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-   -   Best 496 headers? (https://www.offshoreonly.com/forums/general-boating-discussion/152173-best-496-headers.html)

dana marine products 02-26-2007 12:38 PM

To re-confirm, the 496 kits include the Vortex style risers. The picture is due to be updated. The dyno sheets are available for the 496 HO, 496 Mag, and the Raylar 525 converted engine.

The risers are specifically designed to be a Merc replacement. Silent Choice or "S" pipes are not a problem.

There is alot of different systems out there, and I can't say a word about any of them.

What I can say is that we went to great lengths to make our kit make good HP and be easy to install. We had several well known people involved in the development of this kit. We spent alot of $$$ to have accurate dyno numbers and water testing.

There's always going to be questions, but I can tell you, it was not my intentions to spend all this money and time to produce inaccurate or twisted dyno numbers.

Full Throttle Marine has recently purchased two kits and is conducting his own dyno testing. Once completed he will report his results. We're confident his results will be very similar to ours. Hopefully this independent testing will prove that we're not stretching the facts.

Shooter 02-26-2007 01:58 PM

Here's one thing nopt mentioned - the effect taking the turbulator ring out has on estimated hp gains. I understand that is about 10-15 hp an that the manufacturers include this in their overall publication.

I took mine out and it sounds better, but did not notice much - MAYBE another 100 rpm but who knows. Sound was a little better through. I heard this in another thread so if a manufacturer claims 50hp increase over stock - maybe it's more like 35 to 40?

Has anyone dyno'd a stock manifold with the rings out? They do restrict by about an inch on each side.

Undertaker 02-26-2007 02:00 PM


Originally Posted by dana marine products (Post 2039277)
To re-confirm, the 496 kits include the Vortex style risers. The picture is due to be updated. The dyno sheets are available for the 496 HO, 496 Mag, and the Raylar 525 converted engine.

The risers are specifically designed to be a Merc replacement. Silent Choice or "S" pipes are not a problem.

There is alot of different systems out there, and I can't say a word about any of them.

What I can say is that we went to great lengths to make our kit make good HP and be easy to install. We had several well known people involved in the development of this kit. We spent alot of $$$ to have accurate dyno numbers and water testing.

There's always going to be questions, but I can tell you, it was not my intentions to spend all this money and time to produce inaccurate or twisted dyno numbers.

Full Throttle Marine has recently purchased two kits and is conducting his own dyno testing. Once completed he will report his results. We're confident his results will be very similar to ours. Hopefully this independent testing will prove that we're not stretching the facts.


Very well said, can not wait to get mine installed and the boat in the water to do some testing.

Jaime is my boat done yet....LOL


Undertaker

Undertaker 02-26-2007 02:03 PM


Originally Posted by Shooter (Post 2039348)
Here's one thing nopt mentioned - the effect taking the turbulator ring out has on estimated hp gains. I understand that is about 10-15 hp an that the manufacturers include this in their overall publication.

I took mine out and it sounds better, but did not notice much - MAYBE another 100 rpm but who knows. Sound was a little better through. I heard this in another thread so if a manufacturer claims 50hp increase over stock - maybe it's more like 35 to 40?

Has anyone dyno'd a stock manifold with the rings out? They do restrict by about an inch on each side.


I was told taking the turbulators out gives you nothing noticeable. Jaime sent me a great picture showing the minimal restriction with the tubulators in......

Undertaker

Chris288 02-26-2007 03:20 PM

I have read many threads saying that taking the turbolators out is good for 10-15 hp, most boats require 10-15 per extra mph, so you may gain 1mph or so. If these exhausts claim 45 or so hp, your really only getting 30 or so because of removing the turbolators.. so like most real time numbers I have seen an exhaust change will net about 3 mph...

Shooter 02-26-2007 06:09 PM

1 Attachment(s)
I would much rather have a CMI setup but I have heard the 496 exhaust is made by Gil and they are very good for stock. I polished mine and removed the rings. They say that they are more for colder climates - I'm in Fl.

LAKESIDE RESTORATIONS 02-26-2007 06:10 PM

2 Attachment(s)
Here are pics of the tubulators that some one else here had posted a while back in some other thread.. The turbulator removal on its own really wont net much Hp at all on this 496 set up. The manifold & riser are tapered & machined out to accept a turbulator that wont really restrict the flow. The problem is however that the actual exhaust exits could be a little largetr overall & The biggest thing is the need for longer & tuned runners. On the Gil offshore systems that were used on the 500hp's the turbulator removal may net you a little more hp in some circumstances, but still nothing like the DMP units or CMi set ups will do. ;) :)

Jamie / Lakeside

.

LAKESIDE RESTORATIONS 02-26-2007 06:19 PM


Originally Posted by Shooter (Post 2039701)
I would much rather have a CMI setup but I have heard the 496 exhaust is made by Gil and they are very good for stock. I polished mine and removed the rings. They say that they are more for colder climates - I'm in Fl.

Nice job on polishing the factory risers.. :) It looks good.. :)

Yes the stock Merc exhaust is not bad on the 496, BUT it can be improved upon as mentioned earlier.. One of the reasons that many say it is good for a stock system is that compared to the old full cast iron manifold & cast iron riser it is an improvment in weight & performance..

:) Jamie / Lakeside

Shooter 02-26-2007 06:22 PM

Agreed,

I was taking off the riser to polish them, if not I would have left the rings alone. When it comes time for a rebuild, I'll be doing the full monty - along the lines of a Raylar along with pipes.

LAKESIDE RESTORATIONS 02-26-2007 06:23 PM


Originally Posted by Undertaker (Post 2039351)
Very well said, can not wait to get mine installed and the boat in the water to do some testing.

Jaime is my boat done yet....LOL


Undertaker

:D I need to clone myself.. lol..:drink:

You are on the list ;) .. Didnt you also get snow & ice last night & today as well??.. Maybe we should install a set of skates or skis on the thing.! :drink: :evilb: Jamie / lakeside


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