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-   -   Mag Vs HO engines (https://www.offshoreonly.com/forums/general-q/259406-mag-vs-ho-engines.html)

zx14k 08-04-2011 06:07 AM


Originally Posted by CrownHawg (Post 3468699)
ZX, I'm curious about the switch from mags to HOs. I have been considering converting my two 496 mags to HOs but have reservations on how this would affect my reliability. My two 375s will push my 32 Victory w/28p 4 blade bravos to around 77 now(a little faster in cool water), and would be curious of how much gain I could expect.

i have more than 500 HRS after the cam and ecm swap with no issu (easy job)like i said on my boat it was about 3 4 MPH i dont know wit 2 engine maybe 5- 6 mph ???.i dont drive the boat to hard,most of the time between 3500-4000 RPM.

CrownHawg 08-04-2011 07:37 AM

ZX, that sounds great! I spoke with Bob L this summer and he was fairly optimistic as to reliability as well. I figured I could possibly turn a set of 30p props if I went with the HO setup. I am borderline right now turning the 28s at 4700-4800. It came with 26s and they were waaaayy too short, running around 5000-5100. Still pondering.

zx14k 08-04-2011 08:47 AM


Originally Posted by CrownHawg (Post 3469726)
ZX, that sounds great! I spoke with Bob L this summer and he was fairly optimistic as to reliability as well. I figured I could possibly turn a set of 30p props if I went with the HO setup. I am borderline right now turning the 28s at 4700-4800. It came with 26s and they were waaaayy too short, running around 5000-5100. Still pondering.

by my experience i think that you will keep the 28 but you will turn them to 5000-5100.the REV alarm on the HO is 5150.on my baja with the mag and a mirage + 23 the best was 4800, with the HO 5050 on the smartcraft digital RPM.i made the swap in 2002 at this time i have to buy cam and new ecm from mercury but now i think that you can have the ecm reflash and a better cam.you can contact raylar 866-496-8181
858-277-1109_fax
for technical info [email protected]
for sales and services [email protected]
for accounting [email protected]
for vendors and distributors [email protected]

if you plan to do the swap yourself i think i can scan the section in the shop manuel that explain how to do it,the only special tools you need is a puller and a torque rench and a tool to disconec the fuel suply to the rail.

A.O. Razor 08-04-2011 09:35 AM


Originally Posted by CrownHawg (Post 3468756)
Merc website states the HP of the Mag at 375 and the HP of the HO at 425. I'm sure it varies with each motor though.


Originally Posted by onesickpantera (Post 3468838)
Yep and most Mags dyno around 390-395. Again, just what I have read no first hand experience.

According to Dustin @ Whipple who have done alot of testing, they are within 2% of their rated power. (He uses SAE ratings, so it's the same as merc)


Originally Posted by CrownHawg (Post 3468699)
ZX, I'm curious about the switch from mags to HOs. I have been considering converting my two 496 mags to HOs but have reservations on how this would affect my reliability. My two 375s will push my 32 Victory w/28p 4 blade bravos to around 77 now(a little faster in cool water), and would be curious of how much gain I could expect.

If you are running 77 on average, 82ish should be the number, and maybe 83+ on the cool day with the sun in your back ect.

Oh and don't you also have to change th TB?

zx14k 08-04-2011 10:39 AM


Originally Posted by A.O. Razor (Post 3469827)
According to Dustin @ Whipple who have done alot of testing, they are within 2% of their rated power. (He uses SAE ratings, so it's the same as merc)



If you are running 77 on average, 82ish should be the number, and maybe 83+ on the cool day with the sun in your back ect.

Oh and don't you also have to change th TB?

NO you only have to drill the existinng hole in the throttle plate to1quater.it is not a must but the idle will be smoother.

CrownHawg 08-04-2011 10:50 AM

That'd be nice! Oh, and no, I wouldn't do it myself. It would be a winter project for a "professional".... I know just the man.

zx14k 08-04-2011 11:29 AM


Originally Posted by CrownHawg (Post 3469891)
That'd be nice! Oh, and no, I wouldn't do it myself. It would be a winter project for a "professional".... I know just the man.

anyway if you need the the part of the shop manuel shoot me a e mail:[email protected]

CrownHawg 08-04-2011 12:16 PM

Thanks! I may take you up on that!

pqjack 08-07-2011 08:09 AM


Originally Posted by zx14k (Post 3469920)
anyway if you need the the part of the shop manuel shoot me a e mail:[email protected]

zx14k...where are you from?...with a name like that,you're probly not far from me !!

zx14k 08-07-2011 08:41 AM


Originally Posted by pqjack (Post 3471747)
zx14k...where are you from?...with a name like that,you're probly not far from me !!

i am from sherbrooke PQ most of my boating is on the lake memfremagog.


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