Slart

I'm in the middle of planning my first nitrous kit.

I've been thinking about propane injection as well for the octane benefit. I've done a little research tonight and it seems that the options are LPG, and CNG strike me as feasible (neither of which are propane however).

LPG (Liquid Petroleum Gas) is pretty much a mix of Propane and Butane. It has a RON of 112, MON of 95 (so R+M/2 = 103.5). One benefit to LPG is that at room tempature it becomes a liquid at 6 bar. Somehow after talking about 1000 PSI in a nitrous tank, 90 PSI doesnt seem very dangerous.

CNG (Compressed natural gas) is mostly methane. It has a RON of 120, MON of 120(!). CNG is stored at 3000 PSI, so I assume that it's in gaseous form in the bottle.

The 120 octane of CNG sounds nice, but I have a feeling to get the CNG tank filled up on the car I'd have to have to do jump through a bunch of hoops, like doing a complete CNG conversion. Any thoughts?

I'm thinking the LPG sounds a lot simplier, and the 103 octane still beats the heck out of the 91 they sell at the pump here.

The nitrous kit i've already purchased has a dedicated fuel solenoid, nitrous solenoid, distribution block, and NXL nozzles. It seems like if I were to switch the fuel solenoid out with a second nitrous solenoid, and plumb in liquid CNG, it would be a match made in heaven.

As always, discussion is welcome.

Steve

Slart

Folks -

The most appealing solution to me is liquid propane or LPG (propane/butane mix) injection.

I've been studying up on the feasbility of this, and found an article on a gas to LPG conversion contest entry. The article is here:
http://www.gmi.edu/~lpgvan/SAE-LPG.html

The reason I'm posting is I read something I found very interesting. They were having a problem keeping the propane in a liquid state, so they made heat sinks to try and dissipate the heat that the propane was seeing.

Their heat sinks were insufficient, so they looked further and what they found out was most of the heat was getting into the propane via the fuel rails. What they found out is by replacing the aluminum connections between the fuel rails and th replace intake with nylon ones, the heat transfer was reduced 85%.

This applies to nitrous as well I'm sure. Moral of the story: use nylon washers on both sides of every connection of your nitrous system to your intake manifold.

Steve

GoldenVelvet

The site you linked to list the octain of LPG as 104 RON 89 MON. Thats an effective octain of 96.5 ((RON+MON)/2)

Also isnt the fuel noid rated to handel up to 400PSI?

Slart

Wow, I thought the butane in LPG would raise the octane. Guess I'll be using pure propane instead.

I didnt know the fuel 'noid was rated for 400 PSI. Interesting

I'm also wondering if there is a concern about the liquid evaporating at the solenolid could cause any problem. I know it's not supposed to evaporate until it hits the jets, but if there's propane gas in the lines maybe it will?

Slart

I talked to NX today. They were not willing to discuss propane at all because they thought it was unsafe. I told them I'd be using a DOT approved tank outside the car, just like production LPG vehicles use. Still didnt think it was safe.

So much for "next generation"

eviltwins

http://www.btrviper.com/nitrous.html

They do lots of nitrous + propane setups, if you called them up I'm sure they'd be happy to help you get your setup working.

Slart

Thanks. They're actually where I got the idea

What I'm trying to do is different enough that I dont think he'll be willing to help me (I have shot him an email however..). What I'm trying to do direct port liquid propane and nitrous injection, with both the propane and nitrous tanks with pressurized with a nitrogen feed so that their pressure is stable regardless of ambient tempature or evaporation.

The key point of this is to get a consistent air/fuel mixture out of the nitrous system. This being the key to pushing power without breaking anything.

There are other benefits as well: Propane is 103.5 octane (vs 91 for the gas in CA), the evaporation of the propane and nitrous will cool the intake charge, propane will atomize better than gasoline, and the direct port setup will allow me to tune the mixture (as well as total power) seperately for each cylinder based on EGT.

From what I can tell, this setup is really the way to go. Between this a progressive controller I hope to break the record for a nitrous'ed stock engine.

I'm really surprised nobody else seems interested in this setup considering how much potential it has. I wish more people were interested - I could really use some help with some of the issues.

I've talked to an industrial gas suppliers today and learned a few things. Unfortunately this supplier didnt sell propane, but I milked him for information anyway. What he told me was small propane tanks have a check valve that stops you from overfilling it (the check valve is a float - when the liquid propane level gets above a certain height in the container, it raises and shuts off the fill). He also told me all propane tanks have a burst valve into them, so they're reasonably safe to put it in the car if you arrange to dump it outside the car (at least, as safe as nitrous I imagine). He also told me that all propane tanks are liquid discharge, including small ones like BBQ tanks, but by inspecting my barbecue grill I found out he was incorrect. I've got three more gas suppliers I'm going talk to in the next few days, hopefully I can get some better info.

One concern I have is how to pressurize the nitrous at 1100 and propane at 100. 383LQ4SS's current solution for his nitrous tank seems good, but that doesnt solve the problem for the propane.

Another concern is whether there's anything about the liquid propane that will muck up the NX solenoids. It's unfortunate that NX wasnt able to help me with this.

As always, discussion is welcome.


Steve

BoostMluse

iTrader: (3)

I've been reading your posts and I think youre on the right track. I own a propane company and have had some success mixing the nitrous and propane on my brothers Supra. Car made 749rwhp, stock long block and a t-72.

It was a single nozzle set up running a 75 shot. We did have to run 2 nitrous soleniods for the pressure. The propane did clog the fuel soleniod. Although propane is considered a "clean" fuel, there are a lot of contaminents in it. Consider all the different storage tanks that it will be transfered to and from before finally getting to the end user.

The downside to using the liquid side is that its hard to control. As it vaporizes it loses pressure pretty quickly. As you lose pressure, its going to change the AFR. The upside of course is the cooling effect you get from the vaporization and the octane rating which has been debated for while now. Some say 104, some say 118, some say 130+. I do know it has to do with purity. When i recieve a "load" of gas I am given the specific gravity of the fuel in liquid form. Pure propane has a specific gravity of .500 while most of my loads range from .503 to .515.

The valve that you are talking about is an OPD valve(overfill protection device). Basically its a float with an orifice inside the tank that shuts off the fuel flow when it reaches the "full" level. These valves are designed to output vapor and not liquid. However, if you flip the tank upside down, you'll get liquid. But now the float is shutting off the fuel. And by law, nobody is supposed to fill a non-OPD valve cylinder.

Now, about the set up on the Supra. We used a nitrous bottle for the propane storage. This did 2 things for us. Made it alot easier to pass tech. Techs just think we're "Fast and Furious" style...."2 bottles the big ones!!!" Secondly, it gave us the ability to mount it cleanly, stealthy, and store it safely since the propane will never reach those kind of pressures. The major problems i encountered was the pressure drop and vapor pockets in the line itself. I believe the pressure drop can be controlled with a pressure switch and heater, just like the nitrous. The vapor pockets are a major problem that I'm not sure how to correct just yet. You must realize that 1 part liquid is 270 parts vapor. So when a vapor pocket hits the engine, you've got an extremely lean condition. However, once the fuel was flowing, it seemed to be fine. Once you're off the nitrous, the vapor pockets will come back. So I thought what about a purge system? Well, where do you purge a flammable gas into atmosphere that is safe and away from any source of ignition? Its risky and the same reason i never tried it. As far as filtering the propane, i know some welding systems use propane, so I think i would retrofit one of those filters for the soleniod. I think that would be sufficient. I never did continue to research the N20 thing on the Supra because of lack of time and we went bigger turbo.

Hope this helps.

Alex

Slart

I have a question about the OPD valve. If you turn the tank upside down, wont the float go up (= open, when the tank is upside down) when the propane tank is full, then stay open until the propane level is nealry empty?

I like your idea of using a nitrous tank. I was a little hesitant at first because I was hoping to be able to just bring it to a propane supplier and have them fill it, but I guess I could cope.

With regards to the vapor pockets, what the folks did in the GMI competition was get a complete LPG tank, filter and pump system from walbro. I dont know how it works, but It had a pump and somehow it pumped the unused fuel back into the LPG tank.

Now that you've told me about your problems, a proper LPG fuel system is sounding more attractive every day.

Thanks for the info!

Steve

felton316

The OPD is fairly easy to remove once you get the valve out of the bottle. Once the valve is out, the OPD is just unscrewed from the main valve, then you put the valve back in the bottle. Nobody should even know it is gone (ex: fill stations), but you will lose the protection benefit of the device.

This bit of info is for educational purposes only and I do not condone the filling or removing of OPD devices from propane tanks. (Just a little disclaimer) Although, it can and has been done.

Slart

I was unaware you could remove the valve. My goal is to get liquid propane. If the valve can be removed, what's to stop me from modifying the valve to take a siphon tube like the nitrous tank?

Would there be any trouble at fill time, or would this be transparent to the fill station?

Steve

BoostMluse

iTrader: (3)

BiPhase uses the same kind of technology on their retrofit kits. But as far as I know, the tank is constructed with a pump built inside of the tank. And they're able to recirculate the propane, just like gasoline. This undoubtably would be the correct way to do it. However, have you recently priced a DOT tank? With steel prices the way they are, its gonna be a pretty penny much less getting a tank with the pumping system already retrofitted. I do know that most car DOT tanks are running anywhere from $500 to $800 bucks. And thats just the tank. Not sure if weight is going to be a factor as well as space for you. Just a couple more things to think about. I have not researched the liquid pumping avenue so I would be very interested in what you find. Im getting ready to put N20 on my car and was thinking of going alky for the fuel.

As for modifying the OPD cylinder, in theory that really could work. Siphon tubes are placed on domestic tanks sizing from 125gal all the way up and over 1000gal tanks and they work just fine getting the liquid out. All of the OPD tanks will have a liquid level gauge. That small flat head screw on the side that lets out vapor is considered the liquid level gauge. If this gauge is not tampered with when and if mods were made to the valve, there's no reason why a fueling station would know the difference. This could be the best avenue for someone that doesnt have complete access to propane.

Im not saying i condone these actions of course, this is purely education as stated above.

Alex

Slart

Thanks alex for your observations. I've started wondering about a different path though..

What about the disposable 1lb propane camping cylinders ( http://www.ci.redding.ca.us/solwaste...l_cylinder.gif )?

These small containers are not intended for refill, so they probably dont have an OPD valve. Why couldnt I just get a propane torch fitting cut off the nozzle, and mount it upside down under the hood?

Can anybody calculate how many lbs of propane i'd need for 15 lbs of nitrous? Chemistry isnt my strong point, but stoich for propane is 15.7:1, and nitrous is 2/3rds oxygen, it sounds like I'd need .6 lbs of propane for 15 lbs of nitrous.

I do not understand if i'm doing the calculations right. I'm calculating based on a liquid. Do I need to convert to gas volume first?

Steve

Lostpatrolman

iTrader: (3)

I dont see why you cant just run water injection. Wouldnt this give you the same benefits you are looking for but at a fraction of the cost?

felton316

I believe he is using the propane as an alternate fuel then spraying gasoline into his intake via nozzle. The propane will work in place of the needed fuel, where as the water injection would only act as a cooling charge and not a fuel source.


I wouldn't, it doesn't seem safe with out the correct valve. Just get a 5# propane bottle, unscrew the valve, take out the OPD device, screw the valve back in, then mount the bottle upside down.


With a 5#(2gal) propane bottle, it will last a while with a 15# N2O bottle. You can get 6-7 N20 bottles before you need to refill the propane bottle, depending on what pressures you run.


Also, if you are looking for a remote bottle opener for a propane bottle, start looking at RV supply/parts stores. They sell them for around $40. This way the old people in the RV can turn on/off their bottles, with out having to get out. Also some boating/marine supply stores will also carry these.

LS1M

iTrader: (3)

I did this equation after helping my son with his homework. It takes 10 lb of nitrous to 1 lb of propane

C3H8 + (10) N2O -> (4) H2O + (3) CO2 + (10) N2

If this equation is correct, then it takes 10 moles of n2o for each mole of propane. And coincidentally, the atomic weight for both is 44, so the weight ratio is also 10:1.

Combustion in air is 1:24 mole ratio, or 15.6:1 weight ratio

felton316

Theoreticlly that is correct, but since both gasses are running at different pressures, it will be slightly off. Because once the propane(or nitrous) gets too low of a pressure in the bottle, it will no longer be effective(you will not be able to extract 100% of the gas at the pressures needed). Now, if you used a nitrogen(or CO2) push system on both the nitrous and the propane bottles, you would see even a closer results to LS1M's 10:1 ratio.

1fastWS6

iTrader: (3)

felton316:
Have you hooked this up yet? A friend of mine is running a dual stage setup (one dry, one wet w/propane) on his TA. He got all his info from a guy at NOS. He's running a 2# propane bottle and said it lasts at least 15-20 N20 bottles.

Slart

I decided against propane. It's too hard to keep liquid. I've thought of a fe ways, but they're too complex for the benefit. I thought of running gaseous propane injection, but I'm going to be using a progressive controller and I cant find a large enough solenoid that can open/close fast enough for progressive operation.

I've decided to use methanol instead. Methanol has a major advantage over propane: It's highly oxygenated (49% oxygen), so it doesnt hurt much to go rich. The reason (as far as I can tell), is with gas, the extra fuel cools things off.

With methanol, when the molecule breaks apart it's a hydrocarbon and an oxygen molecule, so you gain some energy from that effect. So, the price you pay in reduced heat from too much fuel is offset because the inherant oxygen/hydrocarbon released from the methanol makes heat on it's own.

As a result, going fat with methanol doesnt hurt power as much as gas. So, instead of trying to make a compromise between max power and safety (with gas), you get the best of both worlds.

1fastWS6

iTrader: (3)

How much is the methanol per gallon? Propane is dirt cheap.