Why is the Gen 7 496 such a bad platform to build
09-21-2015, 07:52 PM
#41
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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.
09-21-2015, 07:58 PM
#42
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Ah, here is where I read it:
.028" 
I would be scared to death to run an engine that tight.
The one thing about the HP3 that is unnerving is the extremely close PV clearance of ~0.028" from the HP3 Crane cam's increased lift and duration. That is why GM opted for the Nascar springs. The combination works but I opted to cut the intake valve piston relief deeper in the stock pistons and use lighter valve springs and stock roller lifters. This additional thinning of the stock Hyper Eutectic cast aluminum piston top is probably not the best idea if one intends to consistently run the engine hard.
The 496HO was successfully converted to a ~HP3 w/o the CMI's, Nascar springs, Crane roller lifters, GM ECU, Coyle sproket or HV oil pump. The Mercruiser PCM555 ECU was reprogramed to 5400 rpm rev limit by Dustin Whipple with recorded A/F, MAP, TPS and RPM data provided by Innovate Technologies LM-1 A/F meter/data logger and LM-2 RPM converter/data logger cable. The 43 psi stock fuel pressure was increased to 50 psi which produced A/F that was pretty much dead on throughout the rpm range.
The HP3 race engine program was apparently shut down by GM do to Mercury's displeasure with GM's competing with them in the marine engine/racing engine market. Some hard ball being played with the race teams is also plausable. Seemingly a GM business discision to get out.
Parts are available from Innovation Marine and complete HP3 engines as long as the stock lasts.
The 496HO was successfully converted to a ~HP3 w/o the CMI's, Nascar springs, Crane roller lifters, GM ECU, Coyle sproket or HV oil pump. The Mercruiser PCM555 ECU was reprogramed to 5400 rpm rev limit by Dustin Whipple with recorded A/F, MAP, TPS and RPM data provided by Innovate Technologies LM-1 A/F meter/data logger and LM-2 RPM converter/data logger cable. The 43 psi stock fuel pressure was increased to 50 psi which produced A/F that was pretty much dead on throughout the rpm range.
The HP3 race engine program was apparently shut down by GM do to Mercury's displeasure with GM's competing with them in the marine engine/racing engine market. Some hard ball being played with the race teams is also plausable. Seemingly a GM business discision to get out.
Parts are available from Innovation Marine and complete HP3 engines as long as the stock lasts.
I would be scared to death to run an engine that tight.
09-21-2015, 09:06 PM
#43
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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.
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09-22-2015, 06:04 AM
#45
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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]
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]
09-22-2015, 07:20 PM
#46
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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.
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.
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.
09-22-2015, 07:56 PM
#47
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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.
09-22-2015, 08:18 PM
#48
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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.
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.
Last edited by Keith Atlanta; 09-22-2015 at 08:21 PM.
09-22-2015, 09:21 PM
#49
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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.
09-23-2015, 07:26 AM
#50
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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.
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.
