Importance of Matching Injector Hat To Blower

Does anyone have any dyno numbers showing the difference between a matched hat and blower opening vs a mismatched setup? Say using a 13.25 or a 15.25 hat on a 10.5 blower opening? Its on a tractor pull deal so its not a situation where the air is really being forced into the hat

 

It's always been stressed to me, that the top side of a roots combo should have zero restriction. I would see a shelf like you describe as a restriction.

 

Think of it as water being pour into the injector, what do you think it would be like if the water was hitting a flat surface instead of entering the supercharger

 

Just my opinion, it's more important for the intake of any pump to have a non-turbulent flow at the best angle to load the rotors, in the case of a small opening blower a 45 degrees looks right, and sized to accelerate the air to match the rotor speed, rotors at 11000 rpm have a tip speed close to 200 mph requiring approximately 30-32 square inches measured perpendicular to the throat of the injector. I believe the injector nozzles spraying fuel in on top of the rotors at 45 degrees causes a curtain effect and chaotic turbulent as the fuel is batted upward as it strikes the upward rotation of the rotors pushing fuel back up into the injector against air flow. I mount my fuel injectors at a 45 degree angle so the fuel enters the blower straight down at the edge of the opening, but I put the minimum amount of fuel in on top as I can to keep the blower happy and minimize unequal cylinder distribution, over 60 percent goes in the down nozzles, that right no port nozzles and yes this is bbc

 

I have no doubt that misting nozzles can have an affect on the air temp if located far enough up stream, but putting 9 gpm instead of 5-6 gpm creates a sloppy stream of fuel that is difficult at best to control where and at what rpm its going to end up. once its in the port it's stuck to the walls along with a good portion fuel being sprayed in by the port nozzles ending up in the back of the valve bowl then blown over the valve seat washing the plug sealing the piston rings lubricating the piston and ends up cooling and lubricating the crank bearings JUST like it did in the blower.

I prefer to put the 9 gpm through down nozzles with no defector directed at the back side of the intake valve with a high pressure straight stream, that way the only place the fuel can end up is in the middle cylinder as it gets shredded by 40-50 psi exploding into the cylinder, just my opinion

 

I'm worry Mike I meant that as a sarcastic benefit of your theory more fuel the better in the top of the blower, I have no fuel in the rings, pistons or oil. I lube the blower with spray lube the rings pistons and bearings with undiluted oil

 

Google " Jeff Sitton FuelTech powered ". Great shot of spray bar working. Not what I thought I would see.

 

Seems to prove a theory. Most of the top efi roots cars seem to have all the hat fuel in the spray bar. Is most of the air fuel mix pulled into the set back rotor pocket ?

 

I think the one word to remember in all this is "Flow"...… why create obstacles in the path of the air/fuel if it can be avoided. Just my own thoughts.

 

Thanks for the input guys!

 

what if the injector hat is larger than the blower opening - I would assume that isn't that big of a deal? or is it?

 

OK let me fix that.

Let's say the hat has a larger opening than the top of the current spacer being used. the spacer to the blower is perfect. I hope that's better.

 

OK well I screwed that up again - smh.

Hat opening is 9 1/4" in length
Top of the spacer on the blower opening is 10"

So to finally get my head of my ass the hat is 3/4 SMALLER than the top of the spacer on the blower. The spacer to the blower is a perfect match.

Sorry for the confusion.

it's a carbon hat, should it be matched perfect as well to the 10" or is it a minor detail?

 

Can I ask what blower are we talking about. Hi-helix, mods, set back rotor ???