Re: Removal of 496HO restriction plates
 

He did say a 15 hp gain without them. I took mine out last spring and not sure if I noticed much, but at least good to know in my head that I've freed up 30 hp on twins. :D

Re: Removal of 496HO restriction plates
 

Yeah,this is getting a little confusing,I was referring to the guys math where he figured 40 hp over stock from eddie marines cast manifolds claim of 10% gain in the other thread I was refering to. Raylar was very skeptical of that big of a gain from 2000$ cast manifolds and I garnered from what he was saying that they were definately comparing there gains to stock un-modified factory manifolds. I wasn't referring to the cmi's,BUT, I will say if I had a 496 ho in something I'd just spend the money and get the cmi's for there very impressive gain over stock,it sounds like they really put some development in them,Smitty

Re: Removal of 496HO restriction plates
 

Picture of plates

http://www.offshoreonly.com/forums/s...d.php?t=122974

Re: Rework of Merc 496 manifolds!!
 

We kind of decided to go ahead and offer a fix for the Merc 496 manifolds that some not so deep pocket boaters can afford. We have done a lot of flow bench work on the Merc 496 stock aluminum manifolds on our heads and we have developed a CNC program where we can run existing manifolds thru our 5-axis CNC machine and add some pretty nice cfm flow enhancements. This should also be very helpful to the guys worried about warranties and those adding superchargers and other power upgrades. We will be offering these reworked manifolds on an exchange basis at a very affordable cost. I will post the actual pricing very soon. Any body who has some stock manifolds around email sales @ raylarengine.com and we will most likely be buying up a few sets to get ahead of the demand. Again, Raylar tries to meet the simple needs of 496 owners without "deep-pockets"!!

Regards,
Ray @ Raylar

Re: Rework of Merc 496 manifolds!!
 

What kind of hp gains are you seeing with your manifold work along with removal of the restrictor plates?

Also how much for the exchange on a set?

Re: Rework of Merc 496 manifolds!!
 

Sounds like an interesting proposition. How are you doing the porting??? Extrone Honing would probably work well. Please keep us posted summer is almost here, that would be nice to get done before the season. Best part is it will be a simple swap over, no parts relocation...

Re: Removal of 496HO restriction plates
 

The porting and recontouring is done by 5-axis CNC maching as I previously mentioned. Extrude hone can not properly open the port at just ideal locations and unless you've priced it lately it's way to "Damn Expensive". You guys really like to come up with ways that waste money don't you? Yes these manifolds will be ready for interested parties in April.

Ray @ Raylar

Re: Removal of 496HO restriction plates
 

Ray,any idea of HP gains and cost of rework to the exhaust for those of us who would like to wait until April for your product. Also would a ECM reprogram be a good addition to the header rework?
Thanks, Tony

Re: Removal of 496HO restriction plates
 

Again, how about hp gained and exchange price?

Re: Removal of 496HO restriction plates
 

Nice Ray! Keep it coming. Also congrats on the Powerboat Magazine article on your new 700hp N/A beast. Did GM design a whole new block for you or just overbore the block for you?

Re: Removal of 496HO restriction plates
 

Thank You. No, we had GM use special rework to a special GM racing block so we could configure it as what we now call a GEN 7 symetrical aluminum head engine foundation. We are very proud of this motor and its mild manners, affordable pricing and phenominal braod torque based power. This new engine will also usher in something new to the industry. A motor that is delivered to the owner with its own ECM programming software so an interested owner or builder can take his laptop and fine tune his motor on the "fly" if he so chooses.

Re: Removal of 496HO restriction plates
 

Ray,, what about the stock exhaust re-work questions.. mainly price and expected hp gains..

Re: Removal of 496HO restriction plates
 

Chris:
Patientence my man! We are doing the flow testing now and what I can tell you at this point is that there are four seperate exhaust passages in the stock Merc (Gil) 496 manifold. All three are substaintilally different in the size of the openings under the riser. One will flow 240 cfm, one 202 cfm, one 180cfm and another 205 cfm. This in-balance coupled with low flow on three of the four ports hurts horsepower and is definitly improveable. We have done some minor porting on these in the past and seen 5-10HP gains on our 525Hp motors on the dyno. We are now carefully studying and reworking all four ports to flow about 250 cfm and in the next week or so we should get back on the dyno with a pair and really document the gains. Once we have done this and confirmed there is some realistic power improvement here for the dollar spent, then we will release the real gain numbers and the cost for the exchange manifolds. I suspect its going to be in the $400-$500 per pair exchange range, but thats a guesstimate and only if its worthwhile. Nothing before its time! Stay tuned I'll keep you guys posted.

Ray @ Raylar

Re: Removal of 496HO restriction plates
 

As always, thanks for the info Ray !! :)

Re: Removal of 496HO restriction plates
 

I'm still interested in some ideas on who to try calling around here out of the phone book for polishing the risers out?

Re: Removal of 496HO restriction plates
 

Does this info apply to the older Gil bbc manifolds as well?

Re: Removal of 496HO restriction plates
 

No, not the older Gil HP manifolds. they are a different design than the new Merc 496 manifolds and do not have the same port restrictions. The Merc 496 manifolds were designed and built by Gil for Merc.

Ray @ Raylar

Re: Removal of 496HO restriction plates
 

Thanks for the reply, not familiar with the new stuff.

Re: Removal of 496HO restriction plates
 

Ray, hows the progress on the reworking of the stock exhaust manifolds for the 496ho's? great idea, hope it works. Lets us know as soon as you get anything.
Thanks.

Re: Removal of 496HO restriction plates
 

Ray, any update on the worked exhaust manifolds? Went to your website, and found no info.

Thanks

btt

Reworking 496 manifolds by CNC
 

We were already to release a CNC'd program for upgrading flow on the original all aluminum Merc 496 exhaust manifolds when the "boys' at Mercruiser decided in 2006 to start using an all iron exhaust manifolds instead of the nice aluminum units, which made spreading the long term costs and trouble of our exchange CNC program an unprofitable curve. Considering for single engine applications the Dana actual header manifold can be purchased in complete kit form for about $2600 polished and they produce about 20 more horsepower than our CNC'd stock manifolds its kind of a "no brainer"! Buy a quality aftermarket exhaust like Dana or CMI and loose the stock manifolds (especially the heavy new iron versions) if you really want a reasonable power increase and serious better looks!

Best Regards,

Ray @ Raylar

I took mine out. Sounds much deeper, like a 500, I like the exhaust note. I picked up about 1.5 mph. Pretty good for $0invested.

As an update to the question of turbulator removal, here's a link to some actual dyno results.

http://fullthrottlemarine.com/496%20...%20Article.htm

Bob, as always thanks for the information. Thanks also for having a great shop so close to home. You guys do great work, and at very reasonable rates. Its been a pleasure doing business with you guys. BTW, finally hit the magical 70+ on the GPS, and it was 90 degrees.