500 HP Racing Engine For $2,500 - Is It Possible?

Another advantage of a late-model, roller-cammed motor is that many, if not most, have a built-in windage/surge tray. While not quite as good as the purpose-built pan from Moroso, it will get the job done in most instances. As for the oil pump itself, these do not generally wear. If no debris has gone through the pump we just "port" the pump's main oil passage and likewise prep the main's cap where the pump bolts on. This and a 0.030 washer behind the stock spring typically gives a race worthy pump about 50 psi, which is more than enough for the job. With a stock crank and rods plus rings, bearings and gaskets, you will be into the crank/rods/piston/block rebuild for about $200, or $400 if you upgrade to a Scat crank. Notice there is no balancing involved in this bottom end rebuild. So long as you stick to stock component weights, balancing will be an unnecessary expense. Now it's time to deal with the power producing components, i.e. the heads, cam and valvetrain.

I have run the gamut with three budget performance iron heads here-Dart, EQ and RHS. All have out-of-the-box flow figures that will, allowing sufficient compression ratio and cam, deliver over 500 hp. Just to put that into perspective, we recently made over 470 hp and 444 lb-ft on a motor similar to what we are dealing with here and equipped with out-of-the-box EQ heads. This was not some super high-compression, big-cammed monster. It sported a 10.3:1 compression, a Comp Xtreme Energy 288 cam, and it ran on pump gas.

Since the subject of compression ratio has popped up, let's look further at this topic. The heads featured here all have combustion chambers in the low 50cc range. This means that with a typical dished piston of about 12 cc and a shim-steel head gasket, the compression is well up at some 11.5:1-and there is still some leeway to mill the heads to even less volume.

As you can see from the sidebars accompanying this article, all three featured heads produce very similar flow numbers and for the most part can be bought for $500-$600 a set, bare. By the time acceptable quality hardware (springs, valves and so forth) is added, the cost goes up by about $210. As of now we are looking at $500 for the donor engine, $200 for the block rebuild and $710 for the heads. This totals out at $1,410 so far, leaving $1,090 for the induction system, valvetrain and ignition. It's going to be close but we can do it.

The cheapest price on a hydraulic roller cam outright is about $230, but you can have a stock cam reground, as we have done on several occasions. This has cost us as little as $125 (at Jones Cams in Denver, North Carolina). Now, as good as this appears, there are some limitations. The surface hardness on a stock cam allows a limited amount of extra lift to be put on the cam. The result is the biggest cam you can get will deliver about 0.550 inch lift (with 1.6:1 rockers) and a seat and 0.050 duration of some 300 and 242 degrees, respectively. This is barely enough cam to make 500 hp with the heads we are considering here. It can be done, as we have seen 501 with a cam similar to what is being described, but the compression ratio needs to be a minimum of about 12.5:1. If you want the engine to make it past the 500 hp mark, then a cam ground on a new blank will be called for and that will cost at least $230 (Howard Cams).

To get the stock lifters to work up to 7,000 rpm, they will need to be emptied of oil and reassembled. When it comes time to lash them, they need to be adjusted to within 0.010 of bottoming out. That means you will lash at about 0.014-0.016 at the rockers. Going this route means the lifters cannot hydraulically collapse because they will bottom out before they can do so to any degree. The next lifter gremlin to deal with is lifter pump-up. This happens not because there is anything wrong with the lifter but because there is valvetrain component separation and the lifter simply does its job and absorbs the "separation gap" created. This now has the same effect as a lifter that is too long and the consequence is the valves are held off their seats. The fix is to set the valve spring up with about 140-145 lbs. on the seat rather than the normal 105-120.

At this point, we need to consider rockers. The least expensive are the Comp Magnum stainless steel, roller-tipped series. These are very stiff and about as bulletproof as any race part can be. Our own tests have shown that they are among the stiffest rockers on the market - race quality or otherwise. On the same spring they will, on the Spintron, turn to within 25 rpm of the best aluminum rockers of the same ratio. Bearing this in this mind, and the fact they can be had for under $150 a set, you can see there's real performance value here. If you are determined to go with "all roller" rockers, then expect to pay about $230 a set for the least expensive out there.

Achieving a target output of 500 hp is, at the end of the day, dictated by the cylinder heads. I have seen results with over 500 hp with each set of heads shown here, so you can't go wrong whichever you choose. Although the flow figures vary a little from one to another, be aware that differences in wet flow characteristics and swirl are not taken into account here. Results with any of these heads (2 Dart equipped engines, 2 EQ engines and 1 RHS engine) from one engine to another have looked consistently good, and that should factor into the choice as much as the raw airflow numbers. (See article sidebars for more details on each set of heads.)