Posts Tagged ‘marine exhaust’

Topic: MerCruiser Exhaust Manifold Replacement

Customer Question:

“I am doing a resurrection project on a Formula 1986 357 SR1 , twin MerCruiser 454 motors, with KAMMA surface drives. They need replacement marine exhaust manifolds and risers. I also need to replace the thru hull exhaust hoses that connect from the exhaust riser to the thru hull tips located at the transom of the boat. My current thru hull exhaust tips do not have the internal shutters so I’m interested in upgrading to the tips that contain the exhaust shutters that help prevent water ingestion or reversion.

I will also need the external exhaust flappers that go over the outside of the thru hull exhaust tips. The boat is moored in salt water, with possible access to fresh water flush. We really need to watch our budget with this repower project, so value marine exhaust products are required. Could you provide me with some options we could utilize for this piece of the boat restoration project? Thank you, and regards.”

Response:

Wow! This boat restoration project sounds like it will be very interesting and a lot of fun. Water ingestion (including water reversion) is definitely a concern with the big block 454 and 502 marine engines that have teh more aggressive camshafts. I will include links below not only to my recommended product options but also links to several good technical articles aimed at addressing your technical concerns. I would recommend going with the EDP coated exhaust manifolds as these are not only coated externally but double EDP coated on the inside water passages as well.

What is Water Ingestion….Read More

What are MerCruiser Exhaust Resonators….Read More

How to Determine the Proper Exhaust Riser Height….Read More

Thru Hull Exhaust…..Read More

Exhaust Flappers….Read More

EDP Coated MerCruiser Exhaust Manifolds and Risers….Read More

QUESTION: What is the purpose of the “Turbulator” used in Mercruiser Marine Exhaust Systems”.

This is a question Performance Product Technologies receives on a regular basis being the leading technical source for Marine Exhaust products and technical information.  The history of the “Turbulator” dates back to 1932 if you look at the original patent filings for such devices. However the most similar design to the way it was patented and is currently being used by Mercruiser dates back to a patent filed by Jerry Gilbreath, who at the time was the owner of Gil Marine. Gil Marine was later purchased by Corsa products and later sold to CP Performance who now produces the Gil Exhaust systems through their Hardin marine division.

The basis for the “Turbulator” stems from the need to prevent condensation generated within the exhaust system from entering a Marine Engine through the exhaust manifold and riser. Through the basic process of combustion the exhaust temperature generated with the standard internal combustion marine engine reaches approximately 650F – 750F when idling. With the “Cold Manifold” type cooling systems (click on this link to read more about cold versus warm manifold cooling systems) the cooling jackets of the manifold and riser never reach much above 100F. The result of this 650F versus 100F temperature difference is much like what you will see with a cold glass of iced tea sitting outside on a hot summer day. The result: excessive moisture condensing within the inner passages of the exhaust. In some cases the amount of condensation can be enough to actually cause engine misfire if the exhaust is configured such that enough of this condensation makes its way back into the engine.

Without going into a full blown engineering analysis of the “Turbulator” we will provide a brief explanation of how it functions. The basic premise is based on the following design intentions;

1. The angled section of the plate creates a small reservoir once clamped between the exhaust manifold and riser/elbow (see image directly below). This reservoir then acts as a trap to catch and contain any condensation that is collecting on the internal exhaust passages. This reservoir also collects and water that may be present in the exhaust gas originating from water reversion.
2. The reduction in cross-sectional area as the exhaust flows through the “Turbulator” causes a low pressure area within the reservoir of the “Turbulator” itself at the very point where the condensation is collecting. As the exhaust passes through the “Turbulator” and the reduction in flow area the exhaust gas velocity increases which allows the exhaust gas to pull out any condensation collected in the reservoir, that hasn’t already been evaporated by the heat of the exhaust.

Therefore in summary the “Turbulator” is an effective design at helping to reduce the effects of condensation however the best overall approach in our opinion is the “Warm Manifold” type cooling system. The “Warm Manifold” cooling system design offers other advantages such as more consistent temperatures, better results at preventing moisture from reaching the engine, etc. The following links point to the various Mercruiser product locations where you will find the “Turbulator” being used;

• Mercruiser 4.3L Sterndrive Marine Engines
• Mercruiser 5.0L Sterndrive Marine Engines
• Mercruiser 5.7L Sterndrive and Inboard Marine Engines
• Mercruiser 8.1L Sterndrive and Inboard Marine Engines
• Mercruiser 8.2L Sterndrive and Inboard Marine Engines
• Mercruiser Service Retrofit Kits Addressing Water Ingestion

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