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04-01-2011, 10:14 AM #1
Mercury Sport Jet 2.5 L Conversion.
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
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
04-01-2011, 04:46 PM #2
If the weld is good, it should work just fine....."One of the penalties for refusing to participate in politics is that you end up being governed by your inferiors". Plato .
04-01-2011, 10:37 PM #3
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
04-02-2011, 06:55 AM #4
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
04-02-2011, 01:58 PM #5
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.
Kaase Outboard Hydro/Bottle Fed 300 Drag
04-05-2011, 03:22 AM #6
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.
04-05-2011, 05:57 AM #7
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