GM's SB2 V8 engine questions, answers

(Feb. 27, 2001) -- This weekend's Florida Dodge Dealers 400K event, round 2 of 24 races of the 2001 NASCAR Craftsman Truck Series, will see the series' debut of GM's SB2 V8 engine with the 12:1 compression ratio in the Chevy Silverados, the same powerplant as on the NASCAR Winston Cup and Busch Grand National cars. Teams, however, may continue to use a 9.5:1 compression V8 as well.

Following is a transcript of an interview conducted last year with Jim Covey, NASCAR Engine Development Manager for GM Racing/Engineering, on the approval in 2000 by NASCAR of the GM SB2 engine in the Craftsman Truck Series.

Q) NASCAR says that the GM SB2 engine has been approved for competition in both the Busch and Truck series. First of all, what is the SB2 engine?

A) The SB2 ("Small-Block ­ Second Generation") marks the first time in the 45-year history of the GM small-block V8 that a package of engine components has been specifically developed for NASCAR racing competition. The SB2 made its debut in the Winston Cup series in 1998.

Q) What specifically is the difference between the small-block and the SB2?

A) The SB2 engine package consists of a new cylinder head with revised valve angles and valve layout. To complement the revised valve arrangement the intake manifold designs have also been revised.

Q) With the tremendous winning record of Chevrolet in both Busch and Truck, why change?

A) After 45-plus years of development and racing, the small block in the original configuration had reached its full potential. We listened to what our customers -- race engine builders and race teams ­ said was important to them in a race engine design, and we really focused on customer satisfaction issues with SB2. Reliability, durability and ease of building and maintaining a competitive engine were key considerations in the design stage. Compared with the original small block V8, it's easier for a team to assemble and tune a competitive SB2, and the individual components last a lot longer. For instance, many Winston Cup teams used to replace cylinder heads after 2-3 races because they would develop stress cracks. With the SB2, it's not uncommon for cylinder heads to be used in 8-10 races.

Q) What will happen to all of the small-block engines out there now?

A) Converting from the existing 18-degree cylinder head engine configuration currently used in Busch and Truck will not make all of the base engine components such as the block, cranks, connecting rods, etc. obsolete. If a team desires to sell an existing engine instead of converting to an SB2 configuration engine, there are several racing series such as the Southwest Tour, Winston West and many other late model series around the country where the engines could be used.

Q) Can a team still use their current 18-degree cylinder head engine configuration or must they convert to the SB2 immediately?

A) NASCAR has grandfathered the existing small-block engine so teams need not convert to the SB2 immediately. However, with NASCAR's revision to the compression ratio limit and revised the carburetor rules in BGN, teams will be required to make revisions to their existing engines to convert them from the current compression limit of 9-to-1 to the increased limit of 12-to-1. Therefore, it makes sense to make the conversion to SB2 at the same time that revisions are being made to the engines to meet the new rules for 2001.

Q) How much more power will the SB2 generate? And what part of the increase in power will come from the increase in compression ratio that all the engines will gain?

A) Every dyno is different, so the absolute numbers vary from builder to builder. But most of the teams are seeing a power improvement of a few percent over the old small block V8. They are all confident that the SB2 is competitive with other manufacturers' engines in terms of power, and they are really pleased with its durability, reliability and user-friendly design. As far as the horsepower increase due to the increase in compression ratio, most people think it will be about 3-4 percent.

Q) Does the new SB2 engine package require the use of all new GM components?

A) Not at all. To begin with, all engine components, including the engine block and cylinder heads, have a finite life and are replaced after a certain number of races. How quickly a team upgrades to the SB2 package will be determined based on their available manpower, budget and time. To convert an existing 18-degree engine to an SB2, three of the major components that must be replaced include the cylinder heads, intake manifold and valley plate. GM Racing has developed a plan to assist teams during the conversion process with both technical and parts support. There is a sizable quantity of the necessary components available from GM and the distribution of the parts is being controlled by GM Racing to assure that each team is able to acquire a sufficient quantity of the parts to compete in their respective series.

Several of the components can be reused from the engines currently used by the teams. The components that can be reused include: the cylinder block, oil pump, carburetor, connecting rods, crankshaft, flywheels and oil pans. Some of the engine components that will need to be converted to the SB2 configuration are parts that have a limited life span and need to be replaced frequently as part of a general maintenance program. These components include the pistons, camshafts, valves and valve springs, lifters, pushrods, rocker arms and gaskets.

Q) In the truck series, Chevrolet has won five of the six manufacturer championships, four of six driver titles and 80 of 147 races since the series started in 1995. Won't a new engine configuration for an already proven winner change the competitive level in the truck series?

A) We really don't think that will happen. If you follow the series closely, you will notice there is constant change going on within both series. NASCAR keeps a close eye on everything in order to maintain a level playing field for all teams and manufacturers. One manufacturer might get a new nose or front valence, while another gets some other needed adjustment. Dodge, being the newest manufacturer to join the truck series, has changed a number of parts and pieces over the recent years in order to improve their competitive position within the series. With the SB2, some of the benefits will be off-track rather than on-track. Of course, starting with a new engine design increases potential areas of development.

Q) Will NASCAR benefit from the approval of the SB2 engine configuration?

A) Yes, the SB2 engine will be helpful to NASCAR in a number of areas. First, by having the SB2 approved in all of the three top NASCAR series, the inspection procedures will be more consistent between the inspectors of the various series. Second, GM Racing has worked very closely to establish several reference points that are used by the inspectors to mount the NASCAR inspection fixtures. This includes precisely machined dowel-pin holes that accurately locate the NASCAR templates onto the cylinder head.

GM Racing