Engine Rebuilt Nightmare
#31
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Are you sure??
I will look more into it but for now.
http://www.sterndrives.com/496maghoengine.html
http://www.perfprotech.com/store/art...fications.aspx
http://www.sterndrives.com/496maghoengine.html
http://www.perfprotech.com/store/art...fications.aspx
Last edited by TEXASRPM; 09-09-2011 at 11:35 AM.
#33
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I will look more into it but for now.
http://www.sterndrives.com/496maghoengine.html
http://www.perfprotech.com/store/art...fications.aspx
http://www.sterndrives.com/496maghoengine.html
http://www.perfprotech.com/store/art...fications.aspx
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#35
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Some things to consider?
If you go by 425 prop shaft HP of 496 HO @ 61mph, think of the following.
If you had 560 dyno hp, and account for 10% hp loss of 56 HP at the prop due to parasitic drive loss, you would be looking at 504 prop shaft hp.
Now take the 504 and subtract 425 prop shaft HP and you get 79 hp gain over the stock motor.
Now if you rate 15 HP approx for each mph and multiply by the 5 mph gain you get 75hp. Sounds pretty close?
This extra HP you have and the 66mph may be realistic.
Just my thoughts. THX
If you go by 425 prop shaft HP of 496 HO @ 61mph, think of the following.
If you had 560 dyno hp, and account for 10% hp loss of 56 HP at the prop due to parasitic drive loss, you would be looking at 504 prop shaft hp.
Now take the 504 and subtract 425 prop shaft HP and you get 79 hp gain over the stock motor.
Now if you rate 15 HP approx for each mph and multiply by the 5 mph gain you get 75hp. Sounds pretty close?
This extra HP you have and the 66mph may be realistic.
Just my thoughts. THX
http://www.go-fast.com/boat_speed_predictions.htm
#36
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Thanks for the input and I understand what you are saying. But wouldn't the extension box and 2" shorty also add to the equation of the top speed as well?
http://www.go-fast.com/boat_speed_predictions.htm
http://www.go-fast.com/boat_speed_predictions.htm
#37
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Interesting data
Bob Llyod of Full Throttle Marine has dyno'd a 496 MAG HO at 387.8 HP at the prop at 5,000 RPM. You can find dyno sheets at his site: www.fullthrottlemarine.com
However, 425 - 388 = 37 HP difference.
504 PSHP - 388PSHP = 116HP DIFFERENCE
Based on the revised 116 HP increase from stock.
8 MPH INCREASE ASSUMING 15 HP PER MPH
7 MPH INCREASE ASSUMING 17 HP PER MPH
6 MPH INCREASE ASSUMING 20 HP PER MPH
Knowing that hull design, beam width, and weight has great effect on top speed and in determining HP PER MPH?
IMO whether 79 or 116 extra PSHP , 66 to 68 would be a realistic top speed number for the 26 Outlaw with that addtional HP
Also, were the speeds recorded by GPS, Radar or DreamOmeter?
I think a Outlaw 26 would have trouble breaking 70 with 504 HP?
I see that BobL runs a Land and Sea Dynometer prop dyno. What type of dyno does Mercury run to verify there prop shaft hp ratings?
Thanks
#38
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The speeds I am posting are GPS.
I understand that the Nordic is a stepped hull and ours is not. It is also a 28 foot boat but we probably have the same amount of hull in the water. Their average was 63 (just on the concept of the step this number should blow ours away but it doesn't) just about 1.5- 2 MPH faster than ours with a 496HO. But with the Raylar kit (525) it picked up 9MPH and was comparable to the blue 525. And with my 575 kit/upgrade (560HP) I picked up 5MPH so far and I should be content with that because it is an Outlaw. I understand I have to adjust the A/F ratio and fuel pressure I get that. 525 (473) getting 72MPH is realistic and ours getting above 70MPH is not. This is where I am a little confused.
Then I was under the impression the E-box and shorty would also improve speeds and now some are saying they will not.
Something is wrong.
Who and what do I believe at this point?
I understand that the Nordic is a stepped hull and ours is not. It is also a 28 foot boat but we probably have the same amount of hull in the water. Their average was 63 (just on the concept of the step this number should blow ours away but it doesn't) just about 1.5- 2 MPH faster than ours with a 496HO. But with the Raylar kit (525) it picked up 9MPH and was comparable to the blue 525. And with my 575 kit/upgrade (560HP) I picked up 5MPH so far and I should be content with that because it is an Outlaw. I understand I have to adjust the A/F ratio and fuel pressure I get that. 525 (473) getting 72MPH is realistic and ours getting above 70MPH is not. This is where I am a little confused.
Then I was under the impression the E-box and shorty would also improve speeds and now some are saying they will not.
Something is wrong.
Who and what do I believe at this point?
Last edited by TW720HVY; 09-09-2011 at 09:37 PM.
#39
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The speeds I am posting are GPS.
I understand that the Nordic is a stepped hull and ours is not. It is also a 28 foot boat but we probably have the same amount of hull in the water. Their average was 63 (just on the concept of the step this number should blow ours away but it doesn't) just about 1.5- 2 MPH faster than ours with a 496HO. But with the Raylar kit (525) it picked up 9MPH and was comparable to the blue 525. And with my 575 kit/upgrade (560HP) I picked up 5MPH so far and I should be content with that because it is an Outlaw. I understand I have to adjust the A/F ratio and fuel pressure I get that. 525 (473) getting 72MPH is realistic and ours getting above 70MPH is not. This is where I am a little confused.
Then I was under the impression the E-box and shorty would also improve speeds and now some are saying they will not.
Something is wrong.
Who and what do I believe at this point?
I understand that the Nordic is a stepped hull and ours is not. It is also a 28 foot boat but we probably have the same amount of hull in the water. Their average was 63 (just on the concept of the step this number should blow ours away but it doesn't) just about 1.5- 2 MPH faster than ours with a 496HO. But with the Raylar kit (525) it picked up 9MPH and was comparable to the blue 525. And with my 575 kit/upgrade (560HP) I picked up 5MPH so far and I should be content with that because it is an Outlaw. I understand I have to adjust the A/F ratio and fuel pressure I get that. 525 (473) getting 72MPH is realistic and ours getting above 70MPH is not. This is where I am a little confused.
Then I was under the impression the E-box and shorty would also improve speeds and now some are saying they will not.
Something is wrong.
Who and what do I believe at this point?
#40
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What they make stock Period!
Just to give everyone here some more credible info:
Raylar has dyno tested on ours and other dynos probably more 496Mag and 496HO engines both stock and with our various upgrades, kits and engine packages than almost anybody on the planet.
A stock full y equipped 496Mag makes about 365-380HP at 4800 rpms at the crankshaft.
A stock fully equipped 496MAG HO makes 421-430 HP at 5000 rpms at the crankshaft.
This is on calibrated, SAE standard testing, with correction factors and specific fuel gravity calculation adjustments and these numbers are pretty much spot on - PERIOD!
Best Regards,
Ray @ Raylar
Raylar has dyno tested on ours and other dynos probably more 496Mag and 496HO engines both stock and with our various upgrades, kits and engine packages than almost anybody on the planet.
A stock full y equipped 496Mag makes about 365-380HP at 4800 rpms at the crankshaft.
A stock fully equipped 496MAG HO makes 421-430 HP at 5000 rpms at the crankshaft.
This is on calibrated, SAE standard testing, with correction factors and specific fuel gravity calculation adjustments and these numbers are pretty much spot on - PERIOD!
Best Regards,
Ray @ Raylar