Vortec 7.4 Intake Stats

[willyswanter]

Anyone know the specs on the stock vortec 7.4 intake system? Like CFM, max supported power, mods to increase flow? I know you can buy 1000 cfm throttle bodies for them but what about the rest of the intake system? Not concerned with heads or anything else, just the intake. Also any idea what stock injectors are lb wise? Or where to get larger? What about custom tuning for cams, cubic inch changes, etc?

 

[bigblock72]

I believe the stock injectors are 21 lb, but not positive on that.
The stock throttle body flows around 700 CFM give or take.
The main restriction on the vortec manifold is the intake runner length like the TPI of old they're great for midrange torque but kill power above 4,500 rpm. If you want to make much over 400 horse with them then you need to cut the dividers back as far as you can put in some bigger injectors and a larger throttle body.
Larger injectors are easily available from Summit or Jegs for around $300.00.
IMO if you want to make more than 450 horse then you'll be better off to find another intake.

 

[willyswanter]

According to dyno2000 I'll be roughly 440hp and 620 ft/lbs so it sounds like it should work fine with a TB and injectors... I doubt it will ever see more than 4500rpm, I don't think I've ever gone over that in this truck.

 

[bigblock72]

At that power level you'll want injectors in the 26 -30 lb range. With the right programming sounds like you'll have a strong puller.

 

[bigred81]

The stock injectors are 19 lb/hr and if you ever have problems with the motor starting when hot the injectors are more than likely bad. I have used ford 5.4 injectors to solve this problem and they flow better. A lot cheaper than aftermarket injectors because you can find them in junk yards for cheap with the harness and will fit the factory fuel rail with no problems.

bigred81

 

[bigblock72]

What's the flow rate on the 5.4 injectors? I've heard of guys doing this but didn't know what size the injectors were.
I have seen a few vortec 7.4s with very dirty injectors that leak.But more often than not vortec hard start problems(even the newer 4.8/5.3/6.0s) are caused by a leaking fuel pressure regulator, they leak fuel through the vacuum hose and fill the plenum full of fuel.

 

[bigred81]

The ford 5.4 injectors are 19 lb/hr and chevy injectorts are junk I had 5 sets in less than a year 3 sets under warrenty and replaced every parts in the fuel system including 4 pressure regulators trying to solve the problem. I all was get good gas and keep good fuel filters on my truck. The ford injectors were my last hope tryed them problem has been solved for 3 years now. I have done this conversion on 4 other customer trucks with the same problem at about 140000 to 150000 GM injectors in bigblocks are done for. The leaking injectors cost me two motors due to broke rings from the injectors from washing the cylinders dry. There are many other ford injectors to chose from. Sorry for the long post.

bigred81

 

[Jrgunn5150]

Just to clarify, since I also own a Mustang. All Ford V8's use the same injector's, which are 19lbs. The exception's are the factory supercharged motor's which use either 39 or 42 lb injectors.