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Ok, I have a few tech questions regarding cylinder volume and a few other things.

For starters how can I determine the volume of a cylinder at TDC? What info is needed?

For a standard 302 crank is their 180* difference between #1 and #5 connections (also what is the term used for the part of the crank in which the rods are connected?)?

If so, does the same hold through for the rest of the crank? Example #2 and #6 are 180* apart? If not does anyone know of the degree seperation of the independent connections in respect to #1 at TDC?

How exactially does a MAF work? I understand that it gives and analog voltage reading depending on the Mass of the air flowing through it, does anyone know what the cc volume is of the air at any given voltage or where to find that info? In addition, say the voltage given by the MAF indicated that 50cc of air is currently being passed though it (just a number not a logical value), is that 50cc headed towards a single cylinder or is it divided up between the 8 (I know that greatly depends on intake valve timeing but in general)?

One last question, when an amount of gas is measured as a # how does that reflect it's mass? In reference to something like a 19# injector or an S-trim at 10#. I understand that it's pounds per square inch, but how would I determine the amount actually available?



I'm asking these questions because I need to change my a/f ratio to about 100:1 for an H2 conversion that I'm working on with the AHA (American Hydrogen Association). I have intentions of using a smart-plug (H2 injector and spark plug in one unit) to directly inject H2 into the engine, but I need to use the MAF to determine amount of incomming air...

Thanks
 

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Wow, are you sure you're up to the task?

First off, why would you shoot for an A/F ratio of 100:1? Stochiometric for pure hydrogen as a fuel is barely more than 6.0:1. With rocket engines burning pure hydrogen with pure oxygen as the oxidizer, they barely achieve 5.5:1. What would you hope to accomplish at 100:1? Gauranteed that you're well past the lean flammability limit and won't even have a chance of achieving ignition. I'd suggest referring to a textbook on combustion.

The MAS works basically as a hot-wire anemometer. Check one of your basic controls or thermodynamics books for a discussion on how the hot-wire works. The calibration of the wire is going to be completely dependent on the flow device into which it is installed. There is no answer to your question. There would however be an answer to..."What is the relationship between cc/s of air to voltage output for a C&L MAS with a 24# calibration tube?" There is no single, all-encompassing calibration curve that covers every single MAS or hot wire made. The MAS is a single point measurement taken on the incoming air stream as a whole. It has no way of telling how much of the total air is heading towards any individual cylinder.

The rods connect to the journals. Knowing that #1 and #5 are connected to the same journal, or throw, it would be simple enough to figure out where the #5 piston is at when #1 is at TDC. You'll need to break out your geometry, but its doable just using the principals of similar triangles. You answer will vary depending on crank throw and rod length though.

The clearance volume (entrained volume at TDC) includes the combustion chamber space, valve relief/dome space, piston-to-wall clearance above the top ring, etc. Its simply the sum of all volume above the top ring.

The # rating of an injector is not in psi (pounds per square inch). It is in #/hour, or more precisely, pounds-mass per hour. So you have essentially answered your own question. This is completely different than an S-trim pushing 10# of boost (which is 10 psi of boost). The injector rating is the mass flow rate, which is mathematically:

mass flow = density * velocity * area

The area is determined by the nozzle size of the injector (a fixed geometric value).

Density is the mass-per-unit volume of the gasoline at specific pressure and temperature at which it is being forced through the injector. Be aware that if you're considering gaseous hydrogen for injection, its density is highly dependent on these parameters. Gasoline's density, being a liquid, is less affected by pressure and temperature as it can be considered an incompressible fluid.

Velocity is the speed at which the gasoline is passed through the injector. This velocity is designed into the injector at a specific pressure drop across the injector. The velocity is designed to achieve a desired amount of atomization, to promote an optimum droplet size that can be efficiently burned during the limited duration of the combustion event.

There have been many designs developed on direct hydrogen injection, as well as for many other gaseous fuels. Try doing a search at your library on hybrid vehicles or hybrid engines. One of the primary problems with using hydrogen comes in the methods of handling it. There aren't many people willing to stand next to a vehicle while it gets its hydrogen bottle charged to 2200 psi. Even if you consider loading the vehicle with liquid hydrogen, then going through a vaporization cycle to generate the gaseous hydrogen, it'll be highly inefficient to build a storage dewar into a vehicle that can maintain the LH2 at -423F for extended periods of time, protect it from explosion in the event of an accident, and still be light enough to create fuel efficiency in excess of what we've got with today's fossile fuel vehicles.
 

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Wow, are you sure you're up to the task?
The only thing limiting me me is knowledge. And desire is the greatest influence for learning. I know it's a complacated task, I have quite a bit to learn but I want to experiment.

First off, why would you shoot for an A/F ratio of 100:1? Stochiometric for pure hydrogen as a fuel is barely more than 6.0:1. With rocket engines burning pure hydrogen with pure oxygen as the oxidizer, they barely achieve 5.5:1. What would you hope to accomplish at 100:1? Gauranteed that you're well past the lean flammability limit and won't even have a chance of achieving ignition. I'd suggest referring to a textbook on combustion.
I made a mistake in the A/F ratio the stochiometric ratio, in the reference material I've been reading is 32:1. However (if I'm understanding correctly) you can run it as lean as 180:1.

I appreciate the help and information. I have about 6 more years of college left which is the duration of time I would like to complete this project. I know the probablility of this engine being efficent is non-exitent, but it give me some really good information and experience.

I just want to state that I do understand the complexity of this project, but I don't want to live me life like everyone else and avoiding thing that are currently out of my graps. I am not afraid of what I do not understand....

Oh, and just a little back ground on my planed education

I'm currently 3rd year Computer Science student, after I finish this degree I'll spend 2 years on a Mechanical Engineering Degree and 2 additional years on an Electronical Engineering Degree (math and physics classes are the same between all the degrees)

I'll also have a minor in Math and Physics. I don't have any plans on stopping my education, because it is a never ending process...

Again thanks, and I hope that you will help educate me in the future to assiste this project.
 
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