Hi-Perf Boat Headers

[Mikeski]

Well technically I guess they should be called manifolds but they should flow like headers. Check them out... Should have some numbers after this weekend when I get some time on the water with them.

[DRAGON88]

RE: Hi-Perf Boat Headers

Man the stockers are restrictive! I can't wait to hear the verdict about them, it will definitely be interesting to see how they perform.

[TRBenj]

RE: Hi-Perf Boat Headers

What brand did you go with? The guy on the Malibu forums with the 68MPH Sportster used Eddie Marine, and these look very similar.

[bobchris]

RE: Hi-Perf Boat Headers

If you have a chevy there are tons of options for performance exhaust and several that are true header style instead of the bulky cast aluminum mainfolds and risers. Hope these are going on a v-drive, don't believe they'll fit under a motor box in the middle look's like it would be a little wide and too tall as well. The 351W motor is the hard one to get parts for but you can get true water cooled headers for them from a manufacturer in Austriala.

[JoeCos]

RE: Hi-Perf Boat Headers

Wow, the weight alone is almost half compared to the stockers ! I'm assuming its aluminum - ?

I'm also curious as to the performance and end result, please do update ?

[Mikeski]

RE: Hi-Perf Boat Headers

The idea did come from Eagledriver on the MBO forum, he has provided input. These are revolution marine, very similar to Eddie Marine but I liked the dry joint between the manifold and riser since that always seems to be a source of problems anyway. Yes Joe, aluminum. Yes BobChris, doubtful they would fit under the stock motorbox in a direct drive they are significantly wider and taller. As I understand the longer sweep in the first 90 is where most of the HP gain comes from.

[gotpwr]

RE: Hi-Perf Boat Headers

That is awesome! I'm curious if you will lose any torque with the headers or get into any drivability problems without changing the PCM calibration. I'll definitely be watching this thread unfold.

[Mikeski]

one down one to go...

One down one to go... The difference is much more impressive in person, the RM header is about 2" wider and 2" taller.

[bobchris]

RE: one down one to go...

that's a tight fit with the revolutions

This will fit in any in model inboard and are a true header and not manifolds, notice the 1-3/4" tubing at the flange and only one water connection.

[Mikeski]

RE: one down one to go...

BobChris,

Where do those come from? Weight?

[bobchris]

RE: one down one to go...

hi-tek marine in austriala they run aproximately 1500.00 shipped to the USA, I think there is a distributor in Michigan as well. I think the pair weighs around 30 lbs or less.

I talked to the owner directly and have their e-mail too, real nice people enjoyed talking to the guy, it's your only option if you have a 351W and want real headers. I got lucky on e-bay and got some NOS edlebrock aluminum logs that I'm going to install in a couple of weeks.

[Miljack]

Mike,
cool project, what is the objective? Did you take any pre-project test numbers so you can compare post project?
How much wider are the RM manifolds? It appears in one pic that it's about 2-3" wider, but how do they actually measure when installed?

I'm curious to see if your low end torque is changed with these manifolds. Also, did you look into the Indmar "header" style manifolds?

thanks,
Jack

[NSV]

Mike,
What happens to the engine warranty after you install these headers?

[Mikeski]

The objective with this project was to gain 1-2mph on the top end so the boat will go fast enough to pull one foot barefoot plus losing 60lbs off the rear to help the slalom wake. Not really worried about the engine warranty, I was more worried that running at 5200RPMs pulling footers might cause the engine to toss something. It now can turn the 1160 prop without struggling and this runs at about 4950RPM flat out. I feel more comfortable running just under 5k rather than just over 5k.

Is it worth the $1000 that it cost??? I would say no for 99% of the users out there, but I am probably in the 1% that can benefit from this modification. What the heck, I had the money in my PayPal account anyway.

I really doubt that these would fit under a stock direct-drive motor cover, they are much larger than the stockers. And they do not make them for a Ford (but you probably don't need them if you have the Ford since they make more torque already).

[Mikeski]

Update

Yesterday I finally had a chance to put the boat through it's paces with the new exhausts. With GPS in hand I clocked the boat at a top speed of 45.9mph at 5000rpm. At 34mph the boat turns 3800rpm, with the wakegate in cruise fully loaded with tower, bimini, speakers and a few others stuff it runs a real solid 43.5mph so I think I have accomplished my goal. Too bad there were only two of us I was not able to do any footing to see if it would pull the one footers. In any case if I can't do it now it will be my fault not the boats, so no more blaming weak equipment.

I also seem to be burning less fuel with the 1160 prop and header combo. I seemed to only burn about 4 gallons per hour yesterday but I might have spent more time idling around than usual while calibrating the perfect pass.