Phazar454Mag

If I replace my 454 Mag from 1989 with a 496 HO engine, will that fit my old Bravo One drive and can the old Bravo One drive handle the additional power from the 496 HO ?

I understand from previous threads that engine mounts and exhaust locations should be identical, I hope that is correct ?

articfriends

iTrader: (1)

Hopefully you buy a fully dressed out 496,it will save you alot of dinkin around.As long as your bravo drive isn't tired ( a 89 might have 600-800 hours on it?)you should be fine(mercruiser is putting them behind 496's all the time). Your engine mounts and exhaust locations shouldn't be a problem,i'm sure your old motor is carbed though so you'll have a little work to do on the fuel system(modifying it to mate with a fuel injection motor),Have fun,what doe's a gallon of gas cost in denmark in american currency?

NightHawk

I just swapped a new factory 496 HO into a 1992 Checkmate that had a 454 Bravo 1. Only a few minor difficulties. Although the motor mounts are in the same place the larger oil pan on the 496 would not fit inside the cradle of the old offshore mounts. New mounts had to be fabricated by my marina. Also the exahust risers were slightly wider than the old through-transom exahust and prevented my using the old captains call exahust selector. I simply eliminated them and the Y pipe and used stainless 4" exahust pipe from Trident to connect to the old tips at a slightly inward angle. Be sure you have exahust flappers in good condition and you can discard the exahust resonators supplied with the new motor.
The old wire harness had to spliced and extended since the 496 has the plug on the far side of the engine instead of the front. You will eliminate the old drive lube bottle and power steering cylinder since the new engine comes with them.
The new engine bolted to the old transom and outdrive with no problem and I added a drive shower. Go easy on the outdrive and you should have no problems. The new motor is fantastic compared to the old carburated 454 and the increase in power will make you smile regardless of the price of fuel.

NightHawk

I forgot. As far as the fuel system the only modification you need is to be sure and add a quality in-line fuel filter between the tank and engine. Very necessary on this engine as the boost pump inlet screen clogs very easily.

Phazar454Mag

Thank you for the input. The price of gas here is app. 5.7 USD per gallon. I am currently using Silent Choice exhaust setup and I would like to keep it. I wonder whether you can get another Y pipe that would fit the 496 HO engine, or whether it is possible to do some tweaking to get the current setup to work ?

NightHawk

Sure you can purchase a new Y pipe if turns out to necessary on your boat. Plenty of folks using slient choice on 496's but you might end up having to relocate your exahust tips to a wider dimension,which could be a pain in the ass.

wallynt

I swapped a 454 for a 496 and all above info is correct.

If you want to keep the switchable exhaust you might want to consider changing from Silet Choice to Corsa. They make an offset Diverter specificaly for the 496 so it uses the existing "Y" pipe and exhaust holes from the 454. The Part# is 81020-REPL, it retails for $860.00 US , www.corsaperf.com or [email protected]

Wally.

techelec12224

I just put a 496HO in and I had the new deverter ordered. After I heard the engine run for the 1st time on the crate I called and canceled my order for the new diverter from corsa because it sounded so good. Let that thing breathe.

Phazar454Mag

Do you know how much wider the exhaust outlet location is on the 496 HO compared to the 454 ?

Dave M

Hey nighthawk,

Email me your phone#. I would like to discuss your experience with the swap. I am thinking about doing the same thing.

Dave M
[email protected]