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What's your 1/4 MPH w/ 4x720cc injectors?

Old 04-03-12, 01:14 PM
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What's your 1/4 MPH w/ 4x720cc injectors?

I run 4x720cc but have not taken the car to the track. They are to far away.

I’m currious to see how well this aerodynamic principle adheres to reality:

F2/F1 ~ (V2/V1) **2

Knowing the following:
- Force F1 (but we’ll let it be in this case the total initial injector size),
- the speed (V1) through the ¼ with F1 injectors,
- and the new total injector size (F2),
Solving for V2 should be roughly the speed that can be had with F2.

Let’s agree that a TII (or any turbo’ed FC) that has been mildly modifyed to safely/reliably run on the 4x550cc will be at around 100 mph thought the 1/4. Let’s also assume the BSFC through the power curve are in synch for the most part going from 4x550cc injectors to 4x720cc injectors.

Solving for V2 we get 114 mph!

I’d settle w/ ~108-110. And from the seat–off-pants, it sure seems that way.
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Old 04-03-12, 02:09 PM
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Your equation assumes that quarter mile times can be directly correlated to injector size with no other variables when this is not the case in reality.
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Old 04-03-12, 02:14 PM
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A more relevant comparison would be turbo size/airflow or horsepower to quarter mile trap times, and even then a lot of variables like mixture, timing, torque band and tires will be left out. You can change the injector size all you want, but it won't make a bit of difference unless you cram more air into the engine.
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Old 04-03-12, 06:40 PM
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The equation assumes that an X additional amount of fuel is required to go from Y mph to Z mph at the 1/4 mark. I understand there are many variables.

And, w/out saying, I also realize not just more fuel = more power. The engine needs to be configured correclty to handle the additional boosted mass air flow.

I'm not asking for the flaws in the approach. As I said, I'm curious what MPH , not ETs, when running 4x720cc injectors.

So let's see what them #s are!
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