Im getting ready to build my 406, and I always read CHP. I knew I could find a few proven buildups that would best suit me. While in my search I found two buildups that I really liked, but when I compared them side by side the results AMAZED me.

The 406 with smaller heads, less compression, smaller cam(hydraulic flat tappet vs. Mechanical roller even), and dual plane air gap destroyed the "on paper" way more powerful 406.

The "bigger" 406 has almost a full point of comression, Higher flowing heads, bigger cam(not too much bigger, roller), Victor jr.

They both used Headman 1 5/8" headman headers and a 750 Holley. Can anyone try to help me out here, because this goes against everything we are taught! the 406 ci makes the 210s not too big, but the 180s a little undersized. Sure the 180s should make a little more low end, but the 210s and slightly bigger cam should shine above 5000RPM, but they dont.

Here are the links to the articles: Smaller, more HP/TQ , and Bigger, less HP/TQ

I have made a HP/TQ graph comparing the two to maybe save a little time. Am I missing something here?

 

There's your answer right there. By using 305 headers they created a total mismatch at that point, that would favor the engine that has its peak power at a RPM below the point at which the headers become restrictive.

The test would look very different with properly sized headers.

 

first , don,t believe everything you read, some engine tests are deliberately tuned and altered to make a certain manufacturers parts look good or to prove a point by deliberately mis-matching parts. a few minor changes would make that larger cammed and port engine produce much better power

EXAMPLE

RPM Torque H.P.
4000-509-378
4500-536-459
5000-523-497
5500-500-526
6000-463-528
6500-447-553
7000 - 349-465

554HP
406ci
AFR 210cc Competition Package
10.1
750 Carburator
MSD Distributor @ 36° Timing
Lunati Hyd. Roller Cams 242°-252°
.560-.572 lift 112 Lobe Centers
1 7/8" Hedman Headers
93 Octane Pump Gas

This package is available from Ceralli Competition Engines


look these over

http://www.diabolicalperformance.com/diabolical406.html

http://www.carcraft.com/techarticles/68999/

http://www.wpedirect.com/sportsmanengine.htm

http://www.speedomotive.com/newpage6.htm

http://www.rlpengines.com/chev-406.htm

http://enginenick.50megs.com/81chevette.htm

http://www.camaros.net/racing/SBCombo.html

http://chevyhiperformance.com/techarticles/90719/

http://www.chevyhiperformance.com/fe...ehicles/67318/

 

Thanks guys, I was all FUBAR. I couldnt process it, lol. I was trying to think of what the heck was going on.

 

Part of the reason is the headers. The other is that the roller cam is no bigger than the hydraulic yet it has bigger heads and a single plane intake. The restriction is with the cam/headers not the heads/intake.