AZ Speed's L-18 intake coversion pkg for 496HO
 

Anyone have any experience or an opinion on AZ Speed's intake conversion package for the 496HO?
They claim 100-110hp increase. Too good to be true?

I too am extremely interested in this upgrade. I was quoted 538 HP @5200 and 575 ft/lbs @ 4500, with dyno headers. They also recommended CMI headers, but I don't know if it's E-Top or Sport tube.

I don't believe you can directly compare the 425 HP of the stock engine with the 538 HP of the modified engine because the 425 HP is the propshaft rating and the 538 HP is measured at the crankshaft. If we assume the same 30 HP drop as the HP500EFI (500 HP crank, 470 propshaft) the 425 translates into about 455 at the crank. You're still getting a healthy 83 HP increase, but not the 113 they referenced. I'd love to be wrong!

What do they get for the upgrade?

$3900 on their website.

escape.

i'm pretty sure that 425 is at the crankshaft.

Don

i just looked in my manual... 425 is crankshaft hp.

Don

My "Mercruiser 496 Mag Bravo Models" Operation, Maintenance & Warranty Manual (black cover), on page 40 has a table with engine specifications. It states the propshaft horsepower for the 496 Mag HO is 425 with the following footnote "Power Rated in Accordance with NMMA rating procedures."

I couldn't find any reference to horsepower in the installation manual.

Confusing that Merc is publishing a different rating somewhere else.

here is a scan from my mercruiser book. operation, maintenance & warranty manual.
it's not very good but it does say 425 crankshaft power

I've dyno'd a lot of Mercruiser motors and they have always made the "propshaft" horsepower at the crankshaft. The 496's make 415-430 at the flywheel. Although quoted as propshaft, this is not the case. Nor was the 6.2, 454, 502. All of Mercury Racing's motors have always tested higher than whats published.

Just to let you know, in order to use the Az. setup, you have to change the harness and computer system to the MEFI4, therefore, if you have Smartcraft, it will no longer work.

Our 525 packages will be available in Jan. and use the stock exhaust.

Thanks,
Dustin

Dustin,

Do you have the billet covers and the other polished engine parts ready now. Or if your using stock exhaust, are you going to change the engine look like you were planning on earlier.

Don

Here's my version of the manual. Mine is for a 2002 model. Very interesting that there's a difference! Dustin appears to have our real-world answer.

Dustin,

I have to use the gas available where I boat, which is typically 89 octane, and occasionally (rarely) 87. As I understand your upgrade options, to get a substantial power increase I'd have to run 91 octane based on your ECU recalibration.

What's your recommendation for a person like me?

yeah.. i don't understand why they are different either but mine is on page 53 and my book is a 2003

Don

If you have to run lower octane, then you can do the same work but with less total spark advance which will lower the overall power output. To get some back, we can install Az's intake and then we would recalibrate the factory ECU for those changes. Or you can lower the compression, do all the upgrades, and then supercharge it and make around 650hp on 87 octane. It will make just under 750 with 91 octane.

Were not going to produce the engine covers and were using stock exhaust.

Thanks,
Dustin

Dustin,
are you changing the exhaust and putting tail pipes in place .. i thought the cam overlap was to big to run stock exhaust.

Thanks,
Don

Dustin, Have you had chance to test and come up with a recalibted ECM for the new 525EFI? I have one with low hours but it seems run very rich. Wondering if you could help it out. Thanks.