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About the Project...

The combination was a drag race only 406 cubic inches SBC. It featured all of the goodies that you would expect to find in a drag racing engine: 14:1 compression ratio, custom grind solid roller camshaft, AFR 210cc heads, Edelbrock Super Victor intake, and 950 cfm Holley carb. Nitrous was fed into the engine via a cross-bar plate under the carb.

Our Performance Objective...

The owner was complaining about a lack of top-end power. He felt as though the combination was running out of steam before the finish line stripe. Given that this combination primarily runs the 1/8th mile, this was a real issue. If the owner ever decided to go to a 1/4 mile track the situation would only have gotten worse. Our performance objective was to increase top-end horsepower and extend the usable RPM range while retaining the current short block (namely pistons) components.

What SRS Did About It...

We went to work with our pencils and paper to develop a plan before we started to change parts. Using cylinder head sizing techniques found in the link below, we felt that the AFR 210cc heads were holding the engine back at RPM. If we were to increase power at higher RPM levels, we would have to address the MCSA through the cylinder heads. A limiting factor regarding cylinder head selection on this combination was the stock valve pocket location(s) in the pistons. Originally the pistons were selected to match the AFR 210cc heads (stock valve arrangement). The owner did not want to go through the expense of changing the pistons to a 60/40 pocket arrangement but was open to the possibility of changing the heads if a better-suited head was available that would fit the current pistons. After much research and many phone calls to the various manufacturers that we work with at SRS, a pair of as-cast Dart Pro 1 230cc heads were decided upon. This would open up the MCSA from a measured 2.19 sq. in. in the AFR heads to a measured 2.48 sq. in. in the Dart heads. We also called Bullet Racing Cams and ordered another custom camshaft that would better suit our target RPM and nitrous usage. The original camshaft was 258/269 duration @ .050 and had .688/.672 lift on a 110 LSA. The new cam spec'd by Bullet was 275/290 @ .050 with a .683/.683 lift and a 112 LSA. Our plan was to eventually spray 350 hp worth of nitrous through the cross-bar plate and Bullet ensured us that this camshaft would allow us to do that more efficiently. Custom length pushrods from Manton and a set of shaft mount rocker arms from T&D Machine finished off the new top end. We were ready to run the refreshed combination on the SRS dyno and see if our planning was going to bear fruit.

Simpson Racing Solutions

Dyno Proven Results...

Once all the work was complete, we loaded the combination onto the SRS chassis dyno and went to work to objectively quantify and dial in our work. Initial naturally aspirated testing showed that we were making similar peak power numbers when compared to the original combination, but we were now carrying NA power out all the way past 6,800 rpm. Previously, NA power was starting to fall off by 6,000 rpm. So far so good, but the good news doesn't end there. Bullet stated that this new camshaft would really start to shine once the nitrous was applied, and boy were they right. We loaded two #59 nitrous jets into the cross-bar plate. These are the required jet sizes for a "225" hp shot. Power jumped up by 220 horsepower and carried out past 7100 rpm. Previously, with two #65 nitrous jets (a 250 shot), we made 72 less peak power versus the new combination, and power was starting to fall off rapidly by 6,700 rpm. An interesting note, at 6,700 rpm the new combination was up 90 horsepower (with a smaller nitrous jet) over the old combination. That's a win!

How SRS Can Help You!

Don't leave your engine combination to chance. At Simpson Racing Solutions, we are passionate about helping our customers achieve their performance goals. We have many dyno-proven combinations on file and know what works. If you are planning a new build or want to breathe new life into an existing build, we have the experience to help! Contact us today at +1 (236) 422-1180.


Testing the new 406 combinations on our Superflow Autodyn 30 chassis dyno.

Simpson Racing Solutions


These budget builds managed to produce 510 hp NA and over 670 hp with a "150" shot of nitrous.

Key Components Included...

  • Stock Roller Block, Scat Series 9000 Cast Crankshaft, Scat I-Beam Connecting Rods, Probe Forged Pistons, Hydraulic Roller Camshaft, Heads & Intake Ported by SRS.


Watch as this budget-minded Ford pumps out over 500 horsepower!


The Small Block Ford is what started it all for SRS. Over the years, we have developed a combination of parts that perform well and offer exceptional value for our customers. Boosted, nitrous-assisted, and naturally aspirated combinations are available. We offer turn-key stroker engines for the street and racing.

Simpson Racing Solutions
Simpson Racing Solutions


The foundation is a Dart SHP block. These blocks feature 4-bolt main caps and siamese cylinder walls. The aftermarket block allows us to use up to a 4.185" bore. Typical bore size is 4.125".

Once the block is deburred, it is painted before the cam bearings and plugs are installed. Then the crankshaft is bolted in place. The crankshaft used will depend on the intended use and budget. Note that the inner row of bolts has been replaced with ARP studs.

Pistons from DSS Racing are used for most of our engine builds.  DSS offers piston sets in various configurations for an array of horsepower and budget levels.  We also offer piston options from JE, Diamond, Wiseco, and many others.

We are a dealer for Molnar Technologies crankshafts and connecting rods too. Eagle, Scat, Carrillo, Callies, Manley... connecting rod and crankshaft options are plentiful. Budget and intended use will help us to select the right parts for your build.

Assembled and ready to ship! Heads and valvetrain packages are available to complete your build. Dyno-proven combos to help you reach your goals and remove the guesswork.


About the Project...

The car is a 1973 Camaro with a 383 SBC stroker and a 4-speed manual transmission. Engine modifications include an Eagle 383 stroker rotating assembly that yields a pump gas friendly 9.5:1 compression ratio, aluminum ProMaxx cylinder heads, hydraulic roller camshaft and 1.6 ratio roller rocker arms, dual plane intake manifold, long tube headers, MSD ignition, a Holley Sniper EFI system. I was told that the engine made 500 horsepower on an engine dyno prior to installation. The 12-bolt GM rear axle sports 3.73 gears.

Our Performance Objective...

The car ran well but lacked the low-end grunt that I felt it should have for a street-driven vehicle. Upon closer analysis, I discovered that the hydraulic roller camshaft sported 236/242 duration @ .050" and the lobes were ground on a 110-degree separation angle. In my experience, this is too large for this application and definitely not the best choice for the Sniper EFI unit to work without the occasional issue. Our performance objective was to increase drivability without sacrificing top-end power.

Simpson Racing Solutions

What SRS Did About It...

The plan was to swap out the oversized hydraulic roller for something a little better suited for the street. I was confident that we could "fatten the curves (horsepower and torque curves)" down low in the RPM range without sacrificing significant power higher in the RPM range. Given the relatively modest static compression ratio of 9.5:1, it was important to remain conservative with camshaft timing so that we could trap as much cylinder pressure as possible at low to moderate engine speeds. A grind from Comp Cams was selected that sported 218/224 degrees of duration at 0.050" valve lift on the intake and exhaust, respectively. Lobes were placed on an EFI friendlier 111-degree lobe separation angle.

Dyno Proven Results!

Before we started any work, the car was loaded onto the SRS Superflow chassis dyno so that we could establish a consistent baseline. We wanted to be sure that the final outcome was as objective as possible and that we were not basing our results on our "seat of the pants" feel. The combination produced power that was fairly consistent with similar builds.

After the camshaft change, some significant work was required to bring the Holley Sniper EFI system back into tune. We were required to add significant fuel to the entire table below 4,500 rpm. This was the first sign that the cam change had made a significant difference in power output from idle to 4,500 rpm. More air in requires more fuel. In the end, the combination picked up significantly from 2,500 rpm (the starting point if the test) to 4,500 rpm. Despite the much smaller camshaft, we only sacrificed 5 horsepower at 5,500 rpm (peak power). The end result was much fatter horsepower and torque curves with minimal losses at peak RPM.

What the Customer Has to Say...

The owner of the car was instantly over the moon with the added power throughout the curve. "The car has never spun the tires as it does now" was one remark that stands out to me.

How SRS Can Help You!

Don't leave your engine combination to chance. At Simpson Racing Solutions, we have many dyno-proven combinations on file and we know what works. If you are planning a new build or want to breathe new life into an existing build, we have the experience to help! Contact us today at +1 (236) 422-1180.