Forum for competition engine enthusiasts. RIP Guy Croft 09/11/2020 - This forum will continue both as a source of information and as a memorial to Guy.
I have this little project going on to put K-jetronic 4-point injection system to 1500 Lada engine. I made this simplified intake manifold from copper to prevent leaks since my welding skills (nor the machines) arent quite what they should be.
I was wondering should I have put those four primary 31mm intake pipes further inside the 75mm pipe so that fuel injectors go bit inside the 31mm pipes, considering I dont have velocity stacks for em?
Obiously I could have placed the injectors close to manifold as its usually done but I think ill try this easy way first and see if it works at all.
Last edited by Ilkka on September 1st, 2006, 10:22 am, edited 2 times in total.
I think the little rectangle on the left of the drawing represents the injector, the pipe on the right is to represent the outlet of the manifold into the head port, and the big circle in the middle of it all is the plenum. This is as I understand it.
thank you,
Reuben
I think solution 1 will flow better, but there should be a large radius at the inlet to the port, otherwise the flow coefficient will be bad.
Some FI motorcycles (Ducati?) have similar arrangements with the injector centric to the port, but as I remember a bit closer.
An enthusiast who has researched what he's doing, picked a versatile injection system (K Jetronic), presented the project in very good detail, and done most of the hard work already.
Yes, Thomas, that is absolutely correct, we do not want to see a 'sharp edge entry loss' - either on a straight pipe entrey (1,2) or flared (3), the 'roll-back' radius design offered by Thomas is good.
Because your inlet runners stop where they enter the plenum I would sleeve 4 very short radiused bell-mouths into each runner and bond with Araldite 2002. You don't want them too long or you will generate a new loss in the plenum.
By the way, as you probably know, a light acid dip will clean the copper up nicely, cannot remember which acid, think hydrochloric or phosporic, check the chemistry first.
The factory manifold is a long way from perfect and requires its own set of machining in a conversion like this anyway.
On the other hand the earlier plenum chamber (last used on the Uno Turbo Mk1) does offer some interesting opportunities that reflect what is being discussed above.
The early plenum is cast in three parts with the main plenum tube seperate from the intake runners. This small detail allows the more adventurous to reshape the neck of the runner appertures in the main plenum to form a rolled profile. To do so on later plenums would require you to cut the main tube open and reweld it which offers a whole new set of problems. In such situations it is likely to be more reliable to create a plenum chamber from scratch and you gain the advantage of choosing the best design for your application rather than being dependent on the castings used by Fiat.
Hi
I have done a couple of K injection set ups now, first was on a 225 sloper. I made my manifolds out of Mild steel tube (Because that¢ž¢s what I had). I actually started in the same manor as you I was trying to copy off a SAAB. After playing around I ended up with something more like a Toyota starlet. Any way I ended up with some rules that seem to work ok as well as the normal rules like no sharp corners bends etc.
The closer the injector is to the valve the better or ‚½ the spray diameter back from the valve. I don¢ž¢t know the spray pattern that your injectors have but for example if the spray is at 45 deg and your port is 30mm in dia then 15mm back from the valve should be about right.
You could try an S bend so the tube comes off the head and strait down (or up) then levels out with the injectors taped in at the bend. But that would mean restarting again.
What I would do with what you have already is cut your tubes flush inside and pull your injectors back, more like a 4point throttle body injection, and possibly introducing some turbulence would be a good idea. There may be a bit of a problem with rich running at lower revs.
Or you could go the way like in the 70s and pull the hole setup further back from the head ie longer tubes and having the injectors about level with the end on the tubes but then this means that there is usually not a good air fuel mix in the chamber and a tendency to chuck back fuel when the valve closes.
I have very little time for this project now since i study in different town but i got the intake manifold made installation ready today:
I will sand blow it later if i get it working ok. Im not aiming for those every last horsepower yet since im basically on a zero budget but i hope this setup will work at least better than the original Lada carburetor from which i dont think much of.
