Home About (R) Catalog (1st) MGA / MGB / GT Performance Parts MGA and MGB Parts TR250 / TR6 Performance Parts TR250 and TR6 Parts TR7 / TR8 Performance Parts TR7 and TR8 Parts Spitfire Performance Parts Spitfire Parts GT6 Performance Parts GT6 Parts Sprite / Midget Performance Parts Midget Parts Sprite Parts TR3 / TR4A Performance Parts TR3 and TR4A Parts Gear Reduction Starters K&N Air Filters MGB V8 Conversion Parts ARP Products Services (2nd) Parts Locator Services Engine Re-Building Crankshafts Cylinder Heads High Performance Engine Coatings Complete Engine Rebuilding Cars & Parts Cars (3rd) Salvage Arrivals Cars For Sale Gear Head Gifts (4th) Product Info (5th) Tech Tips Sway Bar Rate Handling Chart What If Scenarios Performance Cam Specs Magic, Mirrors & Myths Facts, Figures & Formulas Links (6th) Contact

Magic, Mirrors & Myths

MYTH - All headers make power.  
FACT:  Some engines are more respsonsive to headers than other engines. For example a TR8 reponds better to headers than a Triumph Spitfire or MGB.

FACT: Headers can/will make power in different RPM ranges. For example , a 4 cylinder engine with a 4-into-1 header design will make power at the high rev range. While a tri-Y design (4-2-1) will make power in the mid-rpm range. This is much more useful on a street car since the majority of the drive time is probably in the mid-rpm range.  Another example  of this is the stock cast iron exhaust manifold on 1963 - '74 MGB's. This is a nicely curved runner 2 outlet manifold that goes into a double exhaust pipe that then necks down to a long single pipe.  We tested some of these in the early '70's and the stock manifold produced more power through about 4800 rpm than the factory competition department header.  Once we got over 4800 rpm, the race header started to perform, but, for a hot street car, having power start at 4800 rpm is not necessarily the best option.