Isotta Fraschini Motors

Isottas were a very hot make for Navy/Customs Patrol Boats and the odd performance cruiser in the 70s/80s but seem to have gone out of favour now.

Fabio Buzzi, multiple World Offshore champion designer/racer, has now switched to FPT (Fiat Power Train) due to their huge backing and resouces. Mercruiser have also gone to FPT for their Zeus drive power units since splitting with Cummins.

http://www.fptindustrial.com/global/en/engines/marine

If you remember the old Buzzi Sea Tech engines, go to where the leaders are now.
I'm sure IF builds great stuff, just can not see it well supported in a recreational craft.

I'd go with Yanmar's in that application.

New Yanmar seems to have every expensive parts.

I would go with FPT (Iveco) or FNM.

Yeah well, you can get Yanmar parts and service everywhere and they have a high power to weight ratio and are high rpm motors which is a perfect fit for the OPs boat. You can't even find a part for those motors here in the US.

We have already proved the Cummins 6Bs with down angle clutch replaces LBCs near perfect.

They would be my second choice (1st in most applications). But the OP has a 45' speedboat, so the higher revving Yanmars generally are a better fit given gear ratio's, outdrives and propellers.

I'm guessing the OP is in or loyal to Italy.
Still Fiat, Yanmar or Cummins (maybe more models) could be more practical than the OPs IF inquiry.

Wonder if Merc will offer a Fiat upgrade kit?
That could be interesting.

Already painted black.
Exhaust issues resolved.
Propeller loads calculated.
Gear reduction already figured out.
Choice of propellers already figured out.
Insurance company may not balk.
Resale value much better than a non factory job.

FPT will have a lot of parts in US since they just signed a new agreement for the Mercury diesel engine. Also the new big Cats are FPT based.

Paul Foulston, a UK Cummins engineer had this to say about the QSB range.

Paul Foulston: There is actually very little common about the block B Vs QSB. However lets get down to some basics. The plain old B loved to scream with no ill effects as the Dodge Ram guys know, in fact it loves to spin around 3200 all day where there no hint of crank activitity at all. Bearing in mind that the B crank does not run into trouble until 4200 rpm, other than a torsional grumble at 2700 rpm bottom end is incredibly robust and torsional free. If you ever get to lay a Yanmar LY crank on the floor alongside a B the 3,300 rpm Yanmar crank which looks like a bent pin and nobody questions it. QSB did not need anything doing to the bottom end up to 380 Hp. The big deal is heat. Power equals heat. Once over 350 Hp the old B block has difficulty getting the heat out of the piston crown. The 91 block refinements improved piston cooling. The 370B has had a small piston design change since it first came out to make it more tolerant to abuse. ISB base motor design recognised the need release more power out of 5.9 liters to match the capability of the bottom end. As I said power is heat. The radical and simple piston cooling nozzles in the main bearing saddle of the B were no longer up to the job. ISB was designed from the outset with ´J´ jet under piston cooling nozzles just under the bottom of the bore in order that the oil jet travel was far shorter and better targeted on the underside of the piston. New higher capacity lube pump and cooler came as part of the ISB. The whole ISB block was redesigned and has far greater tensile strength than B Storm block as well as noise reduction benefits. QSB marine was slow off the blocks, the original top rating of 380 was all about using the 370B cooling package, bear in mind QSB 380 is 375 proper Hp 370B is 355 proper Hp. Higher ratings had to wait for a more capable cooling package. Right out of the box ISB proved to be a potential powerhouse and Cummins subcontracted Ricardo to develop ISB for military ´funny´ applications and 500 Hp came straight out of the box. That was in 2001. However what was apparent was the need to get the fluids pumping around the engine and this work saw the capability of the four valve head to continue to follow at high rpm´s. The four valve head actually demonstrated a better valve control than the two valve B at high rpm, probably due to the lower inertia of the valves. QSB 425 came out with a large heat exchanger an even larger oil cooler, still 3000 rpm rated speed. However Cummins is ultra conservative and they developed a unique con rod with an even larger pin bore than a normal 5.9 which is already generous. I think the larger pin bore is borrowed from the 6.7. If you take the QSB 425 as a base platform and improve the coolant flows by spinning it faster the power grows accordingly. If you consider the 480 will have been signed off at 10% overfuel overspeed for 500 hours before anybody even considered letting it loose to the public you realise what the capability of the engine is. Although the 440/480 benefit from the more muscular rods of the QSB425 the part#´s are different even though they look identical, I suspect they a balanced assemblies. I have been very close to a pair of QSB´s in a raceboat running at 3600 rpm all season with calibrations of over 600 Hp at times. Yes an engine blew. Why too much oil, same old story, oil level becomes super critical at 3600 rpm, increased windage in the pan causes aeration of the lube oil and lube temperature rockets. Boat ran a race with 20 psi lube pressue at 3600 and 600+ Hp! and the crank held out but the block split around the area of main bearings, but it held together. Problem solved with CAREFUL calibration of oil pan. New engine sat at 60 psi at 3,600 at the end of a days racing without any issues after that. To sum up the 3400 rpm QSB certainly not a marginal product it is not the Cummins way. What limits the engine from developing even more power? Just the lube oil cooler design, you just cannot cram any more plates in there. Once Cummins have solved that one like they did with the piston cooling jets somebody will be asking all the same questions about some even higher rating.

Dear , does anybody know where I can buy a book / manual of a Isotta Fraschini ID32 SS 6 LM motor