ACN Road Warrior Dual Port Cylinder Heads, (L5 heads) 40 X 35mm Valves, PAIR are based on a brand new Revmaster 049 head casting, made from aircraft aluminum alloy! We have seen output in the 180-190hp range with perfect tunes, but normally these are good for 160ish HP. Must have 1 5/8" exhaust! Aircooled.Net has sold our L5s for over a decade, and these are now based on an imported casting, with larger ports than stock, along with a top notch valve job! These come cut with 12mm x 3/4" Reach spark plug threads too!
Depending on the bore size you select, chamber size will be the following approximate sizes:
85.5mm, 87 and 88mm Slip Ins ~ 58cc
88mm ~ 60cc
90.5mm, 92mm and 94mm ~ 64cc
If you would like a larger or smaller chamber, or need/want a specifically machined chamber volume, we can provide this for an additional cost to get your compression ratio perfect!
Aircooled.Net has sold the L5 cylinder head for over a decade, and now they are IMPROVED, being based on a recently developed new head casting, featuring 12mm x 3/4" Reach plugs (which prevents cracks at the plug threads), Hi Chrome Valve Seats, 40 x 35mm 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 a 1 5/8" exhaust, or you'll wind up with difficult (IMPOSSIBLE) tuning issues, and likely cylinder head overheating.
ACN L5s flow over 190cfm on the intakes at .600" lift, yet over 180cfm at .500" Lift! This creates an incredibly wide and strong power band and torque curve that is hard to comprehend! In fact, these L5s are the best HP/Dollar you can buy for your engine, assuming you have the cam, exhaust, and intake to go along with them. In fact, this head used to cost over $1k/pair, but the CNC porting and chamber work has dropped the price to where it is now!
Dual 2bbls with venturis in the 36-38mm range are best in your carburetion of choice, whether it's dual 44s, 45s, or 48s! Combustion Chambers are approximately 64cc in basic form, note that these chambers do NOT have the "Step" present, which makes your calculations and assembly easier! We can flycut the chambers to the head cc you desire, contact us for details or assistance.
With these heads we recommend valve lifts in the .450-.550" range, which is where they will perform at their best. If you insist on running more lift than this, you should consider our L6 or L7 heads so that your combination matches overall.