Although the Bullitt put down good power, the recently-rebuilt engine needed some sorting. The engine had been detonating at high rpms, since I first bought the car. Changing the tune didn't fix the detonation, so the engine problem was likely internal.
Fortunately, Piedmont Custom Motorsports is just down the road from me. I hadn't had a chance to work with PCM previously, but I'm fortunate that they know Mustangs of all years and were eager to help me.
PCM found that the power level was actually low—for the surprisingly high 19psi of boost. Reinstalling a stock larger blower pulley for a more reasonable 13psi resulted in a big drop in power. And a leak down test showed poor engine sealing. At this point, the motor came out to have a closer look.
The heads showed previous detonation damage/repair around the spark plug holes.
A new threaded insert on one spark plug hole could be introducing a hot spot into the combustion chamber.
In addition, not all the valves were sealing properly.
PCM dropped the engine/crossmember/trans out from below.
PCM hooked me up with a set of stock replacement heads in great shape for only $300. The machine shop properly cut the oversize valves from the original heads and installed them. At this point, I figured the upgrade to Stage II cams was worthwhile... :)
While the Bullitt was in surgery, I figured I'd clean up the intake. I spent a few hours disassembling, cleaning, and painting...
And I ended up with this. The end-of-day lighting is harsh in this photo...
Here's the intake on top of the motor at PCM. They also installed a Centerforce clutch and adjustable quadrant for me.
Here's a video of the dyno, showing 533hp at only 13psi.
I had a great time getting the Bullitt tuned on the dyno at Fastlane Motorsports last week. So I decided to bring the '66 today. It went well and the car didn't need any tuning at all: the carb and the timing appeared spot on. I was surprised! (I will adjust the valve lash sometime this summer though, since it has been about 2,500 miles since the last adjustment.) The numbers were 349HP/370TQ and the A/F ratio looked good too.
I visited Fastlane Motorsports in Benson, NC. The Bullitt spent a couple hours on the dyno getting tuned this afternoon, and the second and final tune was good for a stout 494HP/466TQ. This was with an outside temperature of about 80 degrees. (In fact, just the "house tune" for my car's particular combo, which we started off with, was already good for 453HP.) Base timing is at 14 degrees, which is safe for 93 and even 91 octane. I wanted to not have to worry about using 91 octane if needed on a trip or something.
I learned a lot about how the car's onboard computer works, and it's way more advanced than I realized. For instance, the computer can pull timing if the Inlet Air Temp gets too high, so there's a margin for safety there even with a supercharged car (if the probe has been installed in the correct location.)
I've decided I'm bringing in the '66 for a pull or two next week! :-)
