Last month, we outlined the premise of a budget-oriented big-block Chevy buildup that would put out close to 700 hp for around $7,000 using a combination of massaged stock components and modestly priced off-the-shelf parts. Although the compression ratio of 12:1 dictates the use of some race fuel, the idea is to run mostly pump gas on the street, with only a splash of race fuel. Alternatively, 100-octane unleaded can be used without a stretch. Considering the high cost of pump gas and the limited street use of the engine, it's not the huge cost you might imagine.
The idea of this engine being a do-it-yourself project was brought home by a trio of UNCC Motorsports students under my tutelage. Bruce Greer, Nathan Bornitz, and Dusty Kennett brought the short-block to completion with the help of T&L Engine Development, which supplied the necessary machining processes. We completed part one with a check of the completed short-block's static turning torque, a good measure of an engine's mechanical efficiency. The 482-inch big-block turned over with a scant 16 lb-ft. In a world where 30 to 35 lb-ft is the norm for a street-bound big-block, we knew we were on the right track.To review, let's take a look at the budget build-sheet for this project, then move on to the induction, final assembly and dyno test.
UNCC Motorsports student Nathan Bornitz performed the porting and assembly of our project engine's Dart Iron Eagle heads from start to finish leaving only the job of bolting them on to Bruce Greer. (For more on these affordable performers, review the story "Iron Clad Horsepower" in the August 2005 issue.) Check out the sidebar "Choosing The Budget Iron Eagle Heads" to see what they produced in the way of flow. We used FelPro gaskets throughout the build, as they are very much a tried and tested deal, especially in terms of the head gaskets.
The next operation was the installation of the pushrods and guide plates. Because of the repositioned valves, the Iron Eagle heads are best used with Dart's adjustable guide plates. This allows the correction of what would otherwise be about 200 thousandths of rocker misalignment.
Selecting pushrods proved to be a very critical job. If you've an idea to use stock pushrods, forget it. They will simple not work and in the process will probably chew out the end of the rocker. The most critical area by far is the intake pushrod. It needs to be of a length that produces the correct sweep across the valve tip, but there is more. This length inevitably produces an excessively acute angle between the pushrod and rocker in the closed position. If the sweep is correct, the rocker/pushrod angle is greater than the pushrod seat in the rocker can accommodate. The key here is to use as long a pushrod as possible to move out of bind on the rocker's pushrod seat, but not so long as to move the contact patch too far off the valve tip center. To get things to work, it proved necessary to make a trade between a centrally located sweep patch, and avoiding bind at the rocker's pushrod cup. This left us with a sweep patch that was biased toward the exhaust port side of the valve tip.
Here's one of our Dart Iron Eagle heads with basic porting. We used the new COMP Cams big-
ARP head bolts and FelPro head gaskets ensured our cylinders would hold out against the 12
The repositioning of the valves on the Dart Iron Eagle heads means using Dart's adjustable
The pushrod length needs to be set to achieve a centralized roller contact patch. A compro
Our big-block's induction system was from Holley. We used the single-plane street/strip Team G rectangle-port intake with a 4500-series 1050 Dominator carb. The manifold choice was predicated on some dyno tests of pre-production prototype manifolds we did for Holley on similar, but slightly more street-oriented big-blocks in the 468- to 482-inch range. At the end of the day, for any big-block build shooting for more than 600 hp, a Dominator-style carb is the way to go. This carb and the Weiand Team G intake made what proved to be a potent power producing combination.
After pulling the intake out of the box, the first job was to check port alignment with the Dart Iron Eagle heads. For the most part, the port runner's perimeter fell marginally inside the ports in the head. The exception was the corners. The corners in the heads were of a bigger radius than those in the manifold, so some minor filling was called for before putting the die grinder to the manifold. After having a couple of days for the filler material to fully cure, Bruce Greer matched the manifold runners to the head ports. In the case of this manifold, matching was made a lot easier by the fact that it was possible to look down the port and check what had been achieved.
Bottom End Finishing Touches
While our manifold work was being done, parts were on their way from Jeg's. This consisted of some smart-looking Moroso valve covers and the bottom end parts in the lube department. The Moroso pump was a competition prepped model PN 22150. This was fitted with a pickup to suit a basic street/strip pan. The pan was essentially an entry-level deal and came with a street-friendly price tag. The block-to-pan gasket was the one-piece FelPro blue gasket. The negative effects of over tightening with this type of gasket are virtually eliminated by means of the metal inserts in the stud/bolt holes.
Top End Finishing Touches
All that was left to do of any consequence on our 482 was to install the Moroso valve covers, the carb, and the distributor. All that is straightforward stuff, but a few words on the Performance Distributor HEI distributor. I have been using their distributors for over 20 years and they have never failed to deliver. There are a few other companies making quality distributors, but the one we chose to use here represents a great-bang-for-the-buck deal and got the nod for its budget-oriented performance.
When it came to dyno test, the UNCC Motorsports Superflow had already been booked in advance by the Formula SAE and the Drag Race team. T&L pretty much dyno tests seven days a week, but once again, T&L's boss, Lloyd McCleary, saved the day by letting us use one of the three SuperFlows he has. Basically, Lloyd donated a Saturday on the proviso that we would be off at day's end to accommodate a Sunday dyno booking by a customer. Normally, a day on the dyno would be all that would be required to cover the setup needs of an engine such as this. However, a few hiccups on our part, such as an intake water leak and a couple of other things like forgetting the Sunoco race gas we needed, meant a late start.
With the timing set at 36 degrees, our 482 pumped out just a fraction under 675 hp and 625 lb-ftt. Since this engine was supposed to have a respectable amount of low-speed torque due to having a relatively short cam (a COMP Cams single-pattern 286 XSR Xtreme street roller), we would've liked to show what it did down in the 2,500-rpm range. The bottom line is that this 482 made too much torque in the lower rpm range for the SuperFlow, which was set up for all-out race engines. Though we don't have hard numbers, you can safely conclude this engine can make some very respectable numbers far lower than our graph shows. And Lloyd's comment on our engine? "I am sure if I could have spent a day fine-tuning, it would've picked up 10 lb-ft and 10 hp. But even without that, your guys did good. It's a great engine." Just as a reminder, T&L does offer several versions of this engine with iron or aluminum Dart heads, mid or high compression, solid or hydraulic roller cam, and in single- or two-plane manifold form.
Log on to www.tandleng.com for details. If you'd rather have T&L build it for you, this exact turnkey engine is available for $7,900 ($8,500 with aluminum heads). They are putting their streamlined cup car building techniques into building these custom crate units. Contrary to what you might think, this has resulted in a drop in crate motor cost, not an increase.
The Dart adjustable pushrod guideplates should be set to achieve the roller/valve tip alig
Note the polyloc's position in relation to the rocker slot. If it is close to the end of t
Here is the Holley Dominator carb we used. It was chosen based on dyno test results over m
UNCC Motorsports student Bruce Greer took the necessary time to precisely match the Team G
One of the advantages to using a single-plane manifold such as the Weiand Team G is that t
A key factor for any successful single-plane big-block Chevy manifold is the form of the r
Here is our finished Team G manifold ready to run. The success of the engine indicated it
Nothing fancy for our timing cover, just a plain $9 item from our local parts store and a
The oil pump used was a Moroso competition unit with the heavy-duty driveshaft and appropr
At $230, our entry-level Moroso street/strip oil pan fit like a high-dollar item. That mea
The one-piece FelPro pan gasket is a big improvement over the old cork multi-piece-style g
T&L's top guns, Lloyd and Ray, made short work of getting our big-block on the dyno, but a
Part of a successful engine builder's resume has to include a lot of dyno time. T&L's Lloy
Big low-end torque numbers prevented us from pulling our 482 much under 3,900 rpm, indicat
Choosing The Budget Iron Eagle HeadsSo why did we chose to run a pair of Dart's Iron Eagles? The reason was twofold. First, we already had one, which we did a basic porting exercise on and saw good results that came pretty easy. Just a good clean up and bowl blend resulted in some healthy flow numbers, as is evident from the graph. Secondly, the heads are a good value for the money and they avoid a ton of hassles trying to recondition a set of 25-year-old stock castings, which frankly are not even in the same ballpark when it comes to quality. The castings we used were the small-port ones (nominally 308 cc). These are normally equipped with 2.250/1.88-inch valves, but we opted to step up the intake valve to 2.3 inches. On the flow bench, this resulted in a small but worthwhile increase in flow in the 0 to .500-inch lift range, although top-end flow remained virtually unchanged. Overall, our head porter, Nathan Bornitz, was able to coax between 8 and 22 cfm more out of the head's intake ports in the lift range from .100- to .700-inch lift. All this was achieved with only about a 5cc increase in port volume, and most of that in the bowl area. The result was an increase in flow and port velocity. On the exhaust side, flow was increased by 3 cfm at 100 thousandths lift and 23 cfm at .700-inch lift. Again, this was done with minimal increase in port volume.
After porting, the heads were milled at T&L by 70 thousandths, which dropped the combustion chamber volume from 121 cc to 107 cc. The last move was to assemble the heads using COMP Cams' new big-block Beehive springs. These delivered 150 lbs on the seat (410 lbs over the nose) with our street roller cam and 1.7:1 ratio rockers. For those of you not familiar with this high-tech spring, those numbers might look a little on the low side. But to understand how effective they can be, you need to bare in mind that a swap to these low-mass springs (a steel beehive retainer is so small it weighs less than a conventional titanium retainer) has more effect on increasing rpm than making a change to titanium valves. A ballpark figure is that with 10 percent less spring, the engine will turn about 12 percent more rpm and show better control all the way up the rpm range.
Putting our Standard Abrasives porting supplies to work on our Iron Eagles showed that eve
We re-cut the intake seats of our Dart Iron Eagle heads to accommodate larger 2.3-inch val
|Component:||Spec:||Notes:||Cost*: ||Carb||1050 Dominator||Big-blocks like Dominators||$676 |
|Intake||Holly Dominator||Has already tested good||$190 |
|Heads||Home-ported Dart Iron Eagles||2.3/1.88 valves, small port||$1,410 |
|Cam||COMP solid street roller||286 x 286 on 107 LCA plus lifters ||$620 |
|Valvetrain||Beehive springs + matching hardware||High-tech perf., low-tech cost. Includes pushrods & rockers||$700 |
|Block||Stock, 4-bolt||Sonic tester selected||$250 |
|Pistons ||Ross + 125||12:1 with heads milled||$660 |
|Rings||Total Seal||Our dyno tests show best||$250|
|Rods||OE items||ARP bolted, lightened and balanced||$280 |
|Crank||Stock cast - ground 10 under (labor)||For street/strip good for 700 hp||$150 |
|Oil Pump||Moroso competition spec||55 psi||$80 |
|Pan||Moroso Street/Strip||Does a great job for the money||$230 |
|Ignition||Performance Distributors HEI||Strong sparks to 7,000+ rpm, priced including plugs and cables||$360 |
|Fasteners||ARP||Best insurance||$80 |
|Gaskets||Fel Pro||Top quality||$120|
|Damper||Professional Products||$70 |
|Block Machining||Bore & hone labor||$250 |