Fuel Injection conversion

[DannytheRadomski]

I'm not in FSAE yet, so this is just a fantasy engine at the moment, but how hard/expensive/stupid would it be to convert a carburetted engine to fuel injection? There's an engine I like that has the right configuration and displacement, but it is a bit carbuetted. I am just wondering, chances are this won't happen, but I would like to know for the sake of learning.

[Warpspeed]

I have done this myself quite a few times.

Probably the most difficult part is fabricating a new inlet manifold to aim the fuel injectors exactly right. You then get to make up a fuel rail to hold the injectors in place.

The other thing you need to think seriously about is the fuel tank and fuel pickup.
With a carb, fuel in the fuel bowl will keep the engine running for a few seconds if the fuel pump gulps a few air bubbles during very heavy braking or cornering.
With EFI, any air at all in the fuel line will cause the engine to miss or stutter.
So you need to figure a way to get solid fuel flow when the tank is almost empty with just a bit of fuel sloshing around.

All the rest is very straightforward. A fuel pressure regulator, throttle body, suitable engine sensors, and a tunable engine management system.
It can cost from a few hundred to a few thousand, depending on how much fabrication work you can do yourself, and if the parts are all brand new or scrounged and improvised.

Then you need to tune it.
How well it is tuned will make a huge difference to how it runs.
If you have access to a dyno and wideband air fuel meter, it is easy.
If you have nothing, it will be either expensive or difficult (or both) to tune it well enough to get the very best results.

Not stupid at all. A well set up EFI system on an older engine will improve it in every possible way.

[DannytheRadomski]

As for the fuel problem, would a fuel cell instead of a tank help at all? I don't even know if they are allowed in FSAE (they are supposed to improve safety, so I don't see why they wouldn't be), but that might solve the problem. I really have no idea, but that popped into my head right away.

[Warpspeed]

Quite a few different ways to solve this problem.
The way the road car manufacturers do it is to have some kind of cup or bowl located inside the main fuel tank that the pump picks up feeds from.

When the tank is almost dry, fuel slops into this bowl, gets trapped there, and cannot easily run away from it. The return fuel line also drains back into this bowl. Seems to work fine.

Race cars often have a dam partition right at the front of the tank.
Under brakes, the fuel rushes forward and keeps this dam area filled.

Another way is to have a fuel pump that pumps from the main tank to a second very small tall tank with an overflow. The EFI pump draws fuel from the second tank which is always kept full.

Not a difficult problem to solve, but a continuous solid fuel feed without air bubbles is a necessity.

[DannytheRadomski]

Wow. Thanks for the help. How cheap would this be? Would it be feasible in an FSAE car (cost effective, easy, quick)?

[Warpspeed]

That isn't really an answerable question.

If you have good fabrication skills, and have access to all the equipment required to put it all together and tune it properely, it should all be fairly painless.

And if you are prepared to track down and adapt secondhand parts it need not be all that expensive either.

How much it costs depends on your approach, and that is entirely up to you.

[Adambomb]

Originally posted by DannytheRadomski:
Wow. Thanks for the help. How cheap would this be? Would it be feasible in an FSAE car (cost effective, easy, quick)?

Up until recently that's what most teams did.

[Owen Thomas]

Originally posted by Adambomb:
Up until recently that's what most teams did.
+1. I believe Queens university still uses an EFI converted, dry sumped F4 (at least they were last year). Totally feasible, if you can justify it.

[mmw2753]

My team still runs converted WR450s because they weren't EFI until the latest model year, and then we would have to buy new bikes which we can't afford.