Secour also added assembl...
Secour also added assembly....
Why not just change the blower pulley? It would be significantly cheaper, right? We hit Dezotell with that question. "Sure, it's cheaper and easier to swap a pulley. We actually did that on this car and it was still a bit lazy, which was due to the low compression. Lower compression ratios can be safer, because there is less chance for detonation, but they lack cylinder pressure and make less power as a result.
Another benefit of raising compression is the increase in power without turning the supercharger to a higher impeller speed. In a blower application, it takes engine power to turn the supercharger, so the less work the engine has to do (in regards to getting more cylinder pressure), the more you will see at the rear wheels. Another byproduct of increased boost pressure is a hotter intake charge temperature. We aren't saying that increasing the blower speed is a bad thing, but there are other ways to achieve increased power.
....lube to the rod caps....
....lube to the rod caps.
On the dyno, Dezotell modified the tune slightly for the higher compression by adding a little more fuel. That was done to help cool the intake charge, which is often necessary with higher compression. He also reduced the ignition timing significantly from the baseline of 19 degrees to 15 degrees. The result was 560 rwhp and 526 lb-ft of torque, which equated to gains of 22 rwhp and 44 lb-ft of torque at the peaks. The torque curves were also noticeably different, and the engine makes power as if it were a completely different combo. Average power was increased by 28 rwhp and 36 lb-ft of torque.
In total, upping the compression ratio increased the cylinder pressure and Gelles' Mustang picked up great power and torque as a result, not to mention much-improved tip-in throttle response, which is nice in any street-driven vehicle.
The short-block is just about...
The short-block is just about ready to go.
According to Dezotell, adding compression has been worth 140 rwhp in one application, but that was a race engine. For the street crowd, adding more compression will change the dynamics of your Mustang and keep you out in front of the local track bully.
The cam gears are slid on...
The cam gears are slid on to the end of the crankshaft. These will turn the overhead camshafts. Dez Racing's Brian Machie marked the gears and the chains at disassembly, which makes the rebuild go quicker.
ARP studs are screwed into...
ARP studs are screwed into the block. Dezotell used factory replacement multi-layer head gaskets.
The Fox Lake-ported Three-Valve...
The Fox Lake-ported Three-Valve heads are slid onto the studs and Machie torques the head bolts to 75 ft-lb. Do not forget to add moly-lube to the studs and bolts before applying torque to each bolt.
Machie applies assembly lube...
Machie applies assembly lube on the cam journals and caps. We reused the stock cams, which provides a smooth idle and great driveability.
The cam caps are torqued to...
The cam caps are torqued to 99 in-lb.
Gelles' Canton oil pan shows...
Gelles' Canton oil pan shows signs of the harsh Northeast winters, but internally it was perfect.
The dyno results speak for...
The dyno results speak for themselves-by increasing the compression ratio a full point (8.5:1 to 9.5:1), Gelles' GT made 560 rwhp and 526 lb-ft of torque. Dezotell said the belt was slipping a bit on the top-end, yet it still produced 22 rwhp and 44 lb-ft of torque over the baseline. The boost curve fluttered at 15 psi when it was above 6,100 rpm, leading Dezotell to believe that with a little more boost the peak power might have been a little higher.
Machie sprayed the valve covers...
Machie sprayed the valve covers black and added the JPC intake, front pulleys, and water pump. It was almost ready to be lowered into the '06 Mustang GT and put back on the dyno.
The fuel system consists of...
The fuel system consists of Ford Racing 60-lb/hr injectors, JPC fuel rails, AN -8 feed line, and twin GT500 fuel pumps. Dezotell relies on SCT software for tuning duties.
The higher compression increased...
The higher compression increased power across the board. The deed was done with 4 degrees less ignition timing (15 degrees versus 19 degrees), and both combos were tested with 93-octane gasoline. The engine has a Snow Performance meth kit, but it was not activated during our testing.