by moore1 | Feb 16, 2018 | News, Pistons/Piston Pins, Top Stories |
By Titus Bloom: “It’s hard for me to be persuaded on the merits of piston balancing,” said a leading oval track engine builder recently. “While operating, the piston is being thrust up against one side of the cylinder wall,” he continued, “wedged in one direction on the even bank and in the opposite direction on the uneven bank. Besides, there’s the action of the connecting rods, their weights, their lengths and where they’re connected to the piston. Then, you might consider combustion forces, and piston domes being assaulted by wedging forces—to say nothing of the degree of tumult in the crankcase. I think you’re splitting hairs,” he argued convincingly. “Fine piston balance is neither here nor there.” But from a piston maker’s approach, there are two types of balancing. First, the conventional balance is used to reduce the prospect of significant piston weight variation in large-bore engines. The objective is to maintain bearing loads within the design range, that is, main bearing loads, as they are the focus of engine crank balancing and also of vibration levels. In addition, crank pin and piston pin loads must also be held within their respective design loads. So, in truth, these efforts are more focused on durability than performance. This is why some engine builders see little value in it. However, certain engines will be more sensitive to piston weight variation than others, so it can be important for engines where bearing capacity or vibration levels are reaching their upper limits. The second type of piston balancing is embraced by those engineers ardently seeking any slight advantage and involves manipulating the mass distribution of...
by moore1 | Feb 14, 2017 | News, Pistons/Piston Pins, Tech How-To |
By Freddie Heaney: Denver Colorado: Gibtec Pistons has announced unique piston pin retention buttons. Their latest design for Pro Mod and big turbo racing engines incorporate a radial locking feature. The advent of the piston button and its subsequent popularity came about because of the convenience it offers. Changing pistons with buttons not only reduces the time taken to replace pistons at the race track but also ends the frustration of fiddling about with round wire locks or the double spiral types. “Some years ago when we were developing the original concept,” says Gibtec Piston’s Robbie Giebas, “the button seemed to offer a further advantage. Where the piston pin bore breaks into the oil control ring groove, we thought the button would prevent the expander in the oil control ring from distorting around the half-moon opening, a deficiency particularly prevalent in power adder engines.” Though partially true, they later discovered the button could, in fact, damage the oil control ring by pushing upward or rotating against it or a combination of both. Now with an innovative radial locking mechanism, Gibtec has filed a patent to protect the design. The patent, apparently, is more extensive than a utility patent but also includes concept coverage. Rob Giebas and Gibtec’s ascension by agility and intellect It was a decisive moment when in 2013 the then 40-year-old Detroit native founded his piston-making venture in Denver, Colorado. The formation of any new business is almost always a protracted struggle, and Gibtec Pistons’ prospects were no less challenging; how could it survive in a diminished market? In fact all markets were dealing with vast cultural changes but...
by moore1 | Jun 2, 2016 | News, Pistons/Piston Pins, Racing Matters, Tech How-To |
By Sam Logan: In our racing world we tend to think of ourselves as the elite corps. But in pistons and more particularly piston ring design, it is not our racing brains that are the driving force but those of the Original Equipment Manufacturers. It would be a glum glimpse of the US racing industry if nothing changed. But it has and nothing could be more illustrative of change than ring development. In fact, if we’re not careful our tow vehicles will operate with 1 x 1 x 2mm ring packs before our race cars. And it’s not just skinny rings that’s been pioneered by the OEMs, the enduring cast iron top and second rings have been replaced by stronger and lighter steel types. Furthermore, thermal face coatings are being applied to top rings by high-velocity oxygen-fueled spray guns at supersonic speed. The force of the collision causes the face coating to become embedded in the rings. What are they seeking? Well, with regard to the thermal face coating, they are pursuing bond-integrity. Second, they are also constantly looking for improvements in overall strength and toughness of the top ring. And third they seek to lower the ring’s coefficient of friction; that is the ratio between the force necessary to move one surface over another and the pressure between the two surfaces. The high-velocity oxygen-fuel technique that applies the thermal face coatings allows the OEMs to run high-tech rings in their latest turbo applications. These are subjected to countless detonation incidents. Tod Richards, a ring specialist at MAHLE, a racer and a race engine builder marveled, “The rings...
by moore1 | Mar 5, 2016 | Pistons/Piston Pins, Racing Matters, Tech How-To |
By Sam Logan: Denver, Colorado: Though piston maker Gibtec was established a mere two and a half years ago, the individuals behind it have specialized in Pro Stock billet piston development since 2003. Notably, during this period their skills contributed to approximately 80 percent of the championship-winning Pro Stock engines. Recently, Tom Prock, the general manager of Venolia Pistons for thirty years said, “Currently, Gibtec is making some of the best Pro Stock pistons I’ve seen.” On the subject of top ring placement, Gibtec Pistons’ head, Rob Giebas explains, “On forced induction and on nitrous applications, which encounter extreme shock loads, we move the top ring down from the piston crown to around 0.300in. However, the top ring could be moved down by as much as 0.450in, depending upon valve size and configuration, as well as the positioning of the valve pockets, the radial width of the top ring and the piston pin height, “Often it’s the intake valve pocket, which is always bigger than the exhaust that determines the position of the top ring. Compact rings and therefore small ring grooves provide more potential for variation in ring placement than larger ring grooves. For example, a naturally aspirated engine with a top ring of 0.6mm (0.0236in) axial depth and 0.110in radial width, which requires a ring groove width of 0.115in, offers more pocket clearance than the top ring spec of a nitrous engine, which might measure 0.043in axial depth and 0.173in radial width. “But on most small-block applications with a standard in-line valve pattern and a power adder, lowering the top ring to around 0.300in protects it and...
by moore1 | Nov 19, 2015 | Pistons/Piston Pins, Racing Matters, Tech How-To |
By Sam Logan: A great many modern drag racing engines are equipped with lightweight piston rings. These rings require combustion pressures delivered through gas ports to achieve complete ring seal. Horizontal gas ports are used in oval track racing pistons to avoid carbon ingress while vertical gas ports are the preserve of the drag racing engine. In either case, the gas ports direct pressure downward and behind the ring to seal the ring to the bottom surface of the ring groove and also to force it outward and seal its thin outer perimeter face to the cylinder wall. To achieve this, it is essential to decide the correct diameter of gas port and to allocate the correct number of gas ports and to equally space them around the piston. Harnessing gas volume and evenness of pressure to a flat ring groove and flat piston ring accomplishes cylinder seal. “So, the number of gas ports, times their diameter creates a volume number,” explains Gibtec’s Robbie Giebas. “On smaller pistons we reduce the diameter of the gas ports and increase their number. To prevent flutter, pressure must be evenly dispersed around the ring. “Also the advent of flatter rings and ring grooves means you can run tighter ring-to-groove tolerances—often as close as 0.0004in to 0.0005in. A decade ago tolerances were significantly greater, probably twice this amount.” Having functional gas ports and perfectly flat rings and ring grooves—with tolerances of 0.00005in to 0.0001in—promote effective ring sealing. But also this sequence of events relies on the fact that every action is the product of a previous action. Gibtec Pistons (PRI Booth #501)...
by moore1 | Nov 12, 2015 | Pistons/Piston Pins, Published Stories, Tech How-To |
Any experienced racing man knows that the components of a successful race car should be compatible—all working in concert. But this formula is never more critical than with engine builders. Professional race engine builders are profoundly aware of how engine parts affect one another and have to be developed as an efficient group. For them, the key to successful race engine building lies in maximizing a power plant’s performance by creating a combination of components that complement each other. In most cases, developing complimentary components requires modifying readily available parts or creating custom ones. Off-the-shelf engine components are often acceptable to builders seeking modest performance gains, but they are hopelessly inadequate when summoned to generate significant power. Click here to read the full article as published in Australia’s Street Ford...
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