EFI, Alpha-N vs Speed Density fueling Strategies

Tony Curcio · 03-13-2014, 10:56 PM

Direct injection is being used this year by the Chevrolet factory teams at LeMans in their GT-1 Corvettes. There is a detailed story about it Engine Technology magazine, a British publication. If anyone's interested, PM me and I'll look for the back issue.

Also, USAC midgets use 4cyl engines with a 23 degree SBC head. They use a nozzle in the intake manifold, and drill a hole from the exhaust side of the head, into the intake port pocket, and call it a "down-nozzle". Every GM powered car in the class seems to do this. Kinzler does the drilling, and provides the the injection system, which looks like old mechanical Hilborns, but are fairly sophisticated electronic controlled units.

Ed Wright · 03-14-2014, 08:07 AM

I had a sprint car during the 1980s . We all ran down nozzles then. That has been around forever. Was still mechanical back then.
The big deal, we thought, was getting all that methanol out of the intake and port runners, making room for more air. Takes roughly twice the methanol as gasoline, which = less air. The nozzles were aimed to shoot fuel past/under the intake valve when open. Thing about those older mechanical systems, there was no injector pulsing, as with EFI. Constant stream of fuel meant an intake bowl full of fuel when the valve did open.
Brodix, AFR, etc, sold/sell their heads drilled for down nozzles.

03-13-2014, 10:56 PM	#1
Tony Curcio Member Join Date: Mar 2002 Location: West Chester, PA Posts: 271 Likes: 1 Liked 4 Times in 1 Post	Re: EFI, Alpha-N vs Speed Density fueling Strategies Direct injection is being used this year by the Chevrolet factory teams at LeMans in their GT-1 Corvettes. There is a detailed story about it Engine Technology magazine, a British publication. If anyone's interested, PM me and I'll look for the back issue. Also, USAC midgets use 4cyl engines with a 23 degree SBC head. They use a nozzle in the intake manifold, and drill a hole from the exhaust side of the head, into the intake port pocket, and call it a "down-nozzle". Every GM powered car in the class seems to do this. Kinzler does the drilling, and provides the the injection system, which looks like old mechanical Hilborns, but are fairly sophisticated electronic controlled units. __________________ Tony Curcio 1860 STK

03-14-2014, 08:07 AM	#2
Ed Wright Veteran Member Join Date: Mar 2005 Location: Sand Springs, OK Posts: 8,132 Likes: 896 Liked 390 Times in 170 Posts	Re: EFI, Alpha-N vs Speed Density fueling Strategies I had a sprint car during the 1980s . We all ran down nozzles then. That has been around forever. Was still mechanical back then. The big deal, we thought, was getting all that methanol out of the intake and port runners, making room for more air. Takes roughly twice the methanol as gasoline, which = less air. The nozzles were aimed to shoot fuel past/under the intake valve when open. Thing about those older mechanical systems, there was no injector pulsing, as with EFI. Constant stream of fuel meant an intake bowl full of fuel when the valve did open. Brodix, AFR, etc, sold/sell their heads drilled for down nozzles. __________________ Ed Wright 4156 SS/JA Last edited by Ed Wright; 03-14-2014 at 09:10 AM.