toolsinbox

so I take from this; if you have accepted that spending several thousand dollars; on exaust alone; will give you several mph gain; you are misinformed; foolish; and setting youself up for poor results.

I see it as a combination of upgrades and adjustments of parts, often hinging on an exaust upgrade, to maximize speed.

type of boat, setup, and conditions, not withstanding.

Keith Atlanta

From my experience of tweaking almost everything on a 496, you are
spot on. But again, alot depends on the size of the boat.

imagecat

iTrader: (2)

Okay you don't think it would be better in the long run to switch ECM's to something that you can adjust yourself. I know this isn't cheaper but I'm hands on like you obviously are. It would just bother me that I have to send my ecm off if I switch anything. Mefi computers are hard to come by. I know you have considered this

dana marine products

With any upgrade, something has to change. You have to move more water somehow. You either have to spin your prop faster, or get a bigger prop. Simply adding horsepower to an engine means nothing if you can't put the rubber to the ground.

As far as adding exhaust alone to give you xtra MPH, well, that depends. If you're running a 496 HO and your spinning a prop at 4700 rpm, we have some room to spin that prop up. Add the exhaust, now you'll be turning that same prop @ 4900-5000 rpm equalling more speed. So in that case, you would pick up speed from just an exhaust install. That statement however cannot be made for all exhaust systems as there are many that are no better than stock exhaust and will not yield extra performance.

And that's not to say that another prop couldn't work even better.

If you're running 5000 rpm with the stock engine, adding exhaust is only going to park you on the rev limiter, you need more bite. So in that case, you would need to prop up 1 pitch so you can get back in the 5000 rpm range. The difference is now your slinging a bigger blade at that RPM equaling more speed.

Rage

If you can afford it and are comfortable giving up the Merc 'Guardian' system, changing over to an ECU that you can program yourself on the fly in the boat while you are running is the best in my mind. You will need the ECU, its harness, appropriate sensors, laptop and the programing software. Since I have never done this there may be more. Talk to pros who know how to do this. Either way you need an AFR meter (with data logger capability to record AFR vs RPM is a very useful option). I suspect it cost me about the same reprograming the PCM555 given all the incremental engine changes made over time. Also Dustin has to do the programing personally in addition to his full time job as the president of the company. He is very busy except in the winter so recals can take a very long time. My last recal was requested in May and was not completed until September. You get the picture. If you have the 496HO ECU it is very saleable.

Raylar

We recalibrate PCM555's for the 496 all the time and no we don't pay Mercury for any unlock code as Dustin -USED TO DO? We have our own software and we keep all the Guardian turned on a working after re-programming. We do this programming for Mag to HO upgrades and various Raylar kit packages and engine we specially build. We won't re-tune an ECM for a stock engine without modifications for supposed hidden power!
Its Raylar's experience that unless you are upgrading a stock 496-375HP Mag to a 425HP HO or such no reprogramming is really going to make a big difference in a stock 496 . If you bump in a lot of extra timing you will put the cast pistons closer to the edge of detonation and possible damage. We also don't think its wise to up the rpm limit on the HO of 5150rpm on a stock head and valve spring engine as the springs are a bit lite in poundage and a little valve float will also possibly make a BASKET engine assembly!
I am always surprised how many boaters think and equate ECM retuning to extra power like some see in emissions engines in today's vehicles. Most marine OEM engines carry a tune in the ECM that allows the engine to make good reliable power, they are not de-tuned and lazy like a lot of emissions engines in vehicles.
You can push the timing limit and fueling on stock marine engine and sometimes gain 15-30HP but its not significant and the risk to the engine is not really a smart long term move.
ECM retuning is always needed and necessary when moderate to major engine changes are made with cams, heads,compression, cubic inches, etc. Again' there ain't no cheap horsepower in most marine engines, if you find a lot cheap, let me know, I would like to sell It!

Best Regards,
Ray @ Raylar

robby dmax

hi ray
been following this thread
just purchased a daytona with a 496 with your 525 package and the dana exhaust on it, did the ecm get flashed or just the fuel pressure get raised ?
and what are the benefits of flashing the ecm with your package?
how can we tell if it was flashed?
thanks

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.