"I have 2 x 1979 ( from se
"I have 2 x 1979 ( from serial numbers ) 6-71NA J&Ts with claimed 310 hp at 2700rpm. I live in Indonesia where fuel is poor quality, thus lose about +- 10% HP. The engines are (60 hrs ago)fully overhauled - new heads, pistons, liners, over-sized bearings etc etc. They now run very well / sweetly and push my 38ft Uniflite up to abt 15-16kts at 2200 rpm. At 2300rpm I get 17 - 19 kts, effectively WOT. The original design speed was 19kts cruise and 22kts WOT. AT 15-16kts it can be knocked off the plane and at 17-19kts it screams like a banshee--
Re-engining is an option but v. expensive and frankly I like DDs better than other engines in this hp range..reliability is the top and the bottom line..
The engines already have J&T over-sized, water-pumps, heat exchangers and oil coolers.
So I want to turbo the engines either with T18A40s which I understand give up to 375hp, or T7302s to 485hp. I think the latter is way too high for old engines, also it over-powers the boat. I dont know if there are more than these 2 turbos as I have seen boats advertised with 410hp 6-71TIs??
DD here and Singapore have no performance curves or Engine Spec Data for the T18A40s , they say the model is too old..but they have the turbos and inter-coolers which they want to sell me.
I'm looking for comments and advice on this turbo up-grade I'm planning. Is a really functional option? Also sources of parts,part numbers. It may be cheaper to source one complete lot of turbo/intercooler kits from the USA. Alternatively is it better to find a 'takeout pair' of 6-71 TIs and re-build them, acknowledging the unknown risks --
I see Garrett and Air Research Turbos for sale only, are there economies to be had with other reliable brands..Does anyone have a ball park figure on cost -- liners, pistons, injectors ( N80s ) must be changed-- Can any one advise me on injector sizes with which turbos.. and the related hps. The questions are a bit broad but any advice will be really appreciated. Ross."
"I have 2 x 1979 ( from serial numbers ) 6-71NA J&Ts with claimed 310 hp at 2700rpm. I live in Indonesia where fuel is poor quality, thus lose about +- 10% HP. The engines are (60 hrs ago)fully overhauled - new heads, pistons, liners, over-sized bearings etc etc. They now run very well / sweetly and push my 38ft Uniflite up to abt 15-16kts at 2200 rpm. At 2300rpm I get 17 - 19 kts, effectively WOT. The original design speed was 19kts cruise and 22kts WOT. AT 15-16kts it can be knocked off the plane and at 17-19kts it screams like a banshee--
Re-engining is an option but v. expensive and frankly I like DDs better than other engines in this hp range..reliability is the top and the bottom line..
The engines already have J&T over-sized, water-pumps, heat exchangers and oil coolers.
So I want to turbo the engines either with T18A40s which I understand give up to 375hp, or T7302s to 485hp. I think the latter is way too high for old engines, also it over-powers the boat. I dont know if there are more than these 2 turbos as I have seen boats advertised with 410hp 6-71TIs??
DD here and Singapore have no performance curves or Engine Spec Data for the T18A40s , they say the model is too old..but they have the turbos and inter-coolers which they want to sell me.
I'm looking for comments and advice on this turbo up-grade I'm planning. Is a really functional option? Also sources of parts,part numbers. It may be cheaper to source one complete lot of turbo/intercooler kits from the USA. Alternatively is it better to find a 'takeout pair' of 6-71 TIs and re-build them, acknowledging the unknown risks --
I see Garrett and Air Research Turbos for sale only, are there economies to be had with other reliable brands..Does anyone have a ball park figure on cost -- liners, pistons, injectors ( N80s ) must be changed-- Can any one advise me on injector sizes with which turbos.. and the related hps. The questions are a bit broad but any advice will be really appreciated. Ross."