I believe I read once before the HP3's ran extremely tight PTV clearance, hence the reason for nascar spec springs in the HP3 motors. I know the Raylar 600 am can not be used with stock pistons because of the shallow valve reliefs.

Ah, here is where I read it:

.028" :eekdrop:

I would be scared to death to run an engine that tight.

since we are talking 8.1's, I have a nice block that I need to sell or trade for a nice std bore gen 6 454 block. the 8.1 is fresh .030 over and cleaned and painted. it is a customer's who brought all the new parts for me to assemble and the parts they sold him are all for a std deck 454 block so it is easier to change blocks than all the other parts. if any one has a gen 6 454 block that will go .030 and wants to trade let me know.
[email protected]

I have some gen6 blocks, but I don't know what I would do with the 8.1 block

I know, the discussion here is based around piston to valve clearance at this point... When I did this 8.1, it was a new learning experience, some people like Larry @ Raylar, act as if this is all top secret information.... Yes; some things are different, but not that much... so the stock stroke isn't exactly 4.375, the bore is 4.250 and the rod length is different along with a wrist pin size of 1.062. The piston wrist pin is offset, less than .050 if I recall, piston clearance to cylinder NA... Valve pockets are shallow, on stock pistons, along with a wrist pin the size for a diesel. The maining bearing upper has a narrow tab for fitting into block, I widened, the upper slot in block, to accept your std BBC H bearings. Rod bearings BBC, cam bearings BBC.... I sent the stock piston to my engineer at CP Pistons, they built a new piston, based on a 2618 forging they use in the Bullet Series Pistons, I think; I went to 4.255 bore, piston was dished, valve pocket for lift cam, .990 pin, no wrist pin offset and I think; I ran about .0045 clearance maybe .005, Hell Fire top, Napier second, ring pack....
That engine was designed to run forever at a continuous rpm, I was told they were designed for generator packages, to run on natural gas.The oil pan and windage design is pretty nice, plus the engine can stand on its own using the oil pan....lol
Its a expensive platform to modify, if you have a nodular crank, I would be limited on HP application, I don't care for the balancer and the long crank snout, this is one reason we spent $2600 on a crankshaft, my client wanted a dependable build, this went into a 27 Eliminator deck boat..
Can someone that has used the Raylar kits tell me how, the rocker arm adjusting nuts are secured ? Are the guide plates stock along with the rocker arm studs? I was told the rocker arm studs are modified....[ATTACH=CONFIG]545485[/ATTACH][ATTACH=CONFIG]545486[/ATTACH][ATTACH=CONFIG]545487[/ATTACH]

Matt, So the cool gap intake is not part of their kits anymore? I remember from old posts that Ray was adamant the stock intake was not worth modding. Seems the consensus has changed. If you look back thru posts from Rage, be ran the gen 2 HP3 cam and had .250 p to v with his flycut stock pistons. I believe it was on a 116-4 lsa.

MER, I see you were able to use the scorpion endurance rockers and polylocks and clear the stock valvecovers. I wondered if they would work. I like that setup with the arp studs vs the netlash raylar rocker afn nut setup.

I have noticed a lot of what Ray said centered on selling their product, no matter what the subject matter. Larry was pretty upfront that the modified stock intake supports up to the 600 horsepower level when ported and matched to a 90 or 100mm throttlebody. He says the cost to produce the cool gap manifold has exceeded the benefits at this point. I would love to talk to more 496 specialists, but there really aren't any that I know of aside from Raylar. Seems like their heads are the best available, and one of my motors is already running their rocker setup for 100 hours and no issues, so I am not really concerned about the AFN nut issue.

I think the possibility for the cool gap is pretty high. I dont think the 600 is even scratcing the surface of the intake. There are a few more people on OSO that did some R&D for Raylar stuff and nobody ever reached the limit of the intake. I mean, its seriously the size of a freakin shoebox and the runners are BIG. That being said, I dont think the 600 in all its glory could ever need more than the cool gap and an 80mm let alone a 90 or 100. There are two people running the 600 set up with a next generation "600 cam" (even bigger than the 600 cam) and they arent out running the 90mm throttle body on a cool gap.

Raylar Rockers - I ran them in the 496 I blew up with HP3 heads and BIG springs and never broke one. I have them in my 600's now with 190 hours and they have been fine. The downside is lack of pushrod guides. You could never run the stock rocker studs and have guides, it would screw the geometry all up.

FWIW, Ray was the marketing guy, Larry was the engineer and most of the R&D brains. A lot of people trash Ray but the guy knew his way around an 8.1. How many people called and asked a million questions and never bought anything... If you actually bought stuff from them they always remember your name and always told me what I should and shouldnt do based on a reliability standpoint. Dont forget, they had a raceboat and ran the crap out of it for a while so they werent idiots.

Definately not idots, they even got Darin Morgan (when at Profiler) to design their heads. So yeh, DonziMatt - you can finally get yourself a set of Profiler heads designed by DM himself. Enter Tim Allen grunt noise here.

About 10 yrs ago.so going of Memory here
We used regular are rocker studs and poly locks.just needs a valve cover spacer.
These were on whippled 496's we built.
Motors got sold and are still running strong in user name Pinball sutphen.

Holy! I forget to check this board for a couple weeks and all sorts of hell breaks loose ;)

Yup. The stock cast pistons, low flowing cylinder heads and intake manifold make the 496 an expensive motor to modify to hit typical 502 power levels.

Yup, cubic inches and air flow dictate power output. A big block is a big block is a big block. We're glad to hear your 600HO is running well and produced such solid power numbers

Ray is gone. The customer service was lacking and he took off with the company bank account.

Sorry for any hassle on your end. We don't sell bare heads. We've had waaay too many people call us after ordering bare heads with "now what size does this have to be" or "what length pushrods do I need" to which we have no idea because at that point the person is building a custom setup. So, we sell the heads complete, but that doesn't mean you can't adapt things to work - you're just a bit better versed than the average consumer is all.

The Dart heads are a bit cheaper than ours if you get cheap components and a bit more expensive than ours with nice components. They're really nice parts, but they still weigh a ton and have the typical iron head issues with compression.

The reason the numbers aren't stated is because GM realized that to make 550hp from a 496, they would need aftermarket pistons, a great big cam, extensive cylinder head porting and intake manifold modification. This means big bucks and a decreased bottom line, and thus 550HP became 525+HP (which they still couldn't get to) and then was discontinued as a result.

To make 525HP from a 496 / 8.1L you'll need aftermarket cylinder heads, a high flowing intake manifold, cam similar to an HP3 with around .530 lift, roller rockers and springs. For those wondering, the best we've seen from ported stock iron heads with a 230ish cam and a high flowing manifold is about 470-485HP.

The modified stock manifold with a 90mm only produces about 80% of the flow of the Cool Gap, but frankly the additional air isn't really needed until you're at the 600HO cam or larger level - and even then the power gain is only up top (5000rpm). The modified stock intake works great for street vehicles that want solid midrange torque with automatic transmissions, but when you're looking to spin em up past 4700, the limits of the modified stock intake start becoming apparent.

Yup. The demand for the Cool Gap isn't really there anymore. It works great in applications all the way up to 632cid. Recently, we ran several intake designs back to back and the modified stock manifold made 580hp from the 600HO kit, so we said, good enough. Even when modified its still a heat soak and terrible looking, but if you want to make more power and want a custom looking top end, there's always a 3.3L Whipple!

Here's a shot of a 632 with a 90mm Cool Gap just cause:
http://www.raylarengineering.com/img...raylar-l18.jpg

The HP3 cam is actually very similar to the 525HO cam (BP203). The 600HO cam (BP206) adds a bunch more duration and lift (.600+). More information here: http://www.raylarengineering.com/cam...alvetrain.html

Guides are stock. The AFN rocker arm nuts use the stock studs and tighten down all by themselves, theres lots of info in this video:
http://www.youtube.com/watch?v=03ci0WdLdKk This is our "new" street kit. Our shop suburban has been running around for 2 years (30k miles) with the 540 kit. You'd be surprised how light you can make a 6000lb suburban feel with the stage 1 540 kit in the article!

If thats not stupid enough, we're just putting the final details on our street 2.9L Whipple kit for the forged bottom ends.
http://www.raylarengineering.com/img...vortec8100.jpg

Here's a little skinny on the stock intake. The runners are torque monsters. The stock plenum to feed them is where it fails.I cut the plenum out completely. The new plenum was four times the size when I finished with it using 6 inch alum pipe cut in half that runs the entire length of the intake. When the plenum was cut out I had full access to all of the runners for porting and cleaning. Everything I could open up in there was opened up. A lot of welding, cutting and fitting took place fabbing up the new plenum. The original vacuum pipe completely gone. Throttle body flange was cut up and material added to open the throat. Four bolt flange welded in place of the original three bolt. Ended up with a 100mm throat feeding the massive plenum. Added a 1 1/4 throttle body spacer that tapered from the 92mm throttle body to the 102mm flange. Air flow was ridiculous. Motor made gobs of power at 5800 rpm.Manifold vacuum dropped tremendously. Swapped to the 102mm with straight 102mm spacer and results even better. The 8.1 manifold no longer a restriction.

To add. Heat soak used to be a problem also. Remedied that also. When the original vacuum tube was removed from the bottom of the intake I was left with a hole at the rear of the intake where the tube used to run. The plenum had a 1/4 inch bent aluminum tube tacked to it acting as a cooling coil with the ends welded at the rear of the intake. I have pressurized cooling water running through it cooling the plenum. Looking at my motor appears pretty bone stock.

My initial plan was to build 640-650HP. That was accomplished. I haven't tried a cool gap from Raylar for comparison but I'm pretty sure the torque numbers would't be what they are with this long runner manifold.

Did I mention my cam builder is the bomb.

Larry, What power levels can be attained with your heads, rockers, modded stock intake and keeping the 496HO cam? Exhaust is stock 496 manifolds, turbulators removed, stock risers modded to mix water in at transom. Whipple Stage 2 tune. I don't want to pull the engine and don't have room to install a cam in boat. Boat runs 72-75 now and would be happy with a solid 80 all day.

Vortec Bandit - how did you determine area sizing the plenum ? This can be tough to zero in on when talking max overall performance. Runner length and cross sectional area easier to figure out with available proven math equations.

I just finished a 588 with Raylar Heads. Put a 105mm on it so see what it does in tha boat.. I can tell you that the Holley EFI System is just absolutely best bang for buck in its category. Way cool - Somebody wish me luck please -

..And with regards to the title 'question' on this thread - my opinion is that anything is a good platform depending on what you already own or started with. Keith has provided the most inclusive, accurate reply to this (which equates to cost comparisons in an honest context). But for the nay-say'ers, what if i go out and buy a 502 crate engine ready for a road application? Have you considered the other 4 to 5 THOUSAND you have to pay for the proper marinization pieces? If you only play in fresh water then you can get away without a lot of it. If you want closed cooling (I'd argue that it's far superior even in fresh water), then it's like anything else you upgrade. You just do it and cost for hp usually comes out same. There is no cheap hp and there is nothing terribly difficult with the 8.1 platform unless you are missing the front half of the engine. For me personally, the difficulty lies with throwing all those expensive accessory pieces in the trash and starting over from scratch.

But I would say that it's interesting how no matter what upgrade path you choose, if you are honest and track the costs, you'll have as much in a given upgrade as the other engine out-of-the-box in a side by side comparison. There will be a + or - but the hp and/or speed all costs same from my perspective.

I pulled the trigger yesterday and started ordering parts with Larry at Raylar. Next season I will have the Raylar CNC heads, the 203 cam, ported stock intake manifold with a 90mm throttle body. The season after that I will do the stroker rotating assembly, the HO600 cam, and an exhaust upgrade. I would have loved to do everything at once, but my budget won't allow that. Fortunately if one of the stock pistons decides to exit stage left I have a spare shortblock I can put together.

I had an opportunity to buy a pair of 525's, but they had almost 600 hours on them with unknown history on the motors or the headers. They would have set me back 20 grand for the pair, I just couldn't justify that for motors that needed a full refresh. I really like the 496's, the boat is already rigged for them, so I am going to make them how I want and hopefully it works out. If I left the boat alone I would just get bored with it. I will try to document the buildup along the way including any pitfalls I encounter.

As a baseline, with the stock 2006 425 horsepower motors the boat will run a consistent 68 mph touching 69 on my lake, and touching 70 in salt water. That is spinning 26 pitch bravo 1 props at 4900-5000 RPM. The motors are bone stock, have the turbulators removed, and have right at 200 hours.

I think you made the right choice. The pricing on used 525's is ridiculous. You should get a nice gain adding 200 hp to the cig. Keep us updated.

You would have come out ahead with two 525s for $20,000 but good luck with the Raylar stuff.

You really think so? At around 600 hours those motors need to be fully gone through. How much do you figure to do that? 5 grand a motor if all it needs is a refresh? And then we have the questionable Merc spec CMI headers with 600 hours on them. How long do you figure they will go for before a leak shows up? Remember I have no history on these motors. They were in a boat that was involved in an accident, the owner didn't make it, the boat was being parted out to cover bills. Maybe if I had a full history on those motors it would be a different story, but I saw a total investment of at least 30-40 grand realistically. Subtract 12 grand for what I could have sold my motors for and you end up at 18-28 grand out of pocket. And that gets me... 525 horsepower. Or I can dump that money into my motors, over the course of a couple of years, and end up at 600 horsepower. I know the condition of my current motors, they are very sound to build on, and I just wanted to do something different than the standard issue 502 based stuff. Call me crazy.

Was that 525 boat local to us ? Sorry for quick derail.

No, halfway across the country, another thing they had going against them.

Yeh, I wouldn't take the chance. Way too much coin to gamble on.

So in anticipation of my first round of parts arriving, I pulled the motors Friday night. A Cafe Racer with bravo drives could be the easiest boat I have ever pulled motors on, I actually really enjoyed it. It helps that if I put one of my lifts up enough to clear the fenders on the trailer I can back the boat all the way into my shop and get around both sides with my forklift. It's nice to stay warm and have tunes going, not to mention I can lock the doors and be left alone while doing it.

[ATTACH=CONFIG]546794[/ATTACH]

From there I got the first motor up on the stand. An 800 pound motor is about all I want to put on this 1000 pound stand, but it took it ok, and now it is ready for surgery.

[ATTACH=CONFIG]546795[/ATTACH]

I had an extra hour today I could pull most of the accessories off to get access to the timing cover, pull the heads, etc. I pulled the power steering pump and raw water pump off because I will put my degree wheel on it and they would be in the way. If I wasn't going to degree in the cams then those could have stayed right on there. You also want to make sure you have a rugged puller for the balancer, they are not keyed as the 496 is an internally balanced motor so not only is the snout on the crank quite long, they are pressed on with some gumption. All the bolts on this thing are metric, so you will need some 10X1.5 bolts for your puller to make it work. A 3/8-16 feels like it will thread in, but it is loose and you will rip the threads out of the balancer, at which point you will be thoroughly screwed.

[ATTACH=CONFIG]546796[/ATTACH]

I am done for now. Time to clean the floor up and get a bench cleaned and prepped for parts. I don't want to open anything else up until I have parts in my hand and according to UPS that will be Tuesday. I plan on popping one pair of valves and measuring the guide clearance as well as installed height but I won't go any deeper than that, I have never heard of anybody having a setup issue with the Raylar heads and the 496's are closed cooling so they are pretty thermally stable. Looks like the only gaskets I need so far are exhaust manifold gaskets. Everything else is designed as a reusable style gasket and they all look good so far.

Following. My 2003, 400 hour 496 MAG decided to develop a death noise backing off the trailer in September. It will be coming out in December.

I lied, I decided to pull a little more apart today. The cam and lifters are in excellent shape, cam bearings look good. This motor already has Raylar's rockers on it from the previous owner upgrading them when he had the heads off. The rockers feel fine and the little AFN retaining nuts all look good, no cracks. I pulled one head and the cylinder walls look great, which I expected since compression and leakdown were perfect and these motors don't use a drop of oil.

[ATTACH=CONFIG]546803[/ATTACH]

Of course, going to set the head back on the motor so I could cap it back up resulted in this:

[ATTACH=CONFIG]546804[/ATTACH]

Split the pinky nail right open in the middle, stings like a sonuva*****. Oh well, no pain no gain.

Cool, cool.

I didn't believe you anyway....about not pulling them down further. Easy bet ! Lol.

Well, your nail is gonna match your motors soon....black. Youch !

:eek:
Just think Matt, if it would have been the Raylar aluminum heads it would just be a bruised finger. :eek:

Did you see Bob Llyod's mention of cracked Raylar heads?

See post #130. Wonder what the root cause was?

http://www.offshoreonly.com/forums/g...-heads-13.html

I saw that. At first I got worked up, then two things occurred to me: one, those may have been early revision heads, I know they have been through a couple of updates throughout the years, and two, what other aluminum head option do I have for a 496? They had issues with rocker nuts cracking early on also, but I pulled mine off after 100 hours and they looked perfect. Going to run her and hope for the best. It's so easy to get worried about stuff you read on the internet. I am trying my best not to fall into that trap.

Bob L mentioned early heads.

Wasn't trying to scare anyone off or stir crap. Just wondering out loud what the problem was or if it was ever determined. You are correct in that you have no other options if going aluminum.

SB I missed the part on early heads. Thanks.

Food for thought.

My .02 is the ECU program. Dont do a ragged edge program. Be slightly conservative and do Raylars flash or Whipples stage 2 and you will stay dsafe.

we always joke that if you don't shed blood working on a machine it wont run right till you do! :D strangely enough i always seem to cut myself each and every time i work on some motor and they all run like tops! :D ;) LOL

x 2.

You didn't fix it right unless you blead and you have a few bolts/nuts left over.

Make sure the customer doesn't see those leftover parts. ;)