Big Power mods for the 8.1 motor!
08-01-2004, 07:43 PM
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Big Power mods for the 8.1 motor!
Are you thinking about doing more than just upgrading your 8.1's induction and exhaust? If so we have some Big Power mods for you! Raylar Engines now has their Big Power series of modifications available for the late model GM big block. These include a set of aluminum cylinder heads that will increase horsepower and take about 100lbs off the front of your truck. Combining these with their Cool Gap intake and cam will get you into the 500 horsepower range!
Cylinder head specifications
Applications: GM 8.1 liter 8100 vortec (L18) engines
Mercury Marine 496MAG or 496HO
GM vortec Marine HP1, HP2, HP3 versions
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.
The "Cool Gap" manifold is engineered to maximize the horsepower and torque levels of the 496-8.1 engine in high performance use with our "BigPower" aluminum cylinder heads and camshafts. The stock manifold was designed for low RPM and emissions use, and even with expensive modifications cannot meet the higher air flow demands of this engine in performance use. The "Cool Gap" manifold is the best answer to the 496-8.1 engine's intake manifold breathing problems. This new manifold incorporates long high velocity runners to provide excellent low and mid range torque levels and a large volume plenum to satisfy this engine's demand for more air at higher RPMs.
The "Cool Gap" manifold gets its name from two air gaps one between the engine lifter valley and the manifold runners and one between the runners and the plenum. These keep the incoming air fuel mixtures cool and dense, additionally producing more power and torque over the entire RPM band.
The "Cool Gap" also features a design that allows it to bolt on in the same space as the stock manifold, and accepts all standard fittings, sensors, brackets, injectors, fuel rails, and accessories without additional modifications to the engine or its wiring.
Each of these products can be found on our website. There is also new 1.8 ratio rockers, upgraded 8.1 piston and accessories to go along with the heads.
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ohnomrbillk (02-01-2024)
08-02-2004, 07:39 AM
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You will need more like a T88 than a T76.
My god that intake as SWEET!!!!! The heads are massive!!!!! You can almost crawl through the runners of that thing.
Tbyrne, hurry up and get them on the Burban.
My god that intake as SWEET!!!!! The heads are massive!!!!! You can almost crawl through the runners of that thing.
Tbyrne, hurry up and get them on the Burban.
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08-02-2004, 10:57 AM
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All of these mods can be done by themselves or as a package. You'll see about 75hp from the heads and a set of 1.8 rockers. The intake is good for about 30hp by itself. The mild cam will produce about 25hp over stock while the big one will show you a 50hp increase. Orders placed now should be ablle to ship in about 2 weeks.
The Suburban probably won't see these unless something happens to the motor but... I might scratch the Whipple idea and go with this instead.
Tbyrne, hurry up and get them on the Burban.
08-05-2004, 04:45 PM
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Quick update about this intake. The one pictured above is an early prototype so it shows the throttlebody facing straight out. The new will have the correct angle to mate up to the induction. A large billet aluminum with an oval opening will be available in the next 1-2 weeks. This will flow about 1200 cfm. Life is getting good for the 8.1s now! 
I'll also be installing one of these with the complete package.
A few people have called about the 1.8 rockers. These are a direct bolt-on that will fit under your stock valve covers. They can be installed with no other modifications required. You'll see about 12hp from them.
I'll also be installing one of these with the complete package.A few people have called about the 1.8 rockers. These are a direct bolt-on that will fit under your stock valve covers. They can be installed with no other modifications required. You'll see about 12hp from them.
