Blue Oval Brawler -- Technical Article -- Engine Masters Magazine

Can a 385-series big-block Ford survive on 91-octane pump gas with 13:1 compression? Livernois Motorsports proved it could be done, making 816 hp with just 509 cubic inches

By Steve Dulcich

Photography by Johnny Hunkins, Matt King

This year's Engine Masters Challenge saw Chevrolet take the top two spots, but the Third-Place Ford entry of Livernois Motorsports was a contender right to the end. Scrutinizing the dyno sheets, one thing is abundantly clear, these fellows know a thing or two about making big power with Ford's 385-series big-block. A score of 1,258 points secured the Third-Place position, and the peak power output of 816 hp and 738 lb-ft of torque left no doubt of the seriousness of the effort. Naturally, we wanted to know a lot more about the specifics, and Livernois's John Lahone was more than happy to share the details.

When asked about his general philosophy in building this engine, Lahone laughed and noted, "My philosophy keeps changing every year. We were running a pretty small bore, but our cylinder head guys didn't let me run it any smaller than 4.300 inches. With the small bore we can run a long stroke and a short rod to speed the piston up, so we could run all that compression and make the cylinder pressure and not detonate so badly. With the short rod, it will pull the piston away from top dead center, so it won't detonate so much." The Livernois engine had one of the highest compression ratios in the competition at 13:1. No doubt that is pushing it with pump gas, but Lahone considered it an edge. John explained, "Last year we ran 11.6:1, and we felt that was too low. We did some combustion chamber stuff, and quenched it as much as we could to help keep it away from detonation." We queried about the quench clearance, and Lahone put it at 0.040 inch.

Maximizing the cylinder pressure without provoking detonation was one of the key objectives in building this engine. Lahone revealed that coming up with the combination required considerable attention to the camshaft. John explained, "We tested quite a few camshafts, testing them at 107- and 108-degree lobe separation. We ended up at 110. We had two torque peaks, and revising the cam got rid of most of the drop from peak to peak. The cam we ended up with got rid of some of the overlap, so we had a little more cylinder pressure at lower speeds, and it helped our numbers." Livernois went into the competition with a COMP Cams solid roller, with specs at 253/263-duration at 0.050-inch tappet rise, and delivering 0.775-inch lift. Working the valves are 1.8:1-ratio COMP steel rockers, stabilized by a Jomar stud girdle. The springs were set up to deliver 215 pounds on the seat and about 620 over the nose. Livernois used Jesel roller lifters, and a Danny B belt drive.

The cylinder heads are a key component in an Engine Masters contender, and here Livernois also made its final selection based on testing. Lahone told PHR: "We tested the first set of cylinder heads, which flowed really well, but the runners were fairly small, and then we tested a second set of heads that were quite a bit bigger, and we had better numbers with that. The airflow was better at the top, and we ended up gaining 13 points with the bigger heads. Instead of going for the higher velocity small ports, we went for a little less velocity and bigger ports and it responded." The approximate runner cross-sectional area was given as 3.25 square inches, which is definitely not huge, while the valve sizes measured 2.300 inches on the intake, and 1.900 inches on the exhaust. The cylinder head castings are the Ford Super Cobra Jet heads, and the modifications were not limited to the ports. The chambers were welded up to reduce the volume to 65cc, and to increase the quench area. Considerable material was added in the vicinity of the spark plug, increasing the surface area of the quench deck, again looking to increase the detonation tolerance.

To compliment the intake ports, the engine featured a much-modified Edelbrock Victor intake manifold. Lahone pointed out that the runner extensions added to the plenum had a noticeable effect: "The manifold was better with the runner extensions. When we made them longer, it helped us on the bottom, but it hurt us on the top. We just went in between, and we had better numbers with them cut back." The manifold was fully ported, and the extensions were rounded and radiused. Turtles were also tested in the intake plenum, but it proved to help on the bottom, but hurt at the top, and in the end no turtle was used. Single-plane intake manifolds were the norm for our big-block event, but Livernois also experimented with a two-plane. John disclosed: "We also tried a 180-degree intake manifold, but it really didn't help us; it made good torque at the bottom, but ran out of steam too fast."

Topping the intake was a Holley Dominator carburetor, and as with the intake and heads, testing determined the final selection. The best carb of several tested was from Dale Cubic--a modified 1250. The boosters are a custom design, with an unusual step. In the carb, the distribution was fine-tuned by staggered jetting, with the best setting determined by trying to find best power with the jetting combination. In competition tune, the brake specific numbers BSFC were as low as 0.330 lbs/hr/hp.

As with most competitors, testing time was at a premium. Waiting for delivery of many of the key engine parts set the Livernois program back, with a ring land failure in low-octane fuel testing being a low point. Overall, there were around 200 dyno pulls in the development effort.

Interestingly, Lohone feels that the engine needs to be built to be capable of making as much cylinder pressure as possible without detonating, and then push it to the point were it is detonating. John told us, "I think you have to detonate it to make it do the best that it can. Last year we didn't detonate, and we didn't do so well, and I think we went too conservative. This year we might have gone just a little bit too high on compression, but let's say 12.5:1 would have been just about ideal. I really think you have to push it far enough to detonate the engine on 91-octane fuel to get the numbers you need. You have to give something at the bottom, to avoid losing too much at the middle and the top."

That's not to say that the Livernois team held back when looking to delay the onset of detonation as much as possible. As a technique to keep the engine away from detonation, Livernois built a reverse cooling system, sending cooling water to the heads first. The quench, and the basic bottom-end configuration of bore, stroke and rod length were designed to allow the highest cylinder pressure possible without detonating, then the edge was pushed right to that detonation point. Moving that point upward, Lohone and crew went further, "We used coatings, and tried to keep the air as cool as possible going into the chamber. We coated the valves and the pistons; I would have liked to do the combustion chamber, but we didn't have the time to do that, and I would have liked to have done the intake manifold, but we were working on it right to the end."

To survive the detonation, custom Bill Miller Racing pistons were used. John filled us in on the details: "They were really heavy, and I don't think they were real good for friction, and I think we lost some points there." The piston tops were CNC-machined with a dish at Livernois, matching the shape of the chamber. The ring pack featured a Total Seal gapless top ring, and a Napier second ring, both measuring 0.043-inch section width, with a 3mm oil ring. The block was sleeved in all eight holes, extending the cylinder walls downward about a half-inch into the crankcase. Lohone disclosed the reasoning behind the sleeves: "I wanted to have the support on the pistons to keep the rings straight in the bores to help them seal better, not so much on the power stroke but on the intake stroke to get a good gulp of air. With the sleeves hanging down, the stability is increased at bottom dead center. I believe they also help keep the oil out of the cylinder bore."

As with most of the serious competitors, minimizing the friction was an avenue to more power. Anti-friction coatings were used extensively, and the journal diameters were reduced to 2.500 inches on the mains, and 2.000 inches on the rods. The bearing clearance was set at 0.0026-0.0027 inch. The rod bearings looked great, but the main bearings showed some signs of distress. John pointed out: "I think that cutting it down to 2.500 inches on the mains and having a 2.000-inch rod on it with that big a stroke lets the crank whip enough to work on the main bearings a little bit." How successful was the effort at minimizing friction? Lohone claimed that the completed engine turned over at only 22 ft-lbs of torque. The rings helped with the low rotational friction, which was reduced to just 6 pounds of tension on the oil ring, and the Napier ring was cut back. Other steps to minimize parasitic losses include roller bearings in the cam journal bores, and controlled oil drainback to the front timing case area.