Why is the Gen 7 496 such a bad platform to build
 

So the 496, seems like aside from Raylar nobody likes modding these motors. Why? Is it just because of the cast pistons that come in the motors? I see some things about these motors that GM did that has advantages, the symetrical ports, the 18 head bolts opposed to the standard 16, the already swapped firing order, closed cooling. If you go into it knowing you are going to beef up the rotating assembly, is this really that bad a platform to start with?

So through Raylar you can buy a 511 CID kit for 9 grand that includes:

BigPower Aluminum Cylinder Heads
BP-206 Max Effort High-Lift Camshaft
CoolGap EFI Intake Manifold
Billet Throttle Body
1.7 Ratio SS Roller Rockers & AFN nuts
ARP Re-torqueable High Strength Head Bolt Kit
Cometic MLS Head Gasket Set
4.5inch Stroke Forged Crankshaft
Forged H-beam Connecting Rods
Forged Flycut Pistons
Rings & Wristpins
High Strength Main / Rods / Cam Bearing Kit

For that you get 625 horsepower. Is that really that much more than building an equivalent earlier gen motor?

These motors seem like such a redheaded step child, I would like to know why they are so frowned on. In my situation, since converting the instrumentation to smartcraft, I have pretty much the option of building what I have, or swapping to something like 525's, but I don't think I could touch a used pair of 525's under 30 grand, and then still they would most likely need the top ends done. I would love some input from guys familiar with building these, and if you are happy with the decision.

Yes, I think the controversial engine builder(s) should be considered as part of the equation too. If you give the package to a dipschjit engine builder, you will get screwed. Less people know & understand the 496 than the Gen 4 and Gen 5. The long and everlasting debate is that you can get far more horsepower out of just selling the 496 and buying a 525 or just building a 500HP for more power. I broke this down on a spreadsheet 50 times and its dead even. I finally gave up and just wanted to be different. I am sure there are naysayers but I am still happy with mine. I mean c'mon, its still cubic inches and cam right? What is the differnce if you built a FORD or MOPAR? More expense? Yes, but the 496 can be done very close to a 525 rebuild cost.

I did the 600HP package from Raylar and had the machine work done locally, a bunch of 75 year old "old timers" (my dad and a bunch of wacky 1960 drag racer buddies) built them, Dustin Whipple reflashed my computers and I am at 200 trouble free hours. They dyno'ed at 640 HP each. "Ray" was still around when I built them. I called and asked for the 600HP kits. Then, when I got the parts, I called and said "give me the main, ring gap and tolerances you prefer for a bullet proof build" he gave it to me over the phone. I gave this to the machine shop and my old man and never looked back. That was 4 years ago now. 95% of the reliability comes down to the build and the ECU program. IMHO

Heck, I would love to do the 8.1 block with a 4.5 bore from DART, the Raylar stroker crank and the NEW Raylar heads... It would be a real thumper.

The downside. I think the block might be a little brittle. Why? I have heard about the motor mounts ripping right off the block/casting failing. But I dont have an Apache running in 8 footers so I dont really care.

The Raylar parts are engineerd for what they are. A 625 HP kit, if you compare the crank to LUNATI you arent going to see it or compaing the Raylar intake to a Wilson intake you are going to fall short of expectations. But, the parts deliver for the intended HP range.

The good side is that I took the heads to 2 differnt shops to have them ported and both shops said you could gain performance but they were more likely to ruin them than make them better (true story). Now, Raylar also has ultra high flow heads too.

I am happy. I have always asked the same question as you. Mine turned out pretty well. When you finally break it down it will be so close it doesnt matter. Just pick the one you want.

Mine turned out well also. They do have a lot of potential. The biggest downfall of the 496 is/was the intake. The right cam for the restrictive intake and a whole Lotta welding and fabbing on the plenum will yield a whole lot of torque. 650hp is obtainable.

So where is Ray now. What caused them to split?

I am also planning to build the 496 in the future. Leaving it stock internal for reliability until rebuild needed. I believe the hate comes from the stock piston horror stories and the fact in stock form they are "fugly motors". Merc really could have cleaned the wiring up with a little attention to detail. Instead they covered the mess with the plastic engine cover. I like the fact that when the Raylar kit is installed the engine drops back in without much re rigging needed. I also like the fact its something different from the norm.

Vortec Bandit has done as much R&D as Raylar themselves. He has been super successful with this platform.

Why is there just a $300 price difference between these two ?
Is the crank only $300 ? I must be missing something.

vs

If correct, that's an easy decision. More is better right?

I have built a 496 8,1 using a Whipple 3.3 kit... It made 900 lbs ft torque and just shy of 900 hp. Replaced the heads with Dart cast iron, cleaned the chambers up, and very little bowl work. Replaced the crank with a 4340 Scat stock stroke forged in the USA , and machined on Scats priority equipment made for the custom cranks this crank was right at $2600. used 6.700 rods and ordered custom pistons from CP, this was a + .005 oversize piston. .990 pin. Used ARP main studs and head studs. MArine Kinetics did the cam. lifters have to be a shrouded type with a .700 wheel or you will dump oil at the wheel slot in lifter , due to the lifter oil galley location.... I used ARP rocker arm studs and locks with Scorpion Endurance rocker arms, this all cleared the valve covers, not using any Loctite on nuts. I used .120" wall pushrods.Timing chain set came from Crane, the most important thing to check is the cam sensor distance .040- .060... do not damage reluctor wheels on crankshaft.. If they are you can order from GM, heat them in the oven and slide them on...
The oil pump is a regular BBC, use a Melling 10770 or 10778. Put a new crank sensor in, no air gap just install set on wheel and tighten bolt.
I tried buying Aluminum heads from Larry@ Raylar, he gave me the runaround, thinking I was friends with his old partner Ray, because of the information I knew on who designed the heads, who cast them and who machined them... There's no doubt in my mind, I would have made more power with the aluminum heads.....Larry, later admitted; to his thoughts on my knowledge after it was too late for me to cancel the Dart heads. There was some secrecy on his part on certain questions I ask relating to pistons and even the oil pump. Being in business, myself I would have answered those questions if ask too me..... I was told some not the truth statements referring to reluctor wheels and locking mechanisms on the rocker arms. I wanted to buy; bare heads with a CNC program porting, no valves or components..Larry, tried to tell me it wouldn't work without his set-up WRONG !!!!!!
Dustin, did all the calibration for this package... we started with a stock crank and decided; the next season we would use the custom so to up boost to 8 psi and not worry about breaking the crank snout off. Scat typically, makes this crank for a 4.500 and 4.750 stroke. I had to machine about .300" off the counter weights to remove the excess weight or the counter-weights would have looked like Swiss Cheese !!!!

Make sure you stick to the factory head bolt torque sequence . Our local marina contacted me searching for 496 cores a couple weeks ago. They had a pair of Volvo Penta 8.1's with bad risers ( not the same as Merc stainless Risers) and had to do the heads. On reassembly , old school tech used regular BBC specs and started pulling threads out of the blocks immediately. He thought they were rotted , so he tried other motor and killed that one . Lightweight blocks ?

Why would changing the sequence pull the threads?

so your saying you got 900hp w/ less than 8lbs of boost?

you may want to recalibrate the tq wrench or were you pulling to the main cap tq?I've never pulled a thread on these blocks and 1 had been rebuilt 7 times.

^^^^ correct and 9 out of 10 times wrong torque is applied because of the operator. Not to go into great lengths here but you can have your snap on guy come out and if all possible bring the torque wrench tester with him. You would be surprise how many techs use a torque wrench wrong. One is you never go past the first click (if click tyoe TW) and stop immediately as soon as the click

I just had a class on this and the testing machine. Not one operator torque was on the money. Everyone was past the torque setting testing it on the machine.

Thats, correct little shy of 900....the 3.3 Whipple makes the difference..... camshaft, piston dish that was 8:1 cr also 5800 RPMs

also depends on how fast you pull on the handle.

and approx. how much duration was this cam?

Basically what I was talking about with the torque tester as it will show you torque wrench accuracy but most important will show you how the person using it is doing it wrong. This is the same guy who taught the class I was in. Watch how slow he uses these torque wrenches and then quickly releases to achieve the torque setting. He also said anytime a torque audit was done most of the apps had improper torque applied from the operator no matter of torque wrench that was used. .

https://www.youtube.com/watch?v=ftnNSeBm8y4

496 heads not really power makers and really the stock valve springs are not that good for durability especially for increased HP levels.

Dart has some good 8.1 Gen VII products to look at.

This is another spread sheet debate. The DART heads look like a good deal but once you buy valves and springs they are more than the Raylar heads. Plus, this debate can go different ways real quick depening on aluminum vs cast heads.

We can start a whole thread on building a DART block 8.1/496 real fast too.

w/ the dart block,,isn't 700ci possible,,if I remember correctly.

Sorry , I meant specs. And not me or my torque wrench. Fact says 22ft lbs first pass , 22lbs plus 120 deg second pass , third pass 60 deg long bolts, 45 deg med bolts , 30 deg short bolts . A little different than Gen 4,5,6.

Damn you! Why did you have to bring that up!

The DART block came out right after I built mine and once I realized they offered it in huge bores I was pissed. For hte cost it would have been worth it too... I guess the spending has to stop somewhere...

They are TTY bolts (Torque To Yield)

I replaced mine with ARP and torqued them to conventional specs.

Just saying to take this a step further Marine OEM the 496 was the heaviest and biggest production engine thrown in a boat. Also I am a huge fan of big block power if done right. The fact of the matter for the average boater who boats with any big block again stock power average boater the horsepower in their app is less than 1 hp per cubic inch and way less . Hell look at what the 4 banger auto guy has like 2 to 4 hp per cubic inch.

Next Volvo Penta before deciding on whether to do a big block when the 496 went away in 2010 - Volvo did many tests and came out with the 6.0 LS. In Volvo testing their stock 6.0 LS smoked the stock 375 hp and the 425hp - 496 apples to apples testing in everything from planning to a drag race. Just saying. In stock form the 496 is not no power house period.

Volvo penta new 5.3 L direct injection engine 350 hp apples to apples in a 24 / 25 boat will smoke a 375 hp 496 - 8.1 L and would give the 425 hp a run for its money. Volvo new 5.3 L direct injection is a power house production marine engine and over 1 hp per cubic inch about darn time someone did this in the I/O market place.

I work with powered boats all day long. The 8.1,s in a 30 to 36 foot cruiser will blow the socks off of the 6L getting on plane. Add 6 to 8 people and it shows that much more. I like the 6L but it has nowhere near the torque and get up and go as the 8.1.

^^^^ The one plus of the 496 MAG/MAG HO is the torque. 500 ft. lbs. +. My single engine boat is 6K lbs. and it planes in no time with a 496 MAG/Bravo III. Now, you get above 4K RPM and the motor starts to show its weaknesses but they are great to get big, heavy boats moving.

I get that BUP isn't a huge fan of the 496, but I certainly am not going to repower my Cig to an LS. As far as large displacement and low output, the 502 Mag was 6 cubes larger and 10 horse less, so the 8.1 did alright filling the gap that was left when Merc replaced it. A quick google search shows a 502 at 1189 lbs with a bravo one drive, and a 496 at 1199 with a bravo one. I am assuming the 10 pounds could be from the closed cooling components.

To realign this thread, I currently have a pair of running 496's and a spare 496 truck long block. I can't afford to buy a twin step Top Gun for a number of years at this point and I really like my boat, it's just a little on the slow side. About 600 horsepower should get me close to where I want to be, I am just trying to figure out the best way to get there. I would prefer to use what I have instead of selling off known good motors to buy unknown motors, not to mention that I wouldn't need to do much in the way of re-rigging if I stick with the Gen 7 motors.

The only difference in the truck block (that I found) was that all bolts were metric except the bellhousing was SAE. Weird, but just an FYI before you try to put a grade 8 in there and get pizzed off.

I realize the torque of the 496 and if you notice I said in a 24 to 25 ft boats for the average boater. Never mentioned anything about 30 or higher ft boats. Like I said its a heavy engine compared to whats out on the market place currently and the largest gas side production engine thrown into a boat. I own a 496 in a 2007 - 28 ft boat myself. I like the low end and mid range of the stock 496 but top end is a dog. IMO if I had a choice I would rather have a 502 because there is so much more in the market place and engineering done for the end user to buy and play with. Just saying.

Also many boat builders installed the 496 during its timeframe in the market place but in a very poor manner. Especially mid level bot builders and down.

And I have worked on 496's since the day they came out in 2001 model year and being a new boat dealer for many years. Also in my day ( @ one timeframe) and the 496 my shop worked on close to 200 - 496's per year. Merc & Volvo combined, so how can I not like them.

This year I have worked on only 25 - 496's. That's it.

For a NON CAT engine they are one of the hardest engine's to work on in a boat. Access is the main problem. Wiring harnesses is the other problem. Then related fuel issues especially Gen III cool fuel along with its poor design plus does not drain water very well for winterization and then a poor designed IAC operation and then a poor quality Gen VII water pump housing. . I am talking about stock OEM apps here

All good points. The wiring is the biggest joke on the engine. What a rat's nest! Has to be the ugliest OEM engine ever.

Bandit I understand where you are coming from and agree with what is said.

But less add - you do not even have a stock black production 496 - 375 hp nor 425 hp in your boat. Hell your engine is far above that - its the GM Vortec HP3 8100 version well over 500 hp and that relates to over 1 hp per cubic inch like it should be.

Matter of fact here how much I know about the 496 and the GM HP3..

GM Vortec HP3 8100 had MEFI 4 controller, Dyno numbers were more like close to 600 ft lbs of torque and something like 550 hp. GM really did not list the exact rating but listed 525 + hp and 560 + ft lbs of torque.

CNC ported cylinder heads and port matched intake manifold, sintered power metal exhaust seat inserts, premium race style Valve springs 1.7:1 ratio roller rockers, rocker arm studs - HP3 push rods, CMI headers, connecting rods forge steel, 75 mm throttle body. Compression ratio 9.1:1 - Valve train Hydraulic roller, crank mounted water pump housing / impeller and that's all I can think of at the moment.

And If I remember correctly this engine was under 750 lbs in weight.

Matt sorry for the off track posts.

Don't be! All of this talk opens up a dialog on an engine that isn't really discussed from a performance perspective. The common thought is the 496 is good stock, junk if you want to mod it. I want to find out if that is true, or if it is more that people try to cheap out on modding it properly and then suffer the consequences. Frankly, if my boat had 502's or even 454's in it, I wouldn't give a thought to repowering with 496's. But that is what I already have to work with, so now I want to know if I set realistic goals and build them properly, can they do what I want reliably, if there is such a thing in a boat.

I called Larry at Raylar today and asked him this exact question. There is a misprint on the website as they have gotten away from the Cool Gap intake and are extensively modifying the stock intake as the sheet metal intake has just gotten to be too cost prohibitive.

I also asked about exhaust requirements. If running the 600HO cam, the exhaust needs to be upgraded. They have a cam between the 525 and 600 cam called the BP205, it essentially runs the duration of the 525HO cam with the higher lift of the 600HO cam. According to Larry with the added displacement from the stroker kit it will end up at 580-590 stock exhaust friendly horsepower. Running that cam also eliminates the need to have the ECM reflashed.

Other upgrades he recommended were upgrading to the Melling 10778 pump and running a larger oil cooler, but for the water I boat in the stock heat exchanger should be sufficient.

In the general performance world, always proceed slowly hearing statements like that last sentence above in quotes.

Man, I used to have the HP3 cam specs in my folders. Can't find it. So for now, I'll just have to say I remember it as very similar to the 525EFI cam, but of course the firing order swap.

I agree and would factor in having Whipple reprogram the ECM's as part of the deal. I did not want to upgrade the exhaust at this time.

I like this thread, and like to see something different for a change, other than the typical "540" or 496 "stroker" build.

I really like the sound of MER's 900HP 8.1L whipple build. You should do that Matt. Those would wake up the Cafe for sure.

Okay, my memory was wrong. What else is new ? Lol.

The Gen 1 HP3 had a cam like the 500EFI's (Crane 230,236 HR on a 114LSA) but, again, with the firing order swap.

According to all this 8.1L HP3 research:
http://www.pacificp.com/forum/viewtopic.php?t=10543
There was a Gen II HP3 which added some more compression, much more cam and etc.

Pretty good read. I think.

You would have to run pistons with valve reliefs for the HP3. I studied the HP3 like a book, we have to get these guys in this thread - Vortech Bandit and another dude on OSO named RAGE are both HP3 gurus. Vortech is a brilliant 496 mad scientist and Rage spent more time mapping his ECU with Whipple than most engineers spend in 4 years of college.

Before blowing them up... I had the HP3 heads (which was a CNC program on stock heads with bigger valves). I ordered and installed the HP3 cam (from a builder on OSO) and it was a gnarley cam. We are talking 7+ years ago but I remember a PV clearance of about .020 or maybe .030 with stock flat top pistons. Needless to say I took it back out and used the Raylar HO 525 cam. This was the typical OSO builder story of yes of course they will work... But after a little homework it just wasnt a good idea. A few years later I suffered reversion from my exhaust and ate a valve anyway, but it was fun while it lasted. The HP3 II is nastier than a 731 and I think the Raylar 600 cam is actually a little hotter than the 731. My guess is the Raylar 600 is very similar to the HP3 cam. Similar... Not a copy. Be careful, I have been know to actually decrease other peoples IQ from a few feet away. Just my .02 cents.