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Discussion Starter · #21 ·
I have been looking for more injector information as a starting point. Not sure but it's looking like all Magnum V6 and V8s use the same injector. Factory rating HP per cyl is about the same for all. It appears they are rated at 22.1 lbs. and most engines make 28/30 HP per cyl. Having rebuilt engines for power all my life I'd be disappointed with less than 1 HP per cubic inch. If the new engine could reach 240 HP that's a large jump 25 % and I'd think it will require a little more fuel. Steve
 

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I have no idea about the balance point, but want to point out - in some ways, swapping injectors is like swapping carb jets. You wouldn't expect to go from a #35 to a #100 without a LOT of other changes, right?

But if the transfer curve is smooth and linear, you could swap in the #100, tune the ECU to know it's a #100, and once it gets past the discontinuity at injector open, it's just as good as the #35 (to use jet sizes as related to injectors - say swapping a 80lb in place of the 22lbs you have now.)

The PROBLEM is that if your ECU doesn't know about it, it's like just swapping the jets, no other tuning - it's absolutely no bueno!

But.

How much horsepower can you get out of an injector?

There's actually injector sizing calculators out there on the Internet!

Let's just use Flow Calculator (fuelinjectorclinic.com) for one.

Using 225HP at the crank, you're good on the 22.1lb injectors (takes a 21lb injector at 90% flow, which you want to max out your math at 90% in case of Murphy - keep your cousin Justin Case happy!)

For more HP, you'll want more fuel. You may be able to get by with a 25lb injector; but even that should have the transfer curve programmed into the ECU.

If you have an adjustable fuel pressure regulator (you don't, it's part of the fuel pump, drats!) you could cheat by upping the fuel pressure some.

But you SHOULD still have the ECU tuned to match.

Again, you wouldn't just swap jets on a carb without adjusting idle speed and mixture screws, would you?

EDIT: Hench my pointing out Banish's books and decipha's forum. Cruise the forum for a while, no need to actually post; read Banish's books.

RwP
 

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Discussion Starter · #25 ·
Well back again with another question. It was ask on the first page with no reply. The crank position sensor bolts to the rear of the right cyl bank. I have installed a new one on my rebuilt engine. The sensor is .048 from the relucttor ring. After pulling old engine and splitting engine and tranny I measured the spacing at .015. The one currently in the old engine is the second one I have installed. The first threw a code and stopped running. The first replacement one only lasted a couple of weeks and threw a code. I would imagine there is a correct space and I'd like to be sure mine is correct. Steve
 

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There's a manual crank position sensor, and an automatic crank position sensor.

I understand the manual one is very slightly shorter, but I could easily be wrong on that.

Hopefully someone who can measure them precisely can tell us.

(Yes, we're reading your post; I just don't have anything definitive to add most times! You're doing good work, BTW. It's been most informative reading your posts since I've not been inside one of these motors.)

RwP
 

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Discussion Starter · #27 ·
I removed the CPS from my recently removed engine and installed it in my new engine. This one measures .025 yes .027 no. I only have the two and I'll take some measurements and see if it's the sensors that are different. I'll have to go back though my records and see what makes I have ordered. It would be possible to file the mounts on the block or the under side of the sensor to adjust. I have three flywheels I can mike the dia of the reluctor. I can use a depth mike and check from block mount face to flywheel. I'll collect some more info and report back. Steve
 

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Discussion Starter · #28 ·
I have taken some time and read some other threads. I'm glad I did as someone was posting about the replacement of the clutch hydraulic system. Even with the engine out it won't be a lot of fun. I have tied the pedal to the steering wheel to avoid a blow out. I'm looking forward to driving an almost completely new drive train in a nearly 20 year old truck. Steve
 

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Discussion Starter · #29 ·
I'm currently having my throttle body flow tested. Not sure that info will help me. I'm trying to select fuel injectors. I think std ones are 21.3 lb per hr. I'm not sure if they are high or low impedance and whats the next step up which appears to be 23 lb per hr. Since I don't expect to operate at full throttle max flow is not important. I'm new to injection and full of wonder. We have a throttle position and manifold absolute pressure sensor. The idea is to have greater air flow at all throttle plate angles. That may change manifold pressure ( try talking to a engineer about zero pressure ) I'm sure other sensors are involved. Looking at the Dodge push rod engines 3.9, 5.2, 5.9 all use the same injector and make roughly the same HP per cyl. I selected 20 HP added as an easy target. Several people have suggested I may do better than that. I'm even beginning to believe this is going to work. Steve
 

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If you change your injector flow rate, you WILL have to change your ECU's programming to match, or it will have fits.

Read up on injector programming at decipha's site, efidynotuning.com . Check the FUEL link from the left side. About 40 to 45% down he starts discussing it; in terms of Ford ECU programming terms, but still he discusses it.

Also there's a link to the injector data sheets for several injectors.

RwP
 
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