yikes

ME TOO. Twin small blocks with stock prop exhausts. I need more! I want to install thru hull exhausts with slip on mufflers. Do you think I can gain 500 RPM? I might be asking too much from just an exhaust change but I would like to break into the 70's.
Let us all know.

SB

I installed a pair of Eddie Marine SBC exhaust manifolds + risers last year.

Here are the notes I wrote down when I compared the two:

Mercruiser SBC Exhaust

Weight
OE Manifolds Weight = 64lbs each X 2 = 128lbs

Eddie Marine SBC w/ tails = 26lbs each x 2 = 52lbs

Net difference = 76lbs total

Exhaust Gas Outlet Size ID”

OE=2 3/8”W X 2”H ‘D’ shaped outlet

Eddie Marine = 3” ID

Exhaust Runners

OE = common plenum

Eddie Marine = individual until just below tailpipe flange. Long 4 into short 2 (2” long?) into common area for tailpipe.

Caincando1

Glad you guys like the Revs. Keep us all posted on the results.

2 Trick Rick

Any news yet>? I'm thinking about a twin pack for my Scarab to help the flow and save some weight.

yikes

Your not the only one! What happened? It hasn't startred to snow yet.

2 Trick Rick

No kidding. Somebody buy a set and tell me how they work…

nordic95

They worked and sounded great on my stock 502s 415 HP motors.But now I am building bigger HP as we speak so I am upgrading to CMI headers.I installed O2 sensor bungs in to RMs and it worked out great for tuning.Anyone need two sets pm me.


Nordic95

pullmytrigger

Oh sorry......thought the 300 rpm would be enough......see what 3 to 400 rpm increase does to your boat near full throttle and that should be about right.......

definatly make the engines sound better at idle.......more lopey.......at first didnt think they sounded much different but last weekend let it idle at the dock with the silent choice open and walked way down to the end of the dock.......definatly better.......not night and day.......but definatly better

no question better out of the hole

my azz dragging Fountain raised up 1.5 to 2" in the rear

again......Id like to see if it would pull a set of 23s with 2 people and no gear (my boat is alwaays loaded with people and all kinds of chit......we almost always overnight) but seeing my drives dont counter rotate Id have to come up with (2) 23 right hand props to borrow (be difficult).......which I wont buy because I have new (hotter)engines and a counter rotating drive for next year

we do have a Poker run weekend after Labour day so the boat will be light......Im already over 5 grand now with the 21s so it will probably go even higher........and you want to prop for 4800 with the stock motor

my stock exhaust was leaking internally so they had to be changed.......overall im very satisfied.......another make may give you incremental more increases......but then maybe not.......and no other brand will beat their price......doug

vandeano

I boat regularly in Pacific Ocean and so far my RM exhaust seems fine after 2 years. But Im also anal about flushing after each use.

KAAMA

Back in the mid 1980's a friend of mine had a 30' Scarab with stock Merc 330hp 454cid engines with the old stock cast iron log style Merc exhausts that exited thru the prop hubs. With the stock set-up he could only turn the engines to about 4300-4400rpm. He bought some dry Hardin Marine exhaust manifolds/tailpipes (thru hull) and swapped them out with the stock Merc exhausts and picked up 400-500rpm---of course those are big blocks,.........but I am quite sure with your small blocks you'll see a definate increase in RPM just from going from a thru the prop hub exhaust set-up to a thru-hull design alone---and even more with an aftermarket exhaust system.

The amount of increase in RPM you will see will be determined with whatever aftermarket system you chose---the quality of the runner design and how well it flows/breaths.