Hi. I've got an '88 f150 with the 300 and a C6. Squirrel nest under the plenum intake caught fire last winter right after I bought it and so I've replaced all injectors, both exhaust manifolds, and the ECU.

I have one leaking gas tank, and my tail pipe fell off a couple months ago, so I think I'm going to replace both the tanks as well as the exhaust, removing the bed and cleaning up/painting the frame while I'm at it.

I'm looking to slowly 'restore' this, I have my own garage with lifts and air everything. Maybe a paint job next year.

For now, though, I'm looking to see what I can do to increase mpg/performance with the exhaust? I have the split manifolds, not the 6>1 single manifold.

While I'm in there I would like to clean up the engine bay some. I don't like that coffee can in front of the blower ...... My state does not do inspections and I am emissions exempt. I plan on removing at least the A/C and smog pump. is there anything else that's relatively easy to delete that doesn't do more harm than good?

Has anyone removed their cat? - better, worse?

anything I can do on the intake end?

Even the little stuff. There's too much clutter in the engine bay for me - PITA to work around and more things to break on this old pig.


(also) is the EFI direct injection? the way the injectors are positioned it looks like it but I've been unable to find anything on it. just curious

 

The EFI is not direct injection - the injectors spray into the intake runners. DI is a relatively new addition to Ford's technology envelope.

 

I'm honestly not sure that there is much to gain from removing the various emmissions equipment on an EFI 300. My 88 has all of the original equipment, but has had the vaccum lines replaced due to rot/age-related problems.

The EFI headers are about as good as you can get, and the EFI system relies on everything being in place to work most efficiently (EGR, PCV, O2 sensor, etc).

Exhaust may gain a little HP, but getting rid of everything on the pollution control side will likely result in poor economy.

My 88 with the M5OD transmission will get about 16-17 city and if I am gentle and keep it under 60, I can pull an even 20MPG on the highway. With a 3.55 rear end, if you step on it, it FEELS quick, but the M5OD shifts glacially slow if the schrynchos feel like cooperating that day, so actual timed acceleration is pretty slow.

If you are doing this as a project, I would suggest starting by replacing the vaccum lines and making sure everything is working. A C6 isn't going to get the same MPG as my setup (especially if it doesn't have a lockup torque converter), but I would imagine 15 city would be doable. I consistently get 14-14.5 MPG towing 5000+ lbs with my truck and not using OD (again, under 60 MPH).

Speed is killer. I have a 79 GMC conversion van project with a SBC400/TH350 combo: It'll do 14-14.5 MPG at 55-60 MPH and usually get 14 @60 MPH, but 70 is 13MPG max and 75-80 is 12MPG max.

 

I usually get about 18mpg in this truck, most of my driving is on turnpikes and back roads - about 35-50mph, not a lot of stop-and-go. This is my daily driver, so I'm looking to get another 10-20 years out of it. just hit 52k miles.

How about the cat? Keep it? replace it? straight pipe?

 

I don't have any references with me, but I don't think OBDI has a downstream O2 sensor after the catalytic converter. IIRC, this was an OBDII requirement to help clean up emissions and I suppose guarantee there is a working CAT installed.

Not a lawyer, but Federal Laws say it's not legal to tamper with/remove pollution control systems. The correct advice would be a to use a high flow CAT with nice 2.25" exhaust. Check out the exhaust clips stickies and go with what you like best.

I have a project GMC van that has true duals running through long glass packs, so that's the vehicle that has the "fun" exhaust. The Ford has the factory setup and is nice and quiet-ish (it does sound like a highway coach at highway speed... kinda annoying drone.