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8.2 MAG H.O. - 430hp

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Old 04-08-2011, 02:38 PM
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We saw this motor at the LA Boat Show and it does appear to have narrowband O2 sensors in it. That being the case, there is probably a relatively small area of the fuel curve that is monitored and controlled via closed-loop operation.

Narowband sensors are only accurate at/near stoich, unless their accurate "spot" has been moved. Stoich is ~14.7:1 A/F for most gasoline today. From air/fuel curves of other Mercury engines, I can't imagine Merc is running this engine in that range for very much of it's range. All one would have to do is to characterize the area where the sensors are in operation, then don't tune in those areas (most likely idle and around idle). The rest would be open to modification via units like our CMD Marine.

So who is going to be the first to install a wideband on a 8.2 to characterize the a/f curve?
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Old 04-09-2011, 12:55 AM
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Originally Posted by STV_Keith View Post
Any idea if those are narrowband or wideband sensors?
They are in fact 4 narrow bands.
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Old 04-09-2011, 01:01 AM
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Originally Posted by sunsation96 View Post
Isn't the new 502 just a de tuned 525 I think? There is alot of power that can be made with this engine!
They share many parts, but they are different. The new 430hp motor has a much smaller camshaft and the entire valve train itself is closer to the old 502 Magnum MPI engine. So, like the older 502 Mag motors, there is plenty of power left over. Its a standard 502 MPI so older headers, superchargers, cams, etc. work.
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Old 04-09-2011, 01:05 AM
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Originally Posted by MattBMiller View Post
Has anyone tried o2 simulators on these engines yet? Headers are not an issue, it comes down to getting programming to bypass the cats. I've used the simulators on a few car engines with good luck.

Matt
They would work in this app but because the motor has very little power enrichment, its more important to have a calibration that will work properly. Doesn't take long to hurt these motors as lean as they are run now (14:1).
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Old 04-09-2011, 01:10 AM
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Originally Posted by A.O. Razor View Post
Very interesting reading for sure. The thing is. If you ask mercuiser, they will say it is prop hp. If you go to merc's website, they clearly state it is @ prop. Just cheked with the new 8,2. When you test the engine in the boat like that, there are a few variables. Engine and drive hours, air temp and humidity, drive oil ect. Now it gets interesting. If you go to merc racing's website, they have changed the rating on the 1100 and 1350 to transmission rating, It said crank shaft rating a month ago! The 1200 is still rated at the crank, thay claim. Confused? I honestly think they will change thier claims as they see fit. What you need to do, is to take a new engine/drive and replicate mercs testing to the smallest detail.

Another way of looking at it is. If the 425 is crank and the 8,2 is prop, the speed diff, would be rather noticable, but it is not. If the 8,2 is 430 prop, it should about 465-470 at the crank. That is a big difference. I asked formula about this some time ago, and they said, there where no difference on a 350ss with a set of 496HO's and the same boat with 8,2HO's. I would say that, a combined increase in hp of about 130 to 140 hp would be felt.

My bottom line is. I just don't think mercury is very accurate or maybe even honest about the hp claims.

From all the motors we've tested, the black Merc Marine motors have all been within 2% of there propshaft HP rating at the flywheel. If you use the SAE standard, they are almost below the power during sweep pools but very close to there rating. During steady state, power levels increase in most of these motors because the clearances decrease and the motor reaches higher efficiency, but its not the 30hp they say the outdrive takes. the 8.2 is rated 5hp more than the 496 mag HO, and 15 more the 502 Magnum MPI, not 30-40 more....
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Old 04-09-2011, 01:13 AM
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Originally Posted by sunsation96 View Post
I don't think anyone has been able to remove them and change the computer program from Merc as of yet, I may be wrong but mu buddy has two of these engines and if they did come up with something he would have it. I know he has spoke to several compaines asking when? they said it will take time to get around the computer.
The PCM is not really a problem at this point. Our SC system will be out around June/July as well as many other upgrades.
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Old 04-09-2011, 07:07 AM
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From all the motors we've tested, the black Merc Marine motors have all been within 2% of there propshaft HP rating at the flywheel. If you use the SAE standard, they are almost below the power during sweep pools but very close to there rating. During steady state, power levels increase in most of these motors because the clearances decrease and the motor reaches higher efficiency, but its not the 30hp they say the outdrive takes. the 8.2 is rated 5hp more than the 496 mag HO, and 15 more the 502 Magnum MPI, not 30-40 more....
Dustin

I see your point. And from my earlier post, i must have calculated with my head under my arm. I did not notice that untill now.
I just lifted these specs for the 8,2HO from Mercury Marines website. As you can see, they say the hp is measured at the prop.

HP/Kw @ Prop 430/321
Max RPM (WOT) 4600 - 5000
Displacement 502 CID (8.2L)
Engine Type V8
Bore & Stroke 4.47 x 4.00 in / 113.5 x 101.6 mm
Compression Ratio 8.75:1
Fuel Requirement 87 Octane (R+M)/2
Engine Control System PCM 555 with SmartCraft CAN Capability
Fuel Delivery System Gen III Cool Fuel
Fuel Injection System Sequential Multi-Point Electronic Fuel Injection
Induction System High-inertia induction system
Ignition System Distributorless Ignition w/Knock Control and Platinum Spark Plugs
Charging System 65 Amp/917 Watt Alternator
Water Drain System Single Point Air-Actuated
Exhaust System Tuned Runner Exhaust Manifolds with 316 Stainless Steel Tubular Dry Joint Elbows
Cooling System Closed Cooling, Long Life 5-Year Anti-Freeze, Brass Sea Water Pump
Accessory Drive System Serpentine Belt, Stainless Steel Spring Automatic Tensioner
Recommended Engine Oil Mercury MerCruiser Full-Synthetic Engine Oil, 20W-40, NMMC FC-W rated
Engine Guardian System Low Oil Pressure, High Coolant Temperature, High Exhaust Manifold, Temperature, Low Drive Lube, Low Sea Water Pressure, Low Voltage, Over-rev control, Knock Control
Bravo One X Ratios 1.36, 1.50, 1.65 (high altitude)
Bravo Two X Ratios 1.81, 2.00, 2.20 (high altitude)
Bravo Three X Ratios 1.81, 2.00, 2.20, 2.43 (high altitude)
Bravo One XR Ratios 1.26, 1.35, 1.50
Bravo Three XR Ratios 1.65, 2.00
Weight lbs/kg (engine only) 1080/490
Digital Throttle & Shift Optional
Warranty 2-year limited (non-SeaCore models)*
4-year limted (SeaCore models)*
*Warranty applies to Installation Quality certified boat builders
Corrosion Warranty 3-year limited (non-SeaCore models)
4-year limited (SeaCore models)

This is why I suspected that the 425 was prop too. In the manuals and old brochures I have, they also state 415 prop hp. for the 502MPI. I don't doubt yours, or Raylars measurement for a second, that is why I am getting confused. Why would merc post it as prop hp if it is crank hp. When you get to dyno a 8,2HO I would be very interested to hear what the results are. The only engine I know of, where Mercury is clearly stating crank hp. is the 1200SCI. My personal belif at this point, is that everything is crank hp, both black and blue motors.

Sorry for the long rant.

Last edited by A.O. Razor; 04-09-2011 at 07:11 AM.
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Old 04-09-2011, 10:16 AM
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It's really a marketing game more than anything else. The standard Merc engines can vary 25-30 HP. That's why you see some boats faster than others with equal power. I've dyno'd 496 HO's from 387 all the way to 430 at the prop. Regular mags 350 to 373 at the prop. The blue motors are much more consistent and ususally make more than advertised. I've also dyno'd a Volvo 8.1 (420HP) that made 385 at the prop. Of course this is with my dyno using sae standard correction factor and an electronic weather station doing the automatic calculations.

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Old 04-09-2011, 11:08 AM
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It's really a marketing game more than anything else. The standard Merc engines can vary 25-30 HP. That's why you see some boats faster than others with equal power. I've dyno'd 496 HO's from 387 all the way to 430 at the prop. Regular mags 350 to 373 at the prop. The blue motors are much more consistent and ususally make more than advertised. I've also dyno'd a Volvo 8.1 (420HP) that made 385 at the prop. Of course this is with my dyno using sae standard correction factor and an electronic weather station doing the automatic calculations.

Bob Lloyd
Full Throttle Marine
Bob

Thanks for info. I sort of had the same thought. Do you only dyno these engines at the prop, or do you have any examples for flywheel hp?

What this boils down to is, that you can buy a black merc that either makes the clamed hp on the flywheel or prop, depending on how lucky you are. That's comforting

When you are saying that the blue motors make a little more than rated power, I quess you are talking flywheel hp? I recall reading that the 525EFI makes around 530-540 crank hp.
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Old 04-09-2011, 02:50 PM
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Originally Posted by A.O. Razor View Post
Bob

Thanks for info. I sort of had the same thought. Do you only dyno these engines at the prop, or do you have any examples for flywheel hp?

What this boils down to is, that you can buy a black merc that either makes the clamed hp on the flywheel or prop, depending on how lucky you are. That's comforting

When you are saying that the blue motors make a little more than rated power, I quess you are talking flywheel hp? I recall reading that the 525EFI makes around 530-540 crank hp.
I've got both dyno's, and my SuperFlow is far more accurate/consistent then my propshaft, so basically I only use our Superflow for almost everything. Every Volvo, Mercury and PCM motor I've seen, keeping in mind they are basically the same, make very close to the stated HP, but all are at the flywheel. Merc has stated propshaft for as long as I can remember, but I've just never come across that.

The 525's make between 540-550hp with standard correction or 515-525hp SAE correction. OEM's must use SAE corrections, and if your in warmer climates such as ours, then you get better standard corrections as it calculates to 60deg F. SAE is a later standard and what most OEM's use.
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