Editors Note: Longtime automotive journalist and Power Automedia freelance contributor Pete Epple is going heads-up racing this year with a classic 1967 Chevelle in the NMCA Chevrolet Performance Stock sealed crate motor class. This story is part two of a multi-part feature on his project, as the car is transformed from a bracket machine to a heads-up track warrior. Epple will narrate the story, and we will follow his progress, from on-track testing right through the end of the season.
In the first installment of our Chevelle project, we laid out our plans to compete in the NMCA’s Chevrolet Performance Stock class. We also briefly introduced you to the car, and covered the DR525 sealed engine required for the class. Now, it’s time to dig into the car and what goes into taking it from an average bracket brawler to a class-specific, heads-up racer. We’ll start by looking at the car from a more general perspective so you can follow our train of thought through the build process.
At the most basic level, this is a power-limited class. What does this mean? Basically, it means the rest of the car has to be built in a very specific manner to minimize power loss and maximize performance. It means an enormous amount of testing goes into freeing up horsepower and finding little advantages to gain any kind of competitive advantage. It also means that it takes a lot of work, time, and money to win — but hey, that’s drag racing at any level.
As we mentioned in the first story, we teamed up with Chris Jones and the crew at Blow-By Racing in Boca Raton, Florida to build and maintain the car. Aside from the shop’s expertise, they also have a Dynojet chassis dyno, which will allow us to test just about anything we want in a controlled environment. Though track testing is a crucial piece of the puzzle, we are hoping that dyno time combined with track testing will give us the ability to bring this basically new car into a competitive position much quicker.
Another crucial aspect of this endeavor is reading the rulebook. You have to be smart and have a very logical approach when you look at the rule package, especially in a class like Chevrolet Performance Stock. You need to look at it as black and white, but you should be able to find some gray area to play in, as well. Innovation has always driven racers to become faster, and this class is the perfect opportunity to take that approach. It’s safe to say there are about half a dozen things that fall into this gray area that we plan on testing once the car is up and running.
Although there’s a probably a great story on how to read a rulebook for what it doesn’t say, this is not that story. The last thing we want to do is give away any secrets we may think we have. But with elapsed times in the mid-to-high 10.30s with only 525 horsepower, chances are we aren’t going to find anything every other racer in the class isn’t already doing.
In addition to thinking outside the box and trying to find room for innovation in the rulebook, sometimes it just takes a lot of money to assemble the right parts. The financial aspect of running a class like this can also be the difference in running up front and mid-pack. For instance, an old TH400 transmission is certainly not the most efficient way to get the power to the tires, but for us (at least at this point) the budget (or lack thereof) keeps us from upgrading to a more trick transmission that weighs less and takes significantly less power to turn.
To sum it all up, we plan to do the best we can with what we have, while running against some incredible racers with incredible purpose-build cars just for this class. As we begin testing and start to figure out what works and what doesn’t, we will chronicle those tests and share some of the results as we go.
When we finished the first story, the Chevrolet Performance DR525 sealed crate engine we picked up from Scoggin-Dickey Parts Center was ready to find its new permanent home in our ’67 Chevelle. This proved to be quite the challenge. Now, I know what you’re thinking … there must to be thousands of Chevelles with LS engines in them — why was this one difficult?
As part of the sealed engine package, the oil pan is a non-specific “musclecar” pan. The sump is in the rear, but it is a basic stock-style cast aluminum pan, and it cannot be changed. The rules also state that the engine cannot be in contact with the firewall, and the firewall cannot be clearanced for the engine. This is a clear cut, black and white rule, and it makes perfect sense — until you try to put this engine combination in a 1967 Chevelle. In order to get the engine even remotely close to a position you would want it in, the entire center section of the frame’s front crossmember needs to be removed.
The next logical thought would be to mount to the engine in the engine bay with motor plates, but that is not allowed per the rules. This meant we needed to cut enough of the front crossmember out of the car to clear the oil pan, but not so much that the stock engine mounts cannot be used. Okay, done.
The next issue is steering. With the engine low enough in the engine bay that the transmission has all the room it needs, the front of the oil pan rests solidly on the steering drag link. The last thing we want is to lose steering on track because the drag link is hung up on the oil pan. This meant the custom engine mounts we were making needed to be tall enough to clear the steering. Easy enough. With all of those issues at least temporarily resolved, the focus was shifted to making sure the engine and transmission were at an acceptable installed angle for our race application.
In order to even begin to measure for this, a large section of the stock transmission tunnel had to be cut out of the car. Modifying the trans tunnel is perfectly within the rules, but the new tunnel cannot be removable. With the stock tunnel removed, the engine and transmission are carefully moved into position and the stock engine mount horns were welded to the frame. The engine attaches to horns with billet LS adapter plates from Moroso. At this point we also fabricated a new transmission crossmember. This was made from thin-wall roll bar tubing and weighed in at less than half of the factory crossmember.
The next big issue that needed to be addressed was headers. Oddly enough, there aren’t many options for LS-swap headers for early A-Bodies. After an exhaustive search (pun intended), we got in touch with the guys at the Hedman Performance Group. Hedman offers a full line of LS-swap components for all year A-Bodies, our ’67 included. The rules limit header primary size 1-7/8-inch. Hedman’s Hustler line of headers offers multiple sizes that fit our application, and we chose a 1-3/4 stepped to 1-7/8-inch version.
The company also offers a multitude of coatings, but we opted for uncoated, since we didn’t know if modifications would be needed to make them fit. Hedman guarantees fitment when used with the engine mounts and oil pan offered by HPG. Unfortunately, the odd oil pan and unusual engine placement meant a few small modifications were needed. In order to get the headers between the framerails, a small section of the lower control arm mount needed to be trimmed on each side. Not wanting to sacrifice any structural integrity, the mounts were trimmed and boxed with plate steel to ensure the strength was not compromised.
Lastly, a small section of one primary tube on the driver’s side needed to be dented for a little extra clearance. This is probably not the best option for maximum power output, but it helped get the headers in the car, which is the main focus at this point.
The rulebook also outlines what is acceptable for the rest of the exhaust system. Exhausts can be no larger than 4 inches in diameter and must exit with 12 inches of the axle centerline, and mufflers must be used. Given the output of the engine and limited RPM levels, we opted for a 3-inch exhaust system.
The system is built from a universal 3-inch X-pipe kit. After the crossover pipe, straight sections of 3-inch pipe feed two Flowmaster bullet-style mufflers and a set of turndowns. We chose to run the Flowmaster bullet-style race mufflers for no reason other than it pays contingency to have them. As the season goes on, we may test other mufflers in the search for more power.
Outside of the exhaust system, there are a few crucial systems that need to be right in order to win. The transmission and torque converter are one of the biggest. Like we said earlier, budget is keeping us in the TH400 that we already have. This transmission has been in race service since the mid ‘90s and has been as quick as 8.40s. While it’s great for a car with a ton of power on tap, it isn’t necessarily optimal for our application. That makes the torque converter that much more critical. For this we turned to FTI Performance of Deland, Florida. FTI is on top of their game when it comes to transmissions and torque converters, especially when you’re talking Chevy drag race applications.
After a phone call and supplying the company with all of the vital specs on the car and engine, we had an order in for a custom 8-inch converter. We have a good idea of how we want the converter to perform. The specs will remain a secret for right now, but we are expecting to make a few changes before it’s perfect for this class car.
Stay tuned, as in our next installment, we’ll bring you the second part of the walk-through of the final build-up of the Chevelle for Chevrolet Performance LS Stock racing, where we’ll hit on the transmission, rear end housing, driveshaft, wheels, and tires. That all leads up to our final chapter, where we’ll finally hit the track for testing and our debut with the NMCA, giving you an inside look at what it takes to make a power-limited ride fly!