Detriot 671TI

[Tuna Taxi]

I have 6-71TI 450HPs in my boat. They are a very good engine for what they are. They are simple, leaky, smoky, rock crushers that will run a long time if taken care of. "A long time" is a relative term, depending on whether you get the N, TI, or TIB version. The claims of high hour operation (>3000 hours) are for naturals, which will literally run forever. The turbocharged engines will need rebuilds at 2500-3000 if you run them right, much earlier if you push them hard.

If you are a wanna-be mechanic, they are a very good engine to learn on because of their simplicity. If they start in the morning they are going to run all day. The sailboaters in the marina will burn pictures of you and your family every time you start them up, but that's just part of the fun!

I love them, love the sound, and fish like them too. DD's parts are getting more scarce, the Reliabuilts (DD rebuild program) leaves alot to be desired in the quality department, and they are not as cheap to maintain as they used to be, but still cheaper than most.

I second JD's recommendation about boatdiesel.com. More DD knowledge on there than at DD. Get a good survey from someone who really knows DD's. Since they are so simple and common, everyone who can print a business card becomes a 2-cycle DD expert. If the engines are in decent shape, you will be able to keep them running for a long time.

shoot me a pm if you have specific questions, be happy to help however I can. I am not a DD expert, just a fan.

[Mako Wish]

I have 6-71's 410 hp I love them. Im in the middle of rebuilding them right now they are fairly reasonable in price to do the rebuild. I have 3100 hrs. on mine and they were ready but I could have ran them more.

Also this is the second 6-71 boat i have run for a extended period of time and I swear those motors pull up fish and many other skippers agree.

[fishpicker]

I have a 671N best engine on the planet I feed her Rotila t 40 Lucas and fresh filters every 150 hr. I run at 1700 I turn up to 2250 the only thing that the last 550 gives me is a emptier fuel tank.

The Ti Are no good for me because I idle so much but one thing that I have learned about ti's Idle down slowly over the course of a few miles this allows the Ti to cool down properly.

[Sea Draggin]

Originally Posted by Logan9581

Thats what I've heard about them too. Anyone else with info, please let me know.

Call Capt. Darryl on the Bluewater Lady. When it comes to boats and Detroits he is very knowledgable. I personnally would not buy a boat without having him look at it, I trust him that much. www.bluewaterladycharters.com

[budddavid]

The boat I fish on has a pair of TI's and I rebuild one little over a year ago, with the help of an old salt friend and Detroit/Allison man. He really knows the beasts but is well over sixty so he directed and I did most of the heavy lifting.
Anyway these TI's motors are tuned to 410 hp this is really determined by the size of the injectors, 450 and 485 hp's are common as well, as Tuna Taxi mentioned the amount of power you are getting out of these blocks really effects the lifespan of the engine as well as the rpm you run them at. The engine I rebuild had about 5000 hours on it. They really are simple engines when you get them stripped down. The captain has water circulating block heaters that keep the engines warm at all times, this dramatically reduces the smoking. The piston rings contract when the engine is cold and this causes the smoking till they warm up and expand.

It is worth the expense to have the engines thoroughly surveyed before you purchase the boat, it will cost you some money, >1K and should include compression check (requires valve cover removal and makes a mess) as well as oil analysis as an absolute minimum. The oil pressure the boat maintains at idle after running hard will tell alot about the health of the motor as well. The transmissions obviously critical as well and an entire different subject.

Overall they are (heavy) tough engines, don't run them too fast, keep oil in them (they will usually need some), invest in oil diapers, but they will always get you back home.

[Vixen]

The 671 are great engines I have the 485tib liittle smokey when first starting but clean up real fast a little less fuel efficient then the other four strokes out there but real easy to work on and very reliable

[Bluewater Lady Charters]

Originally Posted by Logan9581

Anyone know anything about these engines?
They are re-built with about 500 hrs on them.


Reason we are looking is we blew an engine on the way home from Bimini and are looking into a better boat for doing the kind of fishing the owner is getting into.

When they were rebuilt, was it just a liner kit or complete, turbos,blowers mains,pumps ect... How many hours before rebuild? Makes a big diference.

410HP is about max for these motors to get any kind of longevity out of them.
These motors were designed well over a half century ago. Originally about 230hp. Most of the boats getting over 10,000 hours on them are naturally aspirated ... no turbos and are used in commercial boats governed out around 1800rpms.
Used to run them in offroad dump trucks., 250hp, governed at 2000. They lasted about 8-10,000hrs
The turbo models are turning up to 2500rpm. If you look at the boat market any boat with detroits that has over 2000 hrs sits there or sells much lower than one with less. Most of the TIBs- 485hp I have seen usually need a rebuild at 2500 hours.

Take an old stock 283 chevy stock short block, put a cam, bigger valve heads, mount that 6-71 blower on top and two 750 holleys on top of that, turn her up to 7 grand and see how long she lasts.
That is basically what marine engine companys did to the 6-71. Hotroded to the max.

[otseg]

I thought you might want to see a candidate for the biggest boat with the smallest motors.




This was a 67' Infinity that I built in 1984 working for Harry Schoell. It had a pair of 485hp 6-71 TI's. Originally the hull was speced as a motor yacht, but Harry had a customer for a sport fish, so a sport fish it became. Fully outfitted it would do about 19 kts. It since has been repowered with 8-92's.

[lmansoor]

I have a 94 Luhrs 380 Open with the same engines. I had the starboard blow on the way back from Bimini 2 years ago. I majored it and it has about 100 hours on it. I also had the port engine overheat on me and majored it a couple of months ago. It has zero hours.

Keep your RPMs at 2100 or less for older engines and watch your temperature. My gauge was off.
My boat is also located in Stuart and I will be putting it up for sale since I took possesion of a new boat.

I can be reached at familymansoor@hotmail.com if you need additional information.

Originally Posted by Logan9581

Anyone know anything about these engines?
They are re-built with about 500 hrs on them.


Reason we are looking is we blew an engine on the way home from Bimini and are looking into a better boat for doing the kind of fishing the owner is getting into.