Torque loss as a percentage at any rpm will be the same as the horsepower loss, since they are related 1:1.

Michael

Great information. I'm shocked with the 60hp loss through the outdrive :eek: . Maybe my insurance will go down if I tell them my prop shaft horsepower. :drink:

That's what I heard abot the turbolators. For condensation in mid-winter climates like Michigan, Wisconsin, etc.

Hopefully great news about the 496's. Otherwise the cost of boats with a minimum of 525's standard package would jack up. Not to mention drop in re-sale value....:mad:

I guess that also goes to show that the 496ho's are not 425pshp. Ive heard people battling it out that the 496ho is 425 and the hp500 is 470 so theres not much difference.

Great Thread!

Hey Bob,
Have you ever hooked your propshaft Dyno to a 415HP/502MagMPI Bravo 1 package?
I've read that the 502Mag only makes about 400HP at the crank so that would only be about 360 @ the prop?
Thanks,

I've heard that too...that the 502 MAG was always weaker than advertised when dyno'd. I believe Merc and the other manufactures have to be within +/- 10% of the advertised HP.

Probably should leave mine in then since I live in Illinois. My steel storage shed faces Northwest and in the spring I get a ton of condensation on the boat until the ground warms up to more closely match the air temp. I love my 496 MAG and I too hope they keep the motor around.

Shooter, how did you have your elbows polished? I've got the F&M stainless motor covers, and getting the elbows polished would really make for a nice touch on these black motors.

The 496HO is 425 cshp (and ~390 pshp from Bob's testing.) The HP500 was rated 470 pshp which would put it about 517 cshp which is about where it dynos according to most sources.
Merc in the later years dropped the 470 rating...

I wish the 496HO was rated 470 cshp & 425 pshp....:p

I had a metal polisher do them. Getting the paint off was not easy according to him...

That looks nice. I wonder if the cover gives you additional clearance over the stock cover? My boat came sans motor cover as it hits the underside of the hatch if installed. Looks goofy with no cover at all on top of the motor...not that it matters much on a 26' Chaparral! Still, your motor looks great there with those touches! :drink:

Great info Bob. look forward to seeing the Raylar test

itay, I wil be upgrading to a raylr setup or similar when the hours get up there on the engine.

I tried lost of stuff including MEK and I couldn't get the paint off.
I wanted to polish mine but gave up. After all that trying they still look new. It's some tuff paint.

We use a carb cleaner in a 5 gallon vat. It removes paint and powder coat very nicely.

Hey Bob,
I know I'm off the topic of the new 496 engines, but do you have any info how the 502Mag compares?
Thanks,

Way to Bob! Thanks for the info!!

Superior unbiased information upon which to make solid decisions. The high performance boat engine consumer owes you a very large debt of gratitude. I thank you for your effort and personal expense in producing and providing this information to the public. A breath of fresh air!

Great article Thanks!!

Bob, any update on a CMI sport tube dyno test?

Thx

I've not done any stock 502's. I ran a stock 7.4 - 300 HP on the propshaft dyno. It made 307.

Pantera is checking on a set to test. I will probably have that engine back on the dyno next week, so I'll test whatever I have at that point. The customer wants his boat back!:eek:

Quote:
Originally Posted by cobra marty
What was the Torque loss thru the bravo drive? is that constant with rpm? Do you have any curves showing HP and TQ with stock and with Dana exhaust?

Torque loss as a percentage at any rpm will be the same as the horsepower loss, since they are related 1:1.

Michael

Only at 5252 rpm is TQ=HP and 1:1 relationship. When I lookid and the numbers and calculated the difference between crankshaft and propshaft HP and TQ I found that between 3500 and 4000rpm was an area of high loss for both HP and TQ but for further rpm there seemed to be about 43-45TQ loss at all rpm regardless of TQ amount and the HP loss increased with rpm and increase HP. What this means to me is that TQ is a constant loss regardless of rpm or amount and HP loss will increase with rpm which is just what will happen to HP in the HP=TQxrpm/5252 formula.

I would love to see the propshaft test repeated with the Dana's and synthetic lube-Amsoil or redline.

Great post. Thanks.

Great stuff. I have always wondered about gains from removeing the turbulators. It's nice to have the facts.

What about testing a set of resonators?. As far as I know, Mercruiser is still insisting that they be used whenever possible to help reduce exhaust "tuning". If you read the installation sheet that comes with them it says that they do not reduce power, and it some cases actually make power. I've always wondered about this.

Dave

Sorry guys it's boating season in Texas !! :evilb:

Now, if someone wanted to supply me with a substitute motor while Bobl continued testing my 496.....:cool:

Yep, I already have 15 hours on the new baby ZR. The partying has officially begun http://www.mysmiley.net/imgs/smile/happy/happy0167.gif

PS: Mark, Thanks for being the guinea pig on this deal.

more torque = more friction
so more loss with more torque makes sense to me, after all the oil gets hotter at the same rpm doesn't it...

Very informative and well done. Thanks for sharing.

Any CMI's promised or available yet for test?

Very good analysis, great information, thanx a lot!

Now let me contribute my real world experience with the 496 CMI kit with the adapters for the Corsa Q&Q system.

Although I did not expect too much at first I am impressed by the performance gains of this system. My little Baja 272 gained an honest 4mph on the speedo (went from 70 to 74), turning 5050 rpm with an 25 Mirage. Before the change I turned the same rpms with an 23 Mirage, which now is allover the revlimiter. Same load, same conditions.

If it takes about 15hpfor each additional mile thats the 60 hp advertised. No way around it!

The CMIs are alot of money and really a pain in the A** to install, but they deliver, add a lot of nice bling and sound way cool.

But, here comes the problem: With the 2004 and newer ECU the engine runs too lean. Yesterday my boat went into guardian after a prolonged WOT run....I can only guess that the Exhaust gas temperatures went up beyond the desired range and the engine management system intervened....
My engine is a 2003 but with a special ECU program for less transom soot, most likely the same new program data that all the 2004 and up engines come stock with.
Last week I made a test run with the original 2003 ECU (ugly soot on the transom again) but I didnt have any problem with the engine although I ran it a lot harder than yesterday.

So, can anybody share the info of how to up the fuel pressure on my engine by 3 psi keeping the stock components? I heard rumours there is a way, some hidden screw somewhere, but where exactly?

I wanna keep my lean ECU, I hate fouled up transoms :-)

Thanks for your ideas!

Greetings from germany!

Andi

There is a special fuel pressure regulator that is aftermarket for the Gen 3 fuel cool systems. It is adjustable. The factory ones are not. We have been selling the aftermarket regulators for around 200.00 latley. You probably need about annother 2-4psi of fuel psi.. ;) Jamie / Lakeside



.

Excellent article!!! Staying tuned for the Raylar kit.

Jamie@Lakeside:

I might want one of these regulators! Is the installation easy or do I have to take half of the engine apart??
On the other hand I heard Dustin Whipple can reprogram the PCM especially for the CMi application.

Which is the better solution?

Andi

Is there an adjustable pressure regulator avail for 575SCi? (Not one that I have to cut and assemble) Looking for a easy bolt on.

It just pops into the gen3 Fuel cool module & is held in with 2 screws.. You should be fine with just a regulator.. If you are going to do other add ons like cam, heads etc.. then I would also reflash.. :) Jamie / Lakeside

Off the top of my head I am not sure.. However there are ways to bump pressure if you have to, it just may require some work.. If you PM me your serial # from the engine I can check & see what may be available for you.. ;)

BTW, why do you want to up the psi on a 525Sci ?? Did you make some alterations to it?? If not you should probably leave it alone..;) Jamie / Lakeside

It is running a few psi low (2 -3)
Probably nothing to worry about - it doesn't drop below 22 at WOT and at idle it is 25 - 26.
I relpaced sea water driven fuel pump w/ Eikert's hi flow billet.
I want to ensure PR is correct. If I disconnect vac line @ idle, pres goes to about 35.

Just being cautious.

Bob, this business needs more guys like you. I am grateful to people and companies that make an investment in information and share it with the rest of us. Keep up the good work.

Thanks for all the info. Bob