Alternate Fuel Injector Option?

[Sven]

I was doing some injector research and came across a type that sprays a V pattern at an angle of 30 degrees to the centerline of the injector body. I believe an ideal injector setup would direct the spray at the back of the intake valve. One thing that I am not sure of is if the spread of the V will now direct the fuel stream to the sides of the runners before it gets to the valve. In our D-jet log setups the injector is aimed directly at the bottom of the short stub intake piece. I currently run with the 4 hole type - which seems to atomize the fuel better than most. See the link below for the spray pattern options.

http://witchhunter.com/spraypattern1.php4

I found an engine section diagram in the blue books (unfortunately only for a carb'd engine) and drew in the rough location for the injector. If my assumptions are correct then the angle of the fuel spray pattern comes much closer to hitting the valve. The electrical connector would need to the rotated to the drivers side of the rail (which I can accommodate on my custom rail). I may experiment bit this Fall/Winter.

Any thoughts?

Any one have an engine drawing section with the log manifold setup?
Thanks,

 

[decoupe]

Interesting that the last comment on the Witchhunter page is that "It is usually best to use the same type of injector as was originally installed." which assumes that your engine is also stock. Is yours stock? - don't think it is.

All of the different injector patterns seem to be designed for specific manifold and valve assemblies (ITB, twin valve heads) or emissions. The only way to test your results would be dyno each one unless the loss/gain is significant enough to feel it (doubt this as you are likely chasing single digits here). You also might make more power but not start or run as well. Mpg might also suffer. The D and L Jet are both low impedance systems - does MS run those?

You are trying to overcome the angle of the injector boss in the D Jet log by sprying at a stepper angle by using the 30 deg fan. Without any qualifications to back it up, I think your current setup with a well atomized mix is better than the fan shape for the reasons you stated - interference with the runners before the valve. There is probably more to be gained by improving the air flow by porting than trying to aim the fuel at the valve. That's the route I would go.

The modern injector upgrade that was recommended to me to be used in late m30 engine applications (535i) were 4 hole atomizing patterns so I would stick with what you are using and look at the duty cycle to see if you are still within the 75 - 85% range at WOT.

Humble opinions,

Doug

 

[Stefan]

Interesting that the last comment on the Witchhunter page is that "It is usually best to use the same type of injector as was originally installed." which assumes that your engine is also stock. Is yours stock? - don't think it is.

All of the different injector patterns seem to be designed for specific manifold and valve assemblies (ITB, twin valve heads) or emissions. The only way to test your results would be dyno each one unless the loss/gain is significant enough to feel it (doubt this as you are likely chasing single digits here). You also might make more power but not start or run as well. Mpg might also suffer. The D and L Jet are both low impedance systems - does MS run those?

You are trying to overcome the angle of the injector boss in the D Jet log by sprying at a stepper angle by using the 30 deg fan. Without any qualifications to back it up, I think your current setup with a well atomized mix is better than the fan shape for the reasons you stated - interference with the runners before the valve. There is probably more to be gained by improving the air flow by porting than trying to aim the fuel at the valve. That's the route I would go.

The modern injector upgrade that was recommended to me to be used in late m30 engine applications (535i) were 4 hole atomizing patterns so I would stick with what you are using and look at the duty cycle to see if you are still within the 75 - 85% range at WOT.

Humble opinions,

Doug

Hi Sven!
I have to agree with decoupe's views.

But if you got a supercharged modern engine installed in your E9, it would be a confirmed issue.

For all of us other stock engine users, we are normally happy that our old cars still running without any major problems....

 

[Sven]

Doug - You are probably right. Thanks for your insights.

Is yours stock? - don't think it is.

No. Combining a m30b35 engine with a D-jet intake system. Other than a lightened flywheel most elements of the two systems are stock.

The D and L Jet are both low impedance systems - does MS run those?

MS uses high impedance injectors.

It never occurred to me that the reason for the V spray pattern was so a stream was aimed at each valve in a two-valve intake chamber. Maybe a single angled spray pattern would be more suitable - not sure if there is such a beast.

Never hurts to think about these things.