12v71 TI Detroit’s

[edward]

12v71 TI Detroit’s

I have seen hp ratings of , 650,750 850 etc. for these motors . Were they special from J/T , Covington ? What are the differences, heads,injectors, turbos ? Can you easily rebuild a 650 hp motor to 850hp ? Regards, Edward

 

[dottieshusband]

Re: 12v71 TI Detroit’s

I have seen hp ratings of , 650,750 850 etc. for these motors . Were they special from J/T , Covington ? What are the differences, heads,injectors, turbos ? Can you easily rebuild a 650 hp motor to 850hp ? Regards, Edward

I've seen 650 and 675 for my Ti engine. The TA's are higher hp. As far as I know, the N90's are the largest injectors. My sense is you could go from 17 to 1, to 18 to 1, and go to a bigger turbo.. don't know exactly what that would net you.. but more power!

 

[ageless]

Re: 12v71 TI Detroit’s

I have twin turbo 12-71 TA's rated @ 870hp

 

[Briankinley2004]

Re: 12v71 TI Detroit’s

Mine are TI's and rated at 840HP. Covingtons. I have heard there is a lot to go back natural but not sure about increasing HP.

 

[racclarkson@gmail.com]

Re: 12v71 TI Detroit’s

Blower gear ratio change, maybe larger inter cooler, larger oil cooler, larger HE, possibly different water pump plus what’s been mentioned. Should already be four valve heads.

 

[luckydave215]

Re: 12v71 TI Detroit’s

Mine are TI's rated at 1000 hp, so it CAN be done.
Whether it SHOULD be done.....I would say no!

 

[Cricket]

Re: 12v71 TI Detroit’s

There's a lot of different parts on the high horse power turbo DD 2 strokes compared to the parts used and the timing of the lower rated turbo engines. Remember for a long time each of the DD distributors were building their own versions which is why there's so many horsepower differences. Many of those custom parts are no longer available.

 

[kelpy]

Re: 12v71 TI Detroit’s

Mine are TI's rated at 1000 hp, so it CAN be done.
Whether it SHOULD be done.....I would say no!

Are these Covington engines?

 

[Bayside Bert54]

Re: 12v71 TI Detroit’s

I don't think there is anything special about whether the old Detroit 12V71TI engines are BKX or Covington etc. What they did was use big injectors and big turbos. That's the recipe for approx 850HP. Mine dyno 860hp.

My turbo's are: R5101513
Injectors are: 9215P

The original injectors that the builders used are old part numbers I believe.

 

[kelpy]

Re: 12v71 TI Detroit’s

The poster that has 1000 HP 12V-71TIs has had a lot more done to those engines than just larger turbos and injectors.

 

[luckydave215]

Re: 12v71 TI Detroit’s

The poster that has 1000 HP 12V-71TIs has had a lot more done to those engines than just larger turbos and injectors.

Yeah, but exactly what I don't know beyond the NA pistons and big turbos.
I asked the original owner and he never changed anything beyond a fresh in-frame just before I bought her. The only thing I know for sure (as per Roger Wetherington) is that the boat left the factory that way.

 

[Bayside Bert54]

Re: 12v71 TI Detroit’s

The poster that has 1000 HP 12V-71TIs has had a lot more done to those engines than just larger turbos and injectors.

If anybody has 1000 hp 12V71-TI's, the they can start by showing us the part numbers on the injectors and turbos .. then show the exhaust setup. Then, the dyno run. Have a Detroit Technician tell us about these 1000hp 12V71-TI's. This is something you heard .. not fact. I have the dyno run and specs on my 12V71-TI's .. they are 860hp. Yours are likely the same.

Yes, there are hot rodded 12V71's in some tractor pull machine .. not a marinized 12V71-TI with 1000hp.

 

[kelpy]

Re: 12v71 TI Detroit’s

Sure there are. Covington, along with other DD engine suppliers, could and did get that out of them with ease. Your only talking a little under a 12 HP gain per cylinder over your little 860 HP engines.

 

[Bayside Bert54]

Re: 12v71 TI Detroit’s

Sure there are. Covington, along with other DD engine suppliers, could and did get that out of them with ease. Your only talking a little under a 12 HP gain per cylinder over your little 860 HP engines.

Then let's see it. Show me an example of a 12V71-TI marinized with 1000hp. Maybe you mill the heads to produce more compression? Monster turbos of a completely different type, monster custom blowers? Or, a totally different intercooler system (no longer a TI).

It's just surprising that your'e buying this wives tale when the owner of the "1000" hp TI doesn't know what turbos or injectors he's running. That's a clue.

 

[Westfield 11]

Re: 12v71 TI Detroit’s

I don’t get why that’s a disqualifier: I don’t know what turbos or injectors I have either. I’ve been told I have 650hp, but who knows? 30+ years old with 4 different owners....

 

[Bayside Bert54]

Re: 12v71 TI Detroit’s

I don’t get why that’s a disqualifier: I don’t know what turbos or injectors I have either. I’ve been told I have 650hp, but who knows? 30+ years old with 4 different owners....

The point is, it's not possible unless some kind of advanced race mechanic is doing a one-off. This is NOT that so it's simply bull. A wives tale.

 

[rsmith]

Re: 12v71 TI Detroit’s

I always figured Dave hot rodded them himself. Hatteras didn’t bump the hp to 840 in the 60c until 83-84 I seem to remember they had the hi performance badges on them

 

[ageless]

Re: 12v71 TI Detroit’s

my 71 TA's have M15 injectors and JKL 4437(1? 8?) turbos. A recent cylinder job with head and manifold replacement didn't reveal any unusual parts from the lower end, the head didn't have any upgraded machining to it, the manifolds on these are tough to locate as they are different from the TI. I am still educating myself on the ins/outs of these 71's which is a struggle in itself due to the various builders that have chosen to marinize them in random ways.

For instance: I've never heard anyone come on here to discuss their TA/TI engine so who knows what possibilities are out there. Building 1000HP from a BASE 840 doesn't seem unreasonable, but what continues to amaze me is the dwelling on "numbers" specifically HP when as most know, torque is what really matters with these engines

 

[kelpy]

Re: 12v71 TI Detroit’s

Then let's see it. Show me an example of a 12V71-TI marinized with 1000hp. Maybe you mill the heads to produce more compression? Monster turbos of a completely different type, monster custom blowers? Or, a totally different intercooler system (no longer a TI).

It's just surprising that your'e buying this wives tale when the owner of the "1000" hp TI doesn't know what turbos or injectors he's running. That's a clue.

He isn't the only person with 1000 HP 12-71s.

 

[Cricket]

Re: 12v71 TI Detroit’s

I do sort of remember some 12v71's at 1000hp. There was a company, I think in CA, that was using titanium (or some other fancy metal) for the marinization that was claiming high horsepower for a while. Think they had a problem with their parts catching on fire when they over heated, or something.
Stewart & Stevenson was claiming some higher than the rest HP ratings also back then.
Displacement: 12v71 852cu in , 12v92 1,104cu in. 12v92 was rated at 1050hp so 12v71 at anything over 850hp is living on or over the edge.
Locally back in the day we had a bunch of 46c's with hopped up 8v71's. There was a J&T mechanic who worked on the side that did all the work, changing stuff like heat exchangers, oil and fuel coolers, turbos from larger engines and also modifying blower gear ratio, injectors, timing, etc to produce the higher hp. My memory is the boats all added at least a couple of knots and were reliable.