best exhaust manifolds
 

who makes the better exhaust manifolds,want to upgrade from stock.will i really see any performance gains with aftermarket manifolds or should i go with headers?want to keep my silent choice

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.

Re: best exhaust manifolds
 

Do a search in the archives and you will find a ton of info/input, and reading on the aftermarket exhaust subject.

Re: best exhaust manifolds
 

When I was shopping for performance manifolds back in 1992 there were few and far between choices. There were a few companies making BBC parts but no one made SBC exhaust parts. I bought Glenwood HP powdercoat aluminum manifolds and Fastglass powdercoated stainless 4" smooth short risers. They have proved excellent quality and are still going strong 15 years later. Sadly I don't believe either company is still in business.

They provided a nice performance increase especially when the AFR heads and cam went on.

http://img108.imageshack.us/img108/3...oldsil4.th.jpg

Re: best exhaust manifolds
 

This says a lot as better exhaust is just part of a system; by itself, upgraded exhaust may not be worth the investment for a preformance gain in the 0-2 MPH range.

Re: best exhaust manifolds
 

Well said. Exhaust alone will do little, if anything, to your performance. If you have made cam, head and intake mods or changes from stock you can expect decent gains with tubular headers. For most stock applications manifolds are more than adequate.

That being said; a set of polished stainless headers looks GREAT under the hatch but be aware that they come at a cost. Reliability however is NOT one of them. A good set of stainless headers (if properly cared for) will last as long if not longer than cast manifolds.

We sell RMI cast aluminum manifolds that work great in most stock applications and are great deal at the price.

We also have good deals on Lightning Stainless headers for those who have motors that can benefit from a good scavenging exhaust.

Just remember that no matter what exhaust you choose, if you drain your exhaust after you run, you will greatly increase the life of your exhaust system.

Good luck with your decision and I would be happy to help if I can.

Fionn

Re: best exhaust manifolds
 

As I understand it, a true header (with 32 - 36 in. primaries of proper ID) will generally yield some noticeable performance gains on a stock BB. Will the gain be as much as the manufacturerers claim ?? Hhmmmm.... I think that's a discussion for another thread LOL.

Given the cost of a true SS header system, is the cost worth the gain ?? Maybe so, if at some time in the future there are plans to mod/hp the engine. But IMHO if the engine is to stay stock, or only mild mods are to be done to it, I'd say a decent after market aluminum manifold/riser will be just fine. After dropping a ZZ502 in my boat, and after doing some research a few years ago, I bolted on polished aluminum Revolution Marine Exhaust. There was a noticeable mid range gain, limited WOT.

Now I'm in the process of having some substantial mods done to my ZZ502, and have a KE Exhaust to bolt on, which is also aluminum :D So if anyone is interested in a good used Revolution Marine Exhaust system, let me know ;)

Re: best exhaust manifolds
 

I am getting ready to replace my manifolds and based on the research I have done, its narrowed down between EMI, GIL or Stainless Marine. SM has a good reputation but I don't know if they are worth $700 more than the Gils or EMI's. Anybody want to chime in?

Re: best exhaust manifolds
 

One seldom talked about advantage is the servicabilty. Headers are easier to take on and off inside the boat. I can hold a header with one arm while I put bolts in with the other. It's also allot easier to change spark plugs. You can actually see them.

Re: best exhaust manifolds
 

i am thinking about emi also,if i spend 2 grand this year on manifolds and end up supercharging next year will these be ok or am i gonna have to step to cmi headers.only want to do this once

Re: best exhaust manifolds
 

Headers will only help. You might want to talk to your engine builder now and get his opinion.

Re: best exhaust manifolds
 

I agree, talk to your engine builder or supercharger distributer. Headers will definitely help but is the additional money worth the increased HP. All boils down to how much you want to spend.

Re: best exhaust manifolds
 

You may also want to do a search on OSO for DANA exhaust, don't know much about them put they look good for the money.

Re: best exhaust manifolds
 

I had a set of EMI on a 502 EFI Mag. I did not like them as much as the GIL's I had on my other boat or the CMI's I have on my current boat. My ex son in law has SM with long riser/pipe combo on his 540's and the seem to work well. Any exhaust that uses the jumper hose from manifold/header to pipe needs to be checked every year for colaspe. I have found this more than once. Joe Murray

Re: best exhaust manifolds
 

CMIs are worth the money. There are many different models to fit most budgets and applications.

Re: best exhaust manifolds
 

I swapped over from an old stock log style manifold to Dana's. The only reason I picked Dana's over the others is I like the way they look. I think all aftermarket exhaust are going to be close in performance. I'd say headers if you want to spend that kind of money, and if you are making enough power to really make use of them. If nothing else, I save 90 pounds swapping the exhaust.

Re: best exhaust manifolds
 

I had EMI's on an SBC I was running. I really liked the way they sounded.

Re: best exhaust manifolds
 

I changed over my stock cast iron exhaust to SM. Seen no difference in performance, nor was I expecting to, but I did loose around 80#'s. Stock 502 EFI's with silent choice.

Re: best exhaust manifolds
 

I did a lot of research on this matter myself. I chose the
Dana Marines for silent choice system. The Danas and the
EMIs can be colored to your taste. I wanted this over a
standard black manifold. The Stainless Marine choice is an
excellent one and I heard of great customer service. I ordered
my Danas in October and I still do not have them on my engine
due to oil line/filter interference issues and missing parts. I
was assured before I ordered them that there were no known
installation problems. It is now mid January and I still have
no solution from the guys at Dana Marine. Bob at Dana knows
of the problems and said a solution is imminent. I will wait
a few more weeks then I think I will have to send them back.
I really like the way they look and the Danas were highly
recommended to me by Ray at Raylar. I thought I made a
great choice, but perhaps not. They do look good though!!!
Stock Merc 502 Mag MPI.
O.K. maybe my mechanic is not the most knowledgable, but
she works all day for a Mickey Mouse pancake and a side of
bacon.:evilb:

Re: best exhaust manifolds
 

I have SM on mine that have about 400 hours on them-took one apart in September to replace a gasket and they look brand new inside. I do flush pretty regularly but was pretty impressed by what I saw.

Re: best exhaust manifolds
 

There is always a lot of opinions on this subject. However, your best bet is going to be CMI's. You can get exhaust from them that will work for you application and in the long run you will be better off than an alluminum manifold. If you are running in salt you are actually better with a painted cast iron manifold as far as longevity. CMI's will give you the chance to grow with your motor if you ever decide that as an option. If you decide to go with manifold to a riser style exhaust make sure your transfer from your water ports are completly a seperate part of the exhaust not just a riser gasket. That way when they start leaking it will not go into your exhaust ports.
Thanks, Cam-shaft.

Re: best exhaust manifolds
 

thanks for all the input,i like the looks of those danas.it seems like no manifold is going to make me more power in itself.since i want to supercharge next year i think i should go with cmi.are cmi bolt on and go.i went to the web site and seems like they want alot of measurements.i really don't want to modify anything.

Re: best exhaust manifolds
 

dbkski - I spoke with Water and Wheels a few days ago. FYI, I have located a stock Merc late model bracket such as the one on your engine. We have made the necessary modifications, re-powdercoated the bracket, and it's on the way to Water and Wheels. He'll have it tomorrow. Sorry about the delay. I simply have never run into that clearance issue before.

Re: best exhaust manifolds
 

What engine are you running?

Re: best exhaust manifolds
 

There are several options in the CMI line that will probably not break the bank. Each has their own purpose depending on your application.

There is a reason they are the number 1 selling header on market and that's why Mercury Racing and Ilmor use them exclusively.

Give us a call if we can help or provide more information.

Don't settle for anything but the best!

(847)623-2737

Re: best exhaust manifolds
 

97 454 mag carb

Re: best exhaust manifolds
 

I wouldn't mine going the CMI route but I am running EFI and don't want to go through the trouble I have read about on here with reprogramming.

Re: best exhaust manifolds
 

When a stainless steel header fails what are the potential causes in order of probability of occurance?

Re: best exhaust manifolds
 

If you do not want to deal with re-programing then you should not look at anything other than a stock manifold. A good exhaust is going to need to be tuned for sure, that means you are probably going to make more power because you are pulling the fuel and air out quicker. Just an idea.
Thanks, Cam-shaft.

Re: best exhaust manifolds
 

I need to replace my stock manifolds now and I was trying to get something that would work with a repower in the future so I don't have to do this twice. I am getting alot of different opinions on whether the ECM would have to be redone or not. I am running a 7.4 MPI, so I am not looking for any performance gains really and don't want to raise the Rev limiter due to the weak internals. Just trying to get something that will work now but will also swap over to a 540 in the next year or two.

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.

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.

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:D and I only run the ocean.:cool:

Re: best exhaust manifolds
 

mine are going to be 13 this spring:p

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... :drink:

Re: best exhaust manifolds
 

Which headers do not last and what is it that fails?

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...

Re: best exhaust manifolds
 

Is this a corrosion related weld failure from salt water running only or other? If other then what?

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?

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.