ACN Mad Max Dual Port Cylinder Heads, (L6 heads) 42 X 37.5mm Valves PAIR are based on a brand new Revmaster 049 Aircraft Aluminum Alloy head casting! We have seen output in the 210hp range with perfect tunes, but normally these are good for 190ish HP. Must have 1 5/8" or better yet 1 3/4" exhaust! Aircooled.Net has sold our L6 heads for over a decade. These heads have a 66-68cc chamber (approximate and depending on bore size as follows:
90.5mm ~66cc92mm ~66cc
94mm ~ 68cc
If you would like a larger or smaller chamber, we can provide this for an additional cost to get your compression ratio just how you want it.
These heads feature a recently developed new head casting, featuring 12mm x 3/4" Reach plugs (which prevents cracks at the plug threads), Hi Chrome Valve Seats, 42 x 37.5mm Stainless Steel Valves, Silicone Bronze Valve Guides, HD Dual Valve Springs, Chromoly Keepers and Retainers, then finished with a top notch valve job.
These flow so well you MUST get rid of the stock heater boxes, and go with AT LEAST 1 5/8" exhaust, 1 3/4" is even better to utilize the flow capability of these heads! Failure to heed this advice can result in difficult (IMPOSSIBLE) tuning issues, and likely cylinder head overheating.
ACN L6s flow over 210cfm on the intakes at .600" lift, and almost 200cfm at .500" Lift! This creates an incredibly wide and strong power band and torque curve that is hard to comprehend! In fact, these L6s are a top shelf cylinder head, laying waste to most "High Performance" cylinder heads available elsewhere. You absolutely MUST have the cam, exhaust, and intake to go along with them. In fact, this head used to cost around $1200/pair, but the CNC porting and chamber work has dropped the price to where it is now!
Dual 2bbls with venturis in the 40-42mm range are best in your carburetion of choice, dual 45s or 48s will work best (DRLA, IDF, or IDA)! Combustion Chambers are approximately 62cc in basic form, note that these chambers do NOT have the "Step" present, which makes your calculations and assembly easier! We can fly cut the chambers to the head cc you desire, contact us for details
With these heads we recommend valve lifts in the .550-.600" range, which is where they will perform at their best.