porting of heads on 496HO
 

I read elsewhere an engine builder claiming a 60 hp increase by porting the stock heads on a 496HO and retaining the stock ecm. Does this sound possible?

Re: porting of heads on 496HO
 

He must be increasing the fuel pressure then.
The heads are the key to producing HP but they are only part of the equasion.

Re: porting of heads on 496HO
 

Its very doubtful that just porting 496 iron heads will add 60HP We developed a new all aluminum head with awesome flowing ports, velocity and 1 point more compression and thats about what we saw in added horsepower from the heads only. Also if you see our cutawys of the stock 496 iron head you would have to be crazy to start porting them. In some locations the port walls are only .060 thick. There are a few who have tried and ended up with water filled motors.
Good Luck!! Hope you got money for a new motor!
Raylar

Re: porting of heads on 496HO
 

Rylar
What else would you need to change, if anything, by adding a set of your heads on a 496 ho?

Re: porting of heads on 496HO
 

A tech asked me if I wanted to raise the rev limiter on my 496 mag ho to 5450 rpm the last time I was in for service. Would this be ok if the engine has the stock heads?

Re: porting of heads on 496HO
 

I would not raise the rpm limit on stock 496 with stock heads above 5200 rpms. the stock springs are not the greatest pieces and the valves are on the edge from a heavy weight standpoint.
Sutphen 30: our heads have a completely redesigned intake port. The humps are gone the short side is radiused, the roof is raised, the port floor is raised and that crazy step is gone with a whole new bowl and seat design. Our head flows 360cfm at .600 lift on a 2.19 valve and a 295cc port so you can imagine the velocity numbers we have as well as a lot of swirl and tumble. We could not ever figure out the step, I guess they were trying for swirl, but all they did was screw up the port bowl area.Some times GM engineers get a little carried away with their experiments. Our heads will run on any 496 and improve the power levels, however they flow so well that at about 4000rpm, the factory intake manifold runs out of air, thats why we had to build a new manifold. Then we realized the cam needed a whole new profile and timing change to match the components. this is how we got to our current kit.
If anybody is serious about upgrading their 496, take the iron heads, remove a valve, tie on a rope or chain and use them for a boat anchor, get the idea!
Ray @ Raylar

Re: porting of heads on 496HO
 

Raylar,
Knowing the stock springs and valves not being the greatest, when should they be replaced.

Re: porting of heads on 496HO
 

Ray,
Can you run a intercooled 3#'s of boost with your heads inplace of your intake?

Re: porting of heads on 496HO
 

The stock springs and valves are ok as long as you don't buzz them a lot over 5200rpm. they should last the life of your motor to the first rebuild. they are single springs and they don't get hot and need replacing. The problem is they only have about 90lbs. seat pressure closed and with the factory heavy valves they will start acting up with some valve bounce over 5200rpms for long periods.
With our heads you can run three punds of boost if your ECM has been properly reprogrammed for a supercharger. The only question will be on any supercharged 496 is how long the factory piston will last. When they fail, it tends to be ugly and expensive. Best bet is to replace the factory pistons with forged supercharger pistons and rods, then you can run 5-7lbs of boost and really make some power.

Ray @ Raylar

Re: porting of heads on 496HO
 

Thanks Ray.

Re: porting of heads on 496HO
 

What about extrude hone? How much does it help?

Re: porting of heads on 496HO
 

not to change subject I have 496hos with wipples 354 hrs turning 5400 rpms no problems also run 7 lbs boost bob 412781-0881

Re: porting of heads on 496HO
 

raylar so just adding your heads and roller rockers will give the 496 ho how much prop hp ? also what year ho's have the restrictor plate under the exhaust manifolds that you recommend taking out ?

Re: porting of heads on 496HO
 

Can't extrude hone the stock 496 manifold because of the twists, walls, inside plenum, etc.
Our heads, manifold and cam kit increase a stock 496 to an honest 525HP. It takes the manifold and cam to do it because the heads outflow the stock manifold above 4000rpms.
This is all accomplished without reprogramming the Mercury PCM555 ECM. All of the 496's we have seen have the restrictor plate between the two gaskets under the risers on the 496's.
Ray @ Raylar

Re: porting of heads on 496HO
 

raylar then the heads alone with roller rocker change will not get me any more hp?I noticed you sell this combination as one of your kit choices , what would be the hp gain with these items ?

Re: porting of heads on 496HO
 

Hi, Folks!

Raylar, could you send me an offer for that Heads ? [email protected]

And, by the way, what kind of intake is to use to try a x-71 Blower on it ? Is there any shop ? Or does only whipple works ?

Re: porting of heads on 496HO
 

We had a customer contact us recently regarding the Raylar 496 upgrade package. We considered the fact that the heads are “clean sheet of paper” design, without engineering compromise, and the cam/valve train and intake systems were individually designed from the ground up to insure performance and compatibility. We were impressed the amount of R&D, dyno time, and reliability testing invested in the complete system prior to market release and the fact that companies like Reher-Morrison, Profiler, Cometic, and Mahle partnered in the development. We concluded that a reliable 100-150 HP increase, depending on your base engine, was hard to beat, especially at the price point offered. Looking forward to getting on the dyno with this combination.
Bob

Re: porting of heads on 496HO
 

raylar can you please answer the question above about just your heads and roller rocker kit ?

Re: porting of heads on 496HO
 

I think he answered it above with "It takes the manifold and cam to do it because the heads outflow the stock manifold above 4000rpms." Unless there's something more you're looking for.

Re: porting of heads on 496HO
 

sear ray jim if you go to raylars website he sells afew different kit combinations so if he's saying you need all the parts to make it workand get the 525 hp , then why sell it different ways ?

Re: porting of heads on 496HO
 

We sell the parts different ways because some customers want to do their upgrades in steps and some want the whole "banana". Also some gear heads just can't stand it if they just can't tinker with things so we sell them whatever they want within reason. If you have a good solid stock 496Ho and you want 525+HP just buy the full kit, follow a few simple instructions with some secret mods and you will have an honest, reliable 525HP torque monster on your hands. You might want to read my Sunday 1-17 post under the "difference between a 496Mag and HO " post about one of our just completed project boat tests at Lake Havasu, Arizona on Saturday, 1-16.
Ray @ Raylar