Cummins VT555-270hp

Hi,

I have had a lot of exposure to these things in trucks and off highway vehicles.

It is probably the worst thing Cummins ever produced, te rest of the range is excellent but somehow the 555 missed the mark in a big way.

I would not touch them with a barge pole.

Ah, yes, the old 'Triple Nickel'...these saw service in quite a few Bertram 35 & 38s in the late '70s. I don't recall too many problems (whenever the sales guys hear about service issues, then there is a Problem)...they had a Company Boat, a 35, which mostly was used by George Good, Bertram's President at that time.
A young sales guy had the onerous task of shuttling that boat down (or back from) to Ocean Reef or over to Cat Cay...lots of hours on those motors with only an odd quirk late in the game: the boat seemed to have lost speed over time. Bottom was clean, there was not a lot of extra stuff onboard, a mystery... Cummins' answer was to just turn up the PT (pressure-time) or fuel pump to get the speed back.
Bertram's engineering department was not impressed.

Then, there was a Jim Smith ( a sportfisher) with a pair of triple nickels called "Speed Merchant" whose owner hooked up a nitrous bottle to the motors to get an outrageous top end speed (no, I don't remember how fast) for that era and the engines didn't go Kaboom.

Cummins were popular, but they had a reputation for service guys showing up greasy & dirty on sqeaky-clean boats...

I realize that this is an old post, but for future reference, Speed Merchant, the 53' Jim Smith had Johnson & Towers 16V92TA Detroits, not triple nickels.
It was capable of over 50 knots, no nitrous bottle needed.

Maybe, in modern times, the that boat you mention existed.

The Speed Merchant that I am referring to was likely before your time, sonny.

Jim Smith Boats began production in 1981. Back in the bad 'ol days, circa 1977, Mr. Smith entertained a request from a go-fast client--whose name would be familiar to those who knew the previously named Palm Beach International Speedway--to build a fast sportfisherman whose purpose was to 'beat the other guy' in a race over in the Bahamas.
Yes, nitrous oxide was used; however, I got the motors wrong in, perhaps, a Senior Moment...they were Cummins VTA 903s, not the 555s. John at Jim Smith Boats attests to this.
How fast did she go? Dunno, except back then, if your boat topped over twenty, you had a hot rod.

The boat was built in Pompano Beach, Dick won the race, and an almost counter-culture sea story made the rounds. A respected diesel mechanic told me about this roughly a year after it happened.

Additionally, Mr. Crusher, Dick was on his fourth Speed Merchant back in 2006; powered with 183-series MTUs, she'd top out at 54 MPH.

For future reference, as well as past and present reference, this is the Original Speed Merchant Story.

Oh, BTW, welcome to Yacht Forums/Ancient History Division

I experienced my first (and hopefully last) diesel runaway with a 555 in a haulout truck. We tried everything to stop it, even tried to block of the air with a piece of plywood. It just sat there and screamed until it blew up. We finally all just ran away from it.
A runaway diesel is a scary thing.
BTW, that engine was a pure piece of junk. No power and nothing but trouble. I was glad to see it go.

Hi,

The best piece of equipment you can have handy when re starting an engine where anything has been done that might cause a run away or an inability to stop it when you want is the humble C02 Fire Extinguisher.

Squirt it directly into the air inlet and it will stop the most determined engine by simply removing one side of the fire triangle

Makes sense. Good tip!

Having once spent 4 hours squirting CO2 into the blower inlet of a marine diesel I can attest that it doesn't always work that well or quickly - and you'd better have a lot of it available.

By the time we stopped the engine, and it stopped only because the cylinders got so loaded up with lube oil that it finally just slobbered itself to death, we had used around 100 20lb units and 3 wheeled 100 pounders. All the CO2 did was reduce the speed enough that we weren't chased away and were able to keep the sump full of lube oil so the engine wasn't wrecked or suffered a crankcase explosion.

The dock looked like a compressed gas junkyard when it was all over. The inlet trunking to the engine (upstream of the blower) was sucked almost flat so that the air starvation procedure failed immediately.

Squirting halon into a running engine will give everyone downwind of the exhaust a thrill not experienced by many since Ypres or the Somme.

Hi,

I guess there was something else going with that slow or medium speed engine there.

I have seen CO2 used and have used it myself once to stop an engine that was not going to stop by itself till large hardware parts came off it.

It was a standard safety precaution where I did my apprenticeship.

It is not uncommon to see a C02 Extinguisher mounted on the back of a trucks Cab and connected directly to the air inlet as an emergency stop setup over here in Europe.

Another thing I am told works with Detroits as long as the inlet screen is off is a handful of rags which breaks the blower drive shaft.

Can't get much past you ...

It was a FM opposed piston and the upper piston scraper rings were installed upside down.

In the the initial stage of the runaway the guy at the intake end shut the inlet dampers and that sucked the intake trunking flat which opened up all the seams and let enough air into the blower to keep it running. We had to chop a hole in the trunk to be able to shoot CO2 in and when an extinguisher ran out the time it took to insert a new nozzle let enough air in to keep the thing loping along.

Once the fear of violent death passed it just became a holding action. We weren't going to run out of lube oil but we were worried about running out of CO2!

That's a long time to stand next to a hand grenade but I guess the noise would take your mind off impending dismemberment.