To bring you up to date, our...
To bring you up to date, our 289 4V engine was dyno-tested and super-tuned in stock condition in Part 1, then upgraded with an Edelbrock Performer RPM manifold and 600-cfm carburetor in Part 2. The total gain was a modest increase in horsepower and torque. This taught us something about packaging.
Parts 1 and 2 of our "Plan For Ponies" series, we've shown you what changes in induction and ignition do for performance. In Part 1, we removed the air cleaner, changed spark plugs, adjusted the timing, and installed a Pertronix Ignitor--gaining 4 hp and 5 lb-ft of torque. This demonstrated what simple engine-tuning could do. In Part 2, we gained a modest amount of power--installing an Edelbrock Performer RPM intake manifold, a 600-cfm carburetor, and a Pertronix Ignitor module.
This month, West Coast Classic Mustang of Reseda, California, will install Hedman long-tube headers. Magic Muffler of nearby Canoga Park will install a high-performance turbo 2-1/4-inch dual exhaust system from National Parts Depot. Then we're going back to Mike Morgan Motorsports to take another crack at the big drum to see what induction, ignition, and exhaust tuning has done for our Mustang.
1 Packaging should always...
1 Packaging should always be a balance of components that work well together. Installing only a high-performance intake manifold and carburetor without close attention to the exhaust system, heads, and camshaft won't net the power gains you're hoping for. Always plan for power with the correct combination of parts.
What we've learned most from this series is that you must plan for power as a package. And it's a good idea to begin with the exhaust system, not the induction and ignition as we have. We say this because we're convinced that our stock, original Mustang GT dual exhaust system has hindered our efforts. In order for an engine to perform, it has to have good exhaust scavenging; otherwise, no amount of induction, ignition, or headwork will matter.
Our high-performance Turbo 2-1/4-inch exhaust system from National Parts Depot has 2-1/4-inch pipes with Turbo mufflers that not only improve sound, but performance as well. Hedman long-tube headers reduce backpressure and scavenge exhaust gasses, while keeping torque in play. With aftermarket headers and larger exhaust tubing, we wonder what all this will do for performance. We're about to find out.
We took the Mustang back to Mike Morgan Motorsports, and once again, we were disappointed with the result on the first pull. Our rejetted Edelbrock 600-cfm carburetor struggled with an ugly flat spot that was hurting torque something awful. During throttle tip-in, the 289 was gasping for a respectable air/fuel mixture that would allow it to make power. Wide-open throttle passes were made with poor results. This was no reflection on the exhaust system or Edelbrock induction system; it was an issue of proper engine tuning. We did some carburetor tuning and achieved impressive results.
Prior to Run No. 2, we adjusted the Edelbrock carburetor's accelerator pump rod to see if we could eliminate the flat spot. We were marginally successful. The flat spot remained, indicating the need for more extensive carburetor tuning. Despite the surging, we gained 2.3 hp and 5.2 lb-ft of torque. This is due mostly to a warmer engine, not necessarily the accelerator pump adjustment. But this shows us what's possible, given respectable engine tuning.
Using Edelbrock's carburetor jetting kit, we tuned the main metering circuit using the pink metering rod spring. This gave us a richer fuel mixture where we needed it most: under power where an engine makes torque. This netted 5 more horsepower and 6.2 additional lb-ft of torque; not bad considering how easy this performance-tuning trick is.
2 Hedman Hedders has supplied...
2 Hedman Hedders has supplied us with a Jet Hot-coated set of long-tube headers for our 289.
They're easy to Install and...
They're easy to Install and include an adapter that moves the power steering cylinder away from the hot tubes.
3 This high-performance Turbo...
3 This high-performance Turbo 2-1/4-inch dual exhaust system from National Parts Depot includes a prebent, custom-fit, 2-1/4-inch H-pipe; exhaust; tailpipes; and a duo of Turbo mufflers. This quiet exhaust system is designed to improve flow while keeping all-important backpressure.