Wanna make more HP?
Thread Starter
Race Director
Joined: May 2001
Posts: 14,165
Likes: 9
Re: Wanna make more HP? (Matt Black)
Nathan, your rockers are using the stock mounting points? They're not moved back on shaft mounts? This month's (July 2003) issue of "Chevy High Performance" has a nice article on high-ratio rockers on shaft mounts...
[Modified by Matt Black, 8:28 PM 5/19/2003]
[Modified by Matt Black, 8:28 PM 5/19/2003]
If you read this thread http://forums.corvetteforum.com/zerothread?id=537439 I have some pictures of the new rockers right along side of my old ones.
Burning Brakes
Joined: Mar 2001
Posts: 1,200
Likes: 0
Re: Wanna make more HP? (HeaderDesign.com)
If you like, you can send me the elapsed time data and the rest of the data in an Excel spreadsheet or something and I will back calculate the dyno mass moments of inertia. Also, I try to get people I deal with to do the dyno run in tranny gear ratio=1, and the next lower gear (like 4th and 3rd). This gives me the ability to check my calcs for drivetrain inertia, and losses.
Selecting an exhaust lobe for an engine is very tricky. The blowdown timing and rate has to be chosen to put the proper amount of energy into the exhaust to make the best scavenging wave in the header. Too much energy released into the header reduces power. Too little energy released into the header reduces power. Peak lift is sometimes limited to make port velocity more uniform. Other times max lift is dictated or limited just by the opening flank shape used to get the right blowdown. Closing side can be radical. Exhaust lobes are picked from one of several different series to match the exhaust port flow characteristics and engine, then are fine-tuned with the rocker ratio. This is very common in race engines.
Selecting an exhaust lobe for an engine is very tricky. The blowdown timing and rate has to be chosen to put the proper amount of energy into the exhaust to make the best scavenging wave in the header. Too much energy released into the header reduces power. Too little energy released into the header reduces power. Peak lift is sometimes limited to make port velocity more uniform. Other times max lift is dictated or limited just by the opening flank shape used to get the right blowdown. Closing side can be radical. Exhaust lobes are picked from one of several different series to match the exhaust port flow characteristics and engine, then are fine-tuned with the rocker ratio. This is very common in race engines.
