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Archive: August 2008
Nissan VQ35 Component Balance
Posted by Eric Hsu on Monday, August 04, 2008Recently there has been quite a bit of VQ35 work going on in the build
shop here. The VQ35 has a lot of untapped potential from the factory.
Simply bolting on a set of Cosworth CNC big valve cylinder heads,
Cosworth camshafts (available end of summer), Cosworth Twin Plenum intake manifold, a set of headers, and a
good remapping can increase horsepower from the factory 287bhp to
363bhp. That's an increase of 76bhp with just bolt on components!
Walking through the machine shop one day, I saw that Colin was balancing a factory VQ crankshaft for a special project. It turns out that the Cosworth piston, piston ring, rod, and bearing combination is approximately 110 grams lighter per cylinder. With this being the case, it was critical that the crankshaft gets rebalanced with the lighter component weights. Nearly 100 grams needed to be removed (48 grams front and 44 grams rear). Any crankshaft that is not a flat plane design requires rebalancing with bob weights. If you do the math, that's 110g x 6 (6 cylinders of components) + 100g (crank) = 760g total weight savings. That's 1.676 pounds or 26.81 oz. in weight reduction! It may not sound like a lot, but it is the weight reduction and the increased strength of the components that will allow an engine to last longer and spin to higher revolutions while doing so. The Cosworth rods and pistons are forged and the bearings are tri-metal so all of the Cosworth components are superior in strength. Every off the shelf Nissan VQ35DE short block built at Cosworth already has these same components
Bob weights are attached to simulate the weight of the components.
If a clutch and flywheel assembly is to be used, then it should also be balanced with the crank and indexed to the crankshaft. If your clutch and flywheel is already balanced, then it is not a major issue to balance the crank by itself. Most high performance or racing clutches are balanced from the factory.
Here the crank is almost balanced at 0.55 grams. We balance cranks to within 0.5 grams, but Colin is about to make the final adjustments. Precision is everything if you want excellent results.
Walking through the machine shop one day, I saw that Colin was balancing a factory VQ crankshaft for a special project. It turns out that the Cosworth piston, piston ring, rod, and bearing combination is approximately 110 grams lighter per cylinder. With this being the case, it was critical that the crankshaft gets rebalanced with the lighter component weights. Nearly 100 grams needed to be removed (48 grams front and 44 grams rear). Any crankshaft that is not a flat plane design requires rebalancing with bob weights. If you do the math, that's 110g x 6 (6 cylinders of components) + 100g (crank) = 760g total weight savings. That's 1.676 pounds or 26.81 oz. in weight reduction! It may not sound like a lot, but it is the weight reduction and the increased strength of the components that will allow an engine to last longer and spin to higher revolutions while doing so. The Cosworth rods and pistons are forged and the bearings are tri-metal so all of the Cosworth components are superior in strength. Every off the shelf Nissan VQ35DE short block built at Cosworth already has these same components
Bob weights are attached to simulate the weight of the components.
If a clutch and flywheel assembly is to be used, then it should also be balanced with the crank and indexed to the crankshaft. If your clutch and flywheel is already balanced, then it is not a major issue to balance the crank by itself. Most high performance or racing clutches are balanced from the factory.
Here the crank is almost balanced at 0.55 grams. We balance cranks to within 0.5 grams, but Colin is about to make the final adjustments. Precision is everything if you want excellent results.
