Stepped vs Non-Stepped Formula 271
11-20-2018 | 08:31 PM
#31
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Joined: Nov 2008
Posts: 595
Likes: 31
So except if you compare the result from Jwurl 68 mph, I should be kind of happy with my 63,6 gps mph on the SR1 hull non stepped.
I am looking forward to test the boat next season, changed from an old Bravo1 XR Drive to a Bravo1 X Drive, I have been tod the te XR drive steal more power
then the other x drive :-) Do not now if it will be any better result, lets see. I am also considering to change to Custome Marine headers (CMI Top Split Headers)
The advertising says that they gains power and speed ;-)
I am looking forward to test the boat next season, changed from an old Bravo1 XR Drive to a Bravo1 X Drive, I have been tod the te XR drive steal more power
then the other x drive :-) Do not now if it will be any better result, lets see. I am also considering to change to Custome Marine headers (CMI Top Split Headers)
The advertising says that they gains power and speed ;-)
11-21-2018 | 02:23 AM
#32
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Joined: Apr 2007
Posts: 533
Likes: 3
From: Oslo
I do not have a 502 I have a 496 HO
its a 2009 model so its time to change the manifolds anyway..I have an offer to buy this CMI Headers for 400 USD :-) I will of course pressure test them first
Maybe it will give me some more power I do not know
11-21-2018 | 06:18 PM
#33
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Joined: Apr 2014
Posts: 650
Likes: 123
From: North Florida
I upgraded to CMI e tops on a 415 hp 502 and didn’t gain a lot on top. The difference was everywhere else. The torque improvement was noticeable especially from cruise to WOT. The tach needle took half as long to get to 5000. I bought mine new and really regret not getting the O2 ports but otherwise they are still on the boat 5 yrs later. Aluminum head 540 now.
11-21-2018 | 09:07 PM
#34
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Joined: Aug 2007
Posts: 676
Likes: 0
From: Greensboro,NC
My 280 tabs are mounted at the same angle as the hull and mounted 3/4 inch up from the edge . That is the way the mercury instructions said to mount them. The drive is a 1.50 ratio because that is the highest ratio you can get in an Xr.
11-26-2018 | 08:55 AM
#35
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Joined: Apr 2007
Posts: 533
Likes: 3
From: Oslo
Jwurl, I think is the most common way to mount the 280 Tabs
If you look at the picture of my transom you can see how the 280 are mounted.
According to the owner before me, this way works very well to avoid chine walking on the 271.. I can not confirm it my self, because I am so far at 63,6 mph he he
I have seen that some Fountains are done the same way as mine
If you look at the picture of my transom you can see how the 280 are mounted.
According to the owner before me, this way works very well to avoid chine walking on the 271.. I can not confirm it my self, because I am so far at 63,6 mph he he
I have seen that some Fountains are done the same way as mine
