Today, cast-iron is no longer used as an engine block material and the flagship performance platforms like Nissan’s VR38DETT, Mitsubishi’s 4B11, Mazda’s MZR and Honda’s K-series all utilize aluminum engine blocks.
In that test, a specific size âVâ-shaped notch is cut into a specific size rectangular bar of the test material ("specimen"), then the specimen is mounted in a testing machine which has a pendulum-type hammer. Since there are no such options for most other platforms, sleeving the block with high-strength iron or steel sleeves are required when performance levels exceed the power handling capacity of the factory cast-iron cylinders. On the high-horsepower builds in our Club DSPORT machine shop, we’ll select a crankshaft with less than 0.001” of runout (preferably under 0.0005”).
It’s no secret that import performance fans will often push engines to power levels that are double, triple or even eight times the original level. A crankshaft with a runoff of 0.001” is going to require 0.0005” more bearing clearance than a crankshaft with half that runout (0.0005”). When a KA24DE has new M11 Time-Serts installed, a set of 11mm 4G63-EVO head studs can be used.
I was told by one major titanium supplier that the most frequently used alloy for conrods is the old standby Ti-6Al-4V (6% aluminum, 4% vanadium), also known as Grade 5 titanium.
Instead “dry” sleeves are installed with the surrounding area being in contact with the bored-out aluminum material forming the original cylinder walls around the factory liner or plasma-sprayed bore. As an aside: careful examination of Figure 2 reveals the ânecking-downâ a tensile specimen undergoes just before failure. These tiny explosions can eat away at the liner and eventually go all the way through.”, Just as bad as too loose, however, too tight a press can be a problem.
The original solution for aluminum-block designs has been a liner or sleeve made of cast- iron, ductile-iron or steel to provide a surface with proper wear properties against a piston and piston ring. When this alloy is extruded, the mechanical properties are uniform in all directions (isotropic). The fatigue testing of the 2000-based alloys has yet to be completed. Don’t be fooled by appearances, say experts. Avoid solid mounts on the engine.
These alloys contain from 3% to 10% aluminum and smaller percentages of zinc and manganese. Cylinders need to be as perfectly round as possible. For example, if a 9,800 pound tension load was applied to a 1/2-inch diameter bar (0.196 square inch cross-sectional area = diameter x diameter x 0.7854) the tensile stress would be 50,000 pounds per square inch (psi) (stress = load / area = 9800 / 0.196).
This improves rigidity, reduces block distortion and improves cylinder sealing under load. series for a number of popular applicaiions. “The Ra finish of the liner bore, degree of angle of the crosshatch and roundness and diameter of the liner affect the ability of the rings to seal to the liner and play a major role in oil consumption,” Scott continues.
In the nether-worlds where cost is no object (Formula One, Cup, factory Le Mans teams and the like) those numbers might not seem important, but at other levels of racing, the costs can be prohibitive.
As an aside: Table 3 contains some interesting information on several often-used alloys, both wrought and cast.
Note, for example, how the strength of the famous high-strength alloy 7075-T6 drops to 37% of its room temperature value at 300Â°F and to less than 20% at 400Â°F.
to .0003? With Time- Serts, a KA24DE block can be upgraded to accept the 11mm studs. Enlarging the cylinders will require some type of machining operation, while installing a longer-stroke (a.k.a.
A more common solution for a high-performance aluminum block is to receive some type of aftermarket sleeve and machining process to install the sleeves in the aluminum block. When the potential 75-to-85 percent increase in clamping force from the best CA625+ alloy isn’t enough, one can also opt to increase the size of the fastener. We’ve installed Darton M.I.D sleeves in B-series Hondas and it’s proven to be bulletproof to the 1,100whp level. For example, VW began using cast magnesium crankcases for its 1961-model, 40 horsepower flat four, air-cooled engine. Although it features a long stroke, its factory-intended RPM level is less, so Honda decided a girdle wasn’t necessary.
Sleeves offers a variety of different high-performance sleeves.
“The main and ONLY consideration to engine performance is to engineer a solution in which the expected horsepower output over the expected run duration of the engine is built to the task,” Catapang says. This alloy is interesting because, although it has a remarkable combination of properties (strength, fatigue life, impact resistance and ductility), it has somewhat fallen out of favor, primarily because it has been misused.
So let’s say you start with a 2.0-liter engine capable of producing 200 lb-ft of peak torque. In addition to being the home of the engine’s cylinders, the block is also responsible for locating and keeping the crankshaft on its axis.
Limited axial fatigue testing of AirMelt-PESR samples shows an endurance limit of 10^7 cycles at 138 ksi (951 mpa). Here is an example.
“Each manufacturer provides the specs for allowable deviation. Unlike many titanium alloys, this one is easily bendable to form complex fabricated sheet metal parts. Cement has exceptional strength in compression making it ideal as a filler material.
These designs have the coolant channel cast into the top of the deck. “stroker”) crankshaft usually requires some grinding of the block for proper clearance along with custom pistons and/or rods that must accommodate the stroker crank. But that's not all. “A sleeve needs to be measured carefully to determine the amount of press fit,” says Walsh, “and it should actually include an average of six separate measurements.”. Recently, I heard about a new high-strength steel product from Bohler-Edelstahl, which offers potential for improvements in gearing and shafting applications.
When sourcing a shop, it’s best to talk to customers that have engines operating properly for at least a year after the build. “The sleeve material, specifications, heat treating and the manufacturing process are all critical in producing a quality liner. ‘A2’. “The ductile can be warped under a heavy load, but it will return back to its beginning origin because it has tremendous memory. Using this alloy, BMW developed a composite inline-6 engine block (Figure 4) which uses AJ-62 for the external block, and an aluminum alloy for the liners, coolant passages and main bearing bulkheads. The dry-type sleeve is pressed into a full cylinder that completely covers the water jacket. This simple upgrade will maintain a head gasket seal even when torque output of the engine approaches the 400 lb-ft range.
There are some unique material selection challenges in the design of very-high-strength threaded fasteners. The Honda B18C provides superior crankshaft support (compared to the B16A) by adding a girdle that ties the #2, #3 and #4 main caps together.
Time-Sert offers a complete M11x1.5 head stud insert kit with the necessary tools and inserts included. This steel, known as W-360, is a high-strength chrome-moly-vanadium alloy, having somewhat different chemistry (see Table 1) than the exotic chrome-moly-vanadium crankshaft alloy (32-CrMoV-13) discussed in my Crankshaft Design article. While many domestic manufacturers offer high-performance cast-iron blocks with thicker cylinder walls, only the Nissan RB26DETT engine has such high-performance cast-iron block options available from NISMO.
Further, the extra carbon in 300-M allows a 60HRc surface to be produced on 53HRc through-hardened parts by induction hardening and tempering at 300Â°F, making it useful for some challenging gear and shaft applications. The flange prevents the sleeve from dropping, and can be an excellent option for sleeving race blocks, Metchkoff says. Walsh from Melling indicates, however, that in actuality, it’s a much more complex process. This allows cast-iron blocks to have the cylinder walls integrated as parts of the block itself. By setting this clearance on the tighter side with a straighter crankshaft, all of the main bearings are able to support more load.
The exotic nitriding steel (32CrMoV13) used for certain high-end crankshafts can cost over $20 per pound in the very high purity (VIM-VAR) form; over $5000 for a 26" bar of 7" round suitable for a Cup crankshaft, for example.