Raylar

Rage:

We don't do custom remote ECM re-programs because this must be done either on a dyno or in the boat with actual air fuel ratios, knock events monitored and actual power increases measured and confirmed to do a good safe re-program. Kinda close and almost OK re-programs in customized marine high performance engines usually end up with damage and disaster and the small profit from the re-program fee is not worth the reputation and success levels.

As for cams in the 496, why re-invent the wheel and its expense.
Raylar has done over 9 years of cam design, testing and verifyiing on 496's our camshaft profiles and our hundreds of customers can confirm that and speak to our expertise.
Every engine type is different, actual use and applications as well as fuel system types, normal aspiration or supercharged, bore, stroke and cubic inch numbers will determine what camshaft your engine needs. These conditions and specs.all affect the cam grind design and application and no few sizes fill all types and needs.

You are going to spend good money about $400 to $500 for a custom good NEW billet hydraulic roller camshaft for this engine no matter who designs or builds it.
So, if you need a camshaft to work in a 496-8.1L engine for engine power levels, particular performance, reliability and proven results call Raylar and make it easy on yourself, Raylar will get it right!

If you choose to design and spec your own camshafts and experiment on your engines, just keep our toll free number and call us when you need to redo the cam, frustrate yourself with subpar performance or replace parts in the engine when it becomes a basket case!

Best Regards,
Ray @ Raylar

toolsinbox

Rayler

Just 496?

macjazzy

A couple of questions after reading all this great, and very informative info on 496's

1) I have heard and read several times now that the only difference between the 375hp and the 425hp version of the 496's is the cam and ECM program. I understand by changing these things I can make my original "375" engine put out 425 hp

I seem to remember reading somewhere that the 425hp engines use forged crank and rods, where the 375hp engines use cast crank and rods.

Is this true? and how well will a cast crank engine hold up to the extra hp and rpm's?

Also assuming the cam in the 425 is more aggressive are the springs not also more aggressive? If so wouldn't a spring change also be needed to prevent valve float?

(ok so there were a few questions in there, sorry I am grouping them as one )

2) is the Volvo 496 the exact same internally as the Mercury? I.E. cam specs, compression, cast/forged internals, etc If I got a deal could I use a Merc 425 cam in my Volvo 375 engine or vice/versa?


I assume the basic principles of exhaust would be the same, so can we assume approximately the same returns on an exhaust swap, Volvo-Dana as Merc-Dana ?

And can Raylar or Dustin or anyone else perform the needed changes to the Volvo ECM in order to make these changes?

Rage

[QUOTE=macjazzy;3305501]A couple of questions after reading all this great, and very informative info on 496's

1) I have heard and read several times now that the only difference between the 375hp and the 425hp version of the 496's is the cam and ECM program. I understand by changing these things I can make my original "375" engine put out 425 hp Yes plus the throttle body butterfly plate bleed hole needs to be drilled bigger

I seem to remember reading somewhere that the 425hp engines use forged crank and rods, where the 375hp engines use cast crank and rods.No rods and crank in both are cast but good to ~600hp & rods<<6000rpm

Is this true? and how well will a cast crank engine hold up to the extra hp and rpm's?rods and crank in both are cast but good to ~600hp & rods<<6000rpm

but anything above stock rpm needs valve train upgrade

Also assuming the cam in the 425 is more aggressive are the springs not also more aggressive? NoIf so wouldn't a spring change also be needed to prevent valve float?n/a

(ok so there were a few questions in there, sorry I am grouping them as one )

2) is the Volvo 496 the exact same internally as the Mercury? I.E. cam specs, compression, cast/forged internals, etc If I got a deal could I use a Merc 425 cam in my Volvo 375 engine or vice/versa?Very likely but not 100% sure. It is my 'understanding' that the base motor is the same but marinization and ECU/harness/sensors are different. Again not for sure.


I assume the basic principles of exhaust would be the same, so can we assume approximately the same returns on an exhaust swap, Volvo-Dana as Merc-Dana ? YesAnd can Raylar or Dustin or anyone else perform the needed changes to the Volvo ECM in order to make these changes?]Duistin could /not sure about Raylar who can speak for himself.[/QUOTE

Response in red above.

DCB F32

So Ray are you saying that Merc has licensed you to do these chamges.

Do you have standard programs based on engine mods?

Rage

Ray, sounds like a thoughtful & prudent policy to me. Good to hear!

Question, how do you measure/record knock events from a PCM555 ECU?

SDFever

Via the knock sensors.

Raylar

Merc has never really licensed anyone to do PCM555 program changes, they did collect fees from Whipple to unlock source codes on the PCM555's for a while and Whipple would pay a fee for each ECM they were given the program to reprogram. Mercury does not now even own the company anymore that built the PCM555 and developed the programs and programming for them- Mototron. With full data logging our programmer was able to build new re-flash programs for the various 496 packages we offer and build for the various versions of the 496 and we now use this re-programming of various year and model versions of the PCM555 that has been used for the 496 and the HP525efi.
As I mentioned we also leave the Guardian portion of the programs operational even after reprogramming so as to keep the engine protection that was developed by Mercury.
Mercury now uses a new ECM system on their new 2010 and 2011 engines such as the new HO502efi emissions engines, various outboard and inboard engines alike, most likely a case of additional emissions controls program size and power and the fact that a few like us have been able to now re-program the PCM555 which I am sure Mercury does not like for their control loss and exclusivity uses.

As for the forged GM crankshafts versus cast crankshafts in these engines we have never seen a major failure in either crankshaft from power overload even in supercharged versions of 750-800HP and the only crank failures we've seen and heard of the front snout of the crankshaft broke off from excessive supercharger belt tension.

As for the 496-8.1L engine stock components and cams, all marine engine companies as Mercury, Volvo, Crusader, Indmar, Marine Power, etc., GM Powertrain supplied all the 496's in two versions to all the marinizers, the HP1 -370-385 version depending on particular company programing and advertising as well as the the same for the HP2 420-425HP version. Except for the early 2000-2001 HP2 versions which a certain few had a forged crankshaft all these engines have been pretty much identical with a very strong nodular iron pressure rolled fillet cast crankshafts, forged I-beam not so strong connecting rods and all with cast hyper-eutectic pistons, press pin fit in 2000 thru 2004 and full float pin on 2004-1/2 thru 2010 engines. Only two camshafts have been used the truck camshaft rated at 375-385 horsepower in the marine HP1 engines and the 420-425HP version camshaft used in the HP2 engines. Everything else supplied by GM in these 496 8.1L engines is identical regardless of who marinized the engine for sale.

Best Regards,
Ray @ Raylar

Rage

So you have erased all Merc programing from the PCM555 and installed a different ECU programing language that you can reprogram but have included the 'Guardian' features?

Rage

The Merc 496 knock sensors only produce a voltage in response to vibration. Since there is always vibration in an engine there is always voltage coming out of these knock sensors. The PCM555 is programed (calibrated) to 'decide' when a 'knock event' is occuring and respond by retarding timing. Unlike the MEFI type ECU which does have a 'knock event' output that can be accessed/observed the PCM555 as Merc's is set up does not. I have data logged knock sensor voltage output and PCM555 real time ignition timing. I am told that the PCM555 timing out put that can be observed via Diacom is only that of the lookup table and not the actual timing.