Why is the Gen 7 496 such a bad platform to build
01-02-2017, 09:02 AM
#261
Registered
Well I am obviously the odd man out. With the previous 625hp at 5300 rpm engine running extended WOT @ 5800 rpm the 700HP rated Hardin Marine thermostatically controlled oil cooler and AN10 lines kept oil temp feed to engine at 190F but crank case oil temp (at filter head) would continue to climb until I chickened out ~270-280F. Previously believed the increasing crank case oil temperature at WOT was caused by insufficient oil flow rate through oil cooler do to bearing clearances. A similar problem was resolved for a Whippled 496 by increasing bearing clearances and adding external adjustable pressure oil pump to compensate for increased oil flow rate to maintain oil pressure. For my present increased HP build I have plans for an additional stand alone crankcase only oil cooler system if oil temp runaway is still a problem. With the 120F coolant thermostat the coolant never exceeds 150F at WOT and usually in the 140's.
01-02-2017, 09:08 AM
#262
Gold Member
Gold Member
I built it and 1-4 mains were 0.0017 to 0.0026, #5 was 0.0031 and rods all 0.0023 based on nominal clearance.
Current build 1-4 mains are 0.0027-0.0030, @5 is 0.0035 and rods are 0.0023-0.0025 based on minimum clearance. Crankcase oil temp was up to 230F after short WOT ECU tuning run last Fall.
Current build 1-4 mains are 0.0027-0.0030, @5 is 0.0035 and rods are 0.0023-0.0025 based on minimum clearance. Crankcase oil temp was up to 230F after short WOT ECU tuning run last Fall.
01-02-2017, 09:34 AM
#263
Registered
01-02-2017, 02:26 PM
#264
Gold Member
Gold Member
Join Date: Sep 2005
Location: Missouri
Posts: 1,987
Likes: 0
Received 0 Likes
on
0 Posts
Bravo X1 is the water pick up which has the extra water inlet ports on the nose of the gear case. Above 5100 rpm the water pump pressure exceeds max Diacom pressure scale of 43.5 psi. I typically run the Purolator Pure 1 oil filter and Mobil 1 15W50. I tried a K&N high flow oil filter once to see if it made any difference in the WOT high crankcase oil temperature characteristic. It did not. I am now trying the Quicksilver 25W40 for engine break in to see if the lower hot oil viscosity makes a difference in WOT oil temp. It likely will not since historical oil analysis at oil change said used oil viscosity was below a 15W40.
01-03-2017, 07:22 AM
#265
so with all the kits, upgrades and obvious r&d on these 496's whats a stock one pull on the dyno
01-03-2017, 09:08 AM
#266
Registered
iTrader: (8)
01-03-2017, 10:57 AM
#267
nice read thanks for digging it up and replying
now i only have 5 more questions
6 prolly 6
now i only have 5 more questions
6 prolly 6
Last edited by outonsafari; 01-03-2017 at 10:59 AM.
07-23-2018, 02:44 PM
#268
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]
07-24-2018, 01:47 PM
#269
Registered
iTrader: (8)
MER posted that on the first page of this thread. I was looking to do the same thing. Scorpion could only tell me they might work. I then went with Raylar's rockers. They fit under stock valve covers. Valvetrain geometry is perfect as well. The R&D has already been done with the Raylar setup.
