The two risers pictured at left are from the port engine and were standard, the two risers on the right are from the starboard engine and were fitted with the “Dry-Tech Reversion Control System”™, Patent Pending.
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In an August 2001 MerCruiser Service Bulletin the company said there was a problem and recommended as a solution its "Exhaust Resonator Kit," Crusader says it has recently invented a patented solution fitted in the exhaust riser, and Volvo Penta told us that if there is a problem it should taken care of by the engine maker. So, it doesn’t sound like there is much of a problem.
Mac Privott says Problem Persists
But tell that to Mac Privott, president and owner of Carolina Classic. For the last three years he has been telling BoatTEST.com that there is still a problem with water reversion in large block inboard gasoline engines. Privott contends that at idle speeds, valve overlap causes negative pressure and exhaust water will migrate up the exhaust riser into the engine manifold.
Mac builds about 85 Carolina Classics a year in his Edenton, N.C. factory on the shore of the Albemarle River. “I have put transparent tubes on the exhaust manifolds and you can watch the water march right up,” Privott told us this fall at the Norwalk boat show.
He said as recently as this summer he has encountered the problem and that he is working with one of the engine companies to solve it. Performance Resources, LLC, has sent one of their prototype units for Privott to test in a real installation and has promised to indemnify him for an engine replacement if their product doesn’t work.
“I have the product, but have not had a chance to test it,” Privott told us at the Ft. Lauderdale Boat Show, “but I do plan to test soon.”
The "Dry-Tech Reversion Control System" invented by Performance Resources fits into the exhaust riser.
1200 Hours of Testing
The picture at the beginning of this article was sent to us recently by Performance Resources and they claim that these exhaust risers were recently taken off of a patrol boat in Southern California which tested the units on its twin engine installation. Standard risers were left on the port side of each engine and on the starboard side the risers were fitted with the company’s new patented invention, according to the Bob Kelly, president of Performance Resources.
“As you can see, there is quite a bit of corrosion on the risers without our product,” Kelly said, “but on the side with our units, the risers are rust free. As you can see there is no corrosion or salt build up in those risers.” Kelly told us that the risers had been taken off after 1200 hours of use. He said that since patrol boats spend a lot of time at idle, they are ideal boats to test his product.
Kelly and his financial backers say that they have plowed over $1 million into the development of their stainless steel anti-reversion unit and they would like to sell the patent to either MerCruiser or Volvo Penta. They are calling the device the "Dry-Tech Reversion Control System."
Product Going to Market
“Mercury spent many months looking at our unit,” Kelly said, “and finally told us that they were not interested in it. Volvo Penta won’t even look at it,” Kelly said. As a result, Performance Resources plans to market the product on its own to both boat builders and the aftermarket. We were told that they will sell for about $1500 a pair.
In an exclusive interview Chuck Thurman, president of Crusader Marine, told BoatTEST.com's Capt. Robert Smith that there definitely was a problem with water reversion and that his company has devised a patented solution in the riser itself to stop water ingestion.
For more information about water ingestion, we refer you to a MerCruiser Service Bulletin dated August 2001-- click here
All four engine marinizers – MerCruiser, Volvo Penta, Crusader, and Indmar – use gasoline truck engine blocks supplied by General Motors.