496 Exhaust restriction picture
#1
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496 Exhaust restriction picture
Here is a cut away picture of the stock manifold on the 496 HO. Clearly shows the restrictor that many are talking about here on OSO. I can see why the CMIs add 50-60hp. Restrictor.
Last edited by Pismo10; 02-20-2006 at 03:11 PM.
#2
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Re: 496 Exhaust restriction picture
Is it just me or is the restrictor actually just necked down to the size of the riser/collector.
From this picture it doesn't look like removal of the plates would really have that much of an effect.
What does come to mind is that maybe a set of better flowing 3+ inch inside diameter risers would wake these up a bit if increasing hp. You could also ward off reversion with a bit longer riser as well.
Just some thoughts...
Ray?
Dave
From this picture it doesn't look like removal of the plates would really have that much of an effect.
What does come to mind is that maybe a set of better flowing 3+ inch inside diameter risers would wake these up a bit if increasing hp. You could also ward off reversion with a bit longer riser as well.
Just some thoughts...
Ray?
Dave
#3
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Re: 496 Exhaust restriction picture
Doesn't look like too much of a restriction at all. Looks like it's just an exhaust guide to nozzle and smooth the flow. If you remove it, now you have a bumpy, jagged transition - might cause turbulence and other issues?
I've heard of people removing them....What are the real life gains?
I've heard of people removing them....What are the real life gains?
#4
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Re: 496 Exhaust restriction picture
Originally Posted by Nordicflame
Is it just me or is the restrictor actually just necked down to the size of the riser/collector.
From this picture it doesn't look like removal of the plates would really have that much of an effect.
What does come to mind is that maybe a set of better flowing 3+ inch inside diameter risers would wake these up a bit if increasing hp. You could also ward off reversion with a bit longer riser as well.
Just some thoughts...
Ray?
Dave
From this picture it doesn't look like removal of the plates would really have that much of an effect.
What does come to mind is that maybe a set of better flowing 3+ inch inside diameter risers would wake these up a bit if increasing hp. You could also ward off reversion with a bit longer riser as well.
Just some thoughts...
Ray?
Dave
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Re: 496 Exhaust restriction picture
Below is a quote from Ray@Raylar on the subject.
"We have tested quite a few and we know along with various headers systems how they all tend to affect power output of the 496MAGS and HO's These plates can be removed in stock 496's and because they restrict the exhaust opening diameter from 3-1/4" to just about 2-1/4" in diameter and with this restriction they have a moderate affect on the power of the engine especially above 4000 rpms. We have seen about 10 to 15 addtional horsepower at 5000rpms on the dyno and there are several boaters who have removed them and seen measurable increases in power and speed."
http://www.offshoreonly.com/forums/s...&highlight=496
"We have tested quite a few and we know along with various headers systems how they all tend to affect power output of the 496MAGS and HO's These plates can be removed in stock 496's and because they restrict the exhaust opening diameter from 3-1/4" to just about 2-1/4" in diameter and with this restriction they have a moderate affect on the power of the engine especially above 4000 rpms. We have seen about 10 to 15 addtional horsepower at 5000rpms on the dyno and there are several boaters who have removed them and seen measurable increases in power and speed."
http://www.offshoreonly.com/forums/s...&highlight=496
#6
Re: 496 Exhaust restriction picture
The reason why the restrictor plate are build in is to prevent water reversion. Under run it gets really hot caused to the thin sheet metal and non cooling area and will catch the water and steam it out. Just an insurance from factory
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Re: 496 Exhaust restriction picture
Originally Posted by fbh-velocity
The reason why the restrictor plate are build in is to prevent water reversion. Under run it gets really hot caused to the thin sheet metal and non cooling area and will catch the water and steam it out. Just an insurance from factory
I plan on cutting mine down to maybe 3" so to have some protection , but better flow.
If you are worried about the problem by removing them, then going to an after market exhaust will still give you the same condensation problem, because the after market exhaust don't have the tubulater design neither.
The picture is also deceiving because the cut is not thru the center. So you can't really see the 1" difference in hole size.
Last edited by Kanookstr; 04-27-2006 at 08:26 AM.
#9
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Re: 496 Exhaust restriction picture
Originally Posted by Kanookstr
In this pic I cut away more so you can see the 1" difference in hole size.
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Re: 496 Exhaust restriction picture
Originally Posted by CigDaze
Now it's clear. In the first pics it was deceptive.