What is being done to allow speed density to work with forced induction?
 

Mass air or an aftermarket efi unit is not really possible.


Taking a look at aftermarket kits has led me to see a few options:

check valve inline of the map vacuum line

slightly larger injectors

FMU


FWIW, I am thinking of adding 8-10 psi of boost to a 4.9 300.


I contact someone who was supposed to be a tweezer expert and he really didn't have anything to provide in the way of information for the 4.9. Who knows?


Thanks

A good fuel pressure reg, and an FMU with an adjustable onset so the motor doesn't go lean at tip-in.
I've never heard of a check valve going inline with the MAP on a boosted SD setup. Many people just run them like they are.

A chip or tuning software like SCT will definately be needed to dial in your combo with larger injectors.

Have you done a bone yard shopping for a I-6 mass air harness? I looked at a 96 F-150 I-6 the other day that was equiped with mass air. It looked like it would be pretty easy to remove and install on a non MA pickup. Just a thought.

I thought about the mass air but there is nothing to be found locally.


Sure enough, I was looking at a turbo kit for some kinda import of some sort and they mentioned using a check valve on the vac line to the map sensor.


I am more or less trying to mimic what is being done with the GM 6.5 turbo that others have installed on their 4.9 300 and seems a rich idle is a problem more than anything. There is a fella on this board running bone stock SD with larger injectors 19 I believe, other than a resistor on the coolant temp wire, I imagine he's beat on it some and last I read its still running, he seemed to think it ran way too rich.....which happens to be a common complaint when people use larger injectors on the stock SD 4.9, who knows?



Any idea what that junkyard might want for their mass air set up?

It will run rich with larger injectors unless you have a chip/software to adjust the injector slope and pulse. A tip-in-lean condition is one of the biggest obstacles to overcome on any SD boosted application, which is why I mentioned an FMU with an adjustable onset. A Cartech or Vortech Super FMU will work great in this case. With the proper tune, a boosted/SD application with larger injectors will idle and cruise just like, or close to stock.
A turbo'd application may need that check valve for some reason, but a SC'd application doesn't. It does make sense to use one to keep from destroying the MAP, but I don't why a turbo would need one and not a blower. Maybe you could get some info on that and post it here...I'd be interested.

The truck I looked at the other day was up for sale on a used dealer lot and in good running condition.

I would bet you could use an FMU from a 5.0 Powerdyne or Vortech kit and get along fine. i have never seen a kit for a 4.9 but no reason you couldn't fabricate the brackets and run a centrificial, or modify the intake to mount some kind of posative displacement unit. I have see that done on dodge slant 6's. my 91 F250 with a 351 runs a Powerdyne kit with 6PSI anf just uses a FMU and runs fine, no chip or bigger injectors. No doubt that an aftermarket chip will get more out of any combo, but shout not be necessary to get it up and running. You may want to upgrade the stock fule pump as I think you would be right on the edge with that. Powerdyne on the 9PSI lightning kits included an inline fule pump to make sure FMU had enough pressure to work with. Your fule pressure needs to go up by the amount of boost or you could run lean.