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Wednesday 4 March 2020


Wiseco Tracker Series H-D Big Bore Pistons

Wiseco says that its new Tracker Series pistons have been created "to provide a featured, high-performance forged piston option at a more affordable price that is available in various overbore and compression ratio options."
Development on the new Tracker Series began at the end of 2017, with manufacturing having kicked off around April this year. "The hurdle was to find a balance between performance and price - our engineers have succeeded by blending classic piston manufacturing processes with state-of-the-art techniques."

Wiseco offers fully featured high-performance pistons, such as the Black Edition line, but found it was missing a featured performance piston at a mid-level price point. The new Tracker Series piston line is engineered to fill that gap - "a featured, high-performance piston offering for Evo, Twin Cam and Sportsters at a more affordable price point."

Near-Net Shape Forging
"The major challenge in this project was to decrease the end cost to the consumer. That's where near-net shape forging came into play," says Wiseco engineer Dave Sulecki.
"Near-net shape forging is where we form most of the geometry on the top of the piston - it is built-in at the forging process. The crown and the valve pockets are forged into the part. Those areas are machined in most other piston manufacturing processes. 

"You forge out the aluminum and get the slug, then you have to machine all of that metal away to get the valve pockets and the crown to achieve whatever specific design you're trying to hit, or the specific compression ratio you are looking for. At Wiseco we are forging those features directly into the piston. When our near-net forged pistons come off the presses they need less finishing and machining as they go through the factory. The whole crown area comes right off the press and looks like a finished product. It's a really unique way to form a piston."
Sulecki says that upon inspection, "it doesn't take a metallurgist to realize that different processes were utilized during construction of a Tracker Series piston. The mirror-like sheen of the machined area is offset by the textured surface of the forged aluminum left during near-net shape forging. Those visual differences are also noticeable on the underside of the piston.   

The forgings for Tracker Series pistons have crown features designed into them - so when the piston is forged, valve pockets and any other crown designs are already complete, requiring no additional machining.

The valve pockets show a forged aluminum finish because they required no machining. Other features, such as the oil drain backs, are also forged into the part instead of machined, to keep the cost down.

Aligned Grain Flow
"One of the upsides to near-net shape forging is that it gives the piston added strength, since the features are being forged in. This process allows the aluminum to flow through the features of the piston with an aligned grain flow. That grain flow condenses the aluminum for better fatigue strength and overall durability.

Wiseco says that "as with all our pistons, the forging process aligns the grain structure of the aluminum to provide improved tensile strength.

"The other upside, of course, is the cost compared to the combined forging and machining needed for piston ranges like our Black Edition series and ArmorPlating featured pistons. Those cost savings trickle directly down to the consumer - a Tracker Series piston is roughly $80-$100 (at retail value) less than the higher price point offerings."


Aside from outstanding durability and a very attractive price point, Wiseco says that the Tracker Series piston "has a secret weapon in the performance department. ArmorGlide is our solution to reducing friction and is applied to the skirt, and we take it a step further by emblazoning our logo into the dry-film lubricant. 

ArmorGlide skirt coating is a proprietary dry-film lubricant designed to reduce friction and operation noise for the life of the piston.
"Wiseco spared no expense in the Tracker Series piston kit," Sulecki states. "V-twin riders are getting nearly the same level of features, but with less cost on our side, so we can pass the savings on to the end user."
Premium rings are supplied with each piston, with Wiseco using a new high-tension 3 mm oil ring set in Twin Cam applications. "That is really important in that market because we can control oil consumption in the engine. The premium rings, wrist pin and circlips are also found in our Sportster and EVO (Evolution) applications. It pays that we know our audience. We found that the majority of V-twin owners wanted to not only increase the displacement of their engine, but also raise compression. The Tracker Series pistons accomplish both.
"One of our most popular kits for the Twin Cam engine takes it from the stock 96-cubic inch to the 103-cubic inch size," explains Sulecki. "You can increase the stock bore without having to bore the crankcases. Simply bore the cylinder, install the piston, get a bump in compression, and you're at 103 cubic inches.
"Not only that, but we also offer a 106-cubic inch piston option for the Harley-Davidson Twin Cam engine."

 A new high-tension 3 mm oil ring set is supplied with Tracker pistons for Twin Cam, Sportster and EVO models. "Oil consumption control is an important performance consideration in the V-twin market."
One of the most popular Twin Cam kits is the overbore to 103 ci - available through the Tracker Series in multiple compression ratios; 10.5:1 pictured here.

"Bumping up an 883 Sportster to 1200 cc is a popular mod among Sportster riders. Tracker pistons are available for these kits in both 9.5:1 and 10:1 compression ratios."

EVO - Flat Top Vs. Domed
If you have an EVO generation engine, then Sulecki says that "thanks to the Tracker piston, you have the choice between a flat top or a domed piston. The flat top piston has an 8.5:1 compression ratio, which is for a standard application. The domed piston is the higher performance offering with a beefy 10:1 ratio."

The Tracker Series also offers a choice of options for EVO riders - a stock compression 8.5:1 (shown here) and a 10:1.
The Wiseco Tracker Series "provides a featured performance piston that improves reliability for less than a premium price point. Tracker piston kits come complete with wrist pin, rings and circlips.

Increased Displacement
Wiseco says that its number one selling piston in the V-twin market is the Sportster big bore piston kit that takes the stock 883 cc engine up to 1200 cc. "That's a lot of power for a small-scale package - upsizing offers a nice increase in performance. The customer has the choice of stepping up to a slightly higher 9.5:1 compression ratio or going 'whole hog' with the 10:1 ratio. The latter option is preferred in the burgeoning Flat Track series and with Hooligan bike builders and tuners."