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Speed Secrets: Control Your Boost – Cam Swap vs. Pulley Swap!

Everyone knows that it is very simple to make more power with more boost but how does less boost produce more horsepower? Well, the answer is very logical and actually kind of a simple notion in and of itself. You see, boost is essentially a measurement of restriction and by increasing the flow of an engine you cannot only increase the power output of that engine but decrease the amount of boost it uses to make that extra power. Then, you can build that boost back up very easily and make even more power. To prove that it is possible to have your cake and eat it too, Richard Holdener with Speed Secrets and Comp Cams team up on a supercharged 5.0L Mustang engine. 

This 5.0L Ford test engine was equipped with AFR cylinder heads and a GT40 intake manifold with an injector upgrade. Richard then topped the 5.0L with a Kenne Bell twin screw supercharger and dialed it all in with a Fast XFI management system. When ran on the Dyno with the stock camshaft, the combination made 437 HP @ 5,900 RPM and 436 Lb-Ft of torque @ 3,900 RPM. While that is a good start, this application is capable of more power utilizing less boost with a little help from the guys at COMP Cams. 

Replacing the stock camshaft with Comps XE274http://www.cpgnation.com/valve-spring-tech-secrets-of-the-industry-revealed/HR camshaft that has a .555/.565 lift, 224/232 duration, and a 112 LSA, was an easy decision. This particular camshaft is a favorite among many engine builders and is a serious step up from the stock cam. On the Dyno, this combination not only made more power, but also dropped the boost from 8.6 PSI to 7.6 PSI. With 478 HP @ 5,900 RPM and 456 Lb-Ft of torque @ 4,100 RPM out of a whole PSI less boost, its time to bump that boost back up and make some real power.

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At this point all that is needed to increase the boost from 7.6 PSI to 9.3 PSI is a simple pulley swap. By changing the blower pulley, the power output of the supercharged 5.0L jumped to 508 HP @ 5,900 RPM and 483 Lb-Ft of torque @ 4,000 RPM. Thats an impressive peak power output increase of over 70 HP and 47 Lb-Ft of torque. While it is definitely possible to make more power with more boost, you just can’t beat making more power with less boost because you can always turn around and bump that boost back up for a power output not possible with boost alone. 

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