It's Alive!!! After a non-scheduled 10-week vacation, we are happy to report that our Project GT-R has come back to life. "Bigger, better and stronger" explains the differences between the new engine and the previous. In keeping with our systematic approach, we plan on first evaluating the performance improvement delivered by our freshly-built short block. Once the tuning is optimized for our current combination, we will evaluate the additional horsepower delivered by a swap to a pair of bigger turbos, a change to a more-aggressively-ported cylinder head with higher-lift camshafts and maybe even a change to a giant single-throttle body intake manifold.

The Built Short Block

A few months back, we outlined a number of the components that we chose to use in our build-up (Issue #36, December 2005). We sent the block, crank, pistons and rods to Cosworth for machining and balancing. The block was bored and then honed with a torque plate to provide the proper piston-to-wall clearance and finish for the Mahle piston and ring package. These processes made sure that ring seal is optimized which reduces blow-by and maximizes torque and horsepower. After the pistons and rods were individually component balanced, our HKS forged crankshaft was spun up to be dynamically balanced. By balancing the rotating assembly, the engine can safely spin to high rpms without generating vibrations that can damage rod and main bearings.

Once all of the parts were picked up from Cosworth, we cleaned and prepped the block for assembly. First the entire block was cleaned with a bath of soap and water. The block was then dried quickly with the assistance of compressed air to blow water out of bolt holes and other areas when it tends to collect. Before the cylinders could start to rust, we used oiled paper towels to clean and prep the cylinders. A good technique is to go up and down the cylinder a number of times until the paper towel comes out clean. The first few passes will tend to pull out small pieces of metal and dirt left behind after the machining of the bores. The final passes will leave a good film of oil in the cylinder so the pistons can be installed.

With the block ready for assembly, we placed our Power Enterprise F1 Black bearings in the main journals. A mixture of Torco assembly lube and standard SAE30 wt oil was used to dress the bearings before the HKS crankshaft was laid in place. Since ARP doesn't offer a main stud kit for the RB26DETT, we ordered the studs individually. We then verified the clearance on all of the mains with Plastigauge. Since Plastigauge is oil soluble you need to clean any oil off the crank journal or bearing. As expected, we found the clearances to be acceptable. Once the main caps were torqued into place, we checked that the crankshaft could spin freely. With the crankshaft bolted in place, we then turned our attention to the rods and pistons. The rod-piston assemblies were set up with the ring package and rod bearings in place. Each rod-piston assembly was fed through the cylinder toward the crankshaft. A well-oiled ARP 87mm tapered ring compressor made a usually difficult task extremely easy. The clearance on each rod bearing was also checked with Plastigauge during the assembly process. Once all of the connecting rods were tightened to the proper torque, we then installed the baffle plate, oil pump, oil pump pickup and rear main seal assembly. When we tore down the original engine a few weeks back, we sent the pan to XS Engineering along with a GReddy pan sump extension kit. This kit increases the capacity of the oil pan and improves the baffling around the pickup to prevent the pickup from becoming exposed during hard cornering or high G launches. The modified oil pan and ATI Super Damper were the last components bolted into place before the engine was turned over on the engine stand. With the ATI Super Damper in place, we are assured that engine harmonics will be kept in check and our main bearings will experience minimum wear.

Same Top End

While the bottom end was completed upgraded, the top end of the engine remained the same as before. A new Cometic head gasket was sandwiched between the cylinder head and block. This is the same head that we were using before the factory short block failed. You may recall that this head had a street port from Portflow Design along with a set of A'PEX Integration GT Camshafts (270 intake / 280 exhaust with 8.9mm lift). The same intake manifold and turbo system was also retained. By taking this route, we hope to measure the performance gains of the built 2.8-liter stroker short block.

Predictions

No that we have a bottom end that will safely let us visit 9,800 rpm, we are expecting to see some measurably performance increases over the factory short block. In addition, this new short block is almost eight percent greater in displacement and this should translate into a similar increase in torque. On the dyno, we are expecting to edge very close to 900 horsepower with the new short block. At the track, this should allow us to run 9.50s.

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