SS manifolds?

B

Black Pearl

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Joined
Feb 2, 2007
RO Number
25076
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9
Hopefully I don't open a can of worms. Who has installed hi-tek SS manifolds? I have an 06 a volvo penta 8.1 that is in need of manifolds and risers. Besides cost, I am wondering if these are worth installing. I am a huge oem part fab, so going outside my comfort zone.
 
I had considered them on our previous boat, which had Mercruier 5.0 engines, but decided against them because of some of the negative reviews and warnings I had read. I must preface this by saying that many postings were very positive in praising their durability and fit. However, many postings dealt with leakage between the manifolds and the heads due to different cooeficients of expansion. Stainless expands differently than cast iron. That, in turn, could lead to leakage at the gasket. I never did change the manifolds because the ones on the engine checked out as perfect, so I left them. The boat we now have have new manifolds and risers, Mercruiser OEM, with less than 50 hours on them. In a few years (hopefully, not too few), when we have to change them, I'll go with OEM cast iron.Hy
 
I don't have any experience with SS manifolds but I do with aftermarket vs. OEM. My original OEM manifolds and risers lasted twice as long as any of the aftermarket brands I've used.
Rob
 
I can't complain, I got about 6 1/2 years out of the risers and manifolds and are still not leaking. I just pulled the riser and are due for replacement. I am assuming the neutra salt that I have been using from day one has extend their life expectancy. I really like the SS. I only know one boater that installed them in our marina last year and he's happy with em. Just seems to be a huge gamble , not so much in cost as it would be a pain to have to deal with if they don't hold mustard.

Black Pearl
 
The Hi-Tek manifolds are by design, raw water manifolds. I have contacted them in the past and They say they can make anything you want.

The positive side, being one piece manifold/risers, you don' have to worry about leakage at the most vulnerable spot...the manifold/riser joint.

The second most vulnerable area is water reversion, or water being sucked back into the engine via the manifolds at low RPM. This phenomenum is a consequence of the valve over lap built into the valve timing of the cam lobes. The design increases power at higher RPM's by creating a sucking effect when the exhaust gases are exiting at high speed and the intake are opening and intake fuel/air is sucked into the combustion chamber at a higher than normal rate by the vacuum created by the exiting exhaust gasses. The design flaw from OEM and all manufacturers is the mixing of the raw water and exhaust at a spot almost the high point.

If you get the High-Tek manifolds, get the ones with the longest exhaust tail so the water mixes as far from the high point of the manifold/riser.

Give them a call and see about what they have available and if they will modify them to fit your application. They may even add the design to their inventory.
 
Charlie, thanks for your input and suggestions. I have taken photos and specs advsent to hi-teck. I currently have 6" risers with no spacers. Total height is 11.3" high from the manifold. Your suggestion regarding the exhuast tail makes sense. I will have to follow up with hi-tech on that. He did say all the brackets will be welded to fit my current requirements, for filter etc.
 
Those things are really expensive, but if they last 2 times as long as cast iron in salt water (is that what you can expect?) I'd be interested in trying them if I re-power this boat with a new engine. My OMC has the one piece manifold/riser units (no longer available) and I do like the the fact that there is no gasket to leak and no joint to corrode. I have 2 sets of em, I run em 4 years and then take em off to clean out the outlets. So far I have never had any water ingestion.
 
Lou,
I think the problem with the one piece manifold is that they last too long. The design looks very similar to the Hi-Tek

Any time you have a gasket leak from a SS manifold at the exhaust port, fire up the engine til it's hot and leaking, then re-tighten the manifold bolts...not too tight. It should pull the manifolds back to flush.

After talking to Hi-Tek for a while, I decided to design and make my own version of SS exhaust. It incorporated mods we've been doing for a few years now. Having full FWC system, the water passages between the manifolds and risers were welded shut which eliminated any chance of water leakage at the manifold/riser joint. Then design and making a fully jacketed riser, baffled exhaust. The raw water doesn't mix with the exhaust gasses until about 4" from the thru transom exhaust. NO water gets into the engine.
 
I remember seeing pix of the ones you made, really cool looking piece of work.
The problem with cast iron manifolds is you never know when they are too thin till its too late. I have read on another forum that you can test them off the engine, by filling them with acetone and looking in the exhaust ports for leaks. Acetone supposedly has lower surface tension than water and it will find cracks that water will not, when the cracks are first starting.
When I winterize the boat I have always filled the engine and manifolds with -100 Antifreeze with corrosion inhibitors, I don't know for sure if that really makes a difference or not. But if you keep the air out over the winter (which here is usually quite damp since we are about 300 feet from salt water) it should reduce corrosion. I can say that when I change thermostats and when I changed the water pump on the front of the engine there was no flaking corrosion in the intake manifold or in the water passages in the block that I could see.....
 
It could be that merc and OMC had a problem with a patent on the one piece manifold. I can't see any other reason not to keep them around.
 
I bet they cost too much to cast since it must be a bit more complex than a 2 piece design. Merc was not satisfied with the 2 piece with the leak potential and that must be why they went to the dry joint system which looks like an improvement. They are a lot more expensive than the conventional ones.
 
The only thing I have heard recently from those that have installed hi-tek SS, is that they have had to return a great deal of them because they did not fit properly. However, I am not sure if that was because they did not provide the proper specs, photos etc. the cost is not that much more than oem (700). Although a company call SS marine located in fl quoted 2800 which are vs hi-tek at 2500. Down side to hi-tek, if something goes bad you have to ship back to Australia which is 400 for shipping.
 
They were over $2K when I was talking to them. At $700, I woulda snatched them up.

Look around, there was someone that was selling them from Fla.

Forgot to ask, are you fresh water cooled?
 
The hi-tek SS are 2000 he reduced it from 2500, because a buddy was going to buy 2 sets. oem 1300 so it's a 700.00 difference. It's not the cost that is keeping me from getting them. I am just concerned with them cracking / leaking as I have read in other posts. Not to mention having to mail them back to Australia if warranty is needed. Allen for hi- tek has been very helpful.
 
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