all chase races will now include....

FenderBumper said:
FI could make it even harder to get the last gallon out of the tank. Those systems are a bit more sensative to a drop in fuel pressure.

For the life of me, I can't figure out why NASCAR went to a mechanical pump instead of a fuel system kill circuit tied to the ignition.
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No matter what happens a mechanical pump quits pumping when the engine stops running, fool proof and reliable.
Electric fuel pump would have to have a switch or sensor plus wiring and a relay...Not as reliable because switchs, sensor, relays and wiring could fail and leave the pump on dumping fuel all over the accident area.

I dont know of any Oval racing organization that allows electric fuel pumps?
 
FlFlash said:
I dont know of any Oval racing organization that allows electric fuel pumps?
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I'm not sure the Oval distinction matters. Having a running fuel pump after an accident a road course is much more life threatening, since help isn't always close by.

F1 uses both. The primary mechanical pump is fed by 2 electronic pumps. Since Mclaren is the supplier forF1, we may see the same 2 step approach in NASCAR.

The problem with EFI engines is they don't sputter when fuel pressure drops, they shut off. Getting enough fuel pressure by cranking the engine can be near impossible.
 
I added the oval disclaimer because I have a very limited knowledge of what their running in road racing and offroad racing series.

I knew F1 used electric over mechanical butt thats kinda like comparing Avocados to potato's ( Extreme Hi Tech to Low Tech ) NASCAR has always followed the KISS principle up until the introduction of FI next year.....should be interesting to see how well it works out.

By the way FI with mechanical fuel pumps is a very old technology used in aircraft engines in 1936 ( Messerschmitt BF109 had it ) and in automobile's there was the Famous Fuelie small block Chevy from the mid 50's. It's not a problem.
 
FlFlash said:
By the way FI with mechanical fuel pumps is a very old technology used in aircraft engines in 1936 ( Messerschmitt BF109 had it ) and in automobile's there was the Famous Fuelie small block Chevy from the mid 50's. It's not a problem.
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If I'm not mistaken, those were low pressure mechanical injection systems. EFI is a totally different animal.
 
FenderBumper said:
If I'm not mistaken, those were low pressure mechanical injection systems. EFI is a totally different animal.
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Depends on what you call low pressure? The early GM Mech FI only had 2 psi at idle but climbed to 40 psi at 6000 rpm.

Did you know the GM Duramax Diesel can run in excess of 35,000 psi injector pressures? It's done with a mechanical pump that will fit in the palm of your hand.
 
FlFlash said:
Depends on what you call low pressure? The early GM Mech FI only had 2 psi at idle but climbed to 40 psi at 6000 rpm.

Did you know the GM Duramax Diesel can run in excess of 35,000 psi injector pressures? It's done with a mechanical pump that will fit in the palm of your hand.
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Mechanical pump sure can put out a lot of pressure, if they have a steady fuel flow, and fuel flow is my point. IF you have RPM's you get plenty of pressure from any pump. If the cars fuel system picks up air or stalls, your starter may give you 400 - 500 RPM's, and that isn't a good operating range for a fuel pump. An electric pump can run whatever RPM's it needs to get gas flowing again. Yes, I know that's why they can be dangerous.

So, what will happen when a car with just a mechanical pump starves for gas? You won't be able to squirt gas into the carb to get the engine RPM's up to get the mechanical pump primed again.

I'm sure they will address the problem. I'm just wondering what method they might use.
 
Same method currently used, run a pump thats capable of the pressures you need at the rpm you need then use a regulator to keep it in that range.
For restarting engines out of fuel you do what we currently do squirt a lil gas or starting fluid down the air intake.
Your over thinking it Bumper it's really not an issue.
 
FlFlash said:
Same method currently used, run a pump thats capable of the pressures you need at the rpm you need then use a regulator to keep it in that range.
For restarting engines out of fuel you do what we currently do squirt a lil gas or starting fluid down the air intake.
Your over thinking it Bumper it's really not an issue.
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I guess fuel in the intake will work the same.

I still wonder if cars stumbeling on air bubbles on a restart will simply shut down for lack of pressure to the injectors. The loss of the carburator reservoir could become a big factor. It does indeed present a problem, which is likely one of the reasons F1 uses electric pumps to feed the mechanical pump. The early mechanical EF systems had a gas reservoir to help boost the engine when injectors were starved.
 
The sprint cars cured that problem by running a fuel log with a check valve and a regulator built in.

I haven't seen the Cup FI system in it's final ( if it is in it yet? ) stage but I'm thinking that or some type of pressurized resouvoir will be incorporated.

Sorry but I forgotten the original theme of this thread :eek:
 
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