[zukirider21]

hmmm just the thought of the utter simplicity of this system might just drive me crazy enough to go and try it!

 

[martin]

Go ahead and do it but keep us posted on the progress, pictures will be a must.

 

[Hopman]

this system was also used on the Ford 2.8 V6 , it was used in some British sports car whose name escapes me right now , we had one in the senior shop at school for a few weeks

the car was a TVR 280i , it used a K-Jetronic injected 2.8

It was also used on the DeLorean too. But that version required a flux capacitor and 1.21 jiggwats to operate correctly at 88 mph.

 

[superds]

It was also used on the DeLorean too. But that version required a flux capacitor and 1.21 jiggwats to operate correctly at 88 mph.

I think the early '80s Chevy Citation also used a similar mechanical fuel injection system. Now that was a car you could pick up the ladies in!

 

[martin]

And another serious thread goes down the toilet. Incidently the flux capacitor had nothing to do with the injection system it was connected into the ignition and hvac systems.

 

[Hopman]

No, seriously, the DeLorean ( the one WITHOUT the optional time travel package) did have a Jetronic equipped PRV V6 producing about 120 bhp.

 

[LittleHorse]

Don't know much about K-Jetronic but I believe it was the previous phase of the L-Jetronic, which was a HUGELY popular FI system in the 70s and 80s, including BMW and Datsun/Nissan. The Datsun 280Z and 280ZX used it, with and without turbo.

 

[martin]

There's a huge difference between the two systems. one is purely mechanical and the other is computer controlled.

 

[zukirider21]

hmm not sure about the l jetronic, but the reason why i like the k jetronic is because its all mechanical. it looks like i'll be able to piece it together cheaply enough with used parts (stuff is pretty abundant). so when the time comes (i still gotta finish my dd and find a 2.3 reg cab, short bed, 5spd, 2nd gen ranger lol)

but as it looks right now, i AM going to give it a shot.