injector nozzle location article

[norbs]

I came across this article, but I wish I should have read it before I did my manifold. Looks like mine are too close to the flange. Do you think I will have adverse effects?

http://www.hotrod.com/pitstop/hrdp_0704_pitstop_fuel_injector_location/

 

[Mike E]

I've done maybe 50 efi conversions to carb intakes. Everything from high rpm naturally aspirated engines to 2500hp alcohol fueled turbo motors. All but one of those intakes were done just like yours and none ever had any problems related to injector placment. It almost always comes down to packaging as the limiting factor. There are many who would disagree with that article. There is a lot of thought that putting the injectors so that the spray goes against the air stream is the new hp secret. I highly doubt it myself and even if it does have an effect, most people can't use the power they make on a turbo engine anyways. There may be some power in injector placement, but it's something you spend money searching for when you've exhausted everything else and have a big budget.

I've had poeple ask me to do a conversion where the injectors are more inline with the air stream instead of straight up and down. I can tell you it doubles my cost to do one. I do a typical conversion on a v6 intake for $300 ready to go. If I had to angle the injectors, the injector bungs get much more complicated and involved. The rail mounts are more difficult. The porting afterwards to blend the bungs in is more involved. An extra $300 for a chance at 10 more hp is not worth it when you can add one lb. of boost and pick up 30-50 hp.

As an example of why it doesn't matter:
I have a friend that races a twin turbo alky pro-mod car. He runs three sets of 160 injectors at ~70+psi. of base pressure. You would think that much fuel needs a lot of room to atomize. For alcohol, the atomization provides the cooling. So if you can't atomize the fuel, you should get high charge temps. He originally started out with a set of injectors about 20" before the throttle body in the charge tube. Then, he moved them to the top of the intake where the welded plates are. Eventually he ended up with all three sets right as close to the flange as he could get them. There is now a set on the lifter valley side of the runners right next to the flange. Charge temps have never been a problem, the atomization has been good enough with every setup. Volume is the biggest problem, but he can't physically fit or drive any more injectors.

 

[norbs]

Thanks Mike one less thing to worry about.

 

[gnxtc2]

As an example of why it doesn't matter:
I have a friend that races a twin turbo alky pro-mod car. He runs three sets of 160 injectors at ~70+psi. of base pressure.

Why didn't he go with Moran injectors?
http://www.moranmotorsports.com/products/catalog/index.php?cPath=63

Billy T.
gnxtc2@aol.com

 

[Mike E]

Why didn't he go with Moran injectors?
http://www.moranmotorsports.com/products/catalog/index.php?cPath=63

Billy T.
gnxtc2@aol.com

I'm not exactly sure, but probably money. They race pro mod on a budget cheaper than some of us spend on buick street cars. Three sets of 160's is still cheaper than moran 500's. Next step for him will be to switch to mechanical injectors. He's got a lot neat stuff going on with mechaical injection alcohol turbo turning.