Dual fed fuel rail setup

[V6UnderPressure]

So we've confirmed that this is only an issue with alky?

 

[TurboBuRick]

Unless alky pressure was being logged when the meltdowns occurred, you really can't say.

There are 2 problems I find with alky injection. 1 is the pump. 2 is the holding tank.

The pumps don't last. They make great pressure when you first install them but start to drop off shortly after. Give it about a year and they are only making 100psi if your lucky. That's a big problem. Specially with faster cars. How often do you guy's check yours?

The other problem is the where the alky is supplied from. The tank design pulls fluid away from the pickup the faster you go. If your tank is not 100% full you can suck air and loose alky pressure. Specially on faster cars. If you think there is enough g force to pull vaporized alky to the back of the intake, don't you think the liquid in the holding tank is doing the same? Hell that's why fuel tanks are sumps on race cars. Right?

This makes more sense than the g force causing alky to favor the rear cylinders. The way I understand it, akly is vaporized when it enters the intake charge. Supposedly it's no longer in liquid form. Food for thought.

I'm torn on the dual fed rail thing. Surly it wont hurt but IMO the fuel pumps and feed line fall short way before the fuel rail becomes a restriction. You can go a long way with a -8 fitting welded on the stock rail. It's more about the weak stream.

RL

BTW I have a new set of short champion rails and a weldon fp regulator for sale if anyone is interested.

 

[jasjamz]

So we've confirmed that this is only an issue with alky?

I think it becomes an issue when you inject too much alky. So much so that when you are cooling the charge down and still have liquid entering the intake. I've thought about the tank sloshing on launches but don't have a gauge to monitor pressure. I always top off tanks after runs at the track and have yet to see any issues. No blown head gaskets or damaged pistons thus far to #1 or #2.

 

[Ttype6]

You must not completely understand what I posted. If you did, you wouldn't have quoted that.

Focus on 1&2. I you supply them with the same fuel and more air to #1, which will be lean?

I understood what you said. One and two don't get significantly more air to them. I think they get significantly less alcohol. I think I was very clear about that. If it was getting more air than the others,dual feeding wouldn't be the fix because there isn't a fuel distribution problem. If one is leaner than the rest,it's not because the rail isn't dual fed.

 

[jasjamz]

I understood what you said. One and two don't get significantly more air to them. I think they get significantly less alcohol. I think I was very clear about that. If it was getting more air than the others,dual feeding wouldn't be the fix because there isn't a fuel distribution problem. If one is leaner than the rest,it's not because the rail isn't dual fed.

The system was designed to lower the IAT by methanol liquid being introduced into the Airstream and vaporized. It was not meant to be a fuel! I stared that the first time. Excessive amount being used will not vaporize and the problems start. If you have problems like the pictured intake you are using way too much alky!

 

[bison]

The problem isnt about airflow distribution at all. If you ran egt probes you would see that once shutting off the alky you will have much more linear temps front to rear. What does this mean? It means that a % of alky is not vaporized. If its vaporized its part of the homogenous mixture of the of air entering the intake and will be distributed the same way the air is since it is actually part of the air. If its not 100% vaporized it is still liquid which is a separate part of the mixture entering the intake. Guess what? Methanol just like every other liquid has a much greater density than air. Guess what else? Being more dense and seperate from the air it has more inertia. That inertia from the airflow (which increases as engine speed increases, not boost) coupled with the g forces of the accelerating car cause a very high % of this liquid to wind up hitting the back of the intake. Now if you have a wideband correction and are targeting lean you are in big trouble. The more you pressurize the intake the higher the vaporization temp for the liquid. The colder the intake air charge the less likely you are to vaporize the liquid. Too much alky injected upstream is its worst enemy to vaporization coupled with how much is injected. The boiling point for methanol is 149*F at sea level. There is a lot more pressure in the intake at 25-30psi than there is at sea level. Therefore getting a full vaporization on the fuel injected is about impossible since it has such a high latent heat of vaporization. It just drops the air temp so much when a small amount vaporizes that its actually inhibiting the remainder from vaporizing.

 

[TurboBuRick]

Definitely has me thinking. Temperature has allot to do with it I know. If the charge temp drops enough I can see there being issue with vaporizing. Wonder exactly what temperature that is and how much pressure does effect it. You would think the heat from the blow dryer would supersede but with enough alky I guess it can happen.

Interesting............

 

[bison]

Definitely has me thinking. Temperature has allot to do with it I know. If the charge temp drops enough I can see there being issue with vaporizing. Wonder exactly what temperature that is and how much pressure does effect it. You would think the heat from the blow dryer would supersede but with enough alky I guess it can happen.

Interesting............

The pressure has a lot to do with it too. Go read up on thermodynamics of methanol. You can calculate the vaporization % based on the % of methanol in the solution injected, the inlet temp and the manifold pressure. Methanol absorbs water readily and raises its boiling point. The higher the latent heat the higher the energy absorbtion when it vaporizes. There is no set temperature because the manifold pressure isnt constant and the amount of alky injected isnt constant. One thing ill say is that when injecting over 25gph on a 700+hp engine and the charge air temp is going under 70* you are about to be in trouble. Eliminating the intercooler may be the way to go in some instances.

 

[Jerryl]

The problem isnt about airflow distribution at all. If you ran egt probes you would see that once shutting off the alky you will have much more linear temps front to rear. What does this mean? It means that a % of alky is not vaporized. If its vaporized its part of the homogenous mixture of the of air entering the intake and will be distributed the same way the air is since it is actually part of the air. If its not 100% vaporized it is still liquid which is a separate part of the mixture entering the intake. Guess what? Methanol just like every other liquid has a much greater density than air. Guess what else? Being more dense and seperate from the air it has more inertia. That inertia from the airflow (which increases as engine speed increases, not boost) coupled with the g forces of the accelerating car cause a very high % of this liquid to wind up hitting the back of the intake. Now if you have a wideband correction and are targeting lean you are in big trouble. The more you pressurize the intake the higher the vaporization temp for the liquid. The colder the intake air charge the less likely you are to vaporize the liquid. Too much alky injected upstream is its worst enemy to vaporization coupled with how much is injected. The boiling point for methanol is 149*F at sea level. There is a lot more pressure in the intake at 25-30psi than there is at sea level. Therefore getting a full vaporization on the fuel injected is about impossible since it has such a high latent heat of vaporization. It just drops the air temp so much when a small amount vaporizes that its actually inhibiting the remainder from vaporizing.

Exactly!

 

[blackgn1]

Are you guys running race fuel seeing any lean cylinders? Let's say with a proper tune any piston failures?

 

[DR BOOST]

Are you guys running race fuel seeing any lean cylinders? Let's say with a proper tune any piston failures?

in my situation, i had no fuel delivery problems when running racegas with a race gas tune. This is what helped me determine it was a alky distribution problem. If it was a fuel rail problem, the problem would have been worse on racegas since the injector flow demand is higher. I prefer running a modified stock rail because of the mounting issues of the billet rails.

 

[KevinB]

Are you guys running race fuel seeing any lean cylinders? Let's say with a proper tune any piston failures?

I havent. I saw #1 going slightly lean (reading the plugs) when i hit a wall with not enough fuel supply. this was on e85 and stock fuel lines. switched to a bigger feed line and the issue went away. Car was going 127 mph in the 1/4, which i found was the limit for the stock fuel line and e85 on my car. After upgrading to a -10 feed, no more issue all the way up to 139 so far. Remember, e85 needs about 30% more fuel.

 

[Razor]

http://www.turbobuick.com/forums/alcohol-nitrous-propane-tech/363767-new-best-video.html

Stock washer tank used. Kept full.. but non-the-less.
9.3-9.4 without a hitch.

I'll agree with Bison. If the IAT is going below 70 DF, you'll possibly/probably have issues. Especially if targeting a higher afr. Methanol needs 70 DF to flash. On a turbo setup "typically" it shouldnt be an issue. As every psi boost =~11df. The problem comes when you have very cold outside air temps, coupled with an efficient IC.. now the temps are not there. Would seem like the cars with the smaller IC's, in the heat, etc work better.

The old added saying of using alcohol to stop the detonation and use fuel for fueling still plays a role. Where as i'll bet anything that if you get a twin nozzle setup and crank the knob all the way up to max... and dont have a need for that volume your asking for trouble. Datalogging pressure of the meth system and monitoring IAT along with knock is all part of the tuning process.

If the number 1 piston is getting hurt... that typically is a supply problem. So doing the twin rails should cure this. If your hurting number 2.. then that equation is off.

And not to say your not having issue with a target AFR set to high. You cant run 11.5:1 afr and a twin nozzle... cranked up. That is a recipe for disaster. 10.0:1 is a start and go from there.

So.. anyone who has hurt number 1 or number 2 have a datalog of IAT, Pump Pressure, and air fuel?

 

[trixdout]

The problem isnt about airflow distribution at all. If you ran egt probes you would see that once shutting off the alky you will have much more linear temps front to rear. What does this mean? It means that a % of alky is not vaporized. If its vaporized its part of the homogenous mixture of the of air entering the intake and will be distributed the same way the air is since it is actually part of the air. If its not 100% vaporized it is still liquid which is a separate part of the mixture entering the intake. Guess what? Methanol just like every other liquid has a much greater density than air. Guess what else? Being more dense and seperate from the air it has more inertia. That inertia from the airflow (which increases as engine speed increases, not boost) coupled with the g forces of the accelerating car cause a very high % of this liquid to wind up hitting the back of the intake. Now if you have a wideband correction and are targeting lean you are in big trouble. The more you pressurize the intake the higher the vaporization temp for the liquid. The colder the intake air charge the less likely you are to vaporize the liquid. Too much alky injected upstream is its worst enemy to vaporization coupled with how much is injected. The boiling point for methanol is 149*F at sea level. There is a lot more pressure in the intake at 25-30psi than there is at sea level. Therefore getting a full vaporization on the fuel injected is about impossible since it has such a high latent heat of vaporization. It just drops the air temp so much when a small amount vaporizes that its actually inhibiting the remainder from vaporizing.

The pressure has a lot to do with it too. Go read up on thermodynamics of methanol. You can calculate the vaporization % based on the % of methanol in the solution injected, the inlet temp and the manifold pressure. Methanol absorbs water readily and raises its boiling point. The higher the latent heat the higher the energy absorbtion when it vaporizes. There is no set temperature because the manifold pressure isnt constant and the amount of alky injected isnt constant. One thing ill say is that when injecting over 25gph on a 700+hp engine and the charge air temp is going under 70* you are about to be in trouble. Eliminating the intercooler may be the way to go in some instances.

Spoken like a true chemist.