Performance Modifications For high performance applications, sleeves also offer a number of advantages. The displacement of an engine block is limited by the distance between the bore centers and the thickness of the casting. Stroker cranks are popular because they require fewer modifications.
Long stroke cranks are good for low rpm torque, but a short stroke, large bore oversquare configuration is better for high revving power.
Consequently, if you are building a high revving performance engine, you may want to increase the bore size rather than relying so much on increased stroke to create more power. If you are installing dry sleeves in a block to increase displacement, you can remove only so much metal before you run out of block to support the larger cylinder sleeves. One way to overcome this limit is to do a wet sleeve conversion. The existing cylinders are machined away, and wet sleeves are installed in their place.
Installation involves extensive modifications to the block and requires precise CNC machining so it can accept wet sleeves, but the results are worth it. Because the coolant is in direct contact with the outside of the sleeve, wet sleeves can typically handle much higher horsepower and heat loads.
Consequently, you gain increased strength and reliability as well as more displacement. Wet sleeve conversion kits are available for certain late-model import engines as well as domestic V8s. Aluminum blocks have more thermal expansion than cast iron blocks, so they generally require more interference fit to keep the sleeves from moving.
So how much interference do you need? Answers will vary depending on whom you ask. Different sleeve suppliers gave us different recommendations. One said most aluminum blocks typically need about. If the block can accept a flanged sleeve, then you may not need any interference at all. Another said. Bore distortion is bad because it prevents the hole from being round when you hone it. This prevents good ring sealing and allow blowby and compression losses; neither of which are good for emissions or performance.
One supplier said they have changed their thinking about interference fit altogether on some aluminum engine applications. These difficulties have been addressed and solved by this inventive tool and process. The initial basic component of the installation tool is a cylindrically shaped snap ring guide and installation sleeve 38 as best seen in FIGS.
The outwardly directed end portion 41 of the sleeve member 38 includes ring guiding bore 40 which extends through sleeve 38 and functions to guide the snap ring retainer into the piston's bore As best shown in FIG. Subsequently, the retainer 32 is moved axially through the sleeve 38 accompanied by inward radial constriction toward the center axis 44 of bore The diameter of the tapered bore portion 46 progressively decreases in a manner to inwardly radially constrict the snap ring retainer until its diameter eventually matches the diameter of the piston's bore The gradual transition provided by the guide and installation sleeve 38 facilitates a non-stressful movement of the snap ring retainer 32 into the bore Alignment of the inward end portion of the tapered bore 46 and the piston's bore 24 is established and maintained by an elongated plunger assembly 50 which has a pilot stem portion 52 adapted to be inserted into the inner diameter center of the tubular wrist pin This aligns the tool's longitudinal axis with the axis of the wrist pin 18 and the bore In addition to the pilot stem portion 52 , the plunger assembly 50 includes a cylindrically shaped snap ring displacement body portion The diameter of the displacement body portion 54 is only slightly smaller then the diameter of the piston's bore Accordingly, when the displacement body portion 54 is moved axially toward the right as see in FIG.
Eventually, the snap ring retainer 32 is seated in an annular blind slot or groove Specifically, the forward or rightward end of the displacement body portion 54 carries a flat end ring portion 56 which allows it to engage the snap ring retainer once it has been radially constricted by beginning movement through the tapered bore portion 46 of the installation and guide sleeve The plunger assembly 50 further includes a connector stem 58 which projects axially from the displacement body portion 54 to an exteriorly positioned handle portion The handle portion 60 preferably is configured as an enlarged diameter knob 64 readily engaged by an installer of the snap ring retainer.
The knob 64 is secured to the end of the stem portion 58 by a threaded fastener 66 as seen in FIG. The diameter of the knob 64 is sized to conformably fit the palm of the installer's hand and is sufficient to spread the manually applied load evenly over the snap ring retainer The plunger assembly 50 is provided with a tubular snap ring support sleeve member 68 which has a rightward opened end portion and a leftward closed end portion.
The closed end portion has an aperture 59 to receive stem portion 58 therethrough. This construction permits axial movement of the handle, stem and displacement portions 64 , 58 , 54 relative to the support sleeve member As the displacement portion 54 is moved to the right, the snap ring retainer 32 is moved through the bore 40 of the tubular sleeve member As best shown in the sequence found in FIGS. Specifically, FIG. Axial movement of the plunger assembly 50 produces rightward movement of the snap ring retainer 32 along and through the tapered bore The sequence of the preferred method of installing a snap ring retainer is shown in FIGS.
The snap ring retainer 32 is manually or otherwise positioned or loaded into the lead-in portion or bore 42 of the installation sleeve member The guide and alignment stem portion 52 extends into the inner diameter of wrist pin 18 to align the plunger assembly with the bore 24 and wrist pin The thin wall sleeve member 68 and the plunger assembly 50 are moved manually to the left from the position in FIG.
During this slight movement, the sleeve member's end 70 has axially displaced the snap ring retainer accompanied by the beginning of radially inward constriction of the snap ring retainer Installing a sleeve can save a block that would otherwise be unrebuildable. Click Here to Read More Advertisement But sleeves can also be used to strengthen cylinders, especially in performance engines that are being pushed way beyond their original design tolerances.
A prime example of this would be Honda B-Series aluminum blocks. These little 1. They are a popular engine with sport compact enthusiasts because they can be modified to make upwards of 1, horsepower with a big turbo and lots of boost pressure.
The latter approach can also be used to install larger cylinder bores for increased displacement and a better bore to stroke ratio. Advertisement Another example is the 5. In stock form, this engine makes to horsepower. Bolt on a street supercharger or turbo with 6 to 8 lbs.
But as boost pressure and power go up, reliability of the stock aluminum block becomes iffy. Pushing the stock block beyond horsepower increases the risk of a cylinder mushrooming outward and cracking because the stock cylinders are too thin to handle such high loads reliably.
There are some drag racers who are making upwards of 2, horsepower from a stock block 5. Such a modification should allow an otherwise stock block to safely handle 2X to 3X the power it was originally designed to handle.
If you push the block too hard, you risk cracking the cylinders. The factory cast iron sleeves in a stock Chevy LS1 aluminum block are designed to handle peak pressures of about 1, psi. But the cylinders will then be subjected to peak pressures in excess of 3, psi — more than enough to crack the stock cast iron sleeves. Advertisement To handle this kind of power, you can replace the stock block with an LSX block or aftermarket performance block again, spending big bucks or you can upgrade the stock block by machining out the stock cast iron sleeves and installing dry or wet ductile iron sleeves.
Various wet and dry sleeves are available to fit many of these late model engine applications. Ductile iron is about three times stronger than ordinary cast iron, and is more than capable of handling a high output application. Aftermarket sleeves are available in various diameters, lengths, thicknesses and alloys. There are standard sizes and custom sizes.
Some suppliers can make you custom sleeves if there are no standard size sleeves to fit the engine you are building. Stock engines can be fitted with ordinary cast iron sleeves that will work just fine, but for high horsepower engines you want some type of high grade ductile cast iron sleeves. Wet sleeves typically provide better cooling because the coolant is in direct contact with the outside of the sleeves.
This is an essential feature for high horsepower applications. You also gain the ability to easily replace individual sleeves or all of the sleeves without additional machining should that become necessary at a later time. That means a racer can repair or freshen up the motor at the end of the season by simply swapping out the old sleeves for new ones. Advertisement Almost all Top Fuel funny cars and dragsters run some type of sleeved aluminum block. According to one sleeve supplier who virtually owns this segment of the market, the preferred sleeve material is a special ductile iron alloy that has a tensile strength of , PSI and a yield strength of 90, to , PSI.
This alloy is two to three times stronger than most other ductile iron alloys thanks to the unique mix of carbon, manganese, magnesium, silicon, phosphorus and sulfur in the iron, and the way the sleeve is heat treated.
The sleeves are also centrifugally cast to improve density, consistency and quality. The final product can withstand 7 to 9 runs in the punishing environment of a Top Fuel motor before replacement is necessary compared to 1 or 2 runs with other ductile iron liners. Advertisement Heavy-Duty Liners. In the heavy-duty market, wet sleeves liners are mostly used in cast iron blocks for longevity. After , to a million miles, the original liners are pulled out and replaced with new ones.
No boring or machining is necessary, provided the sealing surfaces for the liners are still in good condition and dimensionally within tolerances.
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