HI-TEK Marine manifold is it worth the price?

G

Georgia SeaDawg

New Member
Apr 30, 2009
613
Savannah, GA.
Boat Info
270 Dauntless
Engines
Twin 225 verado's
For those of you who have changed out your OEM mercruiser manifolds, risers, and elbows to the HI-TEK marine manifolds, was it worth it? I'm not really looking for perfomance improvement, however I would not turn down better MPG! I'm looking for reliability and not having to change these out every 3-5 years. And for those of you who have 8.1L mercruisers, how difficult was the change out. I understand I will need to make a slight change for my oil filter.
 
I remember an exhaustive thread on this subject but I can't find it using the forum search. Can anyone provide a link?
 
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Was it worth it... I have the HI-TEK manifolds... I have an extra set because their flanges cracked in the second year of use. The pros: they are light (you save about 200 lbs of weight). They prevent water intrusion (the raw water discharges further away from the engine than OEM, and there are no gaskets because of their one piece design). Cons: The bolts are a PITA to get in and out, and you can't torque them. The SS against the cast iron have different expansion rates, and I have had problems with manifold gaskets leaking. I have a water leaks where the remote oil filter holder bracket is welded to the manifold. If you have a problems, it may take several months to resolve them, as there is no supplies of spares in the US. They require zincs, and my zincs leaked, so I have to use plumber's tape or pipe paste on keep them from leaking. The owner of HI-TEK, Alan, stands by his products and was honest with me. Like all custom modifications, where there is not a larger customer base, there are unique issues. My HI-TEK manifolds are about 4 years old, and when they need to be replaced, if I still have the boat, I will probably go back to OEM cast iron...
 
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I've had my for roughly 1 1/2 years. They are much lighter and getting on plane is easier but I didn;t see much improvement on fuel usage unless you open them up. At neat WOT I definatley use less than before but I only do this twice a year to make sure everything is running as it should. They were a PITA to get on but I've had no problems with leaking (fingers crossed). I figure I'll inspect them around year 3-4 and see what they look like. The zincs are easy to change out and seem to be doing their job. Other than installing them I would probably use them again.

SS Manifold 1.jpg

SS Manifold 2.jpg
 
We put them on our 390 gasser and it was a chore. Plenty of details wrong, but coming from a performance background custom items are normally a bit of a challenge. Very happy with the performance improvement, the fuel gains went from about .6 mpg to .75 or so. Fuel burn dropped from 31 gph to 25 gph. All numbers were logged at 20 mph cruise. Over time it should be a nice savings. Now we want a clear floor panel to show off the beautiful manifolds. Would we do it again? Yes. Ours are only 3 months old so time will tell, but we are happy with them.
 
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Rockyranch, what was the challenge? In speaking with Allen, he says it's an easy swap. However, I was not born yesterday, he is a salesman and gets paid to sell. The price quoted for OEM replacement was the same as the HI-TEK manifolds. If it truly is moving the oil filter only, then not a big deal?
 
Allen is helpful, but he knows of the issues, I offered to document all the things that did not fit and he was interested, did a lot of documenting & then found through other users this had been done before so I did not go any further. Ok here goes:

*Oil filter mounts too high so filter lines do not reach, must find someone that can build the lines using the right material so they do not rust. Top bracket at wrong angle (not that big a deal, just do not overtighten after modding the mount so not to stress the stainless welds), lower mount longer than it should be, need to also bend the extension mount.

*Water inlet ports on bottom of manifolds are not in the exact place, have to loop the inlet hose as placement causes the horizonal hose to hit the oil cooler inlet, took the mount loose & moved the cooler forward to give some relief but the hose needs to be replaced to a longer one so it can form a loop to connect.

*The ports for the exhaust sensors are mounted on the wrong side (rear) so the wires are not long enough to reach & had to be spliced. Touchy job as they are sensor wires so solder & adhesive lined heat shrink is needed. The ports on ours were threaded 3/8 x 16, the sensors are 10 mm, they will not screw in. Cannot get sensors with this thread pitch as all PCM555 units use metric threads. Had to sand down the ends & rethread (touchy job). The sensors seal with an O-ring that seat into a small bevel on the OEM manifolds, these were flat so O-rings just squeezed out. Had to get a bevel bit & relieve the mounting spots to allow for the O-rings.

*Mounts for the relay panel are not located correctly & the legs from the outboard supports hit the manifolds right in the side, had to remove legs, sand clean, prep & paint to prevent rust. Still need to make extra supports but not a big deal.

*No cooling water port for driveshaft seals, had to come up with a way to get cooling water to the shafts, should have had a 1/4 pipe boss welded on forward side of starboard manifolds.

*Do not use the supplied mounting bolts, they are the wrong thread (3/8 x 16) when you need metric. You also want stainless, you can find them here in the US with 10 mm 12 point heads for access, really strong but expensive. All worth it in the long run.

The manifolds really fit the engine great & seem to be well constructed, but there are things to overcome. If you go over all this with Alan he will likely build yours correctly or as close as possible, he is very knowledgeable.
 
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