CMI 496 headers
#41
Reminds me of the old days with the 502.
Let's see, you can do the K&N air filter, ECU reprogram, SM Marine exhaust to get the same HP as a 500 EFI right. Put on a labbed prop and you will pick up 7 mph.......yeah right.
You can do a number of things but in most cases you won"t see much more than 2-3 mph on a v-hull without going into the engine. Unfortunately that is pretty much the way it works.
Let's see, you can do the K&N air filter, ECU reprogram, SM Marine exhaust to get the same HP as a 500 EFI right. Put on a labbed prop and you will pick up 7 mph.......yeah right.
You can do a number of things but in most cases you won"t see much more than 2-3 mph on a v-hull without going into the engine. Unfortunately that is pretty much the way it works.
#43
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Joined: Oct 2009
Posts: 426
Likes: 0
From: Harrison Hot Springs BC Canada
i just had CMI ETops added to my 496 HO over the winter in my 26 lavey
im not disappointed sound good and the motor runs strong
also boosted the fuel pressure up 3 psi no ecu remapping
quite expensive with little to no anticipated benefits
also knocked the baffles out of the tips felt they were far to restrictive
the hull is a new purchase for me so i didnt really have previous numbers to compare it to
bought the boat late in the season for here and i felt that the prop that came with the boat was somewhat to small so i am starting from scratch but so far 63 with the 22p b1 that came with the boat no headers
70 with a 25p mirage plus @5000rpm. headers on
66 with stock merc 24p B1 @ 4900rpm " " yesterday
i purchased a labbed 26p B1 style prop
havent got it wet yet but i am expecting to see speed in the low 70s
im not disappointed sound good and the motor runs strong
also boosted the fuel pressure up 3 psi no ecu remapping
quite expensive with little to no anticipated benefits
also knocked the baffles out of the tips felt they were far to restrictive
the hull is a new purchase for me so i didnt really have previous numbers to compare it to
bought the boat late in the season for here and i felt that the prop that came with the boat was somewhat to small so i am starting from scratch but so far 63 with the 22p b1 that came with the boat no headers
70 with a 25p mirage plus @5000rpm. headers on
66 with stock merc 24p B1 @ 4900rpm " " yesterday
i purchased a labbed 26p B1 style prop
havent got it wet yet but i am expecting to see speed in the low 70s
Last edited by Centsless; 05-09-2010 at 11:13 AM.
#46
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Joined: Nov 2009
Posts: 672
Likes: 0
hi guys paul here from england sorry to go off subject but you all seem to no a lot about 496HO .i have a 28 foot pantera twin 496 HO .only got the boat to the uk a few weeks ago not had it in the water yet but have had it runnig on the hose this is a 2001 boat the oil presure on the electric gaffrig =40 psi on both the motors cold at idle i did rev the motor up a little to 2500 still 40 psi put a mecan oil pr gauge and got 43,,,44 , can anyone tell me wot i should see on the clocks back on subject would love a set of tubes just a bit to steep for me ,still saveing up for a tank of gas costs alot more over here guys approx $9 a gallon that hurts
regards paul
regards paul
#47
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Joined: Jan 2004
Posts: 2,777
Likes: 12
From: San Diego, California
Paul:
Stock oil pressure on 496's with a good 20-50W weight oil on a cold engine will run about 35-45 psi cold and can be as low as 30psi warm at idle, with higher rpm oil pressure at about 45-55 psi cold and about 40-50 psi warm after running at loads. An oil pressure under 30psi at idle or under 40psi at high rpms usually indicates a possible problem with oil weight, oil pump or internal engine issues like bearings and such. The Mercury 'Guardian" alarm feature should sound if the engine goes below 20psi and the power will be reduced significantly to help protect the engine at that point. Also do not overfill the crankscase as this can cause oil foaming and pressure loss from that condition.
Best Regards,
Ray @ Raylar
Best Regards,
Ray @ Raylar
Stock oil pressure on 496's with a good 20-50W weight oil on a cold engine will run about 35-45 psi cold and can be as low as 30psi warm at idle, with higher rpm oil pressure at about 45-55 psi cold and about 40-50 psi warm after running at loads. An oil pressure under 30psi at idle or under 40psi at high rpms usually indicates a possible problem with oil weight, oil pump or internal engine issues like bearings and such. The Mercury 'Guardian" alarm feature should sound if the engine goes below 20psi and the power will be reduced significantly to help protect the engine at that point. Also do not overfill the crankscase as this can cause oil foaming and pressure loss from that condition.
Best Regards,
Ray @ Raylar
Best Regards,
Ray @ Raylar
#48
The Mercrusier tech line said that the oil pressure when the Guardian system will respond to protect the engine is 8-9 psi regardless of rpm. I have personally been as low as 10-12 psi oil pressure at idle and the Guradian did not kick in.
#49
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Joined: Nov 2009
Posts: 672
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thanks Raylar ,ran motors up today all new oil and filters all seems well 40 psi at idle reved it to 2500 went up to 45 psi they both sound sweet they look as good as new only 142 hours .the only reasen i was worried is iam going to buy a coulple of master lubes to pre lube the motors befor start up and the guy said he thought that the 496 ho motors ran 80 but i thingk he was gessing psi thanks again Raylar i will let you no how it runs soon as i take tit out REGARDS paul from uk




