Agent 87, Part II

There are no excuses when it comes to taking a car to the dragstrip to see what it will do. In the previous installment, Ed Taylor of Ventura Motorsports built the first of what will be a series of CHP Agent 87 budget-based small-blocks to see how much power we can make on lowbrow 87-octane pump gas. If you recall, the Miserly Mouse made a solid 390 hp on a grade of gasoline just above kerosene. The dyno test also indicated a thumpin’ 426 lb-ft of torque at 4,000 rpm while making more than 350 lb-ft from 2,400 to 5,800 rpm.

This alone might have been enough for the other magazines, but we decided to go further. Since we race cars and not dynos, we decided to stuff this motor into our pal Pat Peterson’s orange ’65 El Camino, which was just setting in his backyard waiting for an engine. So Pat and his dad Jim dropped the Agent 87 355 in along with a B&M TH-350 automatic and a 2,000-stall, 11-inch converter. Pat’s El Camino also had a 12-bolt with a 4.10 gear out back that was guaranteed to spin the tires.

The plan was to bolt this Agent 87 engine in the car with as many of the same components as we used on the dyno. The Hedman Elite 15/8-inch headers went in with the engine, and we bolted the motor up to the B&M converter with a B&M flexplate. We also used a set of the new polyurethane engine and trans mounts from Energy Suspension to keep our rompin’ small-block from pulling apart the stock rubber mounts. To keep the weight down and provide excellent cooling, we also installed an aluminum Be Cool radiator along with an excellent Spal electric fan using a slick set of Be Cool mounts. Since this is a street car, we needed a performance exhaust as well. Flowmaster makes a great Chevelle/El Camino exhaust system kit that consists of 2-½-inch lead-down pipes that allow sufficient room for a set of 50-series mufflers as well.

With the engine in the car and the exhaust properly plumbed, it only took a little extra work to dial in the carb and ignition. Everything on the engine remained the same, including the Demon 625-cfm carburetor, Edelbrock Performer RPM Vortec intake manifold, and the Pertronix HEI distributor. To get the car running, we set the initial timing at 12 degrees. The Pertronix distributor comes with a rather conservative mechanical-advance curve that is not all in until well past 4,500 rpm, so we swapped in a set of lighter springs to bring the curve in a little sooner. Combined with the initial timing, this gave us 36 degrees of total timing. With the vacuum advance connected, we had well over 40 degrees of timing at part-throttle, which should help the fuel mileage. We then set the idle mixture using a vacuum gauge and managed to generate around 14 inches of manifold vacuum with the trans in neutral at 900 rpm. Finally, we dropped in a K&N filter along with one of K&N’s new Xtreme filter lids to give the engine every advantage to breath deeply. Since engine builder Ed Taylor had test-jetted the engine on the dyno and found the out-of-the-box jetting worked best, we left that as it was.

A quick test-cruise around the block revealed that the motor was very responsive to throttle with no hiccups or hesitations. The big question was whether this combination would detonate on 87-octane fuel in normal street driving. The weather also played a part in our initial testing. With unseasonably chilly weather in Southern California in February, cooler air prevented any kind of true hot-air detonation test since hotter inlet air temperatures increase the tendency for an engine to detonate. We did have a couple of 80-degree days, and Patrick reported that no matter how he loaded the engine, it never rattled. A couple of days of driving doesn’t prove the point, but it did indicate that detonation shouldn’t be a serious problem. Keep in mind that this was with 12 degrees of initial timing and a relatively fast ignition curve. Another point worth mentioning is that the El Camino was equipped with a 4.10 gear and a loose 2,000-stall converter. A four-speed car with taller gears would generate greater off-idle loads that could induce some low-speed detonation that’s not present with the automatic. However, cutting back on initial timing would probably eliminate that problem.

After 150 miles of street driving, it was time to load up and head to the track to see just what this rascal could do. Prior to the trip to the track, we plugged the horsepower curve into the Racing Systems Analysis Quarter Pro simulator. This program assumes a perfect chassis and estimated the El Camino would run in the low 13s (uncorrected for the 3,000-foot altitude) at Los Angeles County Raceway’s (LACR). Since this was a test of the how well the engine works in the car, we intended to run the El Camino with a set of sticky DOT-legal street tires to eliminate tire spin. Unfortunately, we overlooked the fact that Pat’s El Camino was fitted with a wider, second-generation Chevelle 12-bolt that pushed our initial 5-inch backspacing tire and wheel package into the outer fenderwells. This forced us to use Pat’s street tires that consisted of a set of 15x8 Weld Wheels with a 5½-inch backspacing mounted with a set of ancient Mickey Thompson S/S tires in the rear.

We performed our first test on a Friday grudge night and the temperature was in the mid-40s. While this was good for the engine, traction was at a minimum. Despite severe tire spin problems at the launch and on each gear change (including Third gear), the El Camino ran an uncorrected 13.88 at 99 mph. This corrects to a 13.43 at 102.26 mph at sea level. The correction takes into account the thin air present at 3,000 feet above sea level but does not compensate for air temperature or atmospheric conditions. LACR’s 60-foot clocks were not working, but we estimated the 60-foots at no quicker than 2.20s because of the cold track conditions. The following week, we lined up a pair of Center Line 15x8 Triad wheels and mounted a set of 26x8 Mickey Thompson DOT-legal ET Street tires that we knew could handle all the torque our Agent 87 motor could crank out. We also decided to loosen up the front and rear suspension by adjusting the Competition Engineering shocks to full soft on all four corners. Pat had already removed the front sway bar. The next trip to the dragstrip was much warmer with the temperature in the 60s. With the better traction afforded by the M/T tires, the El Camino immediately responded with a best time of 13.571 at 99.51-mph pass that corrects to a sea level 13.13 at 103.04-mph pass. After a dozen passes, this was the best, but the El Camino ran three other passes in the low 13.20s to back up this run.

At this point we ran out of time but since we’re this close, we’re going to really push this 3,700-pound cruiser until it runs at least a 12.99. Even if the El Camino doesn’t knock down the 12-second door, low 13s at 103 mph is more than respectable from this Agent 87 engine. There’s power to be made with 87-octane fuel, and we’ll continue to show you how it’s done.

Agent 87, Part I

Agent 87, Part III