Replacement headers for 525 EFI - Which ones?
 

I'm going to replace the headers on my 525 EFI's. I've read most of the threads on here about the various products, but many of these threads / comments are several years old so I'd be interested to know if experiences have changed since then and what the collective wisdom is now on what headers are holding up best. I have a 2005 38' Fountain with semi-staggered engines and silent choice exhaust; the engines are 2004 models.

I know you may be a little sore to CMI, but I wouldn't look away from them. All headers will eventually leak, however they followed the merc spec to meet a price point and went cheap on the metallurgy for the stock 525 header. They have an upgraded version that will last, and match right up to your existing tails.

I would at least call them. Maybe they will work something out for you, or at least prep your old headers for resale.

I've owned this boat for a total of 6 weeks, so I'm obviously not too happy about this, but I'm not sore to CMI because of it. But knowing there's a problem with them and now having to spend a decent amount of dough to rebuild my top end because of it, I just want to replace them to avoid a catastrophic failure. At this point, I'm going to spend the money, so I'd just like to get the best option available and wouldn't rule anything out. Is the upgraded version you're referring to the Gen-X header?

Stainless marine 525 replacement headers. Will outperform the CMI and have a 5 year warranty (nobody in the industry even comes close). May not look as good but you will eliminate the one flaw 525's have by putting the stainless marine exhaust on. A lot of the race boats run the stainless marine because they care about performance and reliability, not looks...

http://www.stainlessmarine.com/?wpsc...=01-1260010-00

hardin marine 525 lites,,,direct replacement

I agree SM is a safer options, however aside from bling you also lose that raspy header sound.

The stainless marines are now a direct replacement and the stainless marine definitely sounds the same as a header, if not louder. If he wants the noise then he can go completely dry. Everybody who bashes the stainless marines have never had them or dealt with them. Look at some old threads on here and see what people have to say about them. Like the old saying goes, what people don't know, they don't like.

The issue with the SM headers is having to re-tap the block to fit their bolting pattern; not a huge deal, I guess, but adds to the overall cost of this project. Would have to believe there is an alternative that I can just bolt on.

They now have a direct replacement??? Their website says this:


Note: The exhaust bolt patterns on the heads are not the same as the standard GM. Precision drill & tap gigs are provided to match the original GM exhaust head bolt patterns. For more information, please consult with our application sales representative.

I have had SM on tow of my boats. One had dry tails. The exhaust was wonderful IMO, however I can still tell the difference of a boat with headers vs one with manifolds by the exhaust note, not the volume. Again, headers add bling, spark plug access, better access between engines, and a different note. SM exhaust adds security in a fresh water environment. Salt water will erode the cast aluminum lowers faster than they effect true stainless headers.

On another note, one of my old engines got hot and the gauge did not show until it was too late. The sensor was relocated with the addition of blowers and was too far from the engine to show an immediate heat issue. Had the engine rebuilt and shortly after the SM exhaust failed internally. The heat from the exhaust without water caused fatigue and the manifold let loose on my new engine and destroyed that with water. So.....none of them are safe :D

Yes you still have to drill and tap you heads. You will also have to address the mating of the tails on your fountain. You have a split Y tail leading half to the transom and half to the bottom correct? The SM tails are designed to go to a rubber boot, making a big chore when adding to a fountain. Not to mention the plumbing for the staggered engine. If you choose the SM route they can custom build what you need to convert, but the price will go up.

Again, an improved CMI header that will be a direct replacement and utilize your existing tails is the best option IMO

I stand corrected, I thought I read somewhere that a place like Hardin was drilling the manifolds so they would bolt up but I guess not. On another note, it's not the corrosion that usually does in the CMI headers, it's the cracking, which there is nothing that can be done, that is just what happens to stainless after constant temp changes.

Here's what it boils down to:

Bling: CMI
Longevity/Warranty: SM
Sound: 50/50
Performance: 50/50

So it depends what the buyer wants, looks or ease of mind/trouble free boating.

I used the hardin hp500 system with installed bungs for efi , Easy install and have big sound !

the hardins are well built

After making some calls to CMI, Hardin and others based on all of your suggestions, it would appear that the CMI improved header is the best option for me. They are direct replacements, will work with my existing tailpipes and appear to be the most straightforward. All other options will require a lot more work and $$$.. Thank you all for your prompt replies and assistance. Greatly appreciated.

I'm with 302Sport. After cracking the CMI's 3 times and paying for 2 top end rebuilds I went with the SM manifolds. I am on my first season with them. Sound is the same, performance is the same. I had my guy paint them blue to match the 525 and I think they look pretty good. I'll upload a pic or 2 later.

What was the time period for which you cracked 3 CMI headers?

Port collector = 185 hours
Starboard collector = 200 hours
Port(near bottom, same header that went at 185 hours) = 220 hours

Basically ruined 2 of my last 3 seasons.

So roughly 35 hours of run time been through 3 headers and two top ends, sounds like fun.....

Ouch, that's brutal... were they the Gen-X headers?

Yeah, it sucked...bad.

They were the original headers off the engine I believe, which is either an 04 or 05(previosu owner put the 525 in to replace a 496 HO). Here is a pic of the painted up Stainless Marine unit.

Would the dana manifolds perform as well as the already mentioned? For a manifold they look pretty good!

That looks great. If they were the original headers on an 2004 motor, then they were not Gen-X headers. My motors are 2004 as well and they have the lower quality CMI headers that everyone is talking about. The newer upgraded CMI headers are supposedly better. My mechanic called Mercury to get a price from them and they want $11,400 PER MOTOR, that was infuriating!!! Looking at your picture, I have a bit more complicated setup. I have semi staggered motors, and silent choice exhaust so changing out all my tails is not trivial.

The stainless marine is like $3400 a motor from Hardin or cp performance. Yeah it is a little more work getting it all set up but worth every penny, not counting the money you are saving. People have done it with side by side setups with the motors in the boat so your setup would be easier.

He is going to be way past 3400 per side to add to a fountain. My guess is he has about $10k in additional parts/work to add them to a stag fountain ride.

Gladh8er's set up does look great merc blu, the bling is just as good IMO. But that is a basic bravo setup, drill heads and go. Fountain's exhaust routing could not be more complicated. Even without the silent choice option they still run split tails, half leading to the transom assembly.

Im guessing that Gladh8er was repairing his leaking stock header, and it kept causing problems?

Aren't the Gen X headers around $5k through CP? If so I agree that would be the best route.

Yeah, thats about right. As of now, I'm probably going the CMI/Gen-X route. Pressure testing headers this afternoon to make sure that's the problem before I order the headers. Because of the staggered setup, I need swept headers on the port engine and straight on the starboard engine. It's about 5K for the port and about 6.5K for the starboard.

The same set of headers cracked 3 times...all in different places. The first two times I got them welded and those welds are still fine. It just got to be too much, especially with the top end rebuilds. The old CMI's are in my basement waiting to be turned into a coffee table(seriously).

My mechanic hooked me up and gave them to me at cost, which was about $2,400 I believe. $200 for paint, a few hours of labor and it is back together and I never have to worry about those damn CMI's leaking again.

Do you guys drain your headers after each run. I had a set of lightnings in a 20 cig and they ran for years. I would drain them after each run.

It's not corrosion that's killing them. It's heat cycles and cracking.

First the bad news.... need headers on both motors...

now the REALLY bad news... need a new port engine...

And you're going to buy more CMI products??? There's two kinds of headers, ones that cracked and ones that are going to crack. There's plenty of people that have run SM stuff 15+ years without a single issue. Not too many guys running CMI can say that...

Where in the heck did you find your used engine package. Too bad that your 502 mpi mags sold so fast, you could have just installed the full roller parts, intake and carb and been ready to roll with basically HP 500’s. Hopefully you will find something soon. If I did not go with the CMI exhaust I would go with the KE type like gil wet offshore exhaust. Hope your luck changes for the better soon…..

What??? This is the one with the stuck valve? What is so bad that he has decided the engine is a total loss?

Yes. We thought we would just repair and replace the heads and put new headers on. That was until we got the heads off the port motor and found this.. [ATTACH=CONFIG]504503[/ATTACH][ATTACH=CONFIG]504504[/ATTACH][ATTACH=CONFIG]504505[/ATTACH][ATTACH=CONFIG]504506[/ATTACH]

You said you have owned this boat a total of 6 weeks??? if it were me i would drive that boat though the living room the the guy you bought it from...from looking at the pics that rust just did not happen yesterday..that has been happening for a long while..i would confront the old owner firsr and ask for some money back unless you knew about some sort of engine problem..

If they are from cmi and not merc/cmi....good to go

At least it's rebuild able. Hate to have to buy a complete 525. They are just outrageous $$$$

FIXX,
Read some of his other post on this boat. It originally had 502 mag mpi engines that he sold and installed these (525's). So it is not the person that sold him the boat he should be talking to. I would be talking to the person that the engine package was purchased from. I think I read that these engines were supposed to be low hr rebuilds.

My Bay! ,yes i would be going after the guy that sold him the engines..