What IS that?
Getting to understand the internal parts of a high end race engine is something that not many people understand first hand.
So here at Wannabe Racing Enterprises we decided to give a little beginner course for those who may not know. And although these are not the pinnacle of performance, (many secrets need to remain secrets,) this is a good window to what some of the teams have been running for some time, and have become quite common knowledge. And now it is knowledge to you as well. We are contemplating getting into a little bit more detail on the next time around. But lets start simple for now.
Power in a crankshaft?
First we are going to start with crankshafts. And we are starting with the term Billet. (Pronounced just like bullet from a gun, but with an "i".) If I see another crankshaft marked billet on ebay when it is really forged, I am going to scream bloody murder.
The left is a picture of pieces of billet ready to be cut into crankshafts. They are true billet, as they were taken from one solid piece of metal. (That is the definition of billet is completely made from one larger piece.) The right picture is a crankshaft that is forged. Basically a large piece of machinery squeezes the molten metal together into the rough shape. Then cut with precision tools to make the crank and all of the journals precise.
Is there more to a crankshaft than just not bending or breaking. Sure! There is power in crankshafts. The first of these ideas is crankshaft lightening.
The crankshaft has the journals that the rods bolt on to, and counterweights to offset the weight from the centerline of the crank. The weights of the counterweight have to be balanced with special machinery to match the "bob weight", or measured weight of the piston, pin, rings, and connecting rod. So, getting a crank light, is more than just cutting off the counterweight, as you need also to keep balanced. Light weight pistons, pins, rings, and rods come into play here. Next time out we are going to discuss the entire counterweight science. Right now we are going to discuss lightening holes. To make a rod journal lighter and stronger, crank companies will drill out the center of various rod journals. Some will drill out the front and rear, and leave the two centers the same. That is what is called 'two lightening hole' cranks. Where all the rods are lightened, is considered a 'four lightning hole' crank. Different crank companies will use different sizes of holes to take out different amounts of weight.
Then we get to main drilled crankshafts. The same thing applies here, but not adjusting the balance, just the actual weight. The less mass you have to spin around at 10,000, the easier your engine will make power. Once again, different sized holes through the main journals of the crank. The above pictures are a Sonny Bryant big block Chevy crank where the rods and mains are drilled. Now you are thinking, how could that be stronger with less material? Well, actually it is. When the crank is drilled, then the crank is sent off to be heat treated, the heat treating hits the surface area of the crank. So where you would have no heat treating on the inside of the journals, you now have that. And the strength of the heat treating more than offsets the extra steel that was there originally. Unfortunately, these lightening holes mean more machining, and thus, more expense. For a race team to have an average of $5000 in each finished crank is not much at all. The leading edges of the crank counterweights get knife-edged. Basically grinding the front edge that will hit the air and oil first. Grinding it to put a point on the edge so it splits the air, not hitting it with a blunt edge. Yes, it does make a difference.
When someone speaks of a roller camshaft, they are actually speaking of a cam made for roller lifters. A roller lifter uses a roller tip to ride on the cam rather than a flat surface. It takes less resistance as well as allows the cam to ramp open and closed quicker. The science is simple. The round roller has miniscule contact with the cam, and rounds off quickly where the flat tappet hit but hangs over on the sides, so a quicker ramping roller cam would hit the outside of the flat surface lifter.
Roller lifters need to stay exactly in alignment with the rotation of the cam. There are a few ways to do this. The simple way is to connect the tops of two with a bar so the alignment actually references off of the next door neighbor lifter. Then there is the keyway lifters. A bronze busing is pressed into the block with proper oiling provisions and a channel for the key to glide in. Notice the picture and see the Jesel lifter key and the slot in the lifter bushings. The keyway lifters get rid of much of the weight of the other lifters, and are more precise in their alignment. But they cost much more. The two main manufacturers of the keyway lifters are Jesel and Morel. They are darn trick.
Now, don't get roller cam confused with roller cam bearings. A way to get rid of more resistance is to eliminate a solid bearing in the camshaft. These babies are nice. Again, costly, but run forever and make power. A nice addition of roller cam bearings is that they are splash provided. Meaning the oil they run off of is just splashed from other engine parts. They are not force fed oiling like the other bearings. The cam bearings actually plug off the oil holes, and make more oil supply for the mains/rods. Or make it so you can turn your oil pump down and get the same oil amount and pressure, with reduced drag from having the oil pump not running as hard. Every time you say the words less drag or less resistance, you have made MORE POWER! It may not seem like much. But a bunch of 1 and 2 horsepower tricks add up to world championships. And to run with the big boys, you have to play the big boy games.
Certain teams have been playing with roller main and rod bearings, but many forms of motorsports have outlawed them from competition.
Shaft mounted rocker systems.
A cam is the brains of the engine. Tells everything how and when to work. Any time we get better information from the cam, the better things will work. Almost every effort has been made to do this. A machine called a 'Spintron' takes an assembled engine and spins the valve train at the desired rpm while super slow-motion cameras record the findings. We are finding that even the thickest pushrods bend quite a bit. The less flex you can get, the more true your readings from the cam are. Larger diameter and thicker pushrods are now commonplace. Where a high perf sbc pushrod is about .060 thick, and competition bbc pushrods are .080, pro stock cars are using large diameter chromemoly stepped shafts in the .180 range. The pro stock guys have taught us that extra weight on this side of the rocker arm is not as much of a hindrance. Although the other side of the equation needs to be light. Titanium valves, thinner valve stems that help more airflow around the stem, while dropping total weight of the valve. This was getting out of hand, so many forms of motorsports have made minimum weight rules on these parts. Now you want the strongest valve at the minimum weight.
Then we get to rocker systems. Rather than flex around on a single stud and deflect everywhere under large pressures, the trick thing is shaft mounted rockers. Rocker stands are set on a head and are welded together so the stand becomes one large piece. (Some heads have one piece stands that you can order from T&D or Jesel. But when a pro stock guy get a hold of the head, the valves never finish where they were originally cast. So one generic stand does not fit all.)
The bases hold a strong steel shaft that the rocker pivots through. With the tight tolerances, and design, there is very little movement going on in a good shaft mounted rocker system. Again less deflection and less movement, less movement is clearer information from the brain.
One reason for intricate rocker systems, larger pushrods and heavy duty roller lifters is because of valve spring pressures. The Spintron taught us that the valves do not slam closed. They actually bounce closed. The valve closes, but then re-coils open and closes again and again. It is not uncommon to see the valve bounce open six times every time it closes. Larger and heavier springs try to keep the valve closed, or to close it quicker and more precise. Again, trying to get the engine a true reading from the camshaft. (Cuz the cam does not say to bounce closed.)
The spring on the right is a high performance spring and damper for a 400 horsepower street/strip engine. The one on the left is an electropolished triple spring made by PSI for NHRA pro stock. This spring puts over 400 pounds of pressure on the seat, and around 1200psi open. About 10 times the pressure of a simple small block Chevy. These springs would make a pretzel out of a standard valvetrain. Titanium springs were tried for a time, but most teams returned to the steel springs. Titanium springs worked great, but fracture rather than lose pressure, like the steel springs do. Caused a ton of breakage, and did not last as long as the steel springs. With the new alloys, and design changes, the steel springs really throw a thumpin. Of course they only last a few passes before they are thrown away. But how would you like to last at 10,400 rpm lifting over an inch of valve lift?
Although this is far from the high tech racing world, Someone needed to step in and let the world know what an I beam and what an H beam really mean. The rod on the left is a titanium h-beam design. The rod on the right is an I beam. Confusion in the past has stemmed from what direction you look to see the I or the H. This should clear that up. So when you sell you h-beam rods on e-bay, and I buy them and find out they are I beams, I will consider you warned.
Now, a quick ditty about titanium rods. They are becoming more popular every day. They have been outlawed for many years in certain forms of motorsports. That did not stop some people. Teams would take them, get them coated with a coating that had actual steel substance in the coating, so they would register as steel rods in the old magnet test. This fooled many people for many years, but now most forms of motorsports have gone to the minimum weight deal. If you think titanium rods are not an advantage, think again. Taking two identical BBC 6.538 rods, and weighing them without the bolts, the titanium rods are exactly 60.63% the weight of steel rods. They are an advantage, and they are cool!
Eagle has advertised a 3D H beam design. Companies like Carillo that have been running H beams for a long time, and looked at getting more weight out of the center of the rod. Tapered Carillo rods, where the h beam got narrower as the rod went to the pin end were a disastrous mistake. I have, as do every other that I know to run these, have the scrap metal to prove it. Another design idea took a little more material cut out of the middle of the rod leaving a ridge down the center to keep strength. Although many companies make this, Eagle is the one that started calling them the 3D version. So when you hear about an h-beam, or a 3d, h beam, you will know the difference. The steel eagle rods with the L-19 bolts have lived just fine for 300 passes in 1300 dyno proven horsepower, supercharged BBCs. We personally have taken a set over 11,000 rpm in a 565 cubic inch Chevy without failure. We did not mean to. The powerglide blew up and something stuck the throttle open for a few seconds. Even though we did not mean to, it was a successful test, and we swear by these rods.
Various other stuff
Gas porting a piston is something that certain engine builders swear by. There are a few types of gas porting, but we will take vertical gas porting for now, and will get to others next time out. Drilling small holes in the top of the piston that continue down to the top ring land. Actually to the inside edge of the ring land. This takes pressure on the compression stroke, sends it down the holes, and hits an angled cut on the top of the compression ring. This pressure hits that angle and pushed the ring out to create more seal on the compression ring. This takes life away from the ring, so is not intended for use with longevity in mind. There are other tricks to do some of the same ideas, and we will get into them next time. Ideas that are prone to longevity as great as 200,000 miles.
Lets take a quick look at coatings. If you think coatings mean very little, think again. When 18 wheelers show up at PolyDyn or Calico from various nascar teams full of parts to be coated, the parts do not stop with piston tops. The above picture shows different coatings from different manufacturers. The gold top is a traditional coating from PolyDyn. It is a heat transfer coating. Keeps the heat from getting into the piston top. That makes the piston grow much less, and then the teams run tighter clearances 'piston to cylinder wall'. Skirts get an anti friction coating. You may have seen these before, as they are becoming very common. We personally do not use this, as alcohol causes it to erode quicker. The silver coating is an oil retardent coating. Oil cannot stick to it. So the oil flies off of the pistons, and makes them lighter while the oil being removed quickly helps to remove temperature from the piston, making it grow even less. This silver is standard on the underside of the pistons, but fairly unique with our set-up. The black coating in the background is a whole other story for another day. That piston will say hidden for a while. This same silver oil retardent coating is used on crankshaft counterweights to keep oil off the cranks, bodies of connecting rods to do the same, and other internal parts as well. Bearings are coated on a regular basis, and that we know. But did you know that the valve stem gets an anti-friction coating, and the valve head gets a heat barrier coating. Carburetors have more coatings going on inside than you could imagine. Intake runners of the cylinder head get a coating to flow better and keep heat out, exhaust runners get a different coating, and the chamber of the head another coating as well. Every time we coat an internal engine component that touches the fuel and air mixture, specially those during and after combustion, then engine absorbs less heat, and thus needs less fuel per air molecule to run at optimum efficiency. You ever wonder why one NASCAR team gets better fuel economy than the next? Coatings play a huge role in that. Especially in the fuel feuds of the last decade.
Lets not stop there, how about transmission and rear end gears being coated with friction reducing coatings on the teeth, and oil retardent coatings on other parts. You betcha baby! Special coatings on the water and oil passages in the block. The portions of the block where oil drains. Even the cylinder walls for use with special ring packages and piston skirts.
Then we get to special coatings needed to keep things alive with huge vacuum numbers. Yeah, we are running vacuum pumps that pull vacuum out of the crankcase. That keeps air density inside the engine lower, and easier for the crank, rods, and other internals to travel through. It also keeps the air density down so the oil particles cannot be suspended as much in the crankcase. This greatly lessens the droplets of oil hitting the crank and slowing it down. We were pulling so much vacuum that the wrist pins were going dry and welding themselves to the piston and sometimes the rod. A Casidium coating, (often called diamond-like coating), solved that problem on the wrist pins, and the vacuum numbers started creeping up until we started welding the rings to the piston from lack of oil. Coating rings has helped a little. Rings are now sanded to be ultra flat, and ring to ring land clearances are almost non existant. But attempts are being made to eliminate the recurring problem so more vacuum can be pulled. There are current attempts to Casidium coat the ring lands. And just because I did not state other items, don't think for a second that they are not coated. Either completely or partially. Intake manifolds, cams, lifters, headers, exhausts, bearings, pumps, gears. Basically- you name it.
I hope this has helped. If you are a little more advanced, and it did not, maybe next time may. If not then, you probably should write one too. Or maybe you should keep your secrets, secret.