Ok, so I will ask because I am not sure, but my fear is if i actually meet some of the peeps on here I will be stoned or burned at the stake..... I was reading through the buying guides and one said that all 308's the carb models i think, need to run lead additive in with the fuel. I haven't been, I have not driven the car that much, so...... Let me know.
Lead is a great lube. 101LL AV gas has THREE TIMES the lead of what normal consumer leaded gas had. Just do a mix of AV to normal station gas.
Not needed, waste of money, don't bother. Very bad for O2 sensors if you have one of those. If anyone is interested,and says they heard it is needed for such and such reason, post your concerns and I will answer them. The original theory was that the additive kept the valve seats from wearing, but that is only applicable to vehicles that turn ~100K+ miles per year like taxicabs. Doug
The last missive from Ferrari claimed all their 8 cylinder valve seats were suitable for unleaded Image Unavailable, Please Login
We have been running them for years and many with high mileage on no lead with no problem. Not to worry.
May I turn the question around: can it hurt to apply lead additive? I've used it so far on my 1978 308 (carb). Thanks.
When all gas was leaded people used to seek out low and unleaded fuel. The only thing it really helps are low quality valves and seats. It does create deposits that are not good for spark plugs. We also know from a couple of decades of experience now that the Ferraris just dont need it.
Ditto. Engines stay much cleaner internally with unleaded fuel. You are not helping anything by using lead; you are causing reduced spark plug life and increasing valve deposits with NO benefit at all so it's a lose/lose situation.
Am curious, why did the race engine builder specifically spec 100LL AV in unleaded is so good? (not a Ferrari engine)
Huh, no mention of the 308GT4 on the list. I guess I better mix in the avgas! J/K Doesn't lead also poison the catalytic converter, or is it just oxygen sensors?
Most likely your lead additive is a lead substitute additive, containing a manganese compound. These do cause combustion chamber deposits (ash), that can possibly cause hot spots and pre ignition. Note it is illegal to run aviation gas on the street in the US (no road tax paid on it). You can also buy leaded racing fuel, which is actually a better blend for auto use than AV gas, though I also doubt road tax is paid on it. Doug
I use this alternative to lead... http://www.wynns.be/product.aspx?nav=1&g=1&s=24&b=706&p=70612&l=EN Not sure if I'm wasting my time or not!
I don't and would never use leaded fuels or additives in my GT4. The stuff was really formulated before engine materials caught up. Not to mention tetra-ethyl lead (which is what I believe the compound is called) is a starting point for a sequel to Erin Brokovich.
Tetraethyl lead raised octane; with higher octane ratings you can run more compression/spark advance. In the muscle car days, you could buy gas at stations like Sunoco with an equivalent octane rating of 102. Once lead was eliminated; octane ratings dropped to today's level; engine compression/timing had to drop as well. Obviously, as engine builders worked at it, other (superior) ways to improve engine performance were found so current engines can produce more HP than old engines without using "high octane" gas. But on old style engines like 3x8s, IF you could obtain that sort of gas, you could make more power throughout the rev range by raising the compression and changing the timing. Some muscle car engines were 11:1; some special purpose but still available at the dealer cars (like the Mopar Max Wedges) had 12+ compression. A 12:1 US 328 (260HP) with no other changes would make around 280 HP. It's not all that big a gain BUT it is in the entire rev range, not just in one area (usually top end) like cams/exhaust/porting changes, etc. Normally, of course, they would all be done together and there would be substantial power gains and the increased compression would help offset the reduced low/mid caused by the cam/exhaust/porting. Obviously a turbo or SC would theoretically be a lot easier way to get more power...
The Sunoco 260 and Chevron "White Pump" in the muscle car heyday came in around 103 RON. Since 1979 pump gasoline has used the (R+M)/2 scale. 103 RON is equivalent to 98-99 (R+M)/2.
Quite a few modern cars have 11:1 compression too, 355 and 360 just to name two. But have done it through better combustion chamber design and very good engine management.
Brian- You are right. The 575M/SA/612 133 series engines, as well, have a compression of 11.2 to one. Taz Terry Phillips
