NASCAR's fuel system discussion.

[FenderBumper]

I can't find any official NASCAR documents on how their fuel supply will work, but here is a diagram and explaination of the fuel supply system for cars that had carburators.

Scroll down a little and Look at the schematic. You'll see LOW pressure feeder (lift) pumps feeding LOW PRESSURE lines (BLUE) that lead to the EFI HIGH PRESSURE pump that feeds the HIGH pressure fuel lines (GREY).

So, the lift pumps NASCAR is talking about are near the tank and easily primed (if electric). They then feed high volume/low pressure (fat) fuel lines that feed the HIGH PRESSURE EFI fuel pump, which supplies 10x the fuel pressure to the injectors. Why can't they mount the high pressure pump near the tank? I'm guessing that having heavy gauge fuel lines with a bunch of fittings running the length of the car is undesirable.There are high pressure mechanical drive pumps capable of feeding the EFI, but they wouldn't be mounted back near the tank because you would need high pressure lines all the way to the injector rails. These cars are run on and off the gas constantly, so you need that HIGH pressure pump as close to the fuel rail as possible to have quicker throttle response.

------------

This is EXACTLY the system I predicted months back, with the exception of the surge tank and return lines, but rail over-pressure needs to be released somewhere. Lets hear some other guesses. Perhaps NASCAR will eventually come out with a full explaination some day.

 

[FlFlash]

but they wouldn't be mounted back near the tank.

Why not? Hmmmm maybe even In the Tank, think about it.

 

[MOEJOE]

I heard each car will have a monkey running inside of a cage wheel. That will generate enough electricity to make the in tank electric pumps run.

Pictographs courtesy of my daughter.

 

[FlFlash]

BTW, that diagram and link is pertaining to Aircraft FI systems.

 

[FenderBumper]

BTW, that diagram and link is pertaining to Aircraft FI systems.

Do you read things before you decide what they are about? Go back to the link and READ BIG LETTERS ABOVE DIAGRAM THAT SAY...........

Weren't you whining that I always seem to want to put you down by proving what you post is incorrect?

 

[FlFlash]

Do you read things before you decide what they are about? Go back to the link and READ BIG LETTERS ABOVE DIAGRAM THAT SAY...........

Weren't you whining that I always seem to want to put you down by proving what you post is incorrect?

If your remember our previous conversations I had mentioned then that the FI systems I had seen at that point where using mechanical pumps, whats incorrect about that?

Anyhow I very seldom test race cars in this fashion: From your link:
Flight Testing

Flight testing of your new system should always be performed cautiously. Maintain low deck and bank angles until you reach safe altitudes. Start by performing shallow turns, climbs and descents , then progressing to steeper banking turns and steep pitch attitudes both up and down with all pumps on. Then try the same things with only one set of pumps on. Be aware that it may take several minutes to use up the fuel supply in the header tank if the flow from the main tanks to it are interrupted. You should hold the steep attitudes if possible for 3-5 minutes at moderate power settings to ensure that you system will supply fuel under all flight conditions.

 

[FenderBumper]

Question answered. You don't read very well.

Back to blocked so I don't waste my time.

 

[Joniki]

Obviously, I am not the only one here that needs a racing fix.

 

[FlFlash]

Obviousley it's hard to have an intelligent technical conversation

 

[TexasRaceLady]

There is one diagram pertaining to cars with a carb.
The rest of the article seems to me to be concerned with aircraft engine and EFI.

 

[FlFlash]

And that one diagram is incorrect in respect to the race car FI systems I've personaly seen and worked on, but I don't want to upset nobody

 

[mike honcho]

And that one diagram is incorrect in respect to the race car FI systems I've personaly seen and worked on, but I don't want to upset nobody

Party Pooper.

 

[FlFlash]

Party Pooper.

Eeerrrrr you aint callin me Chicken are Ya?

Okay I can't give out diagrams or share some aspects but here's an overveiw.

The fuel cells are specially designed with an immersible electric fuel pump which are capable of 100psi but are regulated to 45-60 psi in most case's, the regulator is also internal to the tank. Cavitation can be a real issue with a high pressure high volumn electric pump so most teams are incaseing the pump in a secondary bladder to keep it surrounded in fuel with some interesting baffleing and check valves, there's also a 30 micron sock type filter in there.
The fuel pumps electrical supplies are routed through a fuel rail sensor at the engine and the FI module. If the module detects no engine rpm from the trigger it shuts off the pump to contain fuel leakage after accidents engine failures etc. All the electrical circuits are wired redundantly.

Several people keep commenting on "Throttle bodys" it's actually a throttle plate with a throttle position sensor mounted in it, No Injectors in it! The injectors are mounted on the intake runners at a location that aims them on the backside of the intake valve ( that varies by engine manufactuar and builder ) the much maligned restrictor plate when used goes under the throttle body.
Some of the teams are working with twin pumps for better fuel pick up and usage, can't say much about that.
Some GM and the Ford boys are using the cable drive with overdriven multiple impeller mechanical pumps and regulators to acheive a consistent fuel pressure, no more comments on that either.

Wish I could show some pics it's really cool chit.....but I need my paycheck on a regular basis.

Thats it I'll say no more about FI

 

[FenderBumper]

There is one diagram pertaining to cars with a carb.
The rest of the article seems to me to be concerned with aircraft engine and EFI.

You'll notice the picture title says "cars that HAD carburators", since you can't have both carb AND EFI.

From the link:

System Basics

It is important to familiarize yourself with the basic EFI mechanical components and function to be able to understand why certain things need to be a certain way. All EFI systems use a high pressure pump to supply fuel to the injectors. This is almost always electrically driven. Most systems run between 35 and 45 psi. Fuel is supplied to fuel rails or a fuel block which is connected to the injectors. The other end of the fuel rail or block is connected to a fuel pressure regulator. Its function is to hold the fuel pressure at a constant differential above the intake manifold pressure. It does this by returning unused fuel back to the fuel tank. The pump always puts out a constant volume of fuel and more than the engine requires at full throttle so most of the fuel is returned back to the tank under idle and low power conditions. Below is a proven fuel system used in racing cars which undergo high G forces. (sound familiar?)

Note: BLUE lines are low pressure from the gas tank LIFT pump. Gray lines are HIGH pressure from the EFI electric pump.

The article then goes on to talk about aircraft EFI, but the diagram title is for a car's EFI system that has been adapted for some aircraft. If you carefully read the diagram, and still don't understand it, it's probably too technical. This stuff is cake for me to understand, which is why I invent.

 

[fastfordfan]

I don't think this is correct for Nascar but here it is

 

[FlFlash]

I don't think this is correct for Nascar but here it is

Everytime I look at that it makes me smile

 

[fastfordfan]

Why won't this work
BTW inlet filter and pump or in tank

 

[FlFlash]

Very nice, thats how a great many production cars are set up. For a race application moving the regulator inside the tank and making it a returnless system ( returning the fuel after pressureizing it and running it thru the fuel rails heats and aerats the fuel, bad for performance ) makes for a less complicated easier to work on and safer system.

 

[fastfordfan]

How can it be returnless

The car won't use as much fuel at idle compaired to wide open

Where does the fuel go

 

[fastfordfan]

Maybe this way


http://shop.wiltec.info/product_inf.../p2604_Race-Tech---R---Benzindruckregler.html

 

[FenderBumper]

I don't think this is correct for Nascar but here it is

Holy Crackers, where did you find that? lol!

Looks like NASCAR will return fuel directly to tank, which makes sense. These guys want to burn every last drop. The lack of a surge tank explains why they are allowing 2 lift pumps to keep up with throttle demand. Lack of a surge tank would also explain some drivers saying when the mash the throttle, EFI reacts a little slower than the carb system, which has accelerator reserve tank(s) built into the carb.

 

[FlFlash]

How can it be returnless

The car won't use as much fuel at idle compaired to wide open

Where does the fuel go

By returnless I mean once the fuel gets to the fuel injectors it dosent come back to the tank, that's made possible by the pressure regulator being in the fuel cell excess pressure and fuel is releived there.

 

[fastfordfan]

By returnless I mean once the fuel gets to the fuel injectors it dosent come back to the tank, that's made possible by the pressure regulator being in the fuel cell excess pressure and fuel is releived there.

Ok so how does the regulator know if the engine is running 1400 rpms or 9000 rpms

 

[fastfordfan]

are u telling me that the system is set up on pressure alone and that the system runs lets say 60 psi all the time idle and wot

 

[FenderBumper]

It's fun watching you 2 work this out. It's all in the diagram I posted, FFF reposted, and the new one FFF posted.

 

[fastfordfan]

It's fun watching you 2 work this out. It's all in the diagram I posted, FFF reposted, and the new one FFF posted.

I personally don't think your diagram is correct

I HAVE BEEN WRONG BEFORE

 

[fastfordfan]

Why won't this work
BTW inlet filter and pump or in tank

I THINK THIS IS CLOSER THAN YOURS

 

[FlFlash]

Ok so how does the regulator know if the engine is running 1400 rpms or 9000 rpms

The regulator dosent care about engine RPM only fuel pressure as long as it's controlling the fuel pressure to it's setting it's happy. So yes if your fuel pressure is set to 48psi its 48psi at 1200 rpm or 9000 rpm.
The pressure setting is set for proper fuel atomization from the injector not engine rpm.

 

[FlFlash]

It's fun watching you 2 work this out. It's all in the diagram I posted, FFF reposted, and the new one FFF posted.

Sure that maybe a workable system for something, but it is Not whats on the Cup cars.

 

[fastfordfan]

The regulator dosent care about engine RPM only fuel pressure as long as it's controlling the fuel pressure to it's setting it's happy. So yes if your fuel pressure is set to 48psi its 48psi at 1200 rpm or 9000 rpm.
The pressure setting is set for proper fuel atomization from the injector not engine rpm.

So that explains to me at least why some are still running cables

Cable turns fast enough on start up to build enough pressure after running out of fuel

 

[FenderBumper]

I THINK THIS IS CLOSER THAN YOURS

Yours doesn't show ANY lift pumps, and we know that isn't right. Like I said earlier, I doubt NASCAR would use the return system shown in my diagram.

I'm not sure they use multiple fuel filters either. HMS was complaining that one of their injectors got clogged, and that fuel is well filtered when supplied to the teams.

 

[mike honcho]

and that fuel is well filtered when supplied to the teams.

Do you have a diagram that would prove that?????

 

[FenderBumper]

Do you have a diagram that would prove that?????

They use Mike Heltons moustache.

 

[mike honcho]

They use Mike Heltons moustache.

That doesn't work very well.There is alot of crap that gets by it everyday.

 

[FenderBumper]

That doesn't work very well.There is alot of crap that gets by it everyday.

Blocks his view.

 

[fastfordfan]

Yours doesn't show ANY lift pumps, and we know that isn't right. Like I said earlier, I doubt NASCAR would use the return system shown in my diagram.

I'm not sure they use multiple fuel filters either. HMS was complaining that one of their injectors got clogged, and that fuel is well filtered when supplied to the teams.

Why does it need a lift pump my pump is capable of pumping 100 psi

 

[FlFlash]

Why does it need a lift pump my pump is capable of pumping 100 psi

IF the hi-pressure pump was mounted externaly and in the front of the fuel system as shown in some of these diagrams it would require a lift pump to keep the Hi-pressure pump primed ( the old mechanical pumps mounted on the engine from years back where a diaphram type pump they created enough vacumn to self prime, electric pumps have impellers and are not self priming ) having the electric pump internal to the tank overcomes that problem because the pump is immersed in fuel. The secondary pump NASCAR is allowing aloows for better scavenging of the fuel cell....every last drop is important!

BTW, Helton has a Bad Ass stash

 

[fastfordfan]

IF the hi-pressure pump was mounted externaly and in the front of the fuel system as shown in some of these diagrams it would require a lift pump to keep the Hi-pressure pump primed ( the old mechanical pumps mounted on the engine from years back where a diaphram type pump they created enough vacumn to self prime, electric pumps have impellers and are not self priming ) having the electric pump internal to the tank overcomes that problem because the pump is immersed in fuel. The secondary pump NASCAR is allowing aloows for better scavenging of the fuel cell....every last drop is important!

BTW, Helton has a Bad Ass stash

Agree my diagram has as i noted an IN TANK FUEL PUMP

 

[fastfordfan]

This is an example of an external fuel pump for it to work properly in must be gravity fed, it is what it is a pump it does very little of any sucking. So it would have to have a lift pump.

 

[SST55]

We ran a Holley electric fuel pump mounted on the crossmember a good 18 inches above the tank pickup and a good foot forward. Yes this was a carb engine and not fuel injected but saying a electric pump won't pick up isn't true.