Preuni

The carbed 454 Mag (94) in my Baja 272 has seen better days, so I am replacing it with a brandnew 496 Mag HO. From similar threads on this board I know that installation wont be a problem concerning engine mounts, wiring harness and connecting to the Bravo 1 drive. My question concerns the exhaust system, in some threads it is said that everything will fit ok, in others it was stated that the exhaust on the newer 496 is spaced wider apart than on the old 454.
I have a Gil silent choice system installed that i would like to keep, so the new engine should be able to meet with the existing Y-pipe from the 454/Bravo setup and with the exhaust tips on the transom.
Can I reuse the system without cutting new holes in the transom (pain!!!) or is a special set of diverters available with an offset to match the older exhaust patterns of the old 454/502 engines (tips and Y-pipe)....
Or could I simply bolt on the old exhaust system of the 454 to the 496? From what I ve heard its the same block. Would I loose power on the 496 by doing that?
I know that many of the OSO members did a similar swap, so any experiences are very welcome! Thanks!

techelec12224

Preuni
I did a swap from a 454 to a 496HO and it was pretty basic. I talked to my buddy about using my corsa diverters and corsa wanted $800.00 for the new parts. I was told to let that engine breath . You are going to love the sound of that motor good luck.

Rich

Dave M

I'm planning the same swap this winter. I had silent choice which I was looking to get rid of anyway. You would not want to use your exhaust off the 454 ever if it would fit. One of the nice things about the 496 is that there is a dry joint between the manifold and riser with a bypass hose. Thus eliminating the cause of death or damage for many engines. I think the plumbing is different too due to the closed cooling.

This thread had some good info ....
http://www.offshoreonly.com/forums/s...t=454+496+swap

bobl

Most likely it will fit with no problem. I did it on a boat with captains call and had no problems. The exhaust is closer together on the 454 but flex in the exhaust hoses will usually allow enough adjustment to get a good fit.

Preuni

Thanks a lot to everybody! I think I will try to make the old system fit to the new engine (hope theres enough flex in the hoses possible) and if not, I still can buy the offset diverters from Corsa. I would love to let the engine breath but would end up with a confiscated boat...noise regulations over here are strict....
I am looking forward the swap, I hope the boat is more fun to drive with the 496...my hopes are not too high, I know that the Baja 272s need a lot of motor to start moving, and 425 hp might not be enough. But better than the 54mph (GPS) with the old 454, hope to get an honest 62 out of it. Next step is to procharge or whipple to reach 70+....:-)

Goofy1103

I changed from Merc HP 465 to 496 HO

The only problem was that the stock elbows of the 496 exhaust were not high enough , so I had to take the 2 inch higher ones

Regards goofy

kr1276

We did the swap from 502's to 496 HO's (twins) and we tried to use the existing setup. It will not work by angling the rubber eahaust hose as it will create a hot spot in the exhaust and burn a hole in it.. We had some pipes fabricated to reroute the exhaust and solve the problem.
Save yourself some trouble and go ahead and have the pipes made.