Dart Machinery – 15-Degree SBC Cylinder Heads

When it comes to V8 racing engines, few have as many aftermarket component options as the conventional small-block Chevy. The lists for induction configurations, cranks & rod combos, and cylinder head designs are vast for the small-block Chevy racer these days and horsepower levels are only limited by the builder’s imagination and customer’s bank account. Dart Machinery is one company that offers nearly every incarnation of the small-block Chevy cylinder head, from the standard 23-degree to hardcore 9-degree angle versions, Dart has you covered.

At 284cc intake ports, expect some very high flow from Dart's 15-degree heads. With some light port work, we heard 404 cfm on intake at .900 lift is not unheard of.

Dart’s 15-degree Chevy heads are a powerful option for those looking to make big, high-rpm horsepower without a power adder and without the need for anything too exotic. Although they are a popular choice in the circle track world, 15-degree heads are an affordable, yet powerful choice even for the drag racer.

A light valvetrain is critical in a high winding combination like this, so Panno installed some 2.200” titanium intake and 1.622” titanium exhaust valves in the 15-degree castings.

Over the last couple years, one of the local allies of FSC magazine, Randy Panno, has been compiling parts for a wild 406 Chevy. We knew that Panno’s shortblock was no slouch and featured many light- weight components designed for high revs, so we thought it would be a perfect candidate to test some of Dart’s 15-degree cylinder heads on. Basically, we wanted find out how much power we could make with these not-too-typical cylinder heads. Panno wants to get 1,000 horsepower from his combination, and although he admits it’s a lofty goal, he’s going to try anyhow. “We plan on buzzing the motor quite a bit and we’re running a sheetmetal tunnel ram from CFE that should flow what we need,” Panno said. “My engine builder [Richard Conley] has built many engines over the years, and even some that currently hold NHRA records, so he’ll be applying some of his tricks to this engine build.” Some of the these ‘tricks’
include oiling system modifications, piston design, and a special camshaft profile.

These heads come with a dual bolt pattern exhaust face to allow for big tube headers. No need for adapter plates!

The heads of this engine project come from Dart’s 15-degree Race Series Chevy line and will be tested in basically out-of-the-box form except for a few modifi- cations, such as copper valve seats for    titanium valves, and some minor hand porting. Dart offers their cylinder heads in a standard configuration, however you can also order these heads with a full range of race series upgrades, including rolled valve angles, high-efficiency chambers and refined intake port designs, along with a slew of features to ensure the heads can be customized and modified to meet the needs of specific racing applications. Other features of these heads include: virgin 355-T61 aerospace alloy construction, compati- bility with most components designed for 18-degree heads, shallow combustion chambers for improved combustion and allows use of larger valves. In addition, these heads can accommodate valve seats that will fit up to 2.200″ intake valves and 1.625″ exhaust valves, and feature a tall, short side radius and deep valve bowl to enhance low lift flow. Other interesting aspects of these heads include a improved spark plug position, closer to the bore centerline to enhance flame travel and reduce spark plug advance requirement, and extra thick decks for 9:1 engines that need to be milled for high compression engines. Dual exhaust bolt patterns are drilled for standard 18-degree and spread-port header flanges and water passages between exhaust ports are cast in to improve cooling and prevent “hot spots” that can cause head gasket failure.

The combustion chamber measures 48cc and is particulaly shallow to allow for ultra high compression. On our engine project we're expecting about 18:1 with the right piston.

The factory valve seats will be removed in order to install titanium-friendly copper seats.

Steel shaft rockers from Crower were used on these 15-degree heads. Aluminum rockers are obviously lighter, but with the immense amount of valvespring pressures Panno is running he needed something that wouldn't flex.

Directing the airflow is this super-nice dual quad tunnel ram from CFE out of Michigan. We knew a single plane just wouldn't have the volume to support the type of power we wanted to produce, so the guys at CFE were able to build this killer intake to support our goals. Look for more pics of this piece in future installments where we bolt up the top end.

In 2012 expect to see this small-block combination touting Dart’s 15-degree cylinder heads in the pages of FSC. Even if we can’t get to 1K, we plan on using these heads to get Panno’s wild, stick bangin’ natural Nova in the single digits before the year is through.

Dart Machinery
248.362.1188
dartheads.com

Crower
619.661.6477
crower.com

CFE Racing Products Inc.
586.773.6310
cferacing.com

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