I have a 89 bronco that originally had a 5.0 it was bad so i had a 289 in my shop the 289 had been built by someone else and had 351w heads installed as it is now it has all the 5.0 injection and electrical stock what can i do to boost the hp can you add bigger injectors? how would i get a chip programmed for that configuration? exhaust is also stock. Has anyone got a 289 with 351W heads and what advantige is this.
I would think with the bigger valves it should have pretty good hp but think that the injection and computer that is stock is restricting it. help anyone

 

The problem of 351w heads on a 289 is low compression. 351w heads are usually up around 68cc combustion chamber volume, while 289's usually had 54cc chambers. Moreover, ALL the stock heads for 289's, 302's, and 351w's don't flow enough air. The 351w heads don't flow much more than 289-302 heads, but have larger chambers.

If your using the stock speed density EFI computor system, going to bigger injectors won't increase your power. Injectors are probably 14 lb's per hour, and that will support more HP than you can get from a Speed Density 289. For example, souped up Mustangs use 19 lb or 24 lb injectors up to 350HP to 400HP, with out problems. 30lb injectors are used with blowers or nitrious. One thing all EFI Fords should have, regardless of mass air or speed density, or in car or Truck, is an adjustable fuel pressure regulator. This really opens up your tuning options. You can do more with fuel pressure and your stock injectors, than by changing injectors. Changing injectors isn't really practical with SD, and even with mass air control systems, you need to re-calibrate the mass air meter to the new injectors.

The stock electronic controls limit your options severely, because you can't significantly increase the air flow with improved heads and cam..ect, without confusing the computor.

Better flowing heads (with cam), ported or after market, with about 58cc chambers, would be better than the 351w heads.

Increasing the displacement would really help low end tourqe. 289 cubes isn't really enough for a vehicle that heavy.

 

P51D Mustang i forgot to tell you the guy who built the motor had also plained the heads not sure of how much or the cam in it. what would i need to do to up the fuel pressure? is there a regulator on the system now or is it regulated by the pump? and would putting a computer from a bronco with a 351 in it do anything or would it even work. looking for easy things to do not really into tearing the motor apart.

 

Oh Okay,

The best thing to do in my opinion, if you don't want tear into the engine proper, is to improve the exaust system, and lower the final gear ratio. A dual 2.25" system will crossover, flowmasters, and high flow cats will improve low end tourqe.

Lower gears(higher numerically), will give you more lift right off idle with the heavy vehicle, and allow the small V8 engine to get up into it's power band more.

The stock fuel system has a regulator, but it isn't adjustable. The way it works, is the in tank electric pumps send fuel to the fuel rails, and then back to the tank in a closed loop. At the back of the fuel rail, (usually)on the passenger side is the regulator, between the fuel rails and the return line. It has a vacuum hose connected to it. It resricts fuel going from the rail to the return line, to maintain a high pressure in the rails. The computor fires the injectors electricly, varying the duration of the time the injector is open, according to the information recieved from the 02 sensors. This rail fuel pressure can vary significantly from truck to truck, depending on the strength of the in -tank pumps.. and so forth. If the pressure is too low the injector gives a weak spray pattern into the intake port for a longer duration. The result can be improved milege, but at the expense of low end tourqe. The 5.0/5.8 likes about a 38 psi reading (at idle with the vacuum hose disconnected) Cranking it up to about 40-42psi improves low end tourqe, but above this it's too rich, and will actually sap power. Less than 38psi improves gas milege, but less than about 35 results in weak power. Adjustable regulators, with guages, for 5.0 Mustangs and F150's, can be obtained from Brothers Performance Warehouse. It's not real cheap, but still a lot less money than 8 new injectors. With a fatter air fuel mixture you can probably also crank up the intial timing to about 12* too. This will give a noticable increase in seat of the pants power.

To really get at significant hP mods, requires significantly increasing the airflow through the engine, with cams, heads...ect... and this really requires converting the engine computor control system to "mass air". Ford has kits to do this, but the truck conversion kits are mainly for manual tranny trucks. IIRC, they have a kit for AOD trannies, but if it has the E4OD it's a major head ache, that is really expensive. This is because the engine and tranny computor control systems are intergrated.

 

Additionally, you may be having a cam to speed density incompatability issue. In that case, it won't run right or make decent power. Try to find out any info possible on the cam. If it's not a speed density friendly cam, you have two options. Install a SD friendly cam or convert to mass air.

 

Bearee


Do you know which 351w heads you have? As mentioned the combustion chamber volume is about the only difference between the 302 and 351w heads, a 302 and 351w head that has the same casting number will flow the same, exception the E5 351w heads will flow less than an equivalent E7 on the exhaust and has a larger combustion chamber. The early 351w heads were 60 cc and the later 80's were 69cc, I think the E7 on the efi 351w were 64 like the 302.

I am almost certain that the only difference between the 289 and 302 is the rotating assembly, so you could use a 302 internals and have 13 or cubes with little effort, not sure it would be worth it though.

 

I would say if it isn't a cam issue, then gears will help that 289 alot.

 

thanks for the info fellas. I'm not sure of the year of the heads but when they were off they had huge intake valves. I think i will try the fuel pressure thing and possibly lower gears. because it does have alot more power when the RRR's get up