496 build
 

Looking for a reputable engine builder to rebuild a 496 HO. I’m located outside Philadelphia. I want to stay with fuel injection. Looking to be actual 600 horsepower.

How much you willing to spend for this ? Heads, intake, throttle body and beefed up internals and really good recalibrations of the PCM 555 or a new stand alone ECM with correct wiring harness needed for a jist of info and start to this info ?

Also stock exhaust is average for improvements. O 2 monitoring is needed as well for the tuning at the very least.

I would be basically keeping the block. All new internals. HCI are pretty obvious. I’m not 100% on the fuel rails along with the injectors/pump as to what there rated for. Honestly my biggest concern is a competent tune. I come from a bracket racing background “small block ford blower motor” To list out what’s to be replaced would be a tedious. 600 horse from a 496 isn’t asking for much.

The early stock aluminum exhaust manifolds flow very well but won't scavenge like headers. Teague used to sell lots of CMI headers for the 496 but I don't know if they still do. Does anyone make a decent intake manifold and throttle body for this engine anymore? Raylar stopped making the cool sheet metal intake. Heads might be hard to find too. Just a few things I'd be concerned about. Your best bet might be to beef up the internals and pro-charge it.

Keep in mind guys I’m looking to get to 600 horsepower.... Forged internals are $2,500. Plus machine work, this work has to be done no matter what route I go. The biggest performance weakness of this specific motor are the heads, therefore the heads either need replaced or ported-polished valves sprigs and rockers replaced. Any motor builder should be able to take the stock heads for the power I’m looking for and achieve this. Cam and intake as stated earlier are obvious. Per the earlier response the tune/engine management will be required, I understand this, I’m simply looking for someone to say I know a good reputable shop in your area.

The 496 exhaust is good to roughly 525hp. After that a tube header will really start to pull away. We're talking staying NA here. There have been 750+hp blown builds using stock 496 exhaust.
Raylar still sells the CoolGap intake according to their website. The stock heads suck.... No way you'll attain your goal of 600hp. You have two options for heads....Raylar 315cnc or Dart Iron Eagle. Order the Raylar HO600 kit. It's been proven to dyno 650ish HP. Whipple Superchargers also has tunes for it. Your stock 496ho fuel rails and injectors are fine. Stock fuel pump and oil cooler are not. They need upgraded.

Thank you for the input. I understand my need for exhaust, this will be addressed. The whipple tune is specific for Raylars kit? I.E. specific for his 600 kit?

BINGO on the exhaust. for one Merc exhaust is not all about power period and are huge anchor weighted manifolds as 80 percent of those are thick cast iron in the 496 line up. . The stock 496 exhaust does not offer anything close for scavenging compared to even a average built header, 525 hp would be MAX if even that.

IMO the injectors at 80 % duty cycle would not support 600 plus hp. The fuel rails are cheap junk on the 496 as the end caps corrode and leak over time. Merc never painted the bottom of those. The very early fuel rails did better against rust. I have no idea what model you have and if you have the gen 3 cool fuel that will never support 600 hp period. The fuel line for the GEN 3 cool fuel is not that big in diameter coming out of the backside of the cool fuel cell. Also the fuel feed port at the fuel rails is tiny as well.

70 percent of the 496 fuel rails that come into me look exactly like this. Does not matter where they come from. This is more the norm of them than not from the pics below. Complete junk cheap fuel rails. Just putting it out there. keep in mind I easily see 200 of these fuel rails and easily 200 sets (1600 ) of 496 fuel injectors per year. By far more than any other boat place and auto shop.

PICS below of the norm condition used 496 fuel rail.

04 496 ho