Hi,

i read lots of interesting stuff about WI/AI lately. Especially when it comes to pre turbo injection, people want nozzles that atomize the water as good as possible.
But i'm wondering, that nobody adresses proper FUEL atomization.
I mean, especially those big injectors flow like garden hoses. That's bad in my book, because there are rich an lean spots. This is bad for power, reliability and fuel economy.
Plus, (now i bridging the gap to auxiliary injection ) properly atomized fuel should be able to pull out some more heat as well, shouldn't it? Combined with a nice WI injection system this should be even more powerful.

kind reagrds
Chris

 

HI Chris,

Some of us do

I prefer to use Bosch motorsport pumps, 044 specificaly because it can run VERY HIGH base pressures and still give good flow rates @ 100+psi, I used to run 65psi static fuel pressure in my Yellow first gen (590bhp car)... there are gains there to be had if your injectors can handle it.

Here in Australia during the Group A touring car days the Nissan GTR's ran mechanical fuel pumps and ran fuel pressures of around 120 to 130psi ! (they had 700bhp or there abouts).

Fuel atomization is always imortant, with really good ECU's like Autronic you can run high pressure and LOW injector m/s opening times (4 x 160lb/hr) is common place on them with perfect drivability.....

Its a little know fact that the phase change of water to steam helps disturb the fuel particles as well during compression phase, I have an indepth article on it from a bible on 1000bhp GP F1 era engines describing Ferrari's "emulstien" WI system developed by AGIP their fuel supplier at the time. It was specific to their system which encapsulated a water molecule with a fuel droplet by probably a similar effect happens with a well atomized water and fuel mixture as well.

Either way atomization is a very important subject on its own, and remember air speed plays a very critical role, no matter how well you vapourise the fuel you need the right air speed to mix it all well too

 

So, what's your current base pressure?
Besides high fuel pressure, is there anything one can do to optimize fuel atomization? I thought about optimizing those "diffuser plates" that are in front of the stock injectors. i had ideas like this: take the diameter of the injector hole (where the fuel flows out) and calculate the surface area. then calculate the needed distance between the plate and injector-tip to maintain the needed surface area (to maintain flow as much as possible) of the gap between injector-tip and plate. Then take a feeler gauge, have it between plate and injector tip, weld it in place. voila, ghetto-precision
The supertight space between plate and injector would force to atomize much more - i hope, lol.

yep, velocity is one important extremely underestimated point! when i raced 100cc two stroke karts, we actually DECREASED portvolume and ended up with more peak power AND more usable power range. cool stuff.

if memory servers correct, fuel droplets stay in supspension if the droplets are smaller than 10 microns - otherwise the droplets hit the manifold runners in bends. obviously, 10 microns it not doable for us (20 superfine atomizing injectors per chamber, anyone? ) Do you prefer a rough finish to keep the droplets in suspension? in know this kinda off-topic, but hey

Chris

 

Rice you mention atomization and vaporization , A lot of the guys out there dont realize there is a major difference, also what must be going on when GMs direct chamber injecttion is at 2250 psi( talk about atomization!!) into a highly compressed air,and temps are already high,friction of the atomized beads against the hot air. and MAZDA has somewhat the same type of systems, a lot of this info is about to be understood, and when the aftermarket guys get on it watch out. sounds interesting!

 

I have beat my head on the wall for years trying to figure how they kept the water from falling out of suspension!!! GRRRRR

I would be more than a little interested in the solution. Hint Hint wink wink.

 

I talked with a guy here in Daytona FL. his name SMOKEY YUNICK< yrs back he was a leading USA engine builder, in 1987 he was invited( by invitation) to go to Japan for a week, to view Japans group, like our SAE group, anyway, they had on demonstration a Dyno room, where they, Japan, said they think would be just about the ultimate Hi power piston engine, (talk about the terrible twos), 2 litre, V-8, turbo, 2000 hp, 20,000 rpm, using a hydrocarbon base fuel, details not revealed. it seemed they were using a form of DETONATION to push the piston down at the 20,000rpm level. it was being developed for Formula 1 racing , so FIA banned turbo units, simple as politics. dont cha love being a slave!! Ron