fat injectors
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Freshman User
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fat injectors
I forget what the opperating psi for the 12lb/hr injectors are, but what would it take to instal 19lb/hr injectors, I know you would have to change the regulator, but would one for a 19 lb/hr system mount right on the fuel rail, or would there be some modifications involved? has anyone ever done this? also, would it be too much fuel for a almost stock engine, an do you think fuel economy would greatly depreciate?
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Joined: Dec 1999
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From: Copley, OH
Your stock injectors are 14 lbs/hr @ 39 PSI. At the increased pressure of the 4.9's regulator (58 PSI), they actually flow 17. That's enough fuel for 164-192 HP
The 19 lb/hr injectors are a straight drop-in, at the 4.9 regulator pressure they actually flow around 23, or enough for 222-260 HP. The adjustable regulator allows you to decrease the thruput of the injectors to tune the fuel system to the engine. The adjustable regulator is not a simple bolt on. You'll have to do some fitting to get it to work.
WHY are you doing this? The larger injectors will not give you any more HP on a stock engine, or even one with a bunch of bolt-on parts. Unless you've done some head work and/or changed the cam, there's no point to the larger injectors. If you have done the heads or the cam then you need to re-flash the PCM or add on a chip anyway and you can readily accomodate the larger injectors in the re-programming. The adjustable regulator is useful only if you have access to a dyno.
The 19 lb/hr injectors are a straight drop-in, at the 4.9 regulator pressure they actually flow around 23, or enough for 222-260 HP. The adjustable regulator allows you to decrease the thruput of the injectors to tune the fuel system to the engine. The adjustable regulator is not a simple bolt on. You'll have to do some fitting to get it to work.
WHY are you doing this? The larger injectors will not give you any more HP on a stock engine, or even one with a bunch of bolt-on parts. Unless you've done some head work and/or changed the cam, there's no point to the larger injectors. If you have done the heads or the cam then you need to re-flash the PCM or add on a chip anyway and you can readily accomodate the larger injectors in the re-programming. The adjustable regulator is useful only if you have access to a dyno.
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I had the head milled .030, any idea how much the compression is now, compared to the stock 8.8:1. also, the cam isnt stock, it is a 270/280 duration, .451/475 lift, with a 110 degree lobe separtaion. also, I have talked to Ken on the computer chips forum, and I am waiting on some info on him, but I plan on getting a chip for it soon. any idea how much my power output will be? I also intend on putting a header with dual exhaust and an xpipe, I put one on my 1970 challenger, and x pipes work very well. thanks for the help.
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Joined: May 2002
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From: Broken Arrow, OK
Milling the head 0.030" will not change the compression ratio very much, maybe get it to 8.9 or 9:1.
If all you are doing is what you have listed it sounds like your combination might be a little mismatched. You have selected a cam that is going to increase the output in the higher rpm ranges at the expense of low end torque, and the LCA is also a little tight for friendly interaction with a speed density EFI system. You didn't mention any head or intake porting. These two components are designed from the factory to boost the low end output at the expense of the top end. If the cam hurts the low end and the head/intake hurts the top end you won't be left with anything.
If all you are doing is what you have listed it sounds like your combination might be a little mismatched. You have selected a cam that is going to increase the output in the higher rpm ranges at the expense of low end torque, and the LCA is also a little tight for friendly interaction with a speed density EFI system. You didn't mention any head or intake porting. These two components are designed from the factory to boost the low end output at the expense of the top end. If the cam hurts the low end and the head/intake hurts the top end you won't be left with anything.
Posting Guru
Joined: Dec 1999
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From: Copley, OH
That sounds like WAY too much cam to me. Something in the range of 206-210° @ .050" lift with a LCA of 112° would probably work much better on the street. If you want to stick with that cam, you're going to need to build the rest of the drivetrain to match. At the very least, you're going to need to open up the head. Get a 3 angle valve job, preferrebly with back-cut intakes and open up the bowls to match, do a minor porting job, cleaning up the ports, smoothing the transitions and contouring the valve guides. Tht will give the engine a chance of breathing well enough to work with that cam. You are also probably going to need to be pulling a bigger gear to get the engine into it's power band.
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Joined: Jan 2004
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From: The KeyStone State
Originally Posted by StrangeRanger
open up the bowls to match, do a minor porting job, cleaning up the ports,
Why did you ask how it would affect a stock engine when yours is "modified."
No comprehende.
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