I recently upgraded a 496 Mag to an HO. We opted for the Whipple stage 2 PCM upgrade and added Dana exhaust. I prop shaft dynoed this boat before and after the mods. Stock the hp was 373 at 4800 rpm, 466 ft. lbs of tq at 3600 rpm. After the mods it made 433.6 hp at 5200 and 502 ft. lbs of tq at 3800 rpm. Just for the record, most 496 HOs I've dynoed make around 390 HP at the prop.

Bob Lloyd
Full Throttle Marine

Just my opinion but I believe the lion's share of the speed improvement came from the change from way under propped to a correct size and labbed prop. Your hull may be one of those that perform better at higher speed from less wetted area with positive trim provided by the better prop. The rest could be chalked up to the improved exhaust. ~500hp with high flow heads, cam and exhaust on a 496 takes about 50 psi with the stock ECU. The increase in fuel pressure from the stock 43 psi to 48 psi probably reduced power. What do your spark plugs look like? Do you smell raw fuel when idleing/running/on start up?

That type of gain did not come from headers on a 496.

i agree gents with both of your statements.....
what the headers allowed me to do was spin a 26 labbed prop

wich is what gave me the speeds i post

as far as the fuel pressure........ i smell no unburnt fuel
it was a fuel module of some sort that my mechanic recomended
the plugs are fine........

just in the very early spring the back end soots up a bit

The soot is normal. I'd be concerned if there WASN'T any soot!

SD Fever is right on the money, 40-50 HP doesn't mean the same thing to every boat. Dana Marine does not make "speed" claims because it would be foolish to do so.

We make a horsepower increase claim. Our claim is based off of countless hours on a SAE dyno with 3 different 496 engines.

From my experience, most peformance upgrades are not done properly due to the lack of resources to the end consumer. Every time we do an exhaust install we do alot of testing before and after. We take a pile of props to the lake and it's on and off the trailer 4 or 5 times before we have final numbers for our customer.

For the record, every boat we've ever done an install on, which is a big list, has seen speed increases. Some as little as 2 MPH, some as much as 6 MPH. Power to weight ratio. It's makes a big difference.

thats what i got 6 mph for $6000
the bottom line is that on water there is no cheap speed gains

LOL, like my shop told me about $1000 per 1 MPH. Well at least you saw gains for your money spent.

OK, I put CMI Sportubes on an stock 496 HO, NO speed gain, NO rpm change. I dump the 496 and drop in a 525. Giving the benefit of the doubt let's rate the 525 at 540 hp. I added 115 hp. I picked up 9-10 mph. Let's call it 9 mph. That means that I picked up 1 mph per 12.77 hp. Of course I had to change props but I went from a labbed 26 or 28p Bravo 1 to a labbed 30p Bravo 1. So no change in prop; Only in pitch. I'm bumping the rev limiter at 5,400 rpm on a good day at 86 mph. Explain that please. And the aluminum 496 exhaust (my '05 was alum.) is very light so the exhaust swap ADDS weight. 2-6 mph on every install? Sorry but no. I already posted links to others who saw NO gain. One dual engine install gained 1 mph. That's almost 10 grand for ONE mph. Something is rotten in Denmark.....
Oh, and you can take "a pile of props" to test on any boat and pick up speed so I say the increases came from the prop dialing in and not the exhaust. Not all of us have access to piles of props.

That is money well spent but it didn't come from the exhaust (IMHO)

My response is obviously the blue text above.

Even if you are maybe only considering doing work to the prop you already own...

the 496 exhaust system is actually quite good
and i had the aluminum manifolds also wich flow quite well
on my lavey the 496 ho comes stock from the factory with a bravo 4b24p with a normal load of bodies and gear its on the rev limiter with that prop at 64 to 65 mph
what the headers really allowed me to do was spin a bigger prop with the few extra hp and ft lbs of torque and one extra pitch in a labbed prop
ive talked to the folks at lavey and they are impressed with the speed i post in my boat telling me that its one of the fastest for its size at that speed
im done with mods on this boat and i am at the limit in its design capabilities
the bottom line like i said before is no cheap speed on the water

SDFever, I know you are not being a smartazz and I appreciate the civil discussion. Good responses, I'll leave it at that :).

Centsless, when you can pick up 1 mph per thousand bucks I would call that cheap speed :). Congrats, sounds like you got it dialed in. I like where I'm at too. Come on spring :evilb::evilb:.

here here to spring........

It sounds like you're not exactly pleased with the results of adding CMI headers to your stock 496. I feel for you, that's alot of money for no results. Please keep in mind, my exhaust is much different compared to CMI and I publish our dyno results for the public to see. All of our dyno testing is on a SAE certified dyno, so there's no funny business or recalculations from a non-certified dyno. As far as explaining your speed increase with the 525 VS. the 496 with CMI exhaust, it's quite simple. In "most" cases you will find that a boat will have a significant speed increase with a 525 VS a 496 - reason - most boats, and I say "MOST", tend to have a significant difference in ride character when you add that kind of HP enabling a bigger blade to be spun. With added boat lift and enough power to carry the nose you will have less drag = more speed. You can't apply a basic mathematical formula to the situation, you crossed over a threshold with that extra 70 HP and it meant alot on your boat. Every boat reacts different to power increases, some boat bottoms simply work better than others - and some boats have different points in time where the boat itself begins working much better. A single engine 22 foot Daytona closed bow, did see an increase of 6 MPH, call Eliminator, it's been documented more than once. We've had customers insist that that our exhaust be installed on that very boat from the Factory after seeing Mitch Garlows new 22 Daytona pickup that kind of speed. Yes, the boat had a "pile" of props tried on it before and after, not just after.

To clarify, I'm not familiar with the 22 Donzi as we don't see many of those out here on the west coast, so I can't comment on that boats specific handling characteristics.

2-6 mph on every install? Sorry but no. I already posted links to others who saw NO gain. One dual engine install gained 1 mph. That's almost 10 grand for ONE mph. Something is rotten in Denmark.....

Well, I don't see how you can possibly make a comment like that when you have very little knowledge of my product, my customers, or the amount of time we spend in boats testing this exhaust. One thing we don't do here is make BS claims. It wouldn't go very far in a small world industry. As far as the twin engine boat you're referring to, I don't know which exhaust was installed on that boat, but this is a classic example of the "power to weight issue" . An 8000 lb + twin engine boat is not going to see a big increase from 45 HP per engine. It's just not going to happen, the boat is too heavy. Not every aftermarket exhaust will yield the horsepower of Dana manifold system, so depending on which system was used, he may not have gained much HP.

Oh, and you can take "a pile of props" to test on any boat and pick up speed so I say the increases came from the prop dialing in and not the exhaust. Not all of us have access to piles of props.

In some cases you can add speed to a boat from prop work only. My interest for the conversation is the prop work after the extra power has been added. With added power, we can turn a bigger wheel. That bigger wheel turning the right RPM's will make more speed. I understand that many consumers don't have access to a selection of props, thus my reason for previously stating that most add-on's like exhaust are not capitalized to their full extent due to this very problem. That is where someone may want to consider having a professional shop do the work. Most of my install shops will run the boat before and after, scan tool on motor for accurate RPM's, GPS and/or Radar for speed and the good guys take portable O2 scanners with auxiliary bungs in the risers. With the right tools and the right products, you can dial in a specific boat/engine and make the most sense out of spending 2-3K on exhaust.

Thank you for the reply and, yes, I'm talking about CMIs and not Dana exhaust but both make claims of big hp gains with no other mods. CMI more so. I'm just trying to give a heads up that someone may well be disappointed and out almost 5 grand (with CMIs). I still feel that aftermarket exhaust is not beneficial to an otherwise stock 496 HO. Just my personal experience and opinion after researching it.

What's Real World?
 

Sometimes we all need to back up and take stock of what "real experts" we really are.

As a boat owner and specific application person and boat owner you tend to have a very narrow view of what works and what does not work. It's because you don't actually have any real experience most of the time with all things other than your own boat or a buddies boat, etc.
Sometimes your research and knowledge comes from what you read and share on forums like OSO and with a few other boaters. This type of knowledge is limited and not always a good measure of what the big picture really is. Lets all remember that all performance boats engine and drive packages, set-ups, boating water, conditions and air temperatures are all different and will almost always produce different results. It becomes easy sometimes to make broad judgments and statements that ultimately are almost misinformation for others to read and set their decisions from.

We should also realize that most all testing is not always very scientific in nature and as such results will vary greatly sometimes just based on conditions and test parameters.
Even as you should know dyno testing can be very distorted and inaccurate based on how and how often the dyno has been calibrated, whether correction factors were entered correctly and used and what state of equipment and accessories were installed and whether the dyno test was run using SAE standards.

Its sometimes easy and inaccurate to research an engine and possible upgrades and then remove that engine entirely and install a much higher rpm and HP engine and make statements that say the OEM engine was so inferior or not capable of equal performance with like increases in equipment and mods.

As an engine manufacturer and engine builder who by most accounts has more experience and knowledge of the 496-8.1L engine I will be the first to say that every engine type and model generally has its limits based on engine components and architecture, but I will also say every time we must compare "APPLES TO APPLES" in any judgment or determination as to what engine is worthy of upgrades or in measuring its performance and output. this also obviously applies to any engine components and systems such as headers and exhaust.
I have written numerous discussions and factoids here on OSO over the years about exhaust headers and manifolds and so have exhaust and engine experts such as Bob from Dana, Bob LLoyd from Full Throttle, Eddie Young, etc., etc.
To condense the comparisons, you must determine first, normally aspirated, or supercharged or Turbocharged, then you have to compare short runner manifolds and riser type exhausts like the stock Merc 496 units, Eddie Marine, Stainless Marine, etc. These should not be equally compared or likened to actual long tube tubular or manifold long tube headers like, Dana, Eikert, Imco Powerflow Plus, etc. It is also important to understand that exhaust headers or manifold headers that work well on normally aspirated engines do not always have any benefit on boosted engines, the two animals are different and they each will respond differently to tube length and tube size.
From all my testing it is very obvious that longer tube or passage header manifolds that have runner lengths in excess of 18" or so and have the 4 tubes merge into a collector make more power and torque on most naturally aspirated performance engines than the straight short runner-passage manifold exhaust systems that merge into a simple round riser. This has been confirmed time and time again by other valid testing in the industry by many independent users and engine builders who don't make and sometimes don't even sell exhaust upgrades.
On most naturally aspirated BBC engines of 450-502 cubic inches with 8to1 - 10to1 compression ratios with mild camshaft grinds, decent cylinder heads will gain 25-45HP changing from a straight short passage manifold and riser to a long tube merge collector type header or header manifold. Is it 60 plus horsepower, no not very often unless head, cam and other changes are made concurrently. Can the numbers be larger on boosted engines, You Bet! , they have to get rid of the extra exhaust volumes and pressures to make more power so the change from short -small runner manifolds and risers to larger tube or passage size headers or manifolds can show much bigger increases in power and torque and runner length is not as critical or necessary in these exhaust systems. Longer and equal length runner lengths for optimum performance from a normally aspirated BBC engine will up to a certain length and the rpm operating ranges, compression, cam size and head flow will determine the ultimate length. Are the header and exhaust systems for Bravo equipped BBC engines optimum, NO, the length and fit is restricted by available room and length to the transom and whether the exhaust is existing the header or manifold into a switchable exhaust, s-tubes, elbows and side hull exhaust detours and such.
Also when testing exhausts on dynos its important to test the header with similar size tips and exhaust length and with water entering the exhaust exactly as it does in the boat. water and water vapor alone in a marine header exhaust or even stock exhaust manifold will generally scrub out about 15-25 HP just for the water intrusion alone! So dry testing or exhaust into large exhaust tailpipes and mufflers totally distorts what will actually happen in the boat.
As for actual boat performance increase and bang for the buck every performance boater who wants to increase his boats speed, acceleration and performance must be prepared to look at other items on the boat such as prop rework and proper prop tuning to the power changes. boat bottom configurations, designs and finish and the old drive height and drive length issues which can play such huge influences on ultimate boat speed and boat performance at all speeds and trims.
And lastly I think its important to always keep in mind and remember that all hulls and boat types are different and will respond differently to added power, torque, rpms and speeds in almost every case!
Its so easy to over simplify performance engine upgrades, exhaust upgrades, drive and prop changes that it really tends to further confuse and frustrate performance boaters that they sometimes probably think, hell why try any, most of these changes tend to be so good or so mediocre or bad that why should I spend my hard earned money with an experiment in performance.
The real answer is try and deal with people who are real experts and make a living producing real results and stay in this game year after year making far more boaters happy than they piss off or abuse!

I am not trying to bash or discount the comments and findings that a lot of performance boaters make here on OSO, I am just trying to get us all thinking and realizing that each individual situation can be vastly different based on a lot of variables and some of the comments and input come from boaters who do not do this work day in and day out for a living or have much real engine expenience, exhaust building experience or boat setup and rigging experience.

If you where about to be opened up on the operating table for brain surgery, would you be discussing the methods and impressing your ideas on the brain surgeon whose trying to save your life! Think About It!

Best Regards,
Ray @ Raylar

Thanks, Ray, for the excellent input. I think 007joe, who started this thread, should install exhaust and report back :).

I would be glad to, if someone on here wants to sponsor "real world" header testing on my boat! :p

Thanks, Ray and Dana marine, for your in depth explanations.
I have spoke to ray several times and has always been very knowledgeable and helpful in these matters.

I will more than likely be trying the camshaft and reflash come spring. So will keep everyone posted...

Thanks again for all the info!

Anybody have experience with who reflashes the computer? I know whipple does it but thought there were other companies? any experience with whipple? Or the other guys?

Yes, I do. As far as I am aware Whipple is the only one liscenced by Merc to reflash the PCM555 ECU that comes with the Merc 496HO & Mag engine. Lots of people can do the various MEFI computers but buyer beware. Software is available to purchase where you could do the MEFI recals as well.

Dustin charges $1000 right ?? Is that each time or what?

It was $800 back in 2006 for my first custom recal. Half of that went to Mercury for the ECU unlock code. After that ~$150 - $200 each time depending what you needed to be done. But for custom recals you have to supply the AFR and MAP vs rpm data from idle to WOT to Dustin so he knows what needs adjustment. These must be accurate or wrong adjustments may be made. The AFR vs rpm would come from instrument like Innovate LM-1 with an rpm converter. The MAP vs rpm would come from a Diacom recording. These two data streams would need to be combined and normalized to the same rpm. Then there is the issue as to if the AFR you are supplying is of a single cylinder of the eight available, one manifold collector combining all four cylinders from that bank or both banks or all eight individual cylinders. You would need to discuss this with Dustin Whipple. Optimum (and quickest) would be to provide the engine to Dustin to calibrate on the dyno.

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.

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

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:)

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.

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.

When to Re-calibrate an ECM??
 

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

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

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?

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

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.

Trust Those Who Know and Prove Their Worth for Value!
 

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

Rayler

Just 496?

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 :lolhit: )

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?

[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 :lolhit: )

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.

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

Do you have standard programs based on engine mods?

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

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

Via the knock sensors.