HPR TT LSx Build Thread Part I
In this thread we are going to outline and show some of the items you might find in a high HP LSx build. In this particular example this is going to be a forced induction, alcohol engine running in excess of 2000 hp.
Over the next days / weeks you will see each item being used and we will try and highlight details on why you might need something like this in your engine, or why you wouldn't.
For privacy of the customer, there will be no pictures shown of the car or final package installed, sorry.
*There are many ways to build an engine in this HP range depending on use, class rules, and mostly budget. This is showing just one way. Enjoy
There are a number of different ways to make and design crankshafts, the three main ways are; casting, forging, and billet. Depending on the budget, power level, use, and number of units being built what might be the best way to go about it.
Casting is probably the most popular off all ways, especially for production use due to the quick and economical way to manufacture the cranks. If you are going to produced crank shafts by the 10's of thousands in one rough size and shape, it is very easy to turn them out quickly without a lot of cost. Production, low HP, low RPM engines are fine with cast crankshafts and can run for hundreds of thousands of miles for a normal driver. Prices can range from $300-600 ea
Forging is the most popular aftermarket upgrade when people talk about a "built" engine. The forging process produces a more compacted material which leads to a much stronger piece at the end. You have a few more options when it comes to the material itself which, again is going to produce a stronger final piece. You will be limited slightly in design with these as there is a high cost in making the forging dies when making the blanks. Counter weight design and stroke are generally limited on how much you can add or move. In the last few years the OE has switched to forged crankshafts for the high performance cars like the LS7, LS9, LSA and similar engines. Because the forging dies are more limited on what the final product is, and the machine wear/time to produce the final product is more....these generally will cost slightly more than a casting. Custom machining can add to this even more. Material is typically 4340. Pricing on average can be $800-1800
When you select a billet crankshaft you have even more control over the final design. Because the crankshaft starts as a solid block of steel, counter weight design, counter weight placement, stroke, main, and rod journals can all be controlled to what ever you would like to do. Because the piece starts as a forged billet, and you have more control still over material choices you can produce an even stronger crankshaft than forged. Most top level drag racing, including Top Fuel, and top level road race cars will use billet crankshafts. Material can be 4340, 300M or other specialty materials. Pricing generally starts around $3000 and can be over $7000 depending on design and material used. The other downside, other than the cost, is the build time. Billet cranks are only made by a handful of companies and lead times can top 10-14 weeks.
Counter weight design can, and is, a vital component of any engine build. Each OE is slightly different in how they produce crankshafts, some OE engines will design and use crankshafts that have counter weights on each (or each pair), of rods to give a more naturally balanced crankshaft. Chevy for what ever reason (probably cost), chose to eliminate the counter weights from the center of their crankshafts. By doing so this typically makes the front and rear counter weights the largest, and reduce as they make their way to the center were no counter weight is included, cast or forged. As you can see in the picture below a forged LS crankshaft is on the right with the standard counterweight design as compared to a fully counter weighted crank on the left...in this case billet.
full counter weighted crank on the left, standard Chevy on the right
Adding the additional counter weights to the middle of the crankshaft will help strengthen the crankshaft even more, and reducing its tendency to S shape under load. Without the weights there, the 2 and 4 journals are acting like bike cycle pedals, trying to twist the crankshaft. CCW (Center Counted Weighted) crankshafts will help to reduce this by naturally balancing out the engine. By greatly reducing the chance to S bend the crank will greatly increase main bearing life of most performance engines. CCW crankshafts are highly suggested to be used in high RPM applications and high HP applications. You will find CCW crankshafts used in NASCAR, ALMS, NHRA, and other pro level racing. Be it a build to make 1500 and more, or a 500hp LS turning 9000 RPM, a CCW crankshaft is the way to go. For the last 10 years, typically only billet crankshafts could be used for a CCW LS crank, but there are a handful of CCW forged crankshafts to help bring some of the costs down.
This LS turbo build is using both a billet, and CCW crankshaft by Sonny Bryant. Because of the high HP requirements of the build by the customer (topping 2000hp) the crankshaft needs to be a strong as it possibly can as it will see a lot of load by the power demands and also continued high RPM use while making passes. This, the center piece of the engine, needs to be one of the most reliable parts of the build.
This particular crankshaft topped the $4000 mark by being a billet piece as well as a CCW design. Another interesting feature using two thrust bearings which I will cover in the next installment as we go over the block as well.
In closing, there are a number of ways you can build your engine and many price points to choose from as well as design. Just the crankshaft costs can range $400-$8000 before ever assembling the engine. While it would be IDEAL for every engine to use a billet CCW crankshaft, in reality, most builds it is not needed. Speak to your engine builder as what be right for your particular build.