496 Mag Exhaust Manifolds, Performance?

[davis777]

Anyone have any reccomendations for upgrading the stock 496 Mag exhaust manifolds and risers?
I currently have a stock system with Corsa diverters and a Y Pipe.
I have looked into Custom Marine's Sport Tube system, and they look bitchen but pricey at 4K
What about Eddie Marine Thunder, Gil Marine or some others?? Custom Marine boasts 50-60HP gain. Would you see some gain from these other Manifold Mfrs. if the Mag could breath better. Merc claims they are high performance manifolds and risers and the EMI Thunders look alot like the Merc stock manifolds. I have the standard 375HP 496 Mag and I just can't justify $4,500.00 for the Custom Marine Headers and install costs, I would rather spend 11K and pick up a fresh 496HO version.
Any suggestions,
Thx,
R-

[carreraboat]

try this
http://tpmarine.com/
ask for don i think he has some in stock and some performance numbers he has done some lake testing

[Sweet Addiction]

Does anyone have some real world Data for these. They sound like they are in my budget. Really thinking about getting headers so I need some feed back.

[shadow]

Anyone have any reccomendations for upgrading the stock 496 Mag exhaust manifolds and risers?
I currently have a stock system with Corsa diverters and a Y Pipe.
I have looked into Custom Marine's Sport Tube system, and they look bitchen but pricey at 4K
What about Eddie Marine Thunder, Gil Marine or some others?? Custom Marine boasts 50-60HP gain. Would you see some gain from these other Manifold Mfrs. if the Mag could breath better. Merc claims they are high performance manifolds and risers and the EMI Thunders look alot like the Merc stock manifolds. I have the standard 375HP 496 Mag and I just can't justify $4,500.00 for the Custom Marine Headers and install costs, I would rather spend 11K and pick up a fresh 496HO version.
Any suggestions,
Thx,
R-
If you want a cheap easy way to get the best out of your stock exhaust,
removed the turbulator plates between the riser and manifold.Take about 20 mins and people have claimed 3mph gain.Second if you take the manifold off and port them they will free up some flow.The runners between each port have quite a bit of material that can be removed.I'll sllok for a pic.

[shadow]

Heres a pic of the turbulator between the manifold and riser.
Choked down to 2" you can remove the 4 nuts holding the risers on,lift the riser up,remove the turbulator plate.
The gaskets are reusable if not damaged,you can also run a bead of high temp silcone around it for insurance.
http://www.hotboatpics.com/pics/data/500/5472DSCF1482-med.JPG

[shadow]

Stock risers stripped & polished
http://www.***boat.com/image_center/data/520/15021753DSCN1504.jpg

[Sweet Addiction]

so maybe your telling me that aftermarket headers are a waste of money. Ok, listen to my problem first and see if you can justify what is going on, and see if I was going about fixing it the right way.
Ok, I am running the 496 mag, I am spinning a Bravo 1-24 pitch, I was running about 4700 RPM.
I took the prop in for lab work, too out the turbulators, and went back to the lake. I lost about 4 mph, and was only running 4600 RPM.
So I though to myself, why not buy some header to free up some HP, and get a couple of hundred RPM's back which would put me where I want, and not mess with the prop anymore.
So does adding aftermarket headers justify what I am trying to do, or does my theory suck.

[shadow]

I,d say if you got the $$ and want to spend it.Have at it.I wouldn't mind a set myself.
Definately will enhance performance,How much?All depends on which type,and the boat/set up.
If you were running 4700rpm and had the prop worked and went down to
4600 and lost 4 mph i'd be looking into the prop situation and who did the work.
Theres no reason that if you were spinning a 24 @ 4700 prior to having the prop worked on you shouldn't have been able to atleast pick up a couple hundred rpm.
I'd first find the prop that gets you to 5000rpm-5200rpm with your current set up then work on modifacations to your engine and prop from there.
You can't fix a prop issue with exhaust manifolds or headers.
Just my 02. :)

[Sweet Addiction]

Well I know eveyone is taking the turbulators out, but for some reason I keep thinking maybe that had something to do with it, but probably not. Well I am going to do some testing with and without the turbulators and write stuff down, if I don't see any change I am going back to the prop shop and have them shave it down some more. I will probably work on the headers later anyway.

[shadow]

Good idea. Run it with the turbulators in & out and that will answer that.
Then from there you will know where you stand with your current prop.
Good luck and keep us posted,there are plenty of curious 496 owners here.

[Beer-30]

Ok, I am running the 496 mag, I am spinning a Bravo 1-24 pitch, I was running about 4700 RPM.
Mine originally had a 24P on it. Mind you, I am running 30 feet and an HO, not standard mag. I was seeing around 48-4900. Took a little while for the nose to roll over on plane.
I got a 22P (smallest Merc Bravo-1 4-blade) and am right around 5100, a lot nicer out of the hole - boat rolls right over on alot less throttle. My speed picked up from 61-62 to 64-65.
I still have my 24P in case I bring the HP up to pull it. But, I run the 22 for all around fun. Oh, and the motor is stock but pulled the turbulators.
I would borrow a 22P and see how you like it on the boat. If you end up doing that and like it, hang on to your labbed prop. You may need it some day.
EDIT: BTW, what boat is that?

[Sweet Addiction]

I will borrow a 22p and see what happens, but I think before I bought it they ran a 22 and the RPM were to high.
It is a 05' 260 Checkmate ZT

[Beer-30]

Ah, you know, I believe the Mag has a 4900 rev limit - as opposed to the HO having 5150. Therefore, you may be right.
With a Mag, you may be at the limit - short of pulling it apart, doing the heads and adding a cam. Plus getting the ECM reprogrammed for all of that.
You would still be cheaper than a whole new motor, though. Adding exhaust would be a nice first step. You could always use them later if you mod the motor.

[kcvega]

does the 496 HO have the turbulators in it? What are they supposed to be there for?

[shadow]

does the 496 HO have the turbulators in it? What are they supposed to be there for?
Yes they all have Turbulators.Some claim that they prevent water reversion.
But inside the ends of your exhaust you should have rubber flappers plus chances are you will have rubber external flappers and with the big s bend in most 496 exhaust i wouldn't worry about reversion.Unless you drive your boat in reverse. :)
I enedend up installing REX stainless internal flappers in my tips and eliminating the external rubber flappers altogether.

[kcvega]

cool, I don't own the boat yet, I'm test driving it this afternoon. It has 112 hours, any other tips, tricks or stuff to look for?

[Havasu47]

The turbulators do cost HP but be careful, they are designed to stop reversion. Not from lake water but from the water exiting the engine mixing with the exhaust while the engine is running at idle. This is Mercs way of helping reduce the possibility of reversion because the head pipes need to be longer and mix water/exhaust further away from the manifold. They are designed to catch the water and turn it into steam so it does not enter the cylinder.
The CMI exhaust is the best option for HP but they are pricey. CMI claims 481 HP with their exhaust and we have seen good performance improvements with them.
Shadow is right. You made a change to the prop and lost RPM's. Fix that problem before going any further.

[shadow]

The turbulators do cost HP but be careful, they are designed to stop reversion. Not from lake water but from the water exiting the engine mixing with the exhaust while the engine is running at idle. This is Mercs way of helping reduce the possibility of reversion because the head pipes need to be longer and mix water/exhaust further away from the manifold. They are designed to catch the water and turn it into steam so it does not enter the cylinder.
The CMI exhaust is the best option for HP but they are pricey. CMI claims 481 HP with their exhaust and we have seen good performance improvements with them.
Shadow is right. You made a change to the prop and lost RPM's. Fix that problem before going any further.
Good info to know! From a reliable source. :) Havasu47,whats your opinon,is the reversion something to be concerned about or just extra precaution on Mercs part?

[Havasu47]

Good info to know! From a reliable source. :) Havasu47,whats your opinon,is the reversion something to be concerned about or just extra precaution on Mercs part?
What's up D? Hope everything is good with you. The HO has more overlap so it is something to watch for. It's like everything. We have seen some with signs of reversion on the spark plugs (rust, or water droplets when checked immediately after running) when the turbulator is removed, but we have also seen some with no problems at all!!!
If the exhaust tips are under the swim step and there is an "S" pipe from the tail pipe to the tip, or if there is a muffling device, there is more of a chance of reversion.
The water / exhaust mixture actually pulsates back and forth in the riser pipe due to the camshaft overlap. The more back pressure, (low exhaut tips or mufflers) the more chance of the mixture working its way past the bend and ito the manifold. At this point it will enter the cylinders.
If you remove them I suggest letting it idle in the water, pull a couple of plugs and keep an eye on it.

[shadow]

Thanks for your input.My turbulators have been out since last season.since i just went through my motor i think i'll pull a couple plugs next time out just for the hell of it.
By the way i've got an aftermarket cam,heads and valve train.Don't think i've got any indication of reversion but what the hell i will double check.Better safe than sorry.
we should be out just about every weekend starting the the next couple of weeks through the summer.Hope to see you out there. :)

[Beer-30]

Pull your flame arrester every now and then and you will see if there is evidence of reversion. It will be blackened slightly around the inlet of the TB.

[Sotally Tober]

My exhaust is corsa. They exhaust above the water line on the side. No "S" in my exhaust. But when the corsa is closed it is run through the drive. Is there much of a chance of reversion? Is it safe to remove the turbulators in this application. Its a HO. There are spacer between my manifolds and risers. They are about 4"-6". Does anyone know of any tall headers? Or are new manifolds my only option? Always looking for some more ponies as my boat is a heavy pig!

[shadow]

Pull your flame arrester every now and then and you will see if there is evidence of reversion. It will be blackened slightly around the inlet of the TB.
Come on now Beer 30.It took you 6 months to figue you had a bad IAC.Who you trying to kid?
AHHH Just ****in with you. :rollside:
Like i said before turbs have been out for probablly 60 hrs.When i went through my engine there were no signs of reversion.But it only takes a minute to pull a couple of plugs to double check after an idle through Thompson bay.

[Beer-30]

5 months and 3 weeks. Let's not exaggerate! :boxed:

[Havasu47]

My exhaust is corsa. They exhaust above the water line on the side. No "S" in my exhaust. But when the corsa is closed it is run through the drive. Is there much of a chance of reversion? Is it safe to remove the turbulators in this application. Its a HO. There are spacer between my manifolds and risers. They are about 4"-6". Does anyone know of any tall headers? Or are new manifolds my only option? Always looking for some more ponies as my boat is a heavy pig!
When the flaps are closed forcing the exhaust through the prop it creates a lot of back pressure. Most of the time this will cause reversion. If you use the Captains Call I would not suggest removing the turbulators The spacers are Mercruiser and are 6". They are designed to keep the elbow above the water line in a deep hull. I am not aware of anyone making a 6' tall one piece tail pipe for the 496 manifold. If you go to aftermarket manifolds you will likely have a problem with water entering the engine while parked because of the heighth of the elbow. Check your waterline compared to the bottom of the bend on the tail pipe.
Hey Darryll (sp) we'll see you this summer for sure. I'll have a cold one for you :D

[Sweet Addiction]

Ok Fellas, I went against Shadow's rule of fix it first with the prop, I ordered a set of EMI headers and risers should be here end of next week. I am going to make some passes myself with no one on board, take some notes of my RPMs fuel and GPS Speed. Then I am going to add the new EMI headers and risers and take more notes. I am not hoping for a miracle but anything helps, plus its a start. I will let you guys know in about a week and a half.

[Beer-30]

Ok Fellas, I went against Shadow's rule of fix it first with the prop, I ordered a set of EMI headers and risers should be here end of next week. I am going to make some passes myself with no one on board, take some notes of my RPMs fuel and GPS Speed. Then I am going to add the new EMI headers and risers and take more notes. I am not hoping for a miracle but anything helps, plus its a start. I will let you guys know in about a week and a half.
Bless your heart.
I still plan on doing the roller rocker thing, so I will probably be next up.

[Sweet Addiction]

Bless your heart.
I still plan on doing the roller rocker thing, so I will probably be next up.
I am real spontaneous to there is not telling what I will do next!!! does a model or single girl come with those headers? Damn this sucks.

[Sweet Addiction]

Bless your heart.
I still plan on doing the roller rocker thing, so I will probably be next up.
I think I will probably try the rockers next. Maybe mid summer I will throw those in.

[Beer-30]

:D

[Sweet Addiction]

Hey I want to paint my manifolds the same color as the boat. What is the best way to do this? Is there a good spray paint I can use, or should I have a professional do it?

[Beer-30]

If you don't powdercoat, take them to a paint shop and let them match whatever color and they can spray it over a nice metal-etching primer so they don't chip.
The finish will be 10X nicer than spray cans.

[Sweet Addiction]

Alright, I think I am just going to powder coat, probably much easier and may stand up to the heat longer than paint.

[Pro Max]

Just wondering if the new exhause has been installed and tested ?
I wonder if anyone has taken the " Tubeulators " out of a 28 magic deck ????
Maybee I will be the first :boxed:

[shadow]

Just wondering if the new exhause has been installed and tested ?
I wonder if anyone has taken the " Tubeulators " out of a 28 magic deck ????
Maybee I will be the first :boxed:
You wouldn't be the first i can think of a few magics and conquests with no
turbulators.

[Sweet Addiction]

Hey guys,
I just received my manifolds yesterday. I am probably going to install them Saturday and take it for a run on Sunday. I need to go run it again stock with my GPS and take some notes for the before and after. I will try and do that so everyone can see how the new manifolds really help out. Have a great weekend, and I will try and report back either Sunday night or Monday morning.

[phebus]

You wouldn't be the first i can think of a few magics and conquests with no
turbulators.
And, even a dreaded Carrera :skull:

[Pro Max]

Phebus, What difference did it make with your boat ?

[Beer-30]

Mine just felt immediately "free-er" out of the hole. I was still pulling the 24P prop and noticed the first time out w/o turbs that it jumped out of the hole easier. A little more bark to the exhaust. About a mph on the top end.

[Pro Max]

And the best thing is
100% free hp, nice !!!! Thanks for the input, I will be pulling out mine this weekend
I have also heard that if you put in a colder thermestat it will pick up HP, I wonder how true that is ?

[phebus]

Phebus, What difference did it make with your boat ?
Nothing real noticeable. Maybe picked up 100-150 rpm, and maybe 1mph. It's a 496HO, I'm not going to beat anyone that matters anyway. I might throw them back in for any insurance they might provide.

[Beer-30]

And the best thing is
100% free hp, nice !!!! Thanks for the input, I will be pulling out mine this weekend
I have also heard that if you put in a colder thermestat it will pick up HP, I wonder how true that is ?
You don't even need new gaskets. It is self explanitory, but the "plate" is sandwiched between two gaskets. Just pull the plate and leave the two gaskets.
Just throw them on a shelf - in case.

[HatenWinter]

Shadow,
Your stock risers look nice polished. Did you get this done in Havasu and if so where and how much did they charge? I may be interested in doing it myself. Everyone knows the best way to make your boat faster is to put more shiny metal on the motor, right? Just kidding.......Thanks!!!

[spectras only]

Out of curiousity I pulled one of the the risers off of my 6.2 yesterday to check out the turbulator issue. For starters , the reduced opening matches the runner size in the manifold itself , so I don't think there's any gain from removing it . A completely different manifold/riser would be the answer for any benefit. The turbulator will not stop reversion with its small capacity holding maybe 5 cc . It is meant to hold small droplets created by condensation during the cooling off. My waterline is below the manifold/riser joint and yet I found slight rust deposit around the turbulator's edge . Every drop of water kept from the exhaust valves and rings are good insurance IMHO . One mile gain isn't enough reason for me to remove it :argue: :)

[Sweet Addiction]

Alright guys, I am running a 26' checkmate with a 496 mag and I installed my EMI exhaust over the weekend and went for a run on Sunday, 75 gal tank little over 3/4 full and 4 adults on board.
So before I was Complaining about the fact that when I had my prop labbed at the shop that I lost about 200 RPM and it felt quite sluggish. I was only able to get a GPS at about 60 maybe 61 and was only running 4600 RPM
After the exhaust was installed, I noticed a deeper sounding engine that seemed to breath better during idle, the hole shot was better, and holy shit mid range will throw you back in your seat.
Although the wind was kicking up into the mid 20's and creating 3-4 swells I still got some driving time in.
I definately had a smile on my face.
So the best I could get today was 4800 RPM, 63.5 mph on the GPS, and the water conditions were crappy.
Plus I am going to take the prop back in do a little adjustment to bring it back down 100 RPM to 4700 and I think I will see a constant 65 mph I hope.
I am happy with them, the install went great except for the damn plugs on the bottom, and it looks good in the engine compartment.
So, thats about all the updates I have for now, Hope this helps some of you guys.
Oh, sorry I did not go run again with the stockers to verify.

[Pro Max]

So I take it your happy ? If you could do it again would you still have purchased them ?
What is involved with the relocation kit ?
Thanks

[Sweet Addiction]

So I take it your happy ? If you could do it again would you still have purchased them ?
What is involved with the relocation kit ?
Thanks
Yea, I am pretty happy with them. Yes, I would still have purchased them, I don't regreat it if that is really the answer you are looking for. To tell you the truth, I want to get back out on the lake asap so I can be for sure that I really want to tweek my prop some more, and put the final polish on it.
Lets see, relocation.
I had to cut off one arm that bolted to the starboard header that helped hold up the throttle control plate, but it had enough bolts in it that taking the one was not a problem. I also found that the relocation of the water intake to the bottom of the manifold did not line up like the stock manifolds, and I had to buy some longer water hose and make a loop so the hose did not kink. It looks ghetto but functions. The only problem with getting the headers on is the space in the bilge area, and me sitting down there holding them trying to bolt them on.
The port header went on well. You have to disconnect the oil lines and use the longer lines supplied, a bracket is included to move the hydraulic reservoir up and the oil filter up and out of the way. It takes some time but its pretty self explanatory. Put your risers on, tighten everything up and away you go.
The only thing I am having problems with are the damn freeze plug holes on the bottom of the manifolds. I stopped at the auto parts store and just bought some brass plugs, and teflon tape. Well they just drip slow, so I guess I need to try some other type of sealant. Thats it though, I was really impressed with everything and I am excited to get back out again. If you want any pics of the after let me know, it may be a while though because it started raining here today and it does not look like it is going to quit for a while. And if anyone has any other questions let me know, I will try my best to help answer.

[Pro Max]

Thanks, The install dont sound so bad,,,,, :boxed:

[Beer-30]

Now, if we could just get someone to install the Lightning kit! I would be the first, but I have got to get the stereo done first.

[Sweet Addiction]

Thanks, The install dont sound so bad,,,,, :boxed:
Not to bad, only about 4-5 hours with haveing to go get the parts to finish.

[Sweet Addiction]

Now, if we could just get someone to install the Lightning kit! I would be the first, but I have got to get the stereo done first.
Your up next, I know you have been thinking about it. :)

[shadow]

Alright guys, I am running a 26' checkmate with a 496 mag and I installed my EMI exhaust over the weekend and went for a run on Sunday, 75 gal tank little over 3/4 full and 4 adults on board.
So before I was Complaining about the fact that when I had my prop labbed at the shop that I lost about 200 RPM and it felt quite sluggish. I was only able to get a GPS at about 60 maybe 61 and was only running 4600 RPM
After the exhaust was installed, I noticed a deeper sounding engine that seemed to breath better during idle, the hole shot was better, and holy shit mid range will throw you back in your seat.
Although the wind was kicking up into the mid 20's and creating 3-4 swells I still got some driving time in.
I definately had a smile on my face.
So the best I could get today was 4800 RPM, 63.5 mph on the GPS, and the water conditions were crappy.
Plus I am going to take the prop back in do a little adjustment to bring it back down 100 RPM to 4700 and I think I will see a constant 65 mph I hope.
I am happy with them, the install went great except for the damn plugs on the bottom, and it looks good in the engine compartment.
So, thats about all the updates I have for now, Hope this helps some of you guys.
Oh, sorry I did not go run again with the stockers to verify.
Congrats on getting your new exhaust installed,I hope you get all the gains expected.
Now let me ask you this?If you were only spinning 4600 rpm before and now getting 4800 rpm,Why would you want to get your prop worked to get you back down to 4700 rpm.
If i'm understanding this correctly you are defeating the whole purpose of installing new exhaust system. Why not install the correct prop to get you up around 5000 rpm-5200rpm?A prop that gets you into this range is going to
be most effient.Not to mention will also feel like you just added some more upgrades. :) Like i said,i'm just curious here maybe i'm not understanding.

[Beer-30]

Congrats on getting your new exhaust installed,I hope you get all the gains expected.
Now let me ask you this?If you were only spinning 4600 rpm before and now getting 4800 rpm,Why would you want to get your prop worked to get you back down to 4700 rpm.
If i'm understanding this correctly you are defeating the whole purpose of installing new exhaust system. Why not install the correct prop to get you up around 5000 rpm-5200rpm?A prop that gets you into this range is going to
be most effient.Not to mention will also feel like you just added some more upgrades. :) Like i said,i'm just curious here maybe i'm not understanding.
Remember, Shadow, he is a Mag, not an HO. His rev limit it what - 4850, 4950?
Still, you're right. I think he should find a prop that hits the limiter and then back it down from there.

[THOR]

I got here a little late guys and am going through this same stuff right now. I am seriously considering having my ECM recalibrated through Whipple. Through their testing they report 28-42 HP increases with that alone. Also, why not get the upgrading air intake through AZ Speed and Marine. That reports about 10 HP. These seem like easy HP gains without doing any motor work.

[Beer-30]

I got here a little late guys and am going through this same stuff right now. I am seriously considering having my ECM recalibrated through Whipple. Through their testing they report 28-42 HP increases with that alone. Also, why not get the upgrading air intake through AZ Speed and Marine. That reports about 10 HP. These seem like easy HP gains without doing any motor work.
What intake kit from AZSM? All there is for the 496 is a K&N. If you are referring to the MSD box, K&N, and fuel pressure regulator, that would be for 454-502s only. Not 496.

[phebus]

AZSM now offers their flame arrestor for the 496

[Beer-30]

AZSM now offers their flame arrestor for the 496
Ok, still no real HP to be gained there. I didn't notice any. I just was curious about the 10HP.

[phebus]

When I switched to the K&N, I didn't notice any gains in speed or rpm. I kept the K&N on for the filtering abilities.
You can see right through the screen arrestor that is stock, so I don't think any filter would flow any more air.

[Beer-30]

When I switched to the K&N, I didn't notice any gains in speed or rpm. I kept the K&N on for the filtering abilities.
You can see right through the screen arrestor that is stock, so I don't think any filter would flow any more air.
Yeah, I was same as you in this respect. I added it about the same time and even posted pics of the crap that was in my inlet bell. I didn't notice any performance gain. Just peace of mind in filtering. :)

[THOR]

AZSM uses the KN but I remember reading somewhere that it added a few HP. I forget where though. :rolleyes:
Either way, I think I will be getting my ECM reprogrammed to gain some extra HP.

[phebus]

I tested the K&N head to head against the stock arrestor one day at Havasu. I would run one filter on a windward and downwind run, and then switch to the other. I repeated theese tests about three different times to get a true comparison. All speeds were taken with a GPS, and only wot top speeds were noted. After the tests, the stock flame arrestor edged out the K&N by an average of less than 1mph (.6 to be exact). the difference was so small, that I left the K&N on for the added filtering.

[Sweet Addiction]

Congrats on getting your new exhaust installed,I hope you get all the gains expected.
Now let me ask you this?If you were only spinning 4600 rpm before and now getting 4800 rpm,Why would you want to get your prop worked to get you back down to 4700 rpm.
If i'm understanding this correctly you are defeating the whole purpose of installing new exhaust system. Why not install the correct prop to get you up around 5000 rpm-5200rpm?A prop that gets you into this range is going to
be most effient.Not to mention will also feel like you just added some more upgrades. :) Like i said,i'm just curious here maybe i'm not understanding.
From what the Mercruiser specs says, a 496 Mag should run WOT at 4700 RPM, I thought adding just a hair to bring the RPM down would give me a little more push I.E. speed, and bring the RPM down in the correct operating range. Although I did run it a good hour, running at 4800 RPM flying through some waves and stuff and it never bumped the rev limiter. So, now I am really kind of scratching my head not sure which way to go. Maybe its at it peak potential just like it is? But I can't resist trying to push it over the edge so I can see 65 on that GPS.

[THOR]

From what the Mercruiser specs says, a 496 Mag should run WOT at 4700 RPM, I thought adding just a hair to bring the RPM down would give me a little more push I.E. speed, and bring the RPM down in the correct operating range. Although I did run it a good hour, running at 4800 RPM flying through some waves and stuff and it never bumped the rev limiter. So, now I am really kind of scratching my head not sure which way to go. Maybe its at it peak potential just like it is? But I can't resist trying to push it over the edge so I can see 65 on that GPS.
Damn!
There is no way I would have the balls to run my engine at WOT for an hour. Or even 5 minutes for that matter.

[Beer-30]

Damn!
There is no way I would have the balls to run my engine at WOT for an hour. Or even 5 minutes for that matter.
Why not? You think it's gonna last forever? Technically, it should run just fine with the stick pinned every time it gets taken out. For years. Until it gets up there in hours and starts losing compression.
In all reality, though, there are very few times one would even be able to run WFO for any length of time.

[THOR]

Why not? You think it's gonna last forever? Technically, it should run just fine with the stick pinned every time it gets taken out. For years. Until it gets up there in hours and starts losing compression.
In all reality, though, there are very few times one would even be able to run WFO for any length of time.
Cuz I am a pussy. I know I could but I just dont trust the motor to hold up. Dont ask why, I just am not a believer.

[Beer-30]

Cuz I am a pussy. I know I could but I just dont trust the motor to hold up. Dont ask why, I just am not a believer.
Hey, good enough. I just figure, if it lets go, the wife will want to still be boating. That will give me the green light to "get it fixed". They don't seem to understand that just because it is still running doesn't mean that it is running PROPERLY. :rollside: :rollside:

[shadow]

From what the Mercruiser specs says, a 496 Mag should run WOT at 4700 RPM, I thought adding just a hair to bring the RPM down would give me a little more push I.E. speed, and bring the RPM down in the correct operating range. Although I did run it a good hour, running at 4800 RPM flying through some waves and stuff and it never bumped the rev limiter. So, now I am really kind of scratching my head not sure which way to go. Maybe its at it peak potential just like it is? But I can't resist trying to push it over the edge so I can see 65 on that GPS.
Well i'm certainly no Merc expert but i'd be pressing to find out where your rev limiter is set.If you've run it up to 4800 and haven't found it then i'd look somewhere in the 5100rpm range.Someone also said recently that Merc says the impeller is good for 300hrs.At 300 hrs you'd be lucky to have any impeller housing left cause they wear so bad.My point is if you can run it up to 5100 rpm then run it or run it up to 5000 rpm.Find the limiter,do the math if you are at 4800 rpm and @ 63.5 now and you either prop or lab the one you've got so you can get all your rpms you should have no problem running at the 65mph that you'd like.Don't worry about over reving the engine thats what the rev limiter is there for. Good luck & like i said before i sure aint no Merc expert just my opinon and what i've found from personal experiences. :)

[Beer-30]

Well i'm certainly no Merc expert but i'd be pressing to find out where your rev limiter is set.If you've run it up to 4800 and haven't found it then i'd look somewhere in the 5100rpm range.Someone also said recently that Merc says the impeller is good for 300hrs.At 300 hrs you'd be lucky to have any impeller housing left cause they wear so bad.My point is if you can run it up to 5100 rpm then run it or run it up to 5000 rpm.Find the limiter,do the math if you are at 4800 rpm and @ 63.5 now and you either prop or lab the one you've got so you can get all your rpms you should have no problem running at the 65mph that you'd like.Don't worry about over reving the engine thats what the rev limiter is there for. Good luck & like i said before i sure aint no Merc expert just my opinon and what i've found from personal experiences. :)
Yeah, what he said.
I still say, borrow or rent a 22P B-1, and hit the limiter. Then, grab a 23P Quad-4 or other 4-blade that comes in 23P and check it out. Then on to 24s.
I would have to say you are close. Whoever is doing your prop work should have a smaller prop to start with. If you are just a few hundy away from it with your existing prop, just tell them you want another cupla hunerd and let her fly.
Like Shadow said, and he knows, don't be shy of the limiter. It needs to be checked from time to time. I should talk, I still haven't quite hit mine yet. But, I only have a couple of hours running the 22P. The few times I've stretched it out, I have been real close. Right around 5080, 5100 by my tach. My 24P only gets me to 48fitty or 4900.

[Pro Max]

I bought the eddie Marine Thunder Exhaust,,,,,,, Stay Tuned for the results
PRE EXHAUST 67mph 24p prop 5100 rpm
AFTER EXHAUST ?????? 26 LAB prop ??????
Maybee 70 or better ??? One can only hope and pray

[Beer-30]

I bought the eddie Marine Thunder Exhaust,,,,,,, Stay Tuned for the results
PRE EXHAUST 67mph 24p prop 5100 rpm
AFTER EXHAUST ?????? 26 LAB prop ??????
Maybee 70 or better ??? One can only hope and pray
That sounds reasonable. I would say you will get every bit of that.
You will definitely be above that 24P for this altitude. Like you said, a labbed 26 customed to about 25 will probably be right-on. I would hang on to the 24, though. If you went to Powell or higher, you would want it back.

[Pro Max]

Go my pipes today and started the install. It is going ok butt trere are a few issues like Texan explained about the bottom water lines and the bad job eddie did running the threads. I am hopeing for the best. Texan do you have any final pics of the assembly ?
I may run it Sunday in Elsinore but most likely next weekend in Havasu.

[Sweet Addiction]

Go my pipes today and started the install. It is going ok butt trere are a few issues like Texan explained about the bottom water lines and the bad job eddie did running the threads. I am hopeing for the best. Texan do you have any final pics of the assembly ?
I may run it Sunday in Elsinore but most likely next weekend in Havasu.
Wow, I apoligize for not getting on last week and seeing this. I had the boat ready to go this weekend and I would have snapped you some photos. I hope your install is going ok, did you figure out what to do with the water hoses at the bottom yet? I had to go to the Auto parts store and buy new hose and just make a loop, not sure it was the best way but it works for now until the light bulbs come on in my head. It is going to be a couple of weeks before I get the boat back out, I will snap some pics but you will be finished.

[Pro Max]

Not so good, The biggest issues are
Computer not reaching new location without severly pulling on the wires
Water hose nightmare ( as you stated )
Engine cover not fitting anymore ( CMI supplies spacers with there kit )
All the holes not taped correctly
I have 8 1/2" risers with my kit ( you may have 10 1/2" ) and the risers hit the temp senders. This is a major issue and I havent solved it yet.
So far Im "bumed out" I hope when it comes together it is worth it.
Did your temp senders fit correctly ????

[Sweet Addiction]

Not so good, The biggest issues are
Computer not reaching new location without severly pulling on the wires
Water hose nightmare ( as you stated )
Engine cover not fitting anymore ( CMI supplies spacers with there kit )
All the holes not taped correctly
I have 8 1/2" risers with my kit ( you may have 10 1/2" ) and the risers hit the temp senders. This is a major issue and I havent solved it yet.
So far Im "bumed out" I hope when it comes together it is worth it.
Did your temp senders fit correctly ????
Yes my computer did not fix just right, the engine cover is kind of tilted to one side but we got it on there. We had to move the wires around for the computer to get it to work. My temp sensors fit just fine, I wonder why your having trouble?

[Pro Max]

When you install the riser it hits the temp sender. :220v:

[Sweet Addiction]

When you install the riser it hits the temp sender. :220v:
HUM, well I am not sure how to help you out?

[Raylar]

Why in the Hell can't these exhaust system manufacturers just get ahold of a stock 496 engine package an do their homework. Thats all we do! Shit its not rocket science. Sorry ,just bugs the hell out of me that people want to put product on the market without doing their homework! You people should not have to be the Guinea pigs for their lack of commitment and somewhat false advertising.
Ray @ Raylar

[TrojanDan]

:yuk: Here I am lurking knowing how much I'd like to pull my turbulators and put the CMI's on my 496HO and there you go bursting my bubble. I hope you guys get your headers on. It sucks you guys are having problems. :cool:

[Beer-30]

Why in the Hell can't these exhaust system manufacturers just get ahold of a stock 496 engine package an do their homework. Thats all we do! Shit its not rocket science. Sorry ,just bugs the hell out of me that people want to put product on the market without doing their homework! You people should not have to be the Guinea pigs for their lack of commitment and somewhat false advertising.
Ray @ Raylar
No kidding. Same with valve covers. Hmmm, let's see, probably the most popular boat motor out there right now? Don't they know how much of this stuff they will actually sell - if it actually worked?
Speaking of which, do you know off of the top of your head how many kits you have out in the world-to-date? Just curious.

[Raylar]

At current count I believe just over two hundred.
Ray @ Raylar

[Beer-30]

At current count I believe just over two hundred.
Ray @ Raylar
Wow, that's a bunch. Good for you guys.

[Nordicflame]

Now, if we could just get someone to install the Lightning kit! I would be the first, but I have got to get the stereo done first.
Here you go...
http://www.offshoreonly.com/forums/showthread.php?t=123879&page=1&pp=20
Lightnings apparently were not without some PITA issues either.
There is a short video of this running on a stand. If you'd like to hear it I could email it to you.
Dave

[Beer-30]

Thanks for the link. Yikes. Sounds real good. Cam sounds perfect.
http://media.putfile.com/Bents-Nordic-Engine

[Nordicflame]

That's Raylars 103 kit; I'm sure the 106 kit sounds even better with the bigger cam :cool:

[Beer-30]

That's Raylars 103 kit; I'm sure the 106 kit sounds even better with the bigger cam :cool:
Oh, I have no doubt that it would. This one just sounded perfect for having a little burble, but still being wife-dockable with manners.

[Sweet Addiction]

Will 496 Manifolds fit a 454?

[Beer-30]

Will 496 Manifolds fit a 454?
From what I understand - yes. The only real difference is the exh water temp sender. I am not 100% sure of that, though.