Replying to Kaz.....
do we really have to break in new motors"50 for 500"?What about switching to synthetic.How about high octain does it help or hurt? "
1. Regarding engine break-in, the only consensus I've seen over the years is that the engine not be run at a steady speed for the first few hours of operation, and also, no idling, especially with new cams. Most of the guys I've worked, myself included, do a lot of "pulls" in moderate gears with coastdowns in gear as well. Try to ramp up to RPM, you know, 2-3,000, repeat a few times, 2-4,000, etc., etc. After a good few hours of this, the rings should be pretty well sealed. Another reason for this type of break-in and probably more critical is the transmission. Gears require a good running in so they can develop a comfortable wear pattern. This is the thin gray line you see when you take apart a gearset. Good loading and coasting along with moderate speeds play a big part in determining whether the transmission will last 50 or 250,000 miles. Also, after a few days of running, drain the oil and replace the filter. Getting the metal fines out of the machine is the single most important key to long life.
2. Properly formulated synthetics will always outperform most mineral oils, mainly because of their ability to:
. Maintain viscosity (film thickness) over a wide temperature range
. Remove heat more efficiently than mineral base oils
. Resist oxidation (cooking) that leads to acid buildup, deposits, and engine wear.
Our experience with all types of engines has shown that engines can be broken in from day one with synthetics. Or, broken in with mineral oils, then switched over to synthetics. This is what I do, mainly since I will be changing out the oil in a very short time, and only need it for a break in flush anyway.
3. Octane in of itself is of no benefit to an engine that is not tuned to take advantage of it. Octane is strictly the resistance of a fuel to detonation. This occurs after regular ignition and is caused by the pressure front of the traveling flame front increasing the pressure/temperature of the remaining mixture. In certain cases this can cause an autoignition to occur from the pressure, which causes the two flame fronts to collide. Instead of a nice "push" on the piston, a sharp pressure spike occurs which, at the very least, causes a slight pinging sound (sonic boom), at worst, the pressure spike and its associated high temperature will blow torch a hole thru head gaskets, pistons, etc. High performance engines are designed to run at much higher cylinder pressures than street engines. This is accomplished through timing advance, increased compression, power augmentation (super and turbocharging, NOS, etc.) Any combination of these changes can require fuels to have higher octane resistance. The only real way to know how much octane is needed is through extensive dyno testing using various timing and mixture maps with the race fuels. Racing fuels not only have high octane, but are usually formulated with heavier components that give more energy and tend to run richer. Engines that experience more power by just changing to these fuels with no timing or compression changes, are typically running too lean to start with and are simply running more efficient with the race fuel.
Hope this helps. One of these days, I'm going to put together an article on some of these topics. Meanwhile, give me a call or email me if you have questions.