Gasser question only obviously, but if we have removed our cat is it safe to put lead additive in our system? I've never tried it, but I have an '81 honda motorcycle that can run on leaded or unleaded, and on leaded it makes more power and gets around 15-20% fuel economy.

I can't see the lead harming the engine itself, the fuel injection system I have no idea about, but emissions equipment I suspect would be the most vulnerable to leaded fuel side effects.

Any ideas? Normally i'd say this idea is retarded... but then again paying $4.39 a gallon is retarded too...

 

are there o2 sensors in the exhaust still? I think they would send bad messages to the computer and possibly cause some driveability issues.

 

While it is safe (with the cat removed) to add tetra-ethyl lead to your gasoline, it won't do anything for you. The gas engines in the Super Duty trucks are optimized to run on 87 octane fuel. Incrasing the octane will not make the engine run better.

Since this does make your Honda run better, you can assume it requires ore octane to make it run properly.

 

Yeah that makes sense, however please correct me if I'm wrong, but isn't the 87 octane maximization ONLY if you keep everything stock? I am not positive how Ford engines electronically keep their timing or if they have a KR sensor or what have you. Are there any threads out that could better inform me?

 

Well, the engine is programmed to run on 87 octane, and yes, the Ford engineers optimize it for stock conditions (they have no choice there.) Aftermarket programs can be installed to optimize the engine for other parameters or fuels, to the extent that the timing and fuel/air mixture can be adjusted by the computer, but still the static compression ratio, swept compression ratio and basic spark timing map are designed to function best on the 87 octane fuel. Because of this, any changes to the F/A map and spark timing map for increased performance are compromises. For best results, you need to redesign the engine for a higher compression ratios (static and swept) and change the cam timing to take advantage of this.

If you want to experiment with higher octane fuels, one of the easiest ways is to add Xylene or Toluene to your gasoline. I use it in my early 60s Pontiac engines, mixed 10 gallons of 92-93 octane unleaded to 1 gallon or Toluene or Xylene. (Look in the paint thinner section of your local hardware store). The Toluene or Xylene has about the same specific gravity and F/A mixture requirements as gasoline, but has 114 octane. 10:1 mixing will give you about 95-96 octane. The mix is safe for catalytic converters, O2 sensors and any seals in the system, but don't spill any on your paint.

 

In order to get more power out of the higher octane you'll need a tune for higher octane fuel. Running higher octane fuel won't give you any better mpg or power on the stock tune UNLESS your getting a ping/spark knock on 87.Run 93 octane with a good custom tune for 93 octane and you can pick up a bit more power and maybe a tad more mpg. Lead additive is for vehicles designed for lead IMO. I don't run my 74' with a lead additive, never had never will.

Your truck has very minimal timing swing the way its setup, maybe a couple degrees +-. The truck will no way compensate for the higher octane fuel in timing. That has to be done by reflashing the computer with a tune for higher octane.

 

THanks for the input, my truck used to run better on 94, without it it would sound like there was a midget inside my engine with a ball pin hammer. I changed the plugs (which were GONE! my feeler guage stops at .140 and there was still play when it was in the plug gap) and kept putting premium in it. I guess I'll give this 87 octane a whirl for my big trip this weekend, should save me some $$$

 

Leaded fuel will destroy your O2 sensors, and without them your fuel economy will drop.

 

Wow, would have never expected to see this being discussed. As noted above, running your engine on a higher octane than recommended won't help you in terms of mileage, but running your vehicle on a lower octane than recommended can have adverse affects.

Since the old regular gas was 89 octane your honda will probably run better on the mid grade stuff. I don't think it was the lead that made the gas better, but the process of removing the lead that changed things. Much like the sulfur content in diesel fuel.