Lynn E. Hanover

This part of an answer to a different question:



One of the reasons I gave up on piston engines was that the SCCA (Sports Car Club of America) would not permit aftermarket connecting rods in order to reduce the cost of racing. In the time we ran the Fiat we exploded 13 engines. At the time I actually followed the rules, and assumed that everyone else did as well.



I am a hopeless optimist. I was nearly alone with the stock rod rule. The stock Fiat rods are barely strong enough to survive on the street. We had no power above 7,200 RPM so we shifted at 7,000 RPM. The rods were just ****. Three weekends and we through them out. It cost time and $200.00 to prepare a stock set.



They were lightened, beam ground and polished. Then sent out 4 sets at a time to get shot peened. Or you could put in a set of Carrilo rods and never loose an engine. I was so stupid.



Here is how you make big power in piston engines. More if your intake is limited as ours was. Use the fastest wearing rings you can find. I used Molly filled Deeves rings. Soft cast iron and seat in an hour on a 500 hone cross hatch. I put in oversized rings so the end gap would close up, and then grind the ends to get a very tight fit on the end gaps. Top ring had .009" the second ring had .008". Later, the second groove got a Total Seal gapless ring set. Or, a second ring that had been fried with a torch so it didn't touch the cylinder. If the rules don't actually require that all of the rings be installed then leave it off. With 14:1 compression I could get zero leakdown with a .020" orifice gage, and 245 pounds of compression cranking.



The oil ring has the highest drag of all. So I used the stock oil scraper which was a dual rail light weight iron scraper with a coil spring expander. I would shorten the expander spring until I had only to cover one coil in compression to get that ring into the bore. So the oil scraper was producing no detectable drag.



If you use a built up oil ring with 3 or 4 pieces, be sure that the ends of the expander touch flat, so one end or the other cannot touch the wall. Again, the object is to have a vestigle amount of expansion pressure on the scrapers. You may have seen pictures of Smokey pulling a piston with rings through a bore with a spring scale. You measure the drag in both directions, because tapered face scrapers cost more drag going down rather than going up. Take the drag figures both directions, times the stroke, times the number of cylinders times the RPM, This gives you a drag figure, in foot pounds. Do the same with the stock ring set. The difference between the two is the amount of torque you cannot recover with stock ring sets. At each RPM point you can develope a HP figure difference between the two ring sets.



That figure will come out just about dead on once you dyno the ring sets back to back.



Perfect sealing is good, but at the range where the engine will be used, may only reprsent less than a one percent difference. For a while I ran Yamaha MX-400 barrel faced Dykes rings with a spacer on top for no drag on the upstroke. The ring opens like a parachute when presurized. So part of the compression stroke and power stroke, it had ring drag. This worked OK. I had pistons made with no top ring groove. I moved the Dykes ring to the top of the piston. Oops......too much heat.



Many second rings are tapered face scrapers, to keep oil consumption down during breakin. Once they have been in use a while, the taper wears away, and the ring becomes another compression ring. If you scond ring fits the top ring groove, a used second groove ring may make a fine top ring. It should have a minimum end gap, but if you have a total seal gapless in the second groove, you can get away with a bigger end gap in the top groove. In any case, the object is to remove drag. So, perfetly round rigid honed bores with a 500 to 600 cross hatch at 30 degrees. Use a head plate and have the motor mounts and main bearing caps and a bellhousing torqued up when you hone. Use the lightest multigrade synthetic racing sump oil. Dan Poelable used to hone with all of that and hot water flowing through the block, so he was honing at operating temperature. More than I was interested in doing, but hey, if it was one HP, maybe I should have.



On the dyno, check full power runs with the throttle body or carb throttle plates at settings below and past fully open. It is often the case that straight up is not the best position.



There you go, 5 free HP. I have more if you want it.



Lynn E. Hanover

j9fd3s

they still have that stock rod rule! we have custom .040" over pistons for our 25hour engine, they are the only set in the world, as honda ony sells .020" over.



but we need the stock rods



its not really a problem, as the NON vtec engines dont make power at a high enough rpm to be unreliable

Lynn E. Hanover

There used to be a company in (now long gone) Columbus Ohio called Piston Ring and Bearing. They had a ring catalogue laid out by size. It had a size, and then the applications that used that size. Like 1940-43 Chrysler 290 Cubic inch trucks, and so on. And then they point out that designers tend to use sizes that already exsist, to keep prices down. So one particular ring might be the same for a 1939 Wosely Hornet, all Fairthorp minors, and all 4 cylinder Chrysler 2 liters. So you could take a bore size and ring groove thickness in and they would hand you a top ring set in any diameter you could want. So you could run the top ring with a tight end gap. Fry the second ring so it does no touching, and lighten the spring tension on the oil scraper to near nothing. Your mission should you choose to accept it:



Is to find a similar company, and find a .040" over ring for your engine. The custom piston people have such catalogues.



Lynn E. Hanover

Dave D

Could these piston ring "secrets" be some of the tricks that the Spec. Miata engine builders are using to free-up power?I also understand they now use alot of the anti-friction coatings,but maybe low-budget home engine builders like us can get favorable results with just using simple,smart and cost effective methods like the ones you touched on!

BTW....what would the service life be of an engine with rings installed as described??



Dave D.

Lynn E. Hanover

These are typical of stock parts classes. Like formula ford and formula Vee. So you look at the rules and right down what must be used, and what parts if any may be aftermarket parts. I never suggest that anyone cheat, as that makes racing very difficult. The pro builders can free up much power with these and many more tricks, but the correct pieces must be used, and output must last long enough to be usefull. If rings are free, by the rules, there are many ideas to work on. If the stock rings must be used, then that requires a different line of thinking. You may have noticed that very old engines with maybe 80,000 miles or more on them run damn good with just a valve job. Or in some cases, just cleaning the valves and hand lapping them with compound. This is because most of the ring set is warn away, and is producing very little drag.



Most store bought (pro built) formula Vees smoke a bit. (No oil ring tension). One rule was that the intake manifold had to be a certain maximum diameter which was actually a hair bigger than most of the stock pieces. It is a dredfull piece of small diameter tubing with the carb sitting on a "T" intersection. So the boys find a company that can push a series of steel bearing ***** through the tubing runs to make all of the tubing the same (Maximum) diameter. They have the tubing expanded to the maximum allowable size, then acid etch away the insides until there is barely enough strength to hold up the carb.

So your 40 HP VW engine has 59 HP on the dyno. And there is nothing in it but stock parts, and its legal and will pass a tear down. Tom Pomery was racing a formula super VEE (VW-411 engine) and it broke rod caps every other weekend. Others were not breaking rods, and he discovered that others were using Carrilo rods. So he bought a set and ended up winning the National Cjampionship race at Road Atlanta.

On teardown his rods disqualified him and first was handed to the idiot who had run him off of the track twice during the race. All of the cars were using either Carrilo's or modified Chevy rods, but no teardown for them. I was in his shop one day using his flow bench when I discovered a drawer full of VW rod big ends. The test for the pieces being legal was that the VW logo had to be on the piece. So I held two big ends together, covering one up with my arm, and said to Tom, why don't you use this style of rod cap, it looks real strong. He took a look and said where did you find that? Then he saw that it was not a cap at all but another rod. But it has the VW logo on it. So I sawed off the beam on 4 of those, and he ground the backs down real nice, and assembled the 411 rods with Dodge 440 rod bolts. He won the Championship race the next year, and the inspectors were waiting for him. They saw the VW logo and gave him the win. He built his own car. His wife was his team. He has no right arm and no feet forward of his instep. He can drive the **** out of a race car.



He rented the car to Curtis Farley the next year, and he won the championship. Two years ago I shipped the nose mold for that car to some guy in Oregon who is restoring it.



The effective RPM range for any engine may be quite low with stock throttle body or carb. So, valve springs that will not float until 9,000 RPM are of little value on an engine that will never turn over 6,500 RPM. So if the valves float at 7,000 RPM because of hand selected soft valve springs, it is not a fault, and the drag on the cam is reduced giving back free HP. Some folks use very accurate bearing clearance and run them tight. Then use 10 weight turbine oil in the sump. Even running the belts loose is a big deal. Even cam belts can be run with less than the factory spec, if none is cited in the rules. Might need a new belt every weekend, but nobody said that racing was cheap. There are lots of things to do........



Lynn E. Hanover

Lynn E. Hanover

Sorry, I forgot to answer one of the questions.



When you select rings for this kind of application, You want to sample as many styles in that ring groove size as is possible. This is to find the softest ring for each application. So you build a jig that allows you to push on one side of a ring and lift a weight on a stick with the other side of the ring. It is easy to build. A piece of a ruler, a nail a block of wood. A bit of tape measure or a steel ruler. So you push on one of side of the ring until the wood ruler lifts up a bit, then mark how far you had to push to lift the ruler. Simple I will make a drawing if you need it. At any rate,

the ring that will generate the lightest load on the cylinder is what you're after. The material of the ring is less important, but Moly filled rings have a bit less drag. If the size is right, a second groove ring my be a better choice for the top groove.

If rings are free, or no ID is specified, make up a jig for the lathe to machine away a bit of the rings ID, to lighten its spring pressure.



Those stock rings are designed to run and seal for perhaps 150,000 miles. So, they will be very stiff and have a bunch of drag. So if nothing else changed but you fry the second ring with a propane torch, so it lays tight against the groove bottom, you have cut the drag in half about, and invested no money. If the rules say stock rings in the stock location, I would use a completely worn out top ring in that groove, and a bit nicer second ring in that groove. Then lighten the spring driving the oil scraper, and you are up 5-8 HP.



See what the pros are doing in the heads, and check the price of a built head from a leading builder. If the builder does a head for $1,000.00 then not much is going on. If a head is $3,000.00 then he is doing a lot of work, and that is where more of his power is coming from. Buy the head off of a blown up engine, and cut out the middle man. Use my free flow bench plans to build a flow bench and experiment with a damaged head to see where it sucks the worst. Then change yours within the rules to see where it needs help. If you carve too far, just buld up the area with childs modeling clay, and go again.



Buy a big degree wheel and dial in the cams to dead nuts on the money. Advance the intake cam as much as the rules allow. Sort though a pile of cam pulleys to find the most advanced vice the keyway, and the most retarded vice the keyway. Get that done for intake and exhaust. Now you should be able to move the lobe centers around and still be stock/legal.



Tighter valve lash gives you a bit longer duration. A bit more lash give you less duration but crisper seating and a bit more bottom end. If you use rockers, you will find that some have more ratio than others. Hand select those that give the very highest legal lift.



Use synthetic trans lube designed for a synchronized transmission. Use a synthetic diff oil. All of the Redline stuff is just hard to beat, and most builders use it, no matter what sticker is on the car.



You can get even more chicken ****, and stretch out the springs on all of your lip seals. The spring is in there to keep the seal tight all the way through 150,000 miles. Lighten the spring load on all of the seals.



Lynn E. Hanover

heretic

Spring in the seals? Who needs it?



Our cylinder hone and line-hone equipment can heat the honing oil to operating temps. Rumor is that it's chicken fat based. It smells awful, at least.

Lynn E. Hanover

Look at the container the stuff comes in. Probably vegetible oil based, and needs an germicide added weekly. If they don't specify, try a cup of bleach each week. You don't need any new life forms in the shop.



Lynn E. Hanover

oldone

Thats exactley (almost) what I was taught.Except we put the car on the trailer,scooted down to the local circuit,I was made to do lap after lap. Then at the end of the session the slicks were put on and I could step on the gas !!!!!!!!!!!!!!!!!!

j9fd3s

i think thats exactly what the spec miata people are doing. every part of the engine is built to the optimum limit of the specs. the crate engines (sunbelt etc) are legal, but expensive due to all the hand work.



the miata people dont stop with the engine either lot of competition