I have a Golen built 383 LT1 that dynoed right at 450 flywheel horsepower. I have a procharger to go on it and am trying to figure out the injector size I need to purchase.
I see people running from 30 pound SVO injectors to 47 pound injectors. I want a smooth idle, don't want to run over 5750 RPM (stock redline) and will only run 6-8 psi of boost.
I believe Golen ran 30 pound injectors for my dyno/break in run, but will I need bigger ones with the supercharger? Or will the FMU increase in pressure to the injectors be enough compensation?

Also, The Ford injectors with the Jetronic connectors require the adapters to plug into the LT1 harness, right?





I have searched through the forums and can't seem to find an exact match for my setup, so I thought I would ask.

 

Forced induction requires significantly more fuel. While you might see a brake specific fuel consumption as low as 0.45 #/HR/HP on a normally aspirated engine, it will be much higher (~0.55 - 0.60 BSFC) with the blower. I believe you will get the most help on the Forced Induction forum. I'll move the post there for you.

You also have to explain how you plan to add the extra fuel required for boost - will you use a boost referenced fuel pressure regulator, an FMU or will the use the PCM tuning, such as running a 2-bar MAP sensor?

 

I'm not sure what to use for the fuel. My ATI kit came with a fuel pump booster, and I have a complete Aeromotive A1000 kit that should deliver as much fuel as I need.

As far as HOW to use it, which is best? I have a FMU but I was leaning toward a 2 bar MAP sensor and a tune to use it. Is it true the standard GM unit is plug and play on the LT1 manifold? That seems easiest as I have to have a tune anyway. And I am sure never going to go above 8 PSI so 2 bar is plenty.

So, if I keep my fuel pressure constant at 43.5 psi, I 'should' need 34 pound/hr for 450 HP, and 56 for 625HP? I'm not sure whatever is closest to 56 pounds could be made to idle right.

36 pound SVO units with an FMU to add 8 PSI would flow 39, and if 2:1 FMU would still only be equivalent to 42 pound units.

This is why I want to find someone with a 'similar' (yea, I know it won't be exactly as my setup) setup to give me a feel for these numbers before I blow $300-$400 on injectors.

I guess, IF a 2 bar sensor, tune and large injectors would work, give similar to stock part throttle drivability I would rather do that, as there are fewer additional 'things' (FMU or special regulator)

But if anyone has drivability issues I just want mine to start when I turn the key, not run pig rich and smell gas all the time, idle with a slight lope is acceptible, idle in 1st gear without bucking like a bronco and take small throttle inputs smoothly. Basically I want a stock driving car with twice the horsepower.

The 2 Bar sensor is for the range 30"" vacuum to like 14.7 PSI, right? Anyone have a preference to Accel, Delphi, MSD units?

 

I run 50lb injectors and have none of the issues that you listed. Idle and driveablity is fine. Larger injectors and tuning are much easier than messing around with an FMU and much, much easier than trying to set up a 2 bar configuration. At 6000 rpm and 6 lbs of boost, data logs show an injector duty cycle of 68%, so I could probably have gotten by with 42's. With the conditions you specified in your post, you could go with 42's and be fine.

 

THANKS!

After talking to pcmforless, we decided 42 pounders would be about ideal.

Always good to hear from people that are running similar setups to validate designs and such.

Now if I could just get my ATI damper to cooperate and install.......

 

Get the ATI damper honed to fit your crank. They make them a few thousands too small on purpose, so you can fit it with about .001" press fit. DON'T RAM IT ON AS DELIVERED. can get ugly. See a machine shop. The instructions in the damper when new elude to this fact, just needs to be done.

 

Someone look at my math....the 50 pounders running at 68% duty cycle are equivalent to 32 pounders at 100% (50*.68) OR my 42 pounders running at 80.1%, which looks to me to be perfect if the air/fuel ratio is in the right ball park. And I am not going to run more than 5-6PSI on this engine... It has all forged internals, H beam forged rods, etc.... BUT my static CR is right at 11:1.


Yea, the damper is a bitch. I already knew better (from a past life) that to hammer it on, I DID buy the installer screw thing, but I had no idea it was that much undersized it needed honed.

So I just measure my shaft diameter and take it to a machine shop?

Time to get out my pully puller. I only put it on like 1/8" before I decided something was not quite right, but it won't pull off by hand.

Actually, I have a lathe with internal diameter gagues, I may give it a go, assuming I can get the damn thing off.....

Thanks again.

 

While I am still fiddling with the damper, I see some people pin it to the crankshaft after it is installed. Is this necessary for a modest blower setup?

Somehow I think drilling between the forged crank and damper would be....tough.