Fuel Injection.

Does anybody have an inside scoop on Fuel Injection?

For the first year or so I see the big teams with a hugh advantage.
You can bet they are already testing the shit out of all different combinations.

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Permalink Reply by Carl Abrams on April 7, 2011 at 1:36pm

I will 2nd that Shane.
Thanks for the info.
It sounds to me like you would be a great candidate for Engine Tuner for this new system.

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Permalink Reply by ShaneH on April 7, 2011 at 3:05pm

You're welcome. I don't feel that going to EFI is as hard on these teams as a lot would think. While there is certainly expense, the plusses balance that out. Especially now that they're using E15. E15 is a great fuel, especially when you have the ability to tune the complete fuel and spark curves across the map, as well as your accelerator enrichment across the map. I never liked it and E85 with carbs because it's a lot more difficult to control the air fuel ratio swings during those transients like when a driver feathers the throttle a few times during wheel spin. FWIW, for pure peak power a carb will win by 2-3% every time over EFI.

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Permalink Reply by GTX - HEMI on April 8, 2011 at 10:32am

Shane......my source says whoever can "lie" to the sensors the best without getting caught will rule.......suppose the computer is programed for 9000 RPM....and you have a way to make it think it is at 9000 RPM.....but you are actually using 9500 RPM...............it is already being done and no finger prints.

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Permalink Reply by ShaneH on April 8, 2011 at 11:36am

The question I have is WHY? There's no benefit to that in this environment. Unless Nascar decides to limit rpm, which I don't see. Limiting rpm is VERY hard on an engine, and it doesn't matter whether you are talking fuel limit or spark limits. Both will shorten the life of them to some extent. I guarantee the fuel and spark maps(unless they choose to keep spark advance analog as it is now, which I just don't see) will be wide open and with the ability to completely tune them. So there's no need to fool the computer. While it's true, that doing that is easy enough with a simple resister circuit, there's no reason for it.

The assumption people are making is that Nascar is going to give out a box with preset maps. It's just not going to happen, as currently a carb allows you to fully tune a system. So there is no need for lying to the sensors. What the box will have is fully programmable fuel maps, accelerator "pump" additive, can-bus interface to transmit tv data as well as nascar black box data, Also, injector sizes will be mandated, with the ability to change sizes in the system locked. In this application that's about all you need.

FWIW........I have a traction control system in my hand that's smaller than a 9 volt battery. It looks at rate of acceleration and then an output goes high when it detects rpm going up faster than the programmed amount. That output is then used to trigger a momentary retard in the ignition ciruit. The NHRA did NOT like that on the ProStock cars, which is why their mandated Digital 7 MSD boxes have a circuit that detects the quick retards(sometimes 20 times in a second) during wheel spin and shuts the MSD box down(it has to be reset by an NHRA tech inspector once it's shut down). I can almost guarantee this type detection circuitry will be present in the Mclaren box and will do the same thing. Doing so would also bring spark map control under the EFI instead with a locked out distributor.

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Permalink Reply by alan4s on April 8, 2011 at 10:38am

Another question related to EFI is what happens at restrictor plate tracks? Will nascar still use the equivilent of a plate, or will the diddle with the EFI unit to try to accomplish the same thing?

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Permalink Reply by ShaneH on April 8, 2011 at 11:44am

There's a few ways to limit the speed. One is by limiting fuel. They could issue specific fuel injectors and an ECM with the injector size locked inside it. For example, you would want 42lb/hr injectors to support 450hp with a bsfc of .50(generally acceptable for a NA engine). For 900hp you'd want 83lb/hr injectors. Now the trick here is that injectors are flowed at 43psi static pressure. If your closed loop fuel system pressure were raised to 60psi those 42lb injectors would support 550hp. So there's some things Nascar would probably want to do. Like issue fuel pressure regulators fixed at 43psi.

I can't see them wanting to limit spark. You're just asking for problems there.

The other way would be same as now, limiting air. You could do that with different size throttle bodies or a tapered spacer between the throttle body and intake.

Lots of possibilities they didn't have before.