Mercury Sport Jet 2.5 L Conversion.

[Neil Pickard UK]

I Have a Toasted 175 XR2 Sport Jet In a Regal 1700. The boat is in good condition Engine is Junk.
2 Cylinders destroyed,
4 Con Rods
6 Pistons
Crankshaft Gone.
Hole in Crank Case.
To name but a few problems.

I'm In England so parts for these motors are none existant.

A freind of mine who has a machine shop races NS2000-F2 Power boats with 2 litre XR2 2 stroke engines, tuned to 200 hp he's suggested using one of his engines and converting it to run on the jet pump.

He's suggested machining the end of a standard merc drive shaft (8 spline) onto the end of the sport jet drive shaft (13 spline) to enable me to use the standard V6 crank rather than a replacement expensive sport jet crank.

Question is has anyone ever tried this aproach ??

The casting s on the 2.0 ltre race engine are almost identical to the 2.5 sport jet

[flabum1017]

If the weld is good, it should work just fine.....

[blazer01]

i puchased a used jet pump to use on my 200 merc the shaft was 5 inches to long i took the shaft out of the pump and to a local machie shop they cut off what i didt need put new splines on it and i havent had a single issue out of it

[Chris Carson's Marine]

Actually the jet crank is much less cost than the outboard one from mercury,although I agree they aren't as plentiful.I'm not convinced the 2.0 will have the torque required to turn the pump,a 2.0 making 200 hp is probably turning 7000-7500 to do it,that wont work on a jet pump to my knowledge,I don't know if smaller impellers are available,etc.Even if they are I don't think it would be good for a pleasure boat,i expect you would trash the pump and gearbox quickly,Chris

[Way2slow on H2O]

The jet pump is limited to 5800-6200 R's with any motor, and I agree the 2.0 will be a disapointment on power compared to a 2.5...... been there, and the 175 makes more bottom end power than the 240 EFI, I proved it more than once.

[Neil Pickard UK]

Thanks Guys,
So basically the converted drive shaft shouldnt be a problem,

But the feeling is the 2.0 ltre motor will have a lot less bottom end than the 2.5 sportjet even though it has been ported and tuned to 200HP.

[Chris Carson's Marine]

The porting and tuning is to increase hp by increasing rpm,not an option on your jet pump,you need torque that comes from the increased cubes in my opinion,Chris