500+ hp out of a 496HO
06-10-2004, 08:36 AM
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Re: 500+ hp out of a 496HO
I think one of the few instances you will see a gain of 26 hp from the addition of 1.8 roller rockers, indicative that the cam in the 496 Mag with Raylar heads on it does not have nearly enough lift. The smaller cam is one of the differences between the Mag and Mag HO motors. To just bolt 1.8 roller rockers on any old motor I doubt you will see these kind of results unless. For what Raylar is trying to accomplish hp wise using the addition of bolt ons, without opening up the motor, makes their package simplistic, which most anyone buying their package could accomplish.
06-10-2004, 10:22 AM
#22
Re: 500+ hp out of a 496HO
Well it sounds like a cam change will help. That is if there is enough clearance with the piston. However, I remember Raylar indicating the stock setup wouldn't take too much more lift.
Raylar, any results from you cam testing this week?
Rick
Raylar, any results from you cam testing this week?
Rick
06-10-2004, 10:28 AM
#23
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Re: 500+ hp out of a 496HO
Originally Posted by causin trouble
Looked at Whipple's but you can only run them in 7-10 min spurts wide open (I like to hammer down at times longer than that in Poker runs)
John
06-10-2004, 11:47 AM
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Re: 500+ hp out of a 496HO
Originally Posted by sutphen30
closed cooling isn't big enough,but if you go to a bigger exchanger which is readily available then let it rip for as long as you want.
Design wise that doesn't make a ton of sense because all the cooling of the inlet charge is dependent upon the primary heat exchanger from closed loop system on the engine. Makes no sense at all when you have an immedaitely available unlimited supply of cold water available. Makes a kit simpler since the plumbing is standardized..
Can you just plumb it straight off the sea strainer instead?
Or am I missing something?
Thanks,
John
06-10-2004, 12:28 PM
#25
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Re: 500+ hp out of a 496HO
Thinking further, is it just the heat creep issue for cooling the engine itself that the primary exchanger cannot keep the engine cool. This is an issue for intercooled or non-intercooled forced induction applications.
Is this what you are talking about with regard to the heat exchanger not being large enough?
John
Is this what you are talking about with regard to the heat exchanger not being large enough?
John
06-10-2004, 02:07 PM
#26
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Re: 500+ hp out of a 496HO
26Sonic:
I will try and make this short and simple. 496HO with just our heads and a slight fuel pressure increase made 478HP @4800rpm and 536ft/lbs torque at 3500rpm. We added the roller rockers upped the fuel pressure a little more and made 504HP@4800rpms and 541 ft/lbs torque @3600rpm. We added our new intake manifold and and a 85mm throttle body and made 531HP@4850 and 576 ft/lbs. of torque @3600rpm. We have changed the cam in the motor to a better profile and we think we will see 550HP on Monday 6-7. We have been down on the dyno for over a week because it broke the strain guage and we had to wait for a new one from Superflow. We have already made over 65 hard dyno pulls, some up to 5500rpm and we have had no problems, wear or breakage in any parts on the motors.
Our production heads are cast and in machining as I write this and the first manifolds should be ready in about two weeks.
Thanks,
Ray @ Raylar
I will try and make this short and simple. 496HO with just our heads and a slight fuel pressure increase made 478HP @4800rpm and 536ft/lbs torque at 3500rpm. We added the roller rockers upped the fuel pressure a little more and made 504HP@4800rpms and 541 ft/lbs torque @3600rpm. We added our new intake manifold and and a 85mm throttle body and made 531HP@4850 and 576 ft/lbs. of torque @3600rpm. We have changed the cam in the motor to a better profile and we think we will see 550HP on Monday 6-7. We have been down on the dyno for over a week because it broke the strain guage and we had to wait for a new one from Superflow. We have already made over 65 hard dyno pulls, some up to 5500rpm and we have had no problems, wear or breakage in any parts on the motors.
Our production heads are cast and in machining as I write this and the first manifolds should be ready in about two weeks.
Thanks,
Ray @ Raylar
I would like to know what the 496 Mag HO made on the dyno before any changes were made. Doesn't Merc rate it at 420 at the propshaft?
Last edited by BGIII; 06-10-2004 at 02:12 PM.
06-10-2004, 06:03 PM
#27
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Re: 500+ hp out of a 496HO
Them are some great numbers Raylar. I will relay the info. Thank you for the info. If I remember I think I sent for a catalog. Is there any way to double check to make sure
Mark Clement
Mark Clement
06-14-2004, 11:38 AM
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Re: 500+ hp out of a 496HO
Hey Guys:
Just to let you know the facts. The stock HO cam is a .501 lift and is 222 duration intake, 230 duration exhaust @.050 with a 114.5 lobe centers. This is a realitivly small lift and duration cam for a 496 big block. The problem is that the factory pistons have a small intake valve relief and at this duration they can only take about a .535 lift and at a bigger duration lets say 236 etc they can take only about .510 lift. Our current testing on the dyno shows that our new .538 lift special duration cam can make about 525hp with our heads and manifold and short tube marine headers. To go higher than this in horsepower will mean either new pistons or flycutting the existing pistons which we have done. Currently with a bigger cam test we have seen some slight lean WOT pulls with the Mercury stock program ECM, so we are still testing to see if we will have to look at ECM reprograming to get to a reliable safe 525hp to550HP level. It is our feeling that the Merc closed cooling system on this engine can easily keep a 550hp 496 engine in a good cooling range, above this horsepower only time and in boat testing will show what the system can do, I do believe some minor raw water pump changes will give a higher system capacity. The stock pump is a low pressure unit, 3 to 5 psi, most of which run about 2.5 to 3.0 psi,which has caused some problems even in stock 496's. We believe a pump with a 5.0 to 10.0 psi pump could greatly increase the systems cooling capacity at high horsepower levels.
Hope my updates and blabbering will answer some of your questions and concerns. We are not going to let any boaters use our products and damage their motors, bad for business!
Ray @ Raylar
Just to let you know the facts. The stock HO cam is a .501 lift and is 222 duration intake, 230 duration exhaust @.050 with a 114.5 lobe centers. This is a realitivly small lift and duration cam for a 496 big block. The problem is that the factory pistons have a small intake valve relief and at this duration they can only take about a .535 lift and at a bigger duration lets say 236 etc they can take only about .510 lift. Our current testing on the dyno shows that our new .538 lift special duration cam can make about 525hp with our heads and manifold and short tube marine headers. To go higher than this in horsepower will mean either new pistons or flycutting the existing pistons which we have done. Currently with a bigger cam test we have seen some slight lean WOT pulls with the Mercury stock program ECM, so we are still testing to see if we will have to look at ECM reprograming to get to a reliable safe 525hp to550HP level. It is our feeling that the Merc closed cooling system on this engine can easily keep a 550hp 496 engine in a good cooling range, above this horsepower only time and in boat testing will show what the system can do, I do believe some minor raw water pump changes will give a higher system capacity. The stock pump is a low pressure unit, 3 to 5 psi, most of which run about 2.5 to 3.0 psi,which has caused some problems even in stock 496's. We believe a pump with a 5.0 to 10.0 psi pump could greatly increase the systems cooling capacity at high horsepower levels.
Hope my updates and blabbering will answer some of your questions and concerns. We are not going to let any boaters use our products and damage their motors, bad for business!
Ray @ Raylar
Last edited by Raylar; 06-14-2004 at 11:48 AM.
06-14-2004, 10:48 PM
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Re: 500+ hp out of a 496HO
BGIII:
Yes, we ran the base 496HO engine on three power pulls which put out between 420 to 433 HP @4900 rpms and the torque was between 526 ft. lbs @ 2500 rpms and 561ft. lbs at 4400rpm. The motor hit the rev limit at about 5050rpms.
Yes, we ran the base 496HO engine on three power pulls which put out between 420 to 433 HP @4900 rpms and the torque was between 526 ft. lbs @ 2500 rpms and 561ft. lbs at 4400rpm. The motor hit the rev limit at about 5050rpms.
