best exhaust manifolds
01-18-2007, 06:49 PM
#31
Charter Member
Re: best exhaust manifolds
dbkski, what issues did you run into?
I've seen many say the SM's were a direct bolt on, but my SM install was far from that. Mainly the remote oil filter pad and line both hit the top of the manifold. I had to put 1/2" spacers under the filter pad to lift it up, and then oblong the engine lift accessory mount hole in front where the oil line comes thru to allow the remote pad to be raised. I would think every MPI motor that has the same setup as mine ran into this same problem on any aftermarket exhaust install.
I've seen many say the SM's were a direct bolt on, but my SM install was far from that. Mainly the remote oil filter pad and line both hit the top of the manifold. I had to put 1/2" spacers under the filter pad to lift it up, and then oblong the engine lift accessory mount hole in front where the oil line comes thru to allow the remote pad to be raised. I would think every MPI motor that has the same setup as mine ran into this same problem on any aftermarket exhaust install.
01-18-2007, 10:26 PM
#32
Re: best exhaust manifolds
Same problems plus the filter's mounting bracket needed to
be cut off at the gear lube bottle attachment point. The bottle
needs to be relocated. I saw a few posts about the Danas but
not about others. Bob at Dana sent out a solution for me
so I hope to see it on the engine next week. I just don't have
access to a machine shop or tools. This is why I needed a
simple bolt on kit. Also my mechanic had never seen the Dana
exhausts so he did not know how to put them on.
be cut off at the gear lube bottle attachment point. The bottle
needs to be relocated. I saw a few posts about the Danas but
not about others. Bob at Dana sent out a solution for me
so I hope to see it on the engine next week. I just don't have
access to a machine shop or tools. This is why I needed a
simple bolt on kit. Also my mechanic had never seen the Dana
exhausts so he did not know how to put them on.
Last edited by dbkski; 01-28-2011 at 12:35 AM.
01-18-2007, 11:08 PM
#33
Registered
Join Date: Dec 2000
Location: EASTON MA.
Posts: 6,281
Likes: 0
Received 0 Likes
on
0 Posts
Re: best exhaust manifolds
I have the same S/M set up for 12 going on 13yrs bought it back in 1994 sounds nice too. so if your looking for a set up that will last stainless marine is it,anyone else with a 13tr old exhaust
and I only run the ocean.
and I only run the ocean.
01-18-2007, 11:10 PM
#34
Registered
Join Date: Dec 2000
Location: EASTON MA.
Posts: 6,281
Likes: 0
Received 0 Likes
on
0 Posts
Re: best exhaust manifolds
There will be many many different views on this subject. If you're racing you may want one type. If you're just a performance boater you may want yet another.
One important factor for me is life. Tube headers probably won't last near as long as an aluminum manifold and stainless riser combination. There may be some difference in top end performance and maybe not. My Stainless Marine aluminum manifolds and long stainless risers do not leak, make good power, look nice ( to me anyway ), save weight, do not pass water through a joint, and may outlast me. They have been pretty much a thing to install and forget about them. That is until the hatch raises and you see the nice stainless tubes. A manifold/riser combo may also be a little easier fit in some boats and seldom if ever requires any hatch modifications. I honestly believe that even if I had a cruiser type boat I would install Stainless Marine exhaust for the extreme added reliability and improved performance. There are other similar types from other manufacturers that work well and live long. I just happen to like the Stainless Marine best.
I realy like the way tube headers look and sound but I appreciate the infinite reliability of my combination more. Mercruiser uses a lot of CMI product. That's obviously a good product. Still, the manifold riser combo will outlive it.
One important factor for me is life. Tube headers probably won't last near as long as an aluminum manifold and stainless riser combination. There may be some difference in top end performance and maybe not. My Stainless Marine aluminum manifolds and long stainless risers do not leak, make good power, look nice ( to me anyway ), save weight, do not pass water through a joint, and may outlast me. They have been pretty much a thing to install and forget about them. That is until the hatch raises and you see the nice stainless tubes. A manifold/riser combo may also be a little easier fit in some boats and seldom if ever requires any hatch modifications. I honestly believe that even if I had a cruiser type boat I would install Stainless Marine exhaust for the extreme added reliability and improved performance. There are other similar types from other manufacturers that work well and live long. I just happen to like the Stainless Marine best.
I realy like the way tube headers look and sound but I appreciate the infinite reliability of my combination more. Mercruiser uses a lot of CMI product. That's obviously a good product. Still, the manifold riser combo will outlive it.
01-19-2007, 06:26 AM
#35
VIP Member
VIP Member
Re: best exhaust manifolds
No need to touch the ECU with HP Manifolds or Headers unless you make internal engine mods or want to raise the rev limiter. If there is concern that the engine might run lean with headers, just raise the fuel pressure a bit. Speaking from experience, ECU recals are a nightmare unless the engine is dyno'd.
The first set of SMs I had lasted more than 10years on two different engines. One started to leak to the outside so I bought a new set for my latest engine. When I pulled the leaking manifold, there was no sign it was leaking into the engine. It has been well documented that SMs last. I run in salt and fresh and only flush my engine at the end of the season.
Exhaust is about the best upgrade for stock engines IMHO. Stainless Marine, Gil, EMI, Imco, Dana, and Revolution all make good HP manifolds. Lots of guys running 700+ engines on HP manifolds. Headers look great but don't last. And the little bit extra you may get over HP manifolds is not nearly worth the $$ or risk, again IMHO...
__________________
Patrick
Patrick
01-19-2007, 08:52 AM
#36
Gold Member
Gold Member
Join Date: Sep 2005
Location: Missouri
Posts: 1,987
Likes: 0
Received 0 Likes
on
0 Posts
Re: best exhaust manifolds
I ran Stainless Marine on my 7.4MPI with good results. My boat gained acceleration mid range and about 100rpm on top with the same prop. I made the same switch to SM on a 502MagMPI and gained 200rpm on top.
No need to touch the ECU with HP Manifolds or Headers unless you make internal engine mods or want to raise the rev limiter. If there is concern that the engine might run lean with headers, just raise the fuel pressure a bit. Speaking from experience, ECU recals are a nightmare unless the engine is dyno'd.
The first set of SMs I had lasted more than 10years on two different engines. One started to leak to the outside so I bought a new set for my latest engine. When I pulled the leaking manifold, there was no sign it was leaking into the engine. It has been well documented that SMs last. I run in salt and fresh and only flush my engine at the end of the season.
Exhaust is about the best upgrade for stock engines IMHO. Stainless Marine, Gil, EMI, Imco, Dana, and Revolution all make good HP manifolds. Lots of guys running 700+ engines on HP manifolds. Headers look great but don't last. And the little bit extra you may get over HP manifolds is not nearly worth the $$ or risk, again IMHO...
No need to touch the ECU with HP Manifolds or Headers unless you make internal engine mods or want to raise the rev limiter. If there is concern that the engine might run lean with headers, just raise the fuel pressure a bit. Speaking from experience, ECU recals are a nightmare unless the engine is dyno'd.
The first set of SMs I had lasted more than 10years on two different engines. One started to leak to the outside so I bought a new set for my latest engine. When I pulled the leaking manifold, there was no sign it was leaking into the engine. It has been well documented that SMs last. I run in salt and fresh and only flush my engine at the end of the season.
Exhaust is about the best upgrade for stock engines IMHO. Stainless Marine, Gil, EMI, Imco, Dana, and Revolution all make good HP manifolds. Lots of guys running 700+ engines on HP manifolds. Headers look great but don't last. And the little bit extra you may get over HP manifolds is not nearly worth the $$ or risk, again IMHO...
01-19-2007, 10:13 AM
#37
VIP Member
VIP Member
Re: best exhaust manifolds
Well maybe I should edit my post. In my experience header don't last as long as manifolds.
The welds or areas around the welds fail...
The CMIs on the Merc 525EFI engines are an example; lots of failures...
The welds or areas around the welds fail...
The CMIs on the Merc 525EFI engines are an example; lots of failures...
__________________
Patrick
Patrick
01-19-2007, 12:05 PM
#38
Gold Member
Gold Member
Join Date: Sep 2005
Location: Missouri
Posts: 1,987
Likes: 0
Received 0 Likes
on
0 Posts
Re: best exhaust manifolds
Is this a corrosion related weld failure from salt water running only or other? If other then what?
01-19-2007, 12:25 PM
#39
Registered
Thread Starter
Re: best exhaust manifolds
when cmi says standard bravo location tailpipes are all boats with bigblocks and bravos the same exit location?i guess my ? is if i order cmi and standard bravo tailpipes will it be a direct bolt-on?and what if i drain them after every use,will this help with the corrosion problem?
01-19-2007, 01:33 PM
#40
VIP Member
VIP Member
Re: best exhaust manifolds
My personal experience with header failure is likely related to corrosion. Both failures, 1 CMI , 1 Hardin Marine, accrued at the flanges. Yes, salt water eats stuff a lot faster than fresh.
__________________
Patrick
Patrick
