toolsinbox

Rayler and Dana

I am convinced of the points you have made here and they make total sense to me.

Ok if; a reasonable ground cam; so engine stays together and along with a quality exaust; good stock heads; and computer left very much as is. Is it possible for you to give a basic guide line cam part number list for a few of the popular engines IE 454; 496; 502; 525; Could you give a list for both wet exaust and dry. Or are you saying the stock one's are pretty much maxing everything out? and leave alone if you want things to stay together. Reason is as I understand it; dry exaust allows for hotter cam (reversion thing) and when I have been reading other threads to get an idea of what I should use; the exaust type is not always clear in a given discussion; I have a wet exaust so that is what I am most interested in but maybe there are others with the dry.

With respect to reversion, can you measure the exposure to this, relating only to the grind of the cam? Or would things like, if the engine was a roller setup or not? Fuel inject or not? I know the type of exaust has a lot to do with it as where it mixes. There must be a point where you draw the line as far as cams go and where you say " if you have a wet exaust this: insert part number______ is the hottest cam you should dare to use" Is there a way to simplify the math?

When is the best time to order a cam in so far as a rebuild. What do you need to know? The idea here is starting points so one won't throw away money. The exaust is a no brainer to me. If you soup up a stove it will have to breath and you get a proven high quality exaust. done carry on. The cam is not so easy. In my case I am starting from scratch but I know what some of my peramatures are and I dont need my boat to go 120 mph and blow stuff up all the time. Well maybe I do but a man's got to know his limitations.

as many others, I want to build a solid engine, that will perform, but it can be confusing to find the right recipe that fits a given boat, and a builders expectations. Thats why I am building one! so it is better than the one I have. I dont expect to take a stock 454 short block and slap on a $5000.00 set of Dana's and expect it to gain me 10 mph! That's ridiculous. I understand the props have to be tested but how does one arrive at the engine recipe so the correct parts are got the first time around?

Rage

So you do not do custom PCM-555 recalibration for a fee?

dana marine products

Ray is pretty good on cam talk, so I'll leave that to him.

In regards to proper riser selection to avoid reversion, that's not an easy answer. The rule of thumb is to run the longest riser you can no matter what. In the case of Dana exhaust (which actually goes for $2500) we don't charge extra money for our shorter stainless risers compared to the longer stainless risers.

We usually have to discuss installations case by case to find out exactly how the boat is rigged. The exhaust routing is pretty much different on everyone's boat and usually has different requirements.

In the case of the 496 engine, we were able to make a system that replicates the exact dimensions of the Merc system. This allows an installation no matter what the exhaust routing is. As long as the stock system is on the boat, ours will replace it.

We also do custom tails, which will run extra $$ depending on the complexity of the riser.

An engine is simply a big air pump, the more air it moves, the more air it draws - When a piston starts it's descent on the intake stroke, the exhaust valve is still hanging open a tick - and it pulls vaccum through the exhaust - introduce water to early into the exhaust stream and you've got reversion.

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.