Seadoo GSX RFI vs GSX 800 Carb Performance

[geers182]

I have done more research than I care to admit and I can't find what I'm looking for. I noticed that the Pump Output rating of a 1997 GSX 800 is 57HP and the Pump Output rating of the 2000 GSX RFI is 45HP (according to the Seadoo Manual). I know about the RFI issues but what I really want to know is if there is a major difference in Holeshot Power between these two machines? I live on a small, calm lake, therefore will be using the machine for twists, turns and small jumps as opposed to top end speed.
Does anyone have both machines and notice a difference? Are the 800 Carbed Models more "fun" than the RFI's?

 

[mikidymac]

Don't worry about the output rating. They are both rated at 110HP.
Performance wise they will be basically the same but the RFI will use less fuel. The RFI's are great, just not as easy to work on as the carb models because of the fuel injection.

 

[geers182]

Thanks. Is the Pump Output rating the same as Crankshaft HP rating? If so, I'm wondering if the difference in ratings is due to the added electrical strain on the engine from the RFI system. I used to work with the electrical systems of cars so the complexity of the RFI system doesn't scare me but I don't want to buy something and find out that I should have purchased the Carb version due to the fun factor.

 

[mikidymac]

No. It is just the jet pump. The actual HP for both is 110.
The rating might just be a difference in measurement since they both have the same HP and pump.

You will not notice any difference in performance between the two and long as they are both running correctly.

 

[geers182]

I did do some research and noticed that they are different pumps. The reason for my concern is it seems that the bigger the engine, the greater the Pump Output Rating is. For instance, the 1997 GSX 800 is rated at 56HP, the 1999 GSX Limited is rated at 71.1HP and the 1999 GSX RFI is rated at 44.9HP. I have attached a 1 page sheet which shows these ratings which are in the Seadoo Shop Manuals.
Have you driven both styles? That essentially is the true test.

 

[geers182]

I thought I would conclude this thread with my findings. It appears that the HP output of a pump is affected by many things including diameter and impeller pitch (which probably isn’t a big surprise to anyone). The RFIs have the 140mm “Big Hub” pump which will affect how much water flows through them, in turn affecting HP rating. Ironically, the “Big Hub” pumps are actually designed to perform better at lower speeds and have better “Holeshot” performance than the other GSX pumps. Thanks for your input Mikidymac!

 

[mikidymac]

Honestly, don't worry about the pump HP.
Both 1997 and 1999 RFI GSX's are 787cc and 110HP and you really would not notice any performance difference.

THe GSX Limited is a 951cc 130HP engine.

 

[Chester]

I thought I would conclude this thread with my findings. It appears that the HP output of a pump is affected by many things including diameter and impeller pitch (which probably isn’t a big surprise to anyone). The RFIs have the 140mm “Big Hub” pump which will affect how much water flows through them, in turn affecting HP rating. Ironically, the “Big Hub” pumps are actually designed to perform better at lower speeds and have better “Holeshot” performance than the other GSX pumps. Thanks for your input Mikidymac!

The big hub RFi pump is sometimes referred to as "a poor man's magnum pump". Some guys use them on their modified XPs.

Chester