Using High Speed Lean-out Fuel

This is directed to Mike Canter:
Mike,
I started this thread because I “broke in” on the whipple lean out thread and needed to take this out of there. In that thread David Chesnutt (sand rat) said “with our set up we add fuel using our high speeds... start way rich and work your way back ...”
In the “high speed” thread, Eli asked a question about Rootes blowers. He asked (paraphrasing) Why can’t you pull the fuel that your high speed is dumping out of the system and put it into the top of the Rootes blower?
I think I know what he is suggesting, but I truly don’t know if it would be effective or not.
As you said, “According to Norm Drazy, the overall efficiency -- mechanical, volumetric and adiabatic -- of the Rootes begins at 40 percent and drops off to 20 percent at the end of a run”. All of that is well known even though I think he is understating the mechanical and volumetric efficiencies. It is a matter of physics that “trying to compress air creates heat”, therefore at high RPM's the adiabatic efficiency goes in the toilet.
So, at the RPM’s when the fuel pump is putting out more fuel than the engine can efficiently burn, we put in a high speed (high pump speed) fuel dump. Normally it is set at a particular pump pressure and returns the fuel to the tank. I “think” that Eli was suggesting that we would take a part of this and put back into the top of the Rootes blower. Therefore, helping to cool the air that is being pumped through the blower (again, higher RPM on a Rootes creates more heat).
I know this was a long one, but I truly didn’t know how to ask this question any other way. I am directing this question for you and all of the others on this site to respond because I respect and appreciate all of your experience and knowledge of Alcohol racing.
Yes I know, I know, ....... the screw blower is more efficient. Many of us out here don't have them so we are looking for a way to make what we have more efficient.
Hope this made sense and thanks to everyone for thinking about this and responding!

 

Mike,

After reading the other 'Hi-Speed' thread and what Dave has continued here, and what he, Gene, and others are thinking about, I wonder if the only way to do this would be to use two separate fuel systems, one for the hat and one for the ports, with the high-speed taken only off the port system? That would allow the hat system to continue putting more fuel in the top to help cool the intake and improve the blower's efficiency, while reducing the overall A/F ratio as required. Make the hat nozzles just large enough to keep the blower happy and achieve the aim of this exercise, and put the rest through the ports.

The downside to all this is two fuel systems (and double the cost) to really mess with your mind, and are you allowed? Having said that, if one really wanted to go to all this trouble, just get a more efficient blower...

Sound feasible? Surely someone must have already tried it?

Paul.

 

Let me explain my theory better, If you come off the port nozzle block, and put the fuel in the hat by way of an other nozzle the FUEL PUMP will still THINK its putting the fuel back in the tank, so the pressure will drop off leaning out the whole system, Now if my theory works and you do cool off the blower and the air going into the hat you in effect leaned out the motor MORE so the fuel that comes out of that extra nozzle gives it the fuel the motor will now need,of course you will have to play with the nozzle till you get the right fuel mixture. but like anything outside of the box were all in, takes some experimenting with. right now I'm back working on a K boat ( blown big block Chevy in 18 foot flat bottom, right now this has no port nozzles, I'm going to put a port nozzle setup on it and I will experiment, with it too, thing is these boats can't use the power they have now, but I want to know if MY idea works,and if it dose None of you forget who tough of it, cuz I was the first to use a slider clutch, and all the guys that were famous back before I ever did any record setting took the credit for it, and that guy put his clutch disks in back-words and the clutch slipped unintentionally and he picked up 1.5 seconds in ET and they didn't know why till they took the car apart (U S Nationals 1967 or 8, I had one in my car in 1966. And if you don't belive me ask my brothers Vic Or Anthony.

 

Hi-speed fuel redirection system

Eli, I will be interested to see if you can find any power/speed gains with your new setup. What do you think of the name in the title? Remember I thought of the name if it takes off! My guess is that you may find a very small gain over a fuel system with NO hi-speed or a power loss compared to a system WITH a hi-speed . Compared to a system with a hispeed, you havent actually taken ANY fuel away with your new setup. You have only altered the balance between the ports and the hat. This may result in a small blower efficiency gain. Like I say- let us know how it goes.
Jim

 

Ah hah!! This is exactly what I have been trying to suggest.
"Manage" the fuel delivery to the monster!
We cut fuel to a rootes blower at high RPM's because it gets real inefficient at those high RPM's. (heat, poor air, etc., etc.) If we manage the fuel delivery and put more to the blower when the heat efficiency really gets bad, maybe we can gain more power because we didn't add fuel too early when it was efficient. We waited until the air charge got higher in temperature and then added the necessary fuel to help cool it.
I'm done with this particular "out of the box" thinking, but I couldn't stand not bringing it up for everyone to think about an comment!
I am now crawling back into my hole

 

To Mike Canter

Mike,
You got it right. I was just trying to
"get out of the box" and see what the thoughts on this subject were.
Rootes Blowers are not efficient, we all know that. But, a lot of us here have them and we are always looking to make them better.
We know that Screw Blowers are more efficient. I was trying to throw something out there for the Rootes guys to think about, maybe making our units work better, making more HP than we have already accepted.
Thanks for your input
Is it Friday yet?

 

It's like what the old maid that pissed in the ocean said, EVERY LITTLE BIT HELPS if it works. P/S cool name.

 

9 hat nozzles, one of them with high speed check and eight ports . High speed leans out not because of less pump pressure cause you got more area, but because you have more of a pressure drop across the hat nozzles.

 

That a good idea too,two high speeds,one to the tank, one to the extra nozzle. thjts suggested that also, If every one jumps on this idea and refines it, it might just work. now here's a system where I would aim the nozzle at the butterfly's from the back of the hat.

 

9th Hat Nozzle

Ok, so now we have to decide where to start. Plumbing won't be difficult because all we're doing is adding another hi-speed and plumbing it to the 9th nozzle. But there are three variables we have to consider;
1. 9th nozzle jet size
2. Original return jet size
3. Opening pressures
With improved blower efficiency we're going to want the return to open later. However, the 9th will need to open at a point where the blower starts to make heat and efficiency falls off (stating the obvious?). Jet sizing will be fun. I'm thinking that the return won't be too much smaller than before because even though we will be improving blower efficiency, it possibly won't be too much, as Jim has pointed out. So how much do we put through number 9? Perhaps start with an amount equal to how much has been taken away from the return? This should maintain the original pressure/volume at the other hat nozzles and the port nozzles.
Is this theory sounding ok so far?
Paul.

 

Heres my problem, I never ran a high speed in the roots setup, And the screw blower car I worked on didn't need one it needed a high speed enrichment valve, So help me out here, some one with this BBC set up can probably clue us in on the basic tune up with presser and jet size for the high speed, ports and hat nozzles, Then we will take the area of the jet and see what % we are takening from the whole system and split the difference with the nozzle and high speed jet, and how do we figure out when the blower starts to pump heat, I'll bet Mert can help there? HELP

 

Eli,

Why wouldn't you just start out with a higher ratio or fuel going through the hat instead of the ports?

EDB

 

I already answered this post once, and some A/ hole removed it, so here goes, Mike Cantor said the same thing, my answer is, If it were that easy everyone would be doing it already.

 

OK!!!! Now it sounds like we are actually "thinking" about if it would work or not and if it "could" work, how would we make it happen! Thanks thjts for making us think a little harder about this possibility of making more HP with the "lowly" Rootes blower. Your theory is sounding great!
I, like many others just accepted the fact the Rootes blowers sucked on performance at high RPM's and we had to live with it. Eli made me think that maybe I could help the performance "a little" at these higher RPM's.
I am thinking that if we "manage" the fuel going to the blower, it could be beneficial to HP.
I really didn't mean to get into this thread again but seeing that there are a few folks that see there are possibilities here, I got "interested" again.
Dave Baker,
There is nothing so habit forming as money.

 

Hi guys! I have been following this thread and will try to put my two cents .

1. To keep your engine runing good you can't change the fuel curve so you can't change the fuel going thru the main or hi speed valves taht way your current setup will NOT change.

2. What need to be done, is to figure the total area of the fuel system and substract some area from the nozzles ( primaries) then plumb the diference in area to a secondary system .
a. Both your regular ports and hat nozzles need to be smaller.
b. A new port and hat system needs to be installed with same nozzle sizes on both to start ( the diference in the area substracted) ... In order to chande the hat and port flow so more "cooling" is achieved a fuel shutoff needs to be installed so its flow to the secondary hat or secondary ports.... A air cylinder or cable attached to the new system shutoff will change flow from sec. port to secondary hat.

IF this works then the engine will not see more or less fuel but in fact you will have changed the amount of fuel tru the blower at any time in the run...

Ps. I will run for cover now as everybody takes a shot at this idea

 

Coating rotors

I know it helps the screw blowers but it really helps a roots, We tried all this stuff opening a normally closed to 4 extra hat nozzles trying to seal the blower. but nothing works like taking up the clearances with solids!

Mark