|
Originally Posted by Monaco20
(Post 4659850)
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 ;-) |
Originally Posted by Zone 5
(Post 4660180)
Yes, 63.6 with a bone stock 502 on an SR 271 is a great speed. And no, adding CMI exhaust to that motor is a total waste of money. You will see nothing except less money in your bank acct. Exhaust only has an effect on power when you modify the stock motor.
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 |
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. |
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.
|
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 |
| All times are GMT -5. The time now is 06:03 PM. |
Copyright © 2026 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.