Those looking for speed secrets...
Those looking for speed secrets in the Griggs valvetrain will be disappointed. The company uses the full Trick Flow treatment, from pushrods to roller rockers, while the timing chain is typically an FRPP piece, so no unobtanium there, either.
Of course, there are plenty of places money must be spent. We already noted the major exception-the FRPP block. Not only is there the price of the block, but also Griggs thoroughly details this beefy piece. Sharp edges are chamfered in the webbing and valley, the whole thing is deburred, and the rod bolt clearance is notched into the bottom of the cylinders, followed by a decking pass in the milling machine. Dodge Reidy, the engine specialist at Griggs, says decking is mandatory both to achieve a desirable gasket sealing surface texture (Fel-Pro's 1011-2 gasket with preflattened copper fire ring is used to keep from tearing up the aluminum heads), along with a zero deck height and block squaring. Griggs checks the blocks for bearing alignment and align-hones as necessary.
Oil improvements are restrictors to the cam bearings to increase main bearing flow and reduce camshaft flow (not much is needed with roller lifters). Oil drainback is helped with lifter galley smoothing and grinding a radius to the passages at the oil filter. Asked if there were any trash screens in the valley, Dodge said no, but they were a good idea. Then Bruce chimed in with, "Nah, they don't go fast enough to hurt themselves."
Mainly to get rid of the stock...
Mainly to get rid of the stock lifter retainers, Griggs runs Crane tie-bar roller lifters, which are happier at high rpm.
Kidding aside, these engines are quite durable. Bruce says they'll go the entire racing season before needing rings and bearings. Given the cost of around $11,000 per engine, that's enough time to find another grand or so for the engine-freshening budget.
See the photos and captions for more details, and the sidebar for dyno results. And for track-winning power, see Griggs Racing.
Once it was installed in owner Keith Videtto's AI race car, our subject engine was run both on Grigg's Racing in-house engine dyno and a chassis dyno. As expected, it made a bit too much horsepower to work with Keith's car weight, so the engine was restricted by pulling ignition timing and fuel via the engine management and a chip using Autologic software. Furthermore, Keith added about 10 pounds of ballast-just to make sure-for the first race he ran with the new engine.
Most importantly, the engine made 369 lb-ft of torque and just 340 hp to the rear tires, after approximately 65 percent of the airbox inlet area was plated off and the engine-management restrictions were in place. This worked great at the track, as Keith was running in a podium position at Willow Springs before spinning off in the only race run before our deadline. And, yes, Bruce Griggs won that race.
As do most engine builders,...
As do most engine builders, Griggs runs ARP hardware wherever the budget allows. For AI engines, this is at least the head bolts.
Unrestricted on the engine dyno, Keith's engine was nearly perfectly square, hovering right around 400 lb-ft of torque and 400 hp, give or take a few numbers. This is on Griggs' Dynamic Test Systems dyno, which reads about 8 percent lower at 6,000 rpm than the commonly used SuperFlow 901 (Bruce verified this by running the same engine on his and a 901 SF back-to-back).
Playing with a calculator (and apples and oranges input), we noted Griggs was able to retain 92.25 percent of the unrestricted flywheel torque in the car, while keeping only 85 percent of the unrestricted flywheel horsepower. Put another way, restricting horsepower allowed 7.25 percent more torque than would have been possible without restricting horsepower. Due mainly to the dif-ferent dynos used, the percentage of power at the rear tires compared to the flywheel readings is clearly optimistic when figured this way, but the percentage difference of torque and horsepower retained after restricting the horsepower output would be the same. And that a restricted engine made 7 percent more torque is what really matters.