Torque Dip

[sierra]

Originally Posted by b.e

I think some of you are missing the importance of the green (INJECTION VOLUME) curve. The fuel rate isn't dropping when the type of injection changes.

Blue injection volume curve?

The problem with that is if it's showing the total fuel being injected at full throttle? Then why is it only showing another 10% of fuel being used at 5,600rpm than is being used at 3,500rpm? Or almost the same fuel at 7,600rpm as at 4,900rpm?

[Grip Ronin]

they should run both much earlier because that mix of port and di give the car its best performance. giving the benefit of the doubt i assume the tuners have tried this already

[sierra]

Originally Posted by Grip Ronin

they should run both much earlier because that mix of port and di give the car its best performance. giving the benefit of the doubt i assume the tuners have tried this already

They do both run much earlier but for some reason the port injection shuts down in the torque dip range.

You would assume they have but have you ever seen this mentioned before?

[Synack]

Originally Posted by ziggz501

has nobody messed with the ECU to keep the port injectors on? it would be interesting to see what the torque curve would look like if they were just kept on and tuned to keep proper air:fuel.

but yeah, a major objective of the direct/port injection system is for emissions.

I was running on 100% port injectors for a little while. Doesn't help your argument because I wasn't anywhere near stock though.

[Synack]

Originally Posted by ziggz501

the torque curve dips around 4000~rpms if i recall correctly, but the port injectors open up at 5000, which almost doubles the amount of fuel being dumped into the engine. my guess is that the engine is using the DI mainly for the purpose of emissions in the early rpms.

Bingo

[sierra]

Originally Posted by Synack

I was running on 100% port injectors for a little while. Doesn't help your argument because I wasn't anywhere near stock though.

Did it do anything to the torque dip?

[Grip Ronin]

Originally Posted by sierra

They do both run much earlier but for some reason the port injection shuts down in the torque dip range.

You would assume they have but have you ever seen this mentioned before?

nope i havent seen anything about the details of their tunes. id really love to cut the bs and put a AEM in it and bring it to my tuner over here in newark.

[sierra]

Originally Posted by Grip Ronin

nope i havent seen anything about the details of their tunes. id really love to cut the bs and put a AEM in it and bring it to my tuner over here in newark.

Just googled AEM tuning and found a whole new world!

[Synack]

Originally Posted by sierra

Did it do anything to the torque dip?

I was turbocharged and had an extremely custom tune. Can't really attest to anything.

[sierra]

Originally Posted by Synack

I was turbocharged and had an extremely custom tune. Can't really attest to anything.

No, turbocharging always fills the torque dip too.
Do you know if Ecutek can turn the port injection back on?

[Sport-Tech]

Originally Posted by sierra

Do you know if Ecutek can turn the port injection back on?

Interesting question - but wouldn't doing so likely hammer the fuel economy?

[ziggz501]

Originally Posted by Sport-Tech

Interesting question - but wouldn't doing so likely hammer the fuel economy?

unlikely. the fuel economy would take a tiny hit at best. keep in mind that the air:fuel remains relatively constant throughout the powerband. the biggest issue is usually getting the air into the cylinder chambers since the camshaft on most cars is usually designed for low end torque. this is why Honda's VTEC is a thing; although, most people have no idea what it does because they have never sat in an S2000 or TypeR.

what would take the biggest hit is the emissions, but if you are messing with the ecu, emissions is probably not your concern.

[sierra]

Originally Posted by Sport-Tech

Interesting question - but wouldn't doing so likely hammer the fuel economy?

As Ziggz has said, the mixture can be kept constant. If restricting the injection to direct, for emissions at that rpm, is restricting the the available power then keeping the port injection operating will restore that power. The fuel consumption might suffer slightly because direct injection is more efficient and the emissions would be slightly higher but let's face it, they look to have done this to pass specific rpm emission requirements which is bending the rules anyway.

[whtchocla7e]

The torque dip is overrated. I don't even feel it..