Convert 671NAs to 671TIs

"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."

"THE T18A40 TURBO WITH {1.32 A

"THE T18A40 TURBO WITH {1.32 A/R HSG} AND 90MM INJ WILL GET YOU 325HP@2300 RPM WOT.
WITH ALL THE CHANGES YOU WILL HAVE TO MAKE ,IT WHOULD BE BETTER TO FIND A PAIR TI ENGINES AND REBUILD THEM. ALSO WANT TO MAKE SURE YOU HAVE ROOM IN ENGINE AREA FOR ALL THE EXTERS ON TI ENGINES."

"Marv, thank you for your advi

"Marv, thank you for your advice. I have read your other posts and note your v.professional and helpful input on DDs. Your advice is the general consensus I get. However in Indonesia there is 30-40% import costs on new engines making takeouts v. saleable n hard to find.
Another guy here has 6-71TIs-with T18A40s with M (N?)95 injectors and claims 375hp @ 2300 ????? Is this possible??
He plans to replace them with 6v-92s and if so likes to sell me his TIs. You say 325 hp ?? am confused.
Is it better to find T7302s, use small injectors and run them easy..
Have been advised a paper 'Boats and Harbours' is a good source of used engines but cannot find it on-line
BTW what is (1.32 A/R HSG )"

"TAKE OUT ENGINES SOUNDS LIKE

"TAKE OUT ENGINES SOUNDS LIKE THE WAY TO GO,I THINK ENGINE WILL ONLY PUT OUT AROUND 350 HP WITH 95MM INJ. ASK FOR DYNO REPORT TO CHECK H.P. A/R IS AIR INTAKE HOUSING.AIR RATIO"

WHERE CAN I BUY DD INTERCOOLER

WHERE CAN I BUY DD INTERCOOLERS?
Have finally decided to TI my 671s with T18A40s and am 1/2 way through but cannot source Intercoolers here in Indonesia.. any help is really welcome