The Boating Forum - Detroit 8v92 rebuild cost - I am looking at a boat that was built in 1990. The engines have 1600 hours since last major overhaul and they have about 4700 total hours. Sound insulation upgraded. Remember your talking diesel not gas - gas measure their use in hundreds, diesel.

This being off topic in another thread, it seemed useful to start a dedicated thread to Detroit Diesel MUSIC. I think we can add insulation ideas, exhaust muffling and backpressure management, air intake improvements as well as blower silencers. Iclone 5 pro free. Regarding that last point, one very savvy forum member told me in confidence that 90% of DD noise comes from the blower. Comments?;) I'll kick off the thread with a quote from a DD fuel consumption post: I didn't realize that this 'blower' was actually a mechanical fuel injection. I'm all sold ever since my old mechanical injection vintage Benz which sure sounded addictive. As for the DD sound, I'll tell you after Sea Trial on Tuesday.

These are the screamers - highest compression ever small sized high pitch screamers: 8V53s. They probably sound way different from 92s. Regarding the sound, I'll probably like (love) it, but for the Admiralty I'm thinking of looking into cheap and simple measures. Some use lead barriers under the salon floor, others prefer Ensolite foam insulation.

And there are those who reported success in adding Salisbury Hydro-Vac exhaust silencers to their boat - they are heat resistant neoprene or marine fiberglass elbows that attach over the exhaust outlet and redirect exhaust and noise under the surface: Anybody here ever used these?!? Could be nice with marina neighbors that hate smoke & noise.

Otherwise there's always Don Hayward's schematic for quietening Detroits by installing a muffler immediately downstream of the exhaust manifold and upstream of the water injection. Seems like it might be worth a shot, unless it can compromise airflow to the engine which depends a lot on the relatively open exhaust of a two stroke? Or just tell 'em to love the noise or walk the plank!:D. Nothing screams louder inside than 53 series Detroits. They really do sing!!!I've had 3-53 and 6V53's and both required sound deadening earmuffs when checking at cruise speed. My current 8V71TI's are much quieter inside despite being 2 or three times the HP.

71's are more deep rumble than high pitched sound. And of course they are rated at 500 less RPM which can't hurt noise levels. But the diesel compression sound is always going to be noiser than gas. Adding Salisbury silencers will do nothing do reduce smoke at start but can reduce exhaust sound.and your ability to listen to exhaust sound for proper tone.

I'd never use them myself as a suddenly loud exhaust while cruising is often the first warning you've lose saltwater flow. Inside, if you want to try to reduce noise levels you need to add sound insulation with a lead layer suspended inside the insulation to stop the lower level frequencies. Lining the hull interior and bulkheads in the engine room to reduce sound reflections can also help. But these are Detroits,mon, so revel in the old loud technology!!! One of our club members had a set of those Salisbury silencers on his boat years ago ( gas 318 Chryslers ) and when he shut down the engines after a day outing one engine rolled backwards and there was enough vacum created to overcome the small vent hole in the silencer and draw saltwater into the engine. The owner didn't know he had a problem until the next weekend when he tried to start the now seized engine.

I don't think I would be a fan of underwater exhaust unless I knew there was enough open vent to prevent that possibility. Truth be told I do love the sound of my 8v53's also) JMHO, Fred. There are many boats that run in my area with detroits. If I am at anchor on a day with standard summer haze I almost always hear them coming before I can see them. The crew boats I have run all seem to have detroits and there is nothing more mind and body numming than a long day at sea listening to them screech. Maybe the ones I have been around had no mufflers or proper sound proofing but there is just something about the pitch and cadence that leaves me with ringing ears. I took to using a set of earmuffs even on the bridge let alone out on the deck.