Injectors Question
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3rd Gear
Joined: May 2004
Posts: 243
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From: 3rd Stone from the Sun
Injectors Question
This was posted on mini2. I copied it here in hopes of more elaboration on the subject:
If the stock injectors provide adequate F/A ratio then what is to be gained by putting in larger injectors? Seems the A/F ratio will be the same regardless of injector size.
If due to engine modification (more boost?) the stock injectors become inadequate, how will one know?
In the event that the injectors are inadequate does the ECU prevent a leaned out condition - say by throttling back with subsequent HP loss?
Finally, at what point with respect to engine modification will larger injectors become necessary?
If due to engine modification (more boost?) the stock injectors become inadequate, how will one know?
In the event that the injectors are inadequate does the ECU prevent a leaned out condition - say by throttling back with subsequent HP loss?
Finally, at what point with respect to engine modification will larger injectors become necessary?
3rd Gear
Joined: Jul 2004
Posts: 285
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From: Manchester, KY
Forgive me if I misquote something, but this is mostly from memory. As long as you're not pushing more air in, adding bigger injectors really gives no gain.
The stock injectors generally only become inadequate near redline, when they can't keep up with demand. This can result in detonation. As for other signs that they're inadequate, I'm not sure...
I think that the ECU does indeed retard timing, resulting in a HP loss, but I'm a little fuzzy on that.
Larger injectors are usually reccomended with at 19% pulley, but to add them, you need an upgraded ECU to recognize them. Otherwise, they'll dump too much fuel and the car will run way too rich. Everyone I've heard who's done the 19%/injectors/GIAC have praised it.
The stock injectors generally only become inadequate near redline, when they can't keep up with demand. This can result in detonation. As for other signs that they're inadequate, I'm not sure...
I think that the ECU does indeed retard timing, resulting in a HP loss, but I'm a little fuzzy on that.
Larger injectors are usually reccomended with at 19% pulley, but to add them, you need an upgraded ECU to recognize them. Otherwise, they'll dump too much fuel and the car will run way too rich. Everyone I've heard who's done the 19%/injectors/GIAC have praised it.
5th Gear
Joined: Dec 2005
Posts: 603
Likes: 1
I can hopefully provide a bit of info with regards to the last part of the post. When most people get to a total of 19% over drive of the super charger they usually opt for larger injectors. They could be using a combination of pulleys wether it be a 17 + 2 or a 16 + 3 or just a straight 19 . A injector size in the 400 cc range is the prefered choice. Additionally those using NOS like to upgrade as well to give a larger margin of saftey in preventing a too lean condition. Hope this hels a bit.
John
John
6th Gear
Joined: Sep 2004
Posts: 5,149
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I have had: stock, 380s, 400s and 440s..... I have had the best results with the 400s.....the 440s can be trimmed to work just fine but for circumstances beyond my control I went back to the 400s and they worked well with out a custom tune...later I tuned them
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