Raylar Performance Parts FAQ

Raylar Cylinder Heads

Why are Raylar's aluminum cylinder heads better than stock or aftermarket iron cylinder heads?

Cast iron heads are designed with cost as the number one priority. Factory cylinder heads use heavy steel valves and components that are not designed to produce good power. Iron heads don't dissapate heat and develop detonation problems at higher than 9.0 to 1 compression. The ports and combustion chambers are not optimized to flow high volumes of air and cannot be properly enlarged or reshaped to provide correct port velocity. Raylar aluminum cylinder heads out-flow every other head on the market. For large displacement applications requiring even more airflow, we offer our CNC Extreme aluminum cylinder heads which flow over 400cfm!

Will the Raylar Big Power aluminum cylinder heads fit my marine engine?

The aluminum Big Power head is designed and built to install on any 496 / 8.1L Vortec 8100 engine package. All stock exhaust, aftermarket headers, marine manifolds, brackets, cooling systems, sensors and hardware will install right back where they were mounted on the stock iron head.

Are special head gaskets required to install Raylar heads?

Yes, Raylar is making a premium MLS stainless gasket that we recommend for a better fit around our combustion chamber. Our stainless gasket kit holds up better in marine applications and are also less expensive than the stock GM gaskets.

Will I have to buy a lot of pieces to make these heads fit my engine?

No. The Big Power cylinder heads are designed to use factory push rods, rocker arms and hardware from your stock heads. Your coil on plug valve covers and all other exterior cooling fittings and manifolds will install on the Big Power heads with no modifications or additional parts. The factory head bolts are a torque-to-yield style bolt designed for machine assembly and should not be reused! Rather than buy new expensive, difficult to torque by hand head bolts we offer high-strength, re-usable ARP head bolts at a lower cost to you than the factory head bolts!

Raylar Performance Kits

Do marine engines need ECM reprogramming?

NO! Our dyno testing has shown that the Crusader Captains Choice 8.1 MPI / 8.1 HO MPI, Mercruiser 496 / 496HO, Volvo Penta Gi /GXi and Vortec 8100 8.1L do not require reprogramming when equipped with our Big Power cylinder heads, intake manifolds and cams. The speed density controlled systems as equipped on these marine engines require only a fuel pressure setting increase to provide new power levels!

Do street engines need ECM reprogramming?

Yes. The computer which controls these engines will need to be reprogrammed after any Raylar parts have been added to them to ensure maximum performance.

Where can I purchase a Raylar marine 525HO / 600HO / 750HO / SRC800 engine?

Due to our ever expanding customer base and limited amount of storage space, we no longer sell complete engines. However, we still offer all of the parts necessary to build your own version of any of our complete engine packages.

Will all my stock engine sensors, wiring, fittings, exhaust system and covers reinstall in the same locations without modifications?
Will the new heads and intake manifold fit in the same space as the stock pieces?

Yes. These new parts were specifically engineered to bolt back in place of stock components without requiring modifications to engine exhaust, wiring harnesses, plugs, sensors, brackets or mountings. Just bolt on and go!

Will Raylar kits install on my boat or truck without major rework of existing systems and components?

Yes, Raylar's philosophy of "keep it simple" engineering has been used to engineer kits and components that are designed to go right in place of stock components with simple "Plug and Play" installation. Electronic wiring, ECM's and brackets fit and are re-used in ways designed to make the installation of Raylar kits simple and easy. Raylar components are designed to fit stock engines without fabrication and with minimum labor and difficulty.

Can I install a Raylar engine kit myself, or can a regular mechanic complete such an installation?

If you have good engine overhaul or service experience on similar engines and have access to good tools and equipment, then you or any qualified mechanic should be able to install a Raylar engine kit or component by just following the detailed instructions that are shipped with every kit.

Will installing the Raylar kit shorten the life or reliability of my engine?

Raylar's components and systems are direct replacements for the components of your engine. They have been engineered, designed and tested to insure that they give a service life and quality of construction that are equal to or better than the life of the original components. Today's finest materials and technologies were used in the manufacture of our products as well as those manufacturer's products we incorporate into our kits. If your kit is properly installed on your engine and your engine is serviced according to the manufacturer's recommended service requirements and the engine is not abused or used in a racing or competition use then engine life will be equal to or greater than if it were still in a stock configuration.

Will installing Raylar kits or components void my manufacturers warranty?

Raylar wants to be careful in informing its customers and users that any modification to their engines will most likely be a reason for their original manufacturer to void a warranty if a mechanical engine failure or damage has occurred after installing Raylar components. This is not because the Raylar components cause failure, but because of the conditions of their warranty. We at Raylar warranty our components for one year as our parts warranty and we will carefully investigate the source of any failures, and we will also inform our customers as to what our determination for any failure that occurred. You the customer will have to decide whether you wish to install Raylar components on your engine prior to the end of a warranty period. We ask that customers also make necessary checks to their engine prior to installation of a Raylar kit. This is also an opportunity for the customer to make a valid warranty claim with their manufacturer for the engine if defects have shown up.

What fuel or octane level is reccomended for Raylar performance kits?

Raylar engine kits are designed and tested to use the same level of fuel or octane that was required by the original equipment manufacturer. The more efficient combustion and efficiency of Raylar kits does not require additional engine timing advance or octane requirements to prevent engine knock or detonation. Therefore you can keep using the same type of fuel you have elected to use in your motor as long as it meets the engine manufacturer's minimum requirements.

Do Raylar performance packages have rough idles, un-smooth acceleration or drivability issues and increased noise levels?

No, the Raylar performance kits are designed with components and settings that allow a stock idle rpm level that is smooth and quiet. The acceleration and power of your motor will increase but normal driving conditions will appear as before, except you will be able to feel the increased power and torque levels during acceleration and wide open throttle uses. You will also notice that the increased power levels will allow you to cruise at normal speeds in a boat at less RPM's due to the efficiency increases developed by the Raylar kit. In trucks and vehicles, you will notice increased acceleration and in most cases, less pedal effort will be needed to achieve the cruising speeds. In both cases, this should result in better fuel efficiency when operating at all but heavy throttle use.

Does the Raylar kit come with all the parts needed for my installation?

In most applications, the Raylar kit or the components on your existing engine contain most all the parts and hardware needed to do a complete installation. Raylar kits are assembled with the additional components that are not being re-used from you original engine. Most of the gaskets on the 496 / Vortec 8100 8.1L engine are designed to be re-used depending on their age and condition. If these components and gaskets are carefully removed and cleaned for proper re-installation, the Raylar kit will require that only a tube of GM gasket sealer and possibly coolant is required to complete the installation.

Iron Cylinder Head Questions

What about Dart's iron cylinder heads?

Dart's Iron Eagle heads are great parts but are sold bare. None of the stock 8.1 iron head parts fit. After you buy the cylinder heads, you also have to buy all new valves and spring components, adding cost. They also still weigh 76 LBS each! Our aluminum cylinder heads weigh 38 LBS, flow more air, provide better heat transfer, have higher compression and won't smash your fingers like the heavy iron heads do.

What about porting the stock cylinder heads?

The stock iron heads can be ported and cleaned up, but will never be able to match the air flow of the Dart or Raylar heads because of the thin wall casting and short side radius.

What roller rockers can I use on the 496 MAG / 8.1L?

Any BBC 1.7 roller rocker will fit on 496 / 8.1L cylinder heads with ARP studs - but they will not clear the stock valve covers. You will have to make custom valve covers or find spacers to raise the valve covers, which may leak. What a pain!
If you don't want to use ARP studs, your machine shop can cut down your polly locks and studs to fit under the valve covers, but there is a great deal of trial and error fitment to make this work.
In all out race engines, stud girdles are great additions for valve train stability. Crower makes shaft mounted rockers for the 496. They are wonderful parts which look like jewelry and run about $1500 for a set. For any engine not in an extreme racing application, its much easier to install Raylar's stainless steel roller rocker kit and be done in 45 minutes.

General 8.1L / L18 / 496 Information

What is a Vortec 8100 8.1L engine?

The Vortec 8.1L represents the 7th generation of the big block chevy engine. The 8.1L is very similar to previous generations of the Chevrolet big block, but a few changes were made to modernize the engine. The key difference in the 7th generation big blocks are the unique cathedral port cylinder heads.

How much does an 8.1L weigh compared to an LSX?

A complete Vortec 8.1L weighs 761lbs. A complete iron block LSX weighs 525lbs and the alumnium block LSX engines weigh 435lbs. It is important to note that the stock 8.1L iron heads weigh 87lbs each! An 8.1L equipped with Raylar alumnium cylinder heads weighs 657lbs.

What are the real weak links in my Vortec 8100 8.1L / 496 engine?

The GM Vortec 8100 8.1L / 496 engine has been tested extensively by GM, Crusader, Levitator, Mercury Marine, Volvo, Raylar and others and have shown tremendous durability and reliability. They are amazingly strong and reliable when it is operating within the designed RPM and horsepower limits. Normally aspirated 8.1L engine applications exhibit excellent engine life and rebuild ability in applications up to 600HP.

stock vortec mercruiser piston damage Supercharger Piston Failures: In supercharged or performance applications with the factory recommended fuel octane levels, many engines have experienced detonation problems which usually show up with piston failure. The Vortec 8100 engine's cast aluminum pistons are not designed for supercharger use and frequently fail in these applications. Don't replace a weak piston with another weak piston! Get rid of your cast pistons with custom made forged pistons and H-beam connecting rods that use the .990 wrist pins instead of the unsupported stock metric wrist pins. Our rotating assembly parts need to be balanced by your machine shop, as they are lighter than stock cast pistons and rods. For any performance oriented build, forged pistons and connecting rods like those available in our engine kits will ensure maximum reliability.

Crankshaft: The standard cast iron crankshaft in the Vortec 8100 / 496 MAG & HO will handle up to 550 horsepower. Early 496HO engines were equipped with a steel crankshaft which will handle 700hp, but they are rare. We offer two forged stroker crankshafts packages, which will allow you to convert your stock 496cid into a 540cid.

What are the torque specs for the 8.1L Vortec 8100 / 496 engine?

Please refer to our torque spec sheet here.

How do I install the cool gap intake manifold on the 8.1L Vortec 8100 / 496 engine?

Please refer to our intake gasket installation sheet here.

How do I install Raylar's roller rockers on the 8.1L Vortec 8100 / 496 engine?

Where can I find instructions on how to install Raylar performance kits on the 8.1L Vortec 8100 / 496 engine?

Please refer to our 103 kit installation manual here.

Want Even More Power?

Modified Intake Power Gains

The stock intake manifold really chokes the Vortec 8.1L engine back. Our intake manifold modification removes all restriction from the intake system, allowing your engine to breathe properly and produce better power - everywhere in the powerband.


Vortec 8.1L Intake Manifold Modification

vortec 8.1l 496cid intake manifold porting Intake Manifold Modification - $950

For trucks not requiring maximum high-RPM airflow, we can modify your stock 496 / 8.1 liter intake manifold. This intake modification will increase airflow to your engine, still retain stock looks and passes emissions. We remove the stock plenum blockages inside the manifold to reduce restriction and free up horsepower and smooth the individual intake runners. Intake manifold modification does not replace the Cool Gap manifold but does offer about 80% as much airflow. Intake manifold modification will show gains throughout the RPM band.

How Much Air Do Raylar Heads Flow?

Raylar big block Chevy / GMC cylinder heads out flow every 8.1L cylinder head on the market. Below are flow numbers for our standard Raylar CNC heads and our special-order CNC Extreme cylinder heads. We’ve included the Dart Iron Eagle 8.1L cylinder head in both 4.5 and 4.26 bores for comparison. Click on the image to see a larger version.

raylar aluminum cnc cylinder head flow

Vortec 8100 / 8.1L 496cid Pistons

The stock Vortec 8.1L cast pistons are not designed to withstand the forces of aggressive boost use. We routinely see engines with cracked, chipped and even shattered pistons which result in catastrophic engine damage. Our stage 2 kits come with fully forged components, ensuring maximum reliability and performance.

Raylar Stage 2

Raylar Stage 3