Why is the Gen 7 496 such a bad platform to build
09-23-2015, 02:51 PM
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10-07-2015, 06:41 PM
#52
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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:
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.
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 mean c'mon, its still cubic inches and cam right? 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.
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 is gone. The customer service was lacking and he took off with the company bank account.
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. 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 !!!!!!
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.
Here's a shot of a 632 with a 90mm Cool Gap just cause:
http://www.youtube.com/watch?v=03ci0WdLdKk
If thats not stupid enough, we're just putting the final details on our street 2.9L Whipple kit for the forged bottom ends.
Last edited by Raylar; 10-07-2015 at 07:14 PM.
10-07-2015, 08:18 PM
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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.
10-07-2015, 08:24 PM
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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.
10-07-2015, 08:30 PM
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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.
10-08-2015, 03:20 PM
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Holy! I forget to check this board for a couple weeks and all sorts of hell breaks loose
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.
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.
10-08-2015, 04:37 PM
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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.
10-13-2015, 04:46 PM
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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 -
10-14-2015, 12:33 PM
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..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.
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.
Last edited by SDFever; 10-14-2015 at 12:42 PM.
