Lead Octane Booster
There are many thoughts regarding the use of lead in our Roadsters' power plant. I typically play out the “what-if” scenario to help me sort through all the discussions and opinions. What if our motors really do need lead and we are not providing it? My training leans me towards the use of data to help make important technical decisions, so I decided to run my own set of test trials and then make my own decision based on my own experience.
What I know as fact is that high compression motors like those in our old Roadsters squeeze a lot of fuel into a very small space. This causes extreme heat which then causes explosions inside the combustion chamber. The explosions produce power. This power must be controlled for maximum horsepower output.
If the fuel starts to burn before the spark plug fires inside the combustion chamber, the result when the plug does fire is two exploding flame fronts within the chamber. When this occurs, excessive heat and pressure is generated, the fuel ignites prematurely and your motor starts to ping. Pinging, also called knocking or pre-ignition, in time will damage any motor.
During pre-ignition, the pistons want to start moving in the opposite direction before the crank passes top dead center. This causes extreme overstressing of the pistons, wrist pins, connecting rods, bearings, valves and crank! Pre-ignition causes extreme cylinder pressure which can lead to blown head gaskets too, resulting in oil in the radiator or water in the crankcase! Pre-ignition will cause the motor to run hot and heads to warp. A good running motor, tuned as specified by the manufacturer, should not normally run excessively hot. Hot running motors can be avoided if properly tuned and timed. And if gone un-corrected, pre-ignition will ultimately cause a hole in the piston crown.
Luckily, there are options to prevent the problem. You can retard the ignition and loose horsepower and torque, or, you can use a high-octane leaded fuel which will prevent premature ignition. It’s been proven that real lead added to unleaded gas will increase the octane rating considerably, depending on the amount added. The higher the octane number, the less likely the fuel will start burning before the spark plug fires. Higher octane leaded fuel will allow the motor to run with more deliverable power and torque. It will run cooler and quieter as well.
So, to help sort through all this information, I decided to test performance for myself over a period of time with numerous test drives. My thinking was that if could detect a change, I could then assess its importance and implement any correction I deemed best for my car. The test vehicles were my 1963 stock TR4 and my 1976 Kawasaki KZ900, (as I figured a sample size of one does not a good test make).
The test ran with the same name brand premium 92 octane gas. I ran (5) gallons per run and alternated runs with and without a real lead octane booster. I repeated this plan numerous times over the course of almost the entire driving season. I used a real lead (tetraethyl lead) octane boost product because there are many octane boosters available that use lead substitutes, NOT real lead
I repeatedly drove the same loop here in the back mountain hills of eastern Pennsylvania so as to know what to expect and where to expect it as direct comparisons makes most sense. Most notable of all was a mile uphill stretch where without lead, I’d need to downshift at the half mile mark. I found that with lead, same speed, same conditions, I would simply power up that hefty grade with all the throaty torque it required, no downshifting! And it felt like much more power was available if needed. This is what totally convinced me. Not only that, but with no lead, this same stretch was where the dry hot exhaust vales would start clattering and the motor would start pinging with pistons slapping like a diesel just before the downshift. This was clearly NOT the case with lead. I confirmed the same results with my KZ900. The best part with my 900 was because rider position is right on top of the motor, you can definitely hear the quieter hum of the motor under any load!
After all this, I can say with conviction that there is a difference and the difference can actually be felt and heard! Yep, the engine sounds different under load. Less piston slap, knocking and vibration equates to a quieter running motor. And as the manufacturer states, an added benefit with real lead is the octane boost essential for full power, maximum torque and overall efficiency. It’s true. It also supports valve seat and guide longevity and good motor health!
I now use and highly recommend octane-boosting real tetraethyl lead, which solves the problem and brings back the power we used to feel when high octane leaded gas was available at the pump, (if you’re old enough to remember!). I do NOT recommend an additive with a lead substitute. Real lead provides the required valve lubricating ability where lead substitutes simply do not.
Lead deposited on the valves and seat surfaces dramatically increase the surface contact area of the mating components thereby increasing heat transfer. Properly lubricated (lead coated) valve seats and guides operate quieter and cooler by transferring heat very effectively to the head, whereby the heat is then dissipated via the water circulating through the block and radiator.
Real lead is definitely the best remedy I have found to restore power and end pre-ignition pinging. Without lead to lube the valves, they will recede into the head, wear prematurely, chip, come out of adjustment, clang and clap and cause a overheated poorly running inefficient motor. Caution: as an added bogy of running without real lead, you might even wear out your synchros by all the needed downshifting!
Still not convinced? Run a little science project and convince yourself. I use and highly recommend a fine product called Octane 130 Supreme, (search the web at http://www.kemcooil.com/products.php?cId=4). I add 2 ounces per gallon. This raises the octane by 5 points or so. It’s not cheap at $125/case, (12) 32 ounce bottles, but to me it’s worth it, especially for what you get in return. You can also buy one 32 oz. bottle at $20.75. All quantities ship free from the link source shown.
To verify and enjoy improved performance by using Octane 130 Supreme, the motor must be set to factory timing specs, compression should be proper and carburetor adjustments must be correct. The quickest road to a less than satisfying experience using any fuel at any price is an ill-tuned motor.
Have fun and enjoy the ride! de
I have been using CD2 for years. It is a super concentrated lead subsitute. I think the difference is negligible. I use it more for peace of mind. With the use of 10% ethanoyl in gasoline nowadays, it acts as a protector against the evaporation which is more prevelent with the new mixes in gasoline. One 16 0z bottle treats 160 gallons of gasoline at a cost of about $12.
It's my understanding that lead was used more for valve lubrication and it's effect of hardening cast iron, more specifically the valve seats in the head, and not for increassing the octane rating of the fuel. If the reason for adding lead to gasoline was to increase the octane rating, then simply purchasing a higher grade of fuel would offer the same result, via a lower cost and less harmful method. It's also worth noting that when older engines are "converted" for use with unleaded fuel, the mod is to install hardened valve seats in the head, and nothing is ever done to lower the compression ratio, which determines the required octane rating of the fuel.
From a practical standpoint, I don't recommend using lead additives or premium fuel in our TR's. 9:1 compression is below the threshold of 9.5:1 where the auto manufacturers begin to recommend premium fuel, and unless your engine is loaded up with carbon which effectively raises the compression ratio or creates hot spots which trigger detonation, they'll run just fine. And regarding the lead additives, you need to view this in the context that these cars are not normally drive more than a few thousand miles a year. Any recession (wear) to the valves and valve seats due to the absence of lead is going to take many years to cause any harm, so it's nothing to worry about and pull the head off of a good runnung engine to perform the "no-lead conversion". Just wait until a valve job or engine overhaul is warranted, and then go ahead and have the hardened seats put in while the engine is apart. I perfom more engine overhauls so that a rear crank seal conversion can be installed than I do for damage from no-lead fuel. Come to think of it, I've never pulled an engine apart as a result of damage from no-lead fuel!
Mark
Hi Mark,
Wow, I have always used the highest octane fuel I could find. I guese I just assumed that a sportscar sold in the 50's & 60's would have required it. I took a look in the TR3 owner's and workshop manuals and I can find no reference to any reccomended octane by Triumph for the TR3's. Only notes on compression lowering kits if high octane fuel can not be found by the owners. What's up with that? I always buy Sunoco 94 then add the 104 octane boost additive. Makes me go FAST!
Darrell
BTW, I had an old school restorer do the 3B's engine in the early 90's. He was one who said there is no need for hardened seats because the TR heads were plenty hard enough from the factory. During the rebuild a few years ago we discovered severe exhaust valve seat recession in the 3B's head.
Darrell:
I think those compression lowering kits were intended for those remote parts of the world where the fuel quality was marginal back in the early 50's. Probably a few places still like that today.
My Grandfather was a Sunoco dealer, and I grew up sniffing a bunch of 260. Maybe that explains a few things about me! Anyway, we had charts for all of the various autos and engine options which recommended the correct grade of "Blue Sunoco" for each. This was primarily tied to compression ratios, but we did have a few 'crazy kids' who'd buy the 260 for their 6-cyl Nova expecting the car to run a little faster! Grandpa laughed all the way to the bank when they came in!
Sorry to bust your bubble, but if you check any road tests in the magazines or new car brochures, you'll find that the recommendations for higher octane/premium fuel starts at about 9.5:1, perhaps a littl more now that the cars have computer controlled timing and knock sensors. At 9:1 compression ratio, a TR engine can skate by on regular with all the performance you'll ever need on the street(assuming factory timing settings and advance curves). But the higher octane won't harm anything in the engine either.
Mark
Not sure if this will load up or even if anyone will take offense, but I thought a little humor would be good.
Attachment: Engine Additive_Ad.wmv (2286.0KB)
" I grew up sniffing a bunch of 260"
Mark, I always wondered what was wrong with you! :-)
p.s. I live near Philly - until recently several gas stations in the area sold 105 octane at a special pump ! I used to treat the 250 to some now and then.
If you have a highly modified TR engine and must run a higher octane fuel, you can mix your own additive and save a substantial amount of money. Note: these additives do NOTHING to reduce valve seat recession!
http://www.gnttype.org/techarea/misc/octanebooster.html
Lots of chat related the use of an octane booster and real lead additives. Some say poppycock, others say good stuff. I think it’s all a matter of your own trials, tests and experience. I read somewhere long ago, and very recently too, that using hi octane gas when low octane will do is a waste of money. It said the best test is to determine what to use for yourself. If your motor does not ping under your typical driving conditions using the lowest (octane) grade gas, then that’s what to use and using anything higher is a waste of money.
One thing for sure is that these old motors were designed to operate on leaded gas. It’s the lead that provides the lubrication and protection to the valves. The lead coats the mating surfaces which are continually changing on the microscopic scale. The lead is the mating surface “corrector” filing and closing the gaps in the changing wear surfaces between the valves and seats, thereby allowing for the proper heat transfer. Proper heat transfer in turn keeps the valves, (the hotter exhaust valves especially), well within the appropriate operating temperature. Poor heat transfer causes motors and valves to run excessively hot. It’s the excessive localized heat that causes chipped and recessed valves and shortens their life.
It is true, lead’s not necessary if a valve conversion has been made. And regarding the higher octane, if you’re not pinging, no worries. But higher octane gas alone is not the answer because it is devoid of lead. And remember, the reason valve conversion kits came to be was because unleaded gas is not good for our OEM valves and seats because unleaded gas has no lead!
So I use a quality lead additive because this is what the original design called for. I like lead coating my valves keeping them cooler and extending their life, (peace of mind). And from the objective and focused tests I have performed, I have found that my stock motor runs better; no pinging ever, and believe it or not, it even runs quieter.
Bottom line; to each his (or her) own. I still recommend lead. Think about it. -de
My experience this week has taught me to always use high octane. My car was in the basement workshop since end of November for storage. During which time I did fluid changes, filter and seal replacements, along with a laundry list of repairs, adjustments and general"tooling". I have to empty the gas tank, seal the gas cap with saran wrap and run the motor dry, before pushing it into the workshop, as my hot water boiler and house heater are also in the basement and as we can all guess, with any low lying gasoline fumes, this could be disastrous if these measures are not taken. Even the vent pipe is capped.
So along comes our first great salt free day after 5 days of rain and I pull my car out of the basement, put 1/2 a gallon of low octane fuel in (87), prime the lines and it starts up right away. Whilst moving it over the grass, around the side of the house to the garage, I could hear the pinging. I parked it in the garage and shut of the ignition. It started to diesel for the longest time. I knew that wasn't good. Later I took a quick drive over to the gas station and filled up with 92 and a shot of lead substitute and she ran so smooth It shut right off when I turned the key to off!
Wow, that was long winded to get to the point!!!
Sounds like it might be time to "de-coke" your engine!
Mark
trthree:
When I was in high school, I worked weekends at a scrap yard. We didn't have recycling companies in those days. One of my jobs was to move junk around resulting in lots of noise, dirt and sometimes sparks. Occasionally there was some excitement when an empty gas tank would explode. Some of these old cars had been in the yard for years. The point is, there is always going to be some explosive vapor in your fuel tank AND an empty tank is actually more of a risk than a full one. Sealing the gas cap really doesn't accomplish too much. There is (should be) and overflow tube which is open to atmosphere and the connections at the tank, fuel pump, fuel lines, carbs, etc always leak a small amount of vapor. Gasoline vapors are heavier than air, so they would tend to form a layer close to the floor. If you have an ignition source in the same room where you store your car you need to provide enough ventilation to reduce the risk. Please be careful.
Sounds like it might be time to "de-coke" your engine! Question. Should I use Diet or Regular
There is (should be) and overflow tube which is open to atmosphere and the connections at the tank.......
hence the statement: Even the vent pipe is capped.
Well OK, but I personally would not store a car in any part of my home that had an ignition source nearby. Would it be possible to add some ventillation close to where the car is parked and near the floor? Just a length of flexiduct with a small in line fan would help.
After checking the S-T factory workshop manual, I see that the correct term is "Decarbonise", and not de-coke, which would refer to purchasing Pepsi! While in the manual, I was surprised to see that Triumph recommended decarbonising after the first 5000 miles, and approximately every 15,000 miles after that if needed. Sounds like someone's brother-in-law owned a head gasket company!
Mark
I wonder how much of the de-carbonizing recommendations were influenced by the anticipation of low octane fuels? Then again, just about every dealer and Jiffy Lube wants your oil changed every 3000 miles, even when the manuals say 7500...
When I rebuild my motor back in 1975 it only had 44.5K miles on it. Before the rebuild, it burned a quart of oil in about 150 to 200 miles, blue smoked like you wouldn't believe. The reason was easy to see when I tore it down, the bottom (oil wiper) ring on all 4 pistons were so badly worn, the top and bottom lips were completely gone. I was surprised that although there were some oily carbon deposits on the piston crown and valves, it wasn't as bad as I would have guessed. Has anyone ever had to teardown only to de-coke? Probably have to clock a couple hundred thousand miles before that would be necessary, no?
