Plan is to run a dual fuel system with one set of injectors. Cruise around on pump gas, upon entering boost triggering an additional pump with 100% meth injected into the rail post regulator.

Trying to determine the percentage of meth to pump gas seen by the injectors.

If maxing out my current injectors puts me around 150gph and I'd like say 20% (30gph)of my total fuel mixture to be methanol. How would I go about getting this mixture at the rail?

If my pump flowed 30gph at say 180psi how would this effect the mixture percentage? Would the additional pressure compound with the current pressure at the rail?Or as long as the aux pump press was higher than the pump gas pressure it would fine?

Any help would be much appreciated.

 

Why not run another set of injectors?

 

Because that would be 10x the cost and effort? I'm running a $500 engine with a plastic intake. Adding the cost of another complete fuel system, intake, then fabrication etc... seems ridiculous. Especially when my current fuel system can handle it. I currently premix 2 gallons of methanol with 10 gal of pump fuel. (12 total) I'd like to accomplish the same thing with out premixing.

The time it would take so stabilize the ratio in the fuel rail would be a factor. As long as you didn't need the added methanol to control detonation until the mixture stabilized would this be a problem? Perhaps it would be better to just turn the pump "on" before a run. This way the mixture in the rail would stabilize before you got into boost at all.

Technically I don’t see how this would differ from spraying methanol pre-throttlebody? If I spray a constant stream of 30gph of meth into the fuel supply line, wouldn't each injector get an equal percentage of that 30gph? Essentially the same as having a direct injected methanol kit? Or would it not mix properly and deliver random amounts of the mixture to random injectors?


Not saying this is necessarily a great idea. I can foresee a problem or two with this method. Was just wondering how to calculate it.

 

How about a surge tank system? This would allow premixed fuels then you can design it to be close to a certain amount by regulation or restriction.
Just a thought maybe?

 

It would for the most part go 100% meth once it purged the fuel back down the return line. Post reg would cause the regulator to open, dumping any unused methenol into the tank via the return line. Depending on how the reg is plumbed. I think a regualer style of methenol injection would be adequate for a "mere" 20%

 

It couldn't. The meth pumps don't flow enough to keep up with the systems demands. The pump has the pressure, but doesn't flow much.

My fuel setup has the supply and return on the regulator itself. Then I have a line coming off the regulator dead headed to the fuel rails. Basically an OEM "returnless" setup but my regulator isn't in the tank

like so...

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Wouldn't bother calculating it. I see way too many problems with this setup to bother with the math

Just my opinion though.
Good luck with it.

 

Trying to think of it as a math problem. Not really concerned with anything else. I'd like to know how to do the math. I honestly don't' know where to start.

Thanks for the input though.

 

Just out of curiosity, wouldn't the cheapest route be to just run a standard Meth injection setup with 100% meth in the intake tract? It sounds like your aiming for only additional octane but you would also have the added benefit of a cooler intake charge. Just a thought.

Edit: I lived in Wichita for many years as a kid, still have family in Abilene.

 

The majority of alky injs benefits take place in the cylinder, not "cooling the charge". The pre-throttle-body kits downfall is in even distribution to the cyls. What I would be attempting is basically premixing the fuels so each cylinder would receive the same amount of alky. Also this method would be cheaper than using nozzles. This is about $12 worth of fittings vs $70+ for 2 misting nozzles and shipping.

Haven't had a chance to do much here in the hell mouth....I mean wichita. -19 with wind chill this morning. We are having an especially nasty winter this year.

 

So your gasoline system is regulated to say 45 psi during normal running, then when you reach a target boost trigger, the methanol system is injected into the system after the regulator at 180 psi? And there is no return line? The volume of fuel injected at 180 psi is limited?

 

Do a static test with the injection system, dumping the fuel into a container, not the engine, and measure the weights of the fuels lost from their fuel cells over a certain time period. This will not be with boost present, but it will give you an idea of what to expect.
With the weights, you should be able to calculate what the mix is like.

 

Yes, the rail is dead headed, return on the regulator. Meth injected post regulator at the rail inlet.

I had thought about that, though I think I'd have to get individual containers per injector. This way I could see the ratio of alcohol to fuel to verify each inj is getting the same, and how long it takes for the system to stabilize. I think the issue will be the activation point time VS the time it takes for each inj to see a constant meth/gas ratio. I think I'd have to activate the system in the staging lanes.

 

You are going to let the O2 sensor correct the injector pulsewidth as the meth is injected? If so, then I don't think the transition time is going to be a worry. In fact, I might welcome a little bit of transition time. I'm sure it wouldn't be a long time period.

 

I was under the impression that changes made by the O2 sensor were made within small windows that eventually altered the overall fuel map. I assume your using the LS1 OEM computer. Is it capable of doing these huge air fuel ratio changes on the fly? Stoich for gasoline and stoich for alcohol are not the same. Besides that, you want a richer mixture than stoich while in boost. I still think you'll have to have two separate maps, injector sets, fuel pumps etc. Flex fuel technology could do what you want, but from what I have heard, that takes a while for the computer to adjust itself when you go back and forth. Is E85 available where you live? Maybe you should just change over entirely.
Congrats on those 1/8 mile times. Awsome for a low budget street car. Really impressive.

 

If you have regulated pressure (fuel system after regulator) and try to blow a different fuel in downstream, wouldn't you have to overcome the regulated pressure with the secondary system? Then wouldn't this cause the fpr to try and lower the pressure further which would decrease the gasoline volume. If this is right, it would seem to me that activating a meth system after regulator would cause the gasoline system to shut off (if the reg could accomplish this) and would run fully/mostly on the meth.

 

Using a gen1 AEM EMS stand alone ECU. The 02 sensor feedback percentage is adjustable. Currently it can add or remove 40% of the current value on my fuel map. This is based on an AFR target map. I have it set to around 11.3 in boost. So if I added meth, the aem is capable of adding 40% fuel to my current value. I usually turn off the 02 sensor feedback. Then tune the car around 10.3 AFR in boost.(e85) Then I use the 02 sensor feed back to pull fuel back to a leaner AFR.

A WB02 sensor does not only target stoich like a narrow band. It will read the full spectrum. The 02 sensor readings are based off lambda. The sensor doesn't know/care what fuel you run.
6.4 is stoich on meth.
14.7 is stoich gas.
They are both read as '1' lambda. This is what the WB02 sensor is reading.

The rx-7 I ran last year was run on E85'¦ (50-70% ethanol even though its labeled as 'E85'.) I'd like to cruise around on pump fuel though and have a separate meth tank. This way I'm only using the meth at WOT. E85 around here tends to clog up injectors with a sticky tar like goo. Seems this stuff is region specific. But of the 4 cars I've had on ethanol, all of them get this 'goo'. (It's NOT fuel tank debris, filter, or fuel line rubber etc).

Thanks!

Yes, you would have to overcome the regular fuel systems pressure. The current pump I run for meth is rated at 300psi. (though I'm sure that's not a 'wide open' rating) Since I'd be adding the METH post regulator, I don't think the regulator itself would even 'see' the added pressure? I'd think the meth pump itself would add all the pressure/volume it was capable of. I'm sure with a 60-70gph nozzle the pump wouldn't put out anywhere near 300psi.

 

My understanding of hydraulic circuits is that the pressure is constant between orifices. If you indroduce a higher pressure after the reg but before the engine (between orifices) the pressure will balance at the higher amount unless one of the orifices (engine) is opened up to flow the amount of extra volume being introduced.

Maybe I am not making sense as I am not very good at typing out thoughts sometimes.

Seems like the best thing to do is give it a shot and let us know how it works.

 

I'd love to. Battling other gremlins at the moment. Need to have the car up and running well before I "play" with anything.

I see what your saying though. The Regulator doesn't care where the pressure is added and will try to send additional pressure/fuel back the return. Though it couldn't send back fuel upstream (methanol) of the regulator. It would just try to equalize the pressure and send back more pump fuel. That could possibly be a good thing.

If the meth inj pump had the flow/pressure to supply the demands of the engine 100% and the return line could handle the extra volume, you should be able to replace the supply fuel with 100% meth. That sure won't happen with the alky pump though. So whatever the alky pump could manage to flow would mix in with the pump gas supply. That’s what I was hoping to find a formula for. Setting up everything necessary to bench test this would take some doing. I don't think I'm brave enough to just plug it all in to my motor and go test driving! If I was, I could have it setup in 30 minutes.

 

It is an interesting idea, thats for sure. I don't blame ya at all about not testing on your engine! Haha

Wonder if you could do the same thing with shop air, a couple regulators and 2 flow meters. Put a flow meter between the first reg and the merge from the second reg. Then put a flow meter at the end of the line. Flow air through the first reg at say 30 psi. Now turn on the second reg at maybe 50 psi and watch what the flow of the first meter does. If it drops a bunch, the secondary pressure is shutting off the first reg.