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This is a BIG POWER mod for your 8.1 motor! You'll be able to pick up 40+ horsepower and also take 100 lbs off the front of your truck with these aluminum cylinder heads.

Cylinder head specifications

Applications: GM 8.1 liter 8100 vortec (L18) engines
Mercury Marine 496MAG or 496HO
GM vortec Marine HP1, HP2, HP3 versions
Volvo Penta Marine GS8.1& GSX8.1 engines
Crusader 8.1 &8.1HO Captains’ choice engines
Indmar 8.1 & 8.1HO Malibu,Mastercraft engs.
Materials: Lightweight a356T56 Alcoa alloy aluminum
Heat treated and hard anodized for marine use
Method: Smooth cast

Machining: all required machining on 5 axis CNC centers
Valve seats: super alloy hardened high strength steel
Valve guides: manganese silicon bronze
Valve seals: super viton in steel "top hat" bodies
Valves: stainless steel EV8 with 11/32" stems, high flow necked stems with black nitride strength treatment after fabrication.

Valve sizes: Intake valve 2.20" x 12degree w/11/32" stems
Exhaust valve 1.725" x 20 degree w/11/32" stems
(Optional Inconel 1.725 exhaust valve x 20 degree avail.)
Rocker arm studs: Hardened steel with 8MM x 1.0 threaded top with
thrust nut base for mounting stock rocker arms with stock nuts, or
(optional) Raylar Stainless roller rocker arms with "all the way down"
adjusting nuts.

Intake Ports: 315cc. High velocity-High flow smooth ports
Exhaust Ports: 135cc.High velocity-High flow smooth ports
Complete Assembly: Includes:
Valves-intake & exhaust
Springs, retainers and locks
Valve stem seals, valve guides
Rocker studs and guide plates
Complete 5-angle valve job with
Back cut valves with special margins and radiuses.

Price - $2799.99 - free UPS ground shipping is being offered for all heads that are pre-ordered. We expect to start shipping these sometime in April!

A totally new intake manifold is in the late stages of development. It will allow much better airflow into this engine at all operating RPMs and allow it to develop more power and efficiency when combined with the new cylinder heads. This manifold will not create any added space considerations nor will it require any modification to stock or aftermarket marine configuration sensors, senders, injectors, fuel rails, brackets or hardware. Horsepower gains for the top end upgrades (heads and intake) will be in the 60-65+ range. More exact numbers will be available soon!

Other 8.1 products that you'll be seeing in the springs are - more aggressive cam grinds along with 1.8 ratio rockers.

Tom



Order line - 1-877-4-TBYRNE
E-mail - [email protected]


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