Riva Exhaust upgrade

[DrivenPhoto]

So, I had an issue with my exhaust silencer box(resonator) getting heated up and leaking as well as corrosion on one water box. I order two Water boxes from Riva, removed the silencers and man.. The stock exhaust must be so restrictive. Its been down on power (thinking wear ring issues from the intakes being clogged) but with this mod and upgrade I can say that its an improvement. Quicker acceleration an easy 55MPH even with the worn rings and the sound is great.

A local performance guy recommended getting a stock Sea Doo intake from a 255 that doesn’t have the intercooler built in and putting an external intercooler like the 250hp model boats have. He also mentioned ditching the catalytic converter as he has seen issues, that too should increase top end and exhaust flow and temps.

Ill try to get some video of the boat this weekend. Hope this helps for those who have thought of upgrading.

 

[DrivenPhoto]

 

[Pirana]

Soooooo....is there a pipe to eliminate the cats? If so, what about the O2 sensors?

 

[DrivenPhoto]

I’m going to test a theory. There’s an inlet and outlet cap with the cat sandwiched between. They have 8 H6 bolts holding them together on each side. I am thinking I can just remove the center(cat) and put the two ends together. The sea doo’s do not cats from what I am told.
As far as I know, we should just get an engine light from the o2 unless there is a shut off for them in the available tuners out there. I’ll call Riva and ask.

 

[ScarabMike]

I don't even know what to say.

Im going to be very indirect because I can assume you are trying to do your homework, but looking in the wrong areas.

1. The seadoo engine, and the Scarab engine are the same in theory, but very different in reality. The Scarab as you can see has a catalyzed engine. Not only does it have o2 sensors for monitoring the emissions, it also had a MAF (Mass Air Flow)sensor. This is a more efficient way to cut down on carbon emissions than the seadoo MAP (Manifold Absolute Pressure) sensor.
2. The catalytic isn't the same as a spark arrestor in the intake manifold, you cannot just gut it and expect the boat to operate normally. It will go into "limp" mode. You need to flash the ECU to remove this. Defoulers will not work.
3. Those water boxes are completely different. The inlet and exits are backwards, and you will need some major custom piping to get it to work. But if you do, the RIVA one is very good.
4. The coolant hose you are pulling with the rope, and crimping it to hell......
5. The Scarab's intake does not have an intercooler built in, no engine does. The intercooler is placed between the supercharger outlet, and the intake manifold.

With the amount of issues these boats are known to have, its not a good idea to mess with the main parts of the engine. Good luck with your build.

 

[DrivenPhoto]

Mike, I appreciate your help and knowledge.

I don't assume to know how the Scarab engine is programmed but I will call Riva, R&D as well as my local tech that inspects race skies for competitions to make sure nobody cheats(He knows these motors well) to make sure i don't mess anything up. My experience with High HP cars there is always a work around for the O2 issues. I will also just unplug it to see what issues it may cause. Great thing about having it on a lift in a lake behind my home. Experiment, test, repeat...

And from what i know, these bottom ends are pretty much the same, same internals etc, with boosting, programming being the main difference in HP.
The water boxes are in, using factory hoses, minus one 4" 45* elbow to adjust the position of one box. Otherwise... I was quite amazed at the fitment and piping. The install is done. Seems you only read partially. But yes, the RIVA's are very good. Excellent build quality.
The Scarab indeed does have an intercooler built into the intake. It runs right down the center of the plenum. There are many applications where it is placed between the motor and the intake or built into the intake... My 800HP CTS-V had a water to air intercooler sandwiched above the supercharger and the intake manifold, along with a heat exchanger. Where as my Grand Cherokee SRT8 that had an aftermarket charger had an external intercooler with heat exchanger and push pull fans. This was an external intercooler that is placed between plumbing of the outlet of the supercharger and the intake. Don't want you to misinform the readers.. since no engine has it?!?

Yes i did pull that hose back to get to the last bolt.

Internal intercooler on a LSA motor in this photo(Top) the cooler sits above the charger incased in the supercharger, intake plenum. There are versions of this where they sit under the charger between the motor and supercharger cooling the air before the air enters into the heads. This is an example of a roots style system. Now centrifugal is different as the blower is mounted different(typically separate from the motor not part of the intake system). Centrifugal is what our boats have. In this case you can have an external cooler or i guess even an intake mounted one too... Photo below to show what the 215 looks like that runs down the center of the intake manifold and the bottom photo is of an external one that Mike knows of...

 

[DrivenPhoto]

Just in case there is confusion. The cylindrical looking intercooler that is mounted in the center of our 215 motor that is pictured above is also pictured exiting the intake manifold in this photo...

 

[SVTSINR]

Nice, can you post a pic of the water boxes installed along with removing the silencers?

Did Riva supply all the parts as a kit?

 

[DrivenPhoto]

Nice, can you post a pic of the water boxes installed along with removing the silencers?

Did Riva supply all the parts as a kit?

I will take some photos for you. So me video too.

Riva only sells the water box which obviously are for a Sea Doo. They make no claims of performance or fitment. This is a complete retro fit. In no way is it a direct replacement... with that disclaimer.... the install was fairly straightforward, you need long arms to get the hose off the exhaust outlet at the back of the boat. Since the Riva is reversed (2 1/2) outlet side, you can flip flop the hoses from port to starboard And visa versa. Starboard side was a bit tricky had to order a new elbow. I purchased a 45 but feel a 90 would provide better fitment.

The silencer box removal and leaving the factory waterbox was a bit more complicated. You'll have to buy some 2 1/2 exhaust pipe(galvanized) so you can make a pivotable elbow, you also have to shorten up one of the hoses... Frankly... The new boxes were a better fitment with less modifications then just bypassing the silencers.

 

[ALAN MANN SR.]

I’m going to test a theory. There’s an inlet and outlet cap with the cat sandwiched between. They have 8 H6 bolts holding them together on each side. I am thinking I can just remove the center(cat) and put the two ends together. The sea doo’s do not cats from what I am told.
As far as I know, we should just get an engine light from the o2 unless there is a shut off for them in the available tuners out there. I’ll call Riva and ask.

Have you tried removing the catalyst? If so what is the results? I have done this on a 1996 Dodge Ram, 2002 Dodge Dakota, 2004 Ford F150 and the O2 sensors don't even know that it is gone. no check engine light, and better gas mileage with the exception of the 1996 Dodge Ram it gets 12 miles to the gallon no matter what.

 

[ScarabMike]

I would highly suggest you monitor your temperatures closely. Remember, PWCs and Jetboats are not the same in many ways. With any upgrades that aren't tested for a 3k lbs boat, and different flow rates going through the jet pump. Im not saying that it isnt going to work, Im saying to keep an eye out. Especially on these boats that are very sensitive, and not too much QC has been taken on their build on older generations. Also, looking at your engine components, try giving your engine bay a bath of CRC 656 or a good silicone spray. It will keep your connections and components from oxidizing, and rusting.

 

[Jpseph296]

Any updates on by passing cats?