Here's what a dyno-ready $2,580, 506 hp engine can look like. Just because it's cheap, it
For the budget-constrained racer (that's most of us) BC does not mean Before Christ. Instead, it means Buy Carefully. At the end of the day that is the key toward cheap power.
The intent here is to walk you through the logic and procedures to build a low-cost engine with some real hp. But, to address this issue of cheap power, I am also going to look at some of the logic in the rules that dictate the use of flat tappet cams instead of a roller cam that is so often seen as significantly more costly. As you will see, the key factors toward achieving 500 hp simply-and at minimal expense-are in selecting the right parts, especially in the head and cam departments. It takes a certain minimum amount of head airflow and a valvetrain to access that flow to get the job done. With that in mind let's see where we can go with this.
Back when the only roller cams were hi-buck aftermarket pieces, the roller cam got a reputation for being too costly for the typical Saturday night racer and, for that matter, NASCAR's top series. Yes-believe it or not-the original reason for a Cup car's flat tappet cam was to keep costs down. But for some 25 years Detroit had been building hydraulic roller cam V-8s by the millions-at a user friendly price
The near-zero wear bores on this block were cleaned up using a three-leg glaze buster. Cos
Go to the wrecking yard (maybe the politically correct term now is Auto Parts Recycling Yard) and you can pick up a late-model (1987 and newer) hydraulic roller-cammed, small-block 350 Chevy for about $500 or so. Let's deal with the issue that these are roller cam motors instead of the often dictated flat tappet cams and see where it takes us in terms of cost and power.
First, any engine we buy to race will have the stock cam swapped out for a race cam. If flat lifters are to be used, this means buying a cam and lifters. If the hydraulic rollers (which rarely wear out) are retained, then the cost of a set of lifters is eliminated. These days, the flat tappet race cam profile designs are pushed to the limit allowed by the metallurgy and unless strict break-in procedures are adhered to and top grade (read: more expensive) flat tappet oils are used, the cam and lifters will wipe out. When that happens, things start to look a lot less cheap.
Here are my thoughts on the subject. Let the engine have a roller cam so it can make about 500 or so hp and from there limit the advantage of any further power increase by specifying a tire that won't hook up with much more power. That should make a great ride for the driver and fast racing for the spectator. If that premise appeals to you, then here is how to build it cheap and have it last the season.
A stock late-model 350 piston is shown at right versus a high performance aftermarket stre
Back to our late-model, hydraulic roller-cammed 350 Chevy. Because these motors were fuel-injected, the piston/bore wear on most of them is low to non-existent, even if the unit has 150,000 miles on it. This means that the pistons can be re-used and the bores, when cleaned up with a deck plate hone job, inevitably end up with right around the best piston-to-wall clearance for a race motor (about 0.004 -0.005). But maybe the bores have so little wear they will clean up with a glaze buster (as in about 30 percent of the cases). You can buy a 3-leg honing stone glaze buster for $29 at NAPA and do the job at home.
The only potential problem here is that the dish volume of some stock pistons is a little on the large size for a decent CR - but that's a situation we will deal with shortly. At this point, with a new set of rings, the piston/bore situation can be brought to a decent race spec for about $200. Not only that but the rings on these late-model engines are a low-friction narrower wall design, and that's good for power. If you bought new aftermarket pistons, such a design would be a more costly upgrade.
These late-model motors inevitably have powder-forged metal rods. These are better by far than the old Pink hi-performance factory rods and, in my experience on just two motors, seem to deal with an average quarter-mile circle track race season.
Next on the agenda is the crank. Most of these motors will have a cast crank. While certainly not the No. 1 choice, we have not had any trouble with these as long as all the crank clearances are middle to top limit and an "as new" stock or good aftermarket crank damper is used. Usually the stock crank is good to go with no more than a journal polish. If you want to make a near-bulletproof but cheap upgrade here, then the Scat cast steel replacement crank (9-10526) is a good bet. It can be bought for under $190.
The powder-forged stock rod is a nice piece for a production item. If the engine is going
To get the stock crank to live under race conditions for a reasonable time, be sure to set
Here is a surge tray typical of many later-model 350s. It will work if the budget is exhau
The iron small-block Chevy heads we have today are light-years from those your father used
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.
Whatever grind you choose for your engine, be sure to have it on a 108 LCA at four advance
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.
To allow the stock pattern, hydraulic roller lifter to reach the sort of rpm needed to mak
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.
Although they may not look quite as hi-tech as a set of aluminum rockers, these Comp Cams
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.)
The Edelbrock Super Victor has proved a good companion to any of the performance iron head
All of the heads we are discussing will work better if the quench clearance is nearer optimal. Getting it there usually involves machining some 0.020-0.030 off the top of the block. That's a $100 deal, minimum. The cheap way to avoid this cost and save money on head gaskets is to use a stamped steel gasket. Felpro's piece has a compressed thickness of 0.016-0.018 compared to the normal 0.038-0.040.
Although the "as cast" flow numbers of all these heads are good, there is still a lot of additional power potential locked up in the ports and chambers. Because the ports are inherently well designed on all these heads, we find that minor casting flaws can have a bigger influence on the final flow numbers than on heads with lesser ports. Spending just a few hours doing the minor work needed to "pocket port" these heads can pay some handsome dividends for those classes where the rules apply to "one inch down from the seats and one inch in from the manifold face." For instance, on the EQ heads, the flow on both the intake and exhaust showed increases starting at about 0.200 lift. At 0.250 the intake flow from pocket porting went up from 163 to 166 cfm. At 0.600 lift the flow rose from 259 cfm to 279. On the exhaust side, the numbers, at the same lift points, were 107 to 111 and 169 to 179.
At this point we have covered the long-block and it's time to consider what we will use for ignition and induction. There are a lot of options but to demonstrate the practicalities of budget power we will not use anything fancy (and otherwise costly). For ignition, it's hard to beat an HEI upgraded with a performance module from MSD or Performance Distributors. We have rescued HEI units from the wrecking yard, cleaned them up, and equipped them with a Performance Distributors module, and for less than $80 had a system good to over 7,500 rpm.
With the typical 200 cc intake ports that seem best suited to a 350 racer targeting 500 hp, the Edelbrock Super Victor repeatedly delivers the goods. Just for the record, EQ has a whole load of these with minor casting flaws for $130 a pop. For carburetion, let's go with what must be the most popular size of four-barrel-a 750. Looking at prices, we have seen a Barry Grant Road Demon go for as little as $300 and an equivalent Holley for only a little more, so power curves with a 750 carb is what we will be looking at here.
Iron Heads & Hydraulic Roller Cam Test These curves demonstrate just how much potential f
Any time cost cutting is a factor, chance-just like a roll of the dice-can be a positive or negative factor. The two example engines shown here are just such cases. The blue curves on the graph are for a 10.3:1 motor on EQ 180cc port heads and a single pattern Comp 288 Xtreme Energy hydraulic roller cam. The red curves are for pocket ported heads, a CR of 12.5:1 and a single pattern Comp Cams 293 Xtreme Energy hydraulic roller cam. For the blue-curve engine, our high mileage donor motor needed a re-bore and new pistons. Some KB hypereutectic pistons were very cost effective here, but this and a few other wear issues put the cost of this engine to just under $3,100.
The red-curve engine was a luckier deal. It was a low-mileage unit that had seen frequent and regular oil changes. It was in pristine condition internally to the extent that we reused all the rings and bearings for the rebuild. Block prep consisted only of a bore deglaze and a really good cleaning. When the pistons were stripped of the rings and cleaned to the bare metal, they came back "as new." This engine ran a total of $2,580 but a new Performance Distributors (good to 8,500 rpm) HEI unit was used. If we had rebuilt our old HEI with a Performance Distributors race module instead of opting for a whole new unit, over $100 would have been saved.
There is more power in the late-model, roller-cam block/iron-headed motor than you see here. I am sure with a fancier race-style pan, a more aggressive cam and a few other refinements, 525 hp is a reasonable expectation. But the cost is going to escalate. On the other hand, if rules are made that restrict the CR to, say, 10:1 (pump gas will work for this) and 0.500 valve lift, along with a 6,500 rpm rev limiter, power would be held in check at a nonetheless healthy 450-470 hp. At this level, most stock parts have a reasonable chance of surviving. Throw in a set of hard compound tires and just maybe we could cut the influence of big bucks by a big margin.
Cost and race classes that call for "as cast" iron heads are the driving forces behind the production of the heads you see here. Fierce competition has brought about the development of cylinder heads that, in "as cast" form, would have at least matched the heads seen on most cost-is-no-object Cup engines of just 25 years ago. The three types of heads we are featuring here have all, during our dyno testing, proven to be very strong performers when used with an appropriate combination of compression, cam, valvetrain and induction.
For a shade under 500 bucks, bare, these heads are a great deal. The casting finish is not quite as good as the other two brands of heads featured here. That said, we have run both the 180 and 200 cc versions in "as cast" form and seen outstanding results on the dyno. There have been more than the odd one or two pro engine builders who have lost bets by underestimating the power production capability of these heads. In addition to being good out of the box, these heads port up easily (we have seen 300 CFM on the intake and 207 on the exhaust at just 0.600 lift) and can be done by a rank beginner over a weekend. In the relatively short time they have been available, these heads have been showing championship winning form on many circle tracks.
|EQ Cylinder Head Data |
|Lift ||In. ||Ex. ||  |
|0.050 ||33.5 ||25.6 ||Available Chamber Vols ||50/64/72 ||50/64/72 ||50/64/72 ||50/64/72 |
|0.100 ||68 ||64 ||Flat Mill Chamber Vols ||45/59/67 ||45/59/67 ||45/59/67 ||45/59/67 |
|0.150 ||103 ||81 ||Available Port Volume ||180 ||200 ||215 ||230 |
|0.200 ||136 ||99 ||Intake Valve Size ||2.02 ||2.02 ||2.02 ||2.08 |
|0.250 ||164 ||113 ||Exhaust Valve Size ||1.6 ||1.6 ||1.6 ||1.6 |
|0.300 ||189 ||126 ||Valve Lengths ||Stock ||Stock ||Stock ||Stock |
|0.350 ||211 ||137 ||Plug Orientation ||Strt/Ang ||Strt/Ang ||Strt/Ang ||Strt/Ang |
|0.400 ||230 ||147 ||Armored Exhaust Seats ||Yes ||Yes ||Yes ||Yes |
|0.500 ||247 ||173 ||Bronze Valve Guides ||Yes ||Yes ||Yes ||Yes |
|0.600 ||259 ||182 ||Screw-in Rocker Studs ||Yes ||Yes ||Yes ||Yes |
|0.650 ||266 ||187 ||Valve Cover Bolt Pattern ||Universal ||Universal ||Universal ||Universal |
|0.700 ||270 ||191 ||Casting Finish ||Good ||Good ||Good ||Good |
The Platinum series of the Iron Eagle heads from Dart is the result of the wet flow technology introduced late last year. Our tests have shown this technology to be worth over 20 hp on a nominally 480 hp test engine. These heads are now just showing their potential. Like the other two head designs featured here, these heads port up very easily. Just optimizing the original Dart port form on a 230cc port (2.08 valve) head and adding a Cup-style seat job resulted in 315 for the intake and 223 cfm for the exhaust at 0.700 (seven hundred thousandths) lift. To put those figures into perspective given the cam, compression and induction, that's more than enough airflow to top the 600 hp mark.
|Dart Platinum Iron Eagle Head Data |
|Lift ||In. ||Ex. ||  |
|0.050 ||33.3 ||25.3 ||Available Chamber Vols ||49/64/72 ||49/64/72 ||49/64/72 ||49/64/72 |
|0.100 ||67 ||57 ||Flat Mill Chamber Vols ||44/58/66 ||44/58/66 ||44/58/66 ||44/58/66 |
|0.150 ||103 ||87 ||Available Port Volume ||180 ||200 ||215 ||230 |
|0.200 ||135 ||99 ||Intake Valve Size ||2.02 ||2.05 ||2.05 ||2.08 |
|0.250 ||163 ||115 ||Exhaust Valve Size ||1.6 ||1.6 ||1.6 ||1.6 |
|0.300 ||190 ||129 ||Valve Lengths ||Stk/+.10 ||Stk/+.10 ||Stk/+.10 ||Stk/+.10 |
|0.350 ||212 ||143 ||Plug Orientation ||Strt/Ang ||Strt/Ang ||Strt/Ang ||Strt/Ang |
|0.400 ||233 ||155 ||Armored Exhaust Seats ||Yes ||Yes ||Yes ||Yes |
|0.500 ||265 ||180 ||Bronze Valve Guides ||Yes ||Yes ||Yes ||Yes |
|0.600 ||272 ||191 ||Screw-in Rocker Studs ||Yes ||Yes ||Yes ||Yes |
|0.650 ||274 ||197 ||Valve Cover Bolt Pattern ||Pre 87 ||Pre 87 ||Pre 87 ||Pre 87 |
|0.700 ||277 ||200 ||Casting Finish ||Excellent ||Excellent ||Excellent ||Excellent |
Experience with just one set of these heads on the dyno involving a cam testing session showed great potential, to the extent re-visiting them was made a high priority. Although the combination tested was a little off optimal in terms of induction (it was not our engine), results were still excellent. And excellent in this context means race winning capability. Such results were not of any great surprise here as the current design of the chambers and ports on these heads is the result of about 10 years of development. The casting quality on the pair of heads currently in our shop being readied for an engine is among the best seen to date.
|RHS Pro Action Head Data |
|Lift ||In. ||Ex. ||  |
|0.050 ||35 ||27 ||Available Chamber Vols ||50/64/72 ||50/64/72 ||50/64/72 ||50/64/72 |
|0.100 ||68 ||62 ||Flat Mill Chamber Vols ||45/58/66 ||45/58/66 ||45/58/66 ||45/58/66 |
|0.150 ||103 ||85 ||Available Port Volume ||180 ||200 ||220 ||235 |
|0.200 ||133 ||101 ||Intake Valve Size ||2.02 ||2.02 ||2.02 ||2.02/2.08 |
|0.250 ||159 ||116 ||Exhaust Valve Size ||1.6 ||1.6 ||1.6 ||1.6 |
|0.300 ||187 ||133 ||Valve Lengths ||Stk/+.10 ||Stk/+.10 ||Stk/+.10 ||Stk/+.10 |
|0.350 ||211 ||151 ||Plug Orientation ||Strt/Ang ||Strt/Ang ||Strt/Ang ||Strt/Ang |
|0.400 ||231 ||163 ||Armored Exhaust Seats ||Yes ||Yes ||Yes ||Yes |
|0.500 ||266 ||180 ||Bronze Valve Guides ||Yes ||Yes ||Yes ||Yes |
|0.600 ||282 ||191 ||Screw-in Rocker Studs ||Yes ||Yes ||Yes ||Yes |
|0.650 ||285 ||195 ||Valve Cover Bolt Pattern ||Pre 87 ||Pre 87 ||Pre 87 ||Pre 87 |
|0.700 ||283 ||198 ||Casting Finish ||Excellent ||Excellent ||Excellent ||Excellent |