FI rules

[chuckBYU]

I've been reading everywhere in the rules and searching on here for rules relating to the fuel injection (specifically location of fuel injectors). As of yet I haven't found any rules stating where the fuel injectors have to be. Can you put them anywhere (IE anywhere in the runner, plenum, restrictor, throttle body)? The rules give a specific order for the location of turbo and restrictor and throttle but no fuel injectors. What do the judges think about injectors in other locations besides right before the intake ports? Thanks for the help.

BYU Engine guy

[chuckBYU]

I've been reading everywhere in the rules and searching on here for rules relating to the fuel injection (specifically location of fuel injectors). As of yet I haven't found any rules stating where the fuel injectors have to be. Can you put them anywhere (IE anywhere in the runner, plenum, restrictor, throttle body)? The rules give a specific order for the location of turbo and restrictor and throttle but no fuel injectors. What do the judges think about injectors in other locations besides right before the intake ports? Thanks for the help.

BYU Engine guy

[Chris Boyden]

Some issues to think about:

Are you running batch fire or full sequential?
With batch fire(phase sequential), you may want to fire the injectors directly on the back of the valve, so that the heat vaporizes the fuel between intake events, whereas full sequential systems may benefit from fuel injector placement at the top of the runner designed for higher rpm fuel/air mixing. It may be beneficial to shoot the injectors against the incoming air to generate turbulence and aid mixing. With batch fire, the only position that makes sense to me is to squirt right into the port onto the back of the valves.

[Dan G]

Squirting fuel before the runners means you must be very careful with equal flow distribution (not a bad thing to keep track of anyways). Also, fuel before the restrictor will hurt you due to the fact that you're taking up valuable airspace with fuel droplets.

I'm not aware of any rules regarding injector placement, although you will be subject to a safety inspection, so I don't think injecting before the filter is going to fly.

[Psychosis]

hi guys,
been having a discussion with the engine guys today about economy. My thoughts were that sequential injection gives better fuel economy and a marginal increase in power. is this correct? correct me if im wrong! im really just trying to decide if its worth trying to get an engine with a cam sensor, a more expensive ECU and hence run sequential. cheers!

[Dan G]

Unless you're actually tuning individual cylinder mixtures, your results with sequential shouldn't differ much from bank or batch injection.

[Psychosis]

cheers, i was just curious because if there isnt much difference, why do most cars and bikes run sequential?

[Greg 08]

I don't know much about engines, but I heard they do it for emissions from our "clean snowmobile team". From what I understand the power increase is barely noticable, but I haven't seen any data, just reliable heresay.

Greg Ehlert
Michigan Tech University FSAE

[BryanH]

FYI, 2 weeks ago did a back to back on a 20V 1600 toyota. These engines come with a quad throttle body setup.
Applied sidecutters to it's multi point microtech that I mapped 3 months before and fitted a sequential HaltechE8. WOT power curve was identical, making extra 1.4kw (111kw)
however idle quality hot and cold and off idle throttle response was massively improved, it's actually very difficult to stall it. (End of injection angle needs to be optimized)

Big diff was being able to switch on and off inlet cam advance correctly. Testing on the dyno found on @ >2500, off @ >6300 and on @ > 67% throttle
combined with a 2nd fuel map for the advanced setting resulted in major power gains, 50% @ 4000rpm!, and 127kw max. Power at the 7500 rev limit was still within 1.5kw of orig setup.
VVT is a good thing!