pqjack

i agree...the automotive industry faced that challenge some years ago,and the cats have improved tenfold;the hiperf cars such as the corvette can be equipped from the factory with efficient cats,and still deliver 500-600 horsepower,and last for years...the marine market will surely follow,even if the parameters are a bit different

qaberdeen

So, i guess for a repower..the 8.2 without the cats should be a good option going forward..

07DominatorSS

Ray,
Thats funny, because I know of a 2011 32 Sunsation that has run 91.7 GPS with the new 502ho's with the cats, and that is about 10mph faster than the same boat with 496ho's. This owner is pretty happy with them. 90mph boat right out of the box, is pretty impressive in my eyes.

Raylar

Glad to hear that has happened. I guess these guys should talk to that boat owner and factory and find out what is different and what is working for that boat. Also , a question? Was this boat equipped with the new catalytic exhaust engine or the non-catalyst version? boat might have been built under one of those non-green emissions state requirements.

Best Regards,
Ray @ Raylar

Knot 4 Me

There are differences other than the motors for there to be a 10 MPH difference 496HO's vs. 502HO's. Matt never had 496's in his boat so you cannot claim that difference as fact.

07DominatorSS

No, but I have 496ho's in my 32SS, so thats what I'm comparing them to.

07DominatorSS

It does have the cats on them. So, not real sure, but I know he's pretty happy with the performance right out of the box.

Raylar

I guess I have to somewhat question your info here. As it was said by another poster here how do two engines like the 496HO and the new 502HO with almost identical horsepower and more torque out of the 496HO have a nearly 10mph speed difference?? My limited boat knowledge and expierence tells me that " Ain't gonna Happen" in two nearly identical boats.
Have not had any conversations with Matt about his boat, but I think it was or is for sale and I would think he would hold his comments close to the vest if he indeed wants to make a sale no matter what his expierences have been?? Obviously not knocking the boat or the engines just relaying some direct conversations I had with some new boat owners with this new 502 emission version engine and their subsequent results.
If the majority of the new owners of this new engine offering are satisfied and happy with the engine performance in their boats then that is the majority real world answer and result. Let's see if we can get more comments here on OSO from real owners and situations.

Best Regards,
Ray @ Raylar

Best Regards,
Ray @ Raylar

Knot 4 Me

Matt's 32 XRT with 502 HO's has to have a higher X, lighter layup, blue-printed bottom, etc. over Corey's old 32 SS to see that kind of difference in speed. Even then that is a huge spread given the same HP. I'm sure Matt would give some details if you PM'd him on Sunny's site. Boat is still for sale.

HaxbySpeed

I got to mess with both CAT and non 502's at Merc School last year. The first question I asked was how long they thought the O2 sensors would remain accurate in a marine environment. The answer was that a considerable amount of time and r&d went into it and they'v located them in an area that is easy to access for replacement..

No one there really had a ton of info on the engines, but from what I gathered the emissions side of things can throw codes and put the engine in guardian but the engine is still run in open loop and is not referencing the O2's for fuel trim. There are multiple cats in each manifold so restriction is not really an issue. I have done PDI's and sea-trials on both engines and honestly couldn't tell the difference between them. I would however opt for the non cat given a choice. The motors do feel more powerful the the 496 but the calibrations still need some work. The power transition from mid to moderate throttle was not super smooth on the engines I tested but they do pull hard and the idle is much smoother then the 496.