Circle Track's Limited Late...
Circle Track's Limited Late Model Chevy small-block is hooked up on the dyno and ready to roll.
It may feel like you are done when you bolt the valve covers on your new engine, but if you can possibly afford it, a dyno session should really be your next step before dropping that engine into your waiting race car. There's a lot you can learn by running your engine for the first time on a dyno instead of in your race car. Yes, you can break in your engine in the car on a test day. The rings will probably seat OK, and if you can keep from loading the engine, the lifters should mate to the camshaft as well. But getting those first runs on a dyno not only helps you verify engine power, they can also make your life a lot easier in the long run.
For example, simple things like oil or water leaks are easier to spot-and easier to repair-when the engine isn't surrounded by the body and framework of your race car. Likewise, all the metering options available on an engine dyno make it infinitely better at tuning for maximum power. The conditions are controlled, and it's easier to minimize variables when you're trying to make back-to-back tests.
Even if you do all the work yourself, many engine builders with dynamometer facilities will rent you time to dyno your engine. The cost may seem steep at first (usually anywhere from $500 to $1,000 for a day's worth of dyno time), but the value comes from knowing exactly how much power your engine makes-and where in the rpm range it makes it, getting the carburetor matched to the engine, and even testing what header design works best. This will also help you with gearing choices right out of the box. Plus, you can avoid the hassles of pulling the engine back out of the car if you hit the track and then discover a problem.
We used KT Engine Development in Concord, NC, for all the machine work on our Limited Late Model engine build, so as soon as the assembly was complete we took the engine back to its shops for dyno validation. There's more to getting a productive dyno session than hauling your engine to the closest shop and handing it over. And since we're talking about real money here, the final edition of this engine-build series will cover not only our dyno results, but tips you can use to make your time on the dyno as productive as possible.
Pictures simply can't do justice to any race engine on a dyno. See and hear our Limited Late Model Chevy make a run for yourself at www.circletrack.com. Click on the videos section on the righthand side.
This may seem obvious, but it needs to be said. The first step when it comes to dyno'ing your engine is preparing it for travel. Make sure all openings, such as exhaust ports, the water neck, and anything else you can find, are covered so that no trash will get into the engine while it is travelling down the road in the back of a pickup truck. Plain old duct tape works best here.
Don't try to travel with the carburetor in place. Pull it and replace it with an engine lift plate, which will make handling the engine a lot easier than a chain bolted to the ends of the cylinder heads. Lift plates can usually be had for about $15 at most speed shops.
We're using Cometic's multi-layer steel exhaust header gaskets which should provide a good seal without having to resort to high-temp silicone. The headers for this test are the same Tri-Y units from Schoenfeld that we used in the header dyno test in the June '08 issue.