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Old 11-14-2003, 02:49 AM
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496 build up >>> NEED ADVICE

hi

I want to build a bbc 496 for my 2 door 81 chevy malibu

is it possible to make 600hp out of it ( using 95 octan fuel )

I will buy the whole rotating assembly from either Scat or Eagle
Need advice on heads ( oval, rect, iron or alluminum )
cam ( solid roller )
compression ratio

I intend to use up to 250shot of nitrous on it
should I use forged crank ????

It will be my weekend toy ( street racer )


thanks in advance

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Last edited by terror385; 11-14-2003 at 03:13 AM.
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Old 11-14-2003, 05:45 AM
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600 HP should be a breeze, but it will not be cheap. Take your pick of the aftermarket heads and they will provide the power you are wanting. I would not worry about low end power, with that many cubes it will be there.

Go with so big Brodix or the like heads and you will have room to grow way past that 600 HP when you decide to put a wicked cam in it and bump the compression a little. For the pump, keep compression around 10:1 and it will not be too hard to deal with. 10:1 will still make very good power.

You will also need a pretty healthy cam to make 600, but nothing off the wall. 250-260 duration @.050 range cam ought to get you there. Keep the lsa pretty wide like around 112 and it will still idle okay and hold a little bit of idle vacuum. You will also want he wide lsa for the nitrous. I would get a devoted nitrous cam if you know you are for sure running it. Comp Cams makes a good selection.

For that large cube engine, I would look at a brodix single plane intake and go ahead and get setup with a dominator type carb. Again, when you decide to make that thing churn you will not have to upgrade. A 496 with good heads, a little compression and a roller cam will easily make 800 HP. As a matter of fact, with nitrous, you will be there.

Have fun,

Chris
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Old 11-14-2003, 08:39 AM
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I would have to agree with everything that turbo said. One thing though is that with a 496, going with a rectagle port head would probably work, but it would be on the edge of being too big without running around 7000 rpm and/or more compression. I would look into AFRs new 290cc CNC ported oval port heads, they flow as good as alot of rectangle port heads, which means that the velocity in the ports is much greater. But like turbo said, if someday you are going to want to go with high compression and a higher power range, you might want to look at the AFR CNC ported 315cc heads. On a 496, the AFR ovals and something like a comp cams magnum 305h (253 253 dur @ .050 .575 .575 lift) or 304hr (244 244 dur @ .050 .612 .612 lift) would work well and easily get you the 600hp you are looking for on 10:1-10.5:1 compression.

Adam
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Old 11-17-2003, 06:06 AM
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thanks guys for your great help


what is the maximum CR that can I use with 95 octan ???

also
I've found this
524ci
using 454 GM block
4.5 stroke

http://www.flatlanderracing.com/stroker454524.html


is that possible ????
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Old 11-17-2003, 08:31 AM
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It is no problem what you are doing. When I designed
some marine engines back 6 years ago this kind of power
was no problem. The 540 made 656HP at 5200 and was
689#/ft at 4000. These were 8.5 to 1 engines using the small
square port Canfield head. Camshaft was a very mild hyd
roller profile in the 230 range.

If you need more info you can PM me.

Cstraub
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Old 11-17-2003, 08:42 AM
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First of all keep it realistic.A 4.250 stroke is plenty.People go too overboard with stroke.The rod ratio is bad enough with a 4.00 stroke and gets worse from there.I always use a 6.405 rod legnth and alway's use a Dart pro 1 cyl head on applications where the frame is stock.The brodix heads have ex. port's that are raised .700 and cause hedder issues.the darts are only 300. I would use the 310 heads and no wider than 110 lobe sep with the ratio of 1.50 that this eng will have with 6.405 rods and 4.250 stroke.PM me with the car info and I will give realistic specs. on a cam that will work.
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