I am looking for cam recommendations for a 580” BBC I am building. 4.5” stroke, tall deck Dart block w/ steel caps, 6.535” Eagle H-beams with L19 bolts, SRP flat top pistons. Compression with 120cc heads is 10 to 1. Ported Brodix BB1 (285cc ports) heads flow 315 cfm on the intake at 0.700” but reach 300 cfm at just over 04.00”. Exhaust is approximately 82%. Stahl side exit headers with 2 1/8” primaries, 4” collectors and JCL baffles for mufflers. Intake is Brodix HV1 with a prepped 4150 carb.

Comp Cams recommended a 258/262 (at 0.050”) 0.672” solid roller using their CR series lobe on a 110 center. After looking closely at Comp’s latest catalog, I see they have a Xtreme Street roller that actually has a more aggressive ramp (duration between 0.050” and 0.200”) than the old CR series. So now I am thinking a 254/260 with 0.660”/0.666” lift. The Xtreme lobes also run a much tighter lash which I think is probably good. I am not sure where the lobe centers should be.

The car is about 3,100 lbs, open track/street car with 3.08 gears and a Richmond 5-spd (non-overdrive). So I want a whole bunch of torque coming off the corners. Top RPM about 6,000.

Any thoughts please?

 

Just off hand I would say that your cam durations would be very mild on such a big ci motor. You should invest in some motor combo software and run simulations on all the different cam grinds.

My question for you is what kind of tires do you have that can hookup that kind of power coming out of a turn. Most of the Viper road racers that I have talked to really don't hop up their motors that much. Because they can't put it all to the ground.

 

All I can say is you have the making of a heck of a tractor pulling engine!! That sucker is going to have so much low end it's going to be unreal. Not sure of all your goals and parameters, but I can give you my experiences.

The first version of my 540 was very mild ( to my stds). I used Brodix 2Xtra heads that flowed 381 cfm (tested after 2 years running..probably a little better when valve job was new). I used a custom solid roller with 262/273@.050, .672/.675 cam on 112 LSA. It idled very well and actually sounded pretty mild compared to my buddys small block with a 106 LSA roundy pounder cam. I used an old Team G single plane intake since it would fit under hood and a 1050 Dominator. It made 732 hp at 6200-6300 and 678 ft lbs at around 4600 it seems like. The issue is it ran out of air quickly after 6500 rpm. It was down to 591 by 7000 rpm..falling real quick. It made 615 RWHP with pipes open.

I've found that unless you get some real airflow through the heads, these big engines choke up quickly. The Dart 335's and AFR 335's with CNC ports would work well. I ported my heads out to the 428 CFM range and it really woke up. A change to a 272/278 @.050 on 110 LSA cam, a Super Victor intake and the head work moved it up to 825 hp and still made 676 ft lbs. The peaks were pretty high though..mine likes 7400+ rpm on HP and 5300 or so on TQ. I think the cam grinder was right, he suggested I keep my old cam and do the head/intake first and see how it worked. I know some folks who have run that Comp cam, and it does well. Mark (ML67 and 69 NOXratt I believe) they had it on a 112 LSA.

Mark and I were almost identical on power on the chassis dyno. Both had 540's. I had larger unported Brodix heads, he had smaller heavily ported Brodix. We had similar intakes, but his was ported also. I ran a 1050 Dominator and he had a 1020 cfm 4150. I had 2" headers..he had 2-1/8" ones. I had 3" pipes and rear exit flowmsters, he had 3 or 3.5" pipes in sidepipe covers. I used a larger cam than he did. It was amazing how these similar but different parts combos added up to be within like 1 hp of each other when capped up. I don't think he ever ran his uncapped to compare with my uncapped numbers.
The combination of the larger heads and cam and maybe carb, allowed me to be with him and his ported better flowing stuff. On the other hand, his better flowing stuff allowed him to run a smaller cam and probably have better street manners. His engine hung on the top end better than mine due to better airflow that even my larger cam couldn't keep up with.

So overall, I think you really need to look at heads with much more airflow than the B-1's. They are great on a 427/454 but they're going to starve that 580 big time!

My car is much easier to drive and much more controllable with some of the bottom end power killed and the RPM range extended. It was just stupid before on street tires. By the time you got it halfway straight you had to shift. It still makes the same TQ..just a little higher.

If you are ever going to run slicks, you might check with 69 NOXratt...he's got a complete 12 bolt Vette IRS for sale!


JIM

 

If you are thinking about the Comp Cams 254/260, .660/.666 XR292 R10, I have a brand new one sitting here....

Steve

 

I would wonder about using heads that flow so little on so many ci. Hot rodded small blocks run very nice with 300+ cfm of intake flow and your planning on running an additional 200 cubic inches.

If you could get me the flow chart for the different lifts on those heads and the cam card valve events @.050 I would run some simulations for you.

I was watching the NASCAR race yesterday and the slowest place on the track was was over 120 mph and the top speed was near 170 before braking. With their sub 360 ci motors they couldn't floor their cars coming out of the turns without spinning them the full length of the straight away.

 

gkull, I would love a simulation. I am waiting for the head porter to get his computer repaired and print out the flow data for the heads, so I will get back to you on that.

I know these are small port heads, I originally bought them for a 427. The port size is the smallest rectangular port heads available. I suspect this combo will make a lot of torque, then maybe some new heads next year.

 

68427 could you get me the cam card specs and I could get pretty close on some custom flows with a 315 at .700 max.

My other question is how do you come up with 580 ci. Is it something like 4.530 X 4.500

 

Thanks for the insightfull help everyone, based on these comments I will be looking for some new heads but first I think I'll get it running with what I have.

I would like Steve's cam, I think it will work fine for now.

Bore and stroke is 4.530 x 4.500, I'll have a number of overbores left in the block and can go up to 605 with off-the-shelf pistons

 

It's gasping for more air! I would also go for higher compression. I just did another simulation and that cam retarded 4 degrees raised the peak hp to 603 at 5500 rpm

Click on the picture to Super Size it





[Modified by gkull, 9:04 AM 2/25/2004]

 

Wow, that's an enlightening simulation. 600 lbs of torque at 2,500rpm? That sounds like a diesel. This belongs in a tow rig. I'm going to assemble it so I have something to take to the track this summer while I look for some bigger heads, something that flows about 400cfm. If I reduce chamber size to 112 to 116cc I can pick a point of compression too.

Thanks for the sim! I'll put it on a chassis dyno later and see how it compares.

 

I don't think that people realize that higher flowing heads will actually make more tq at all the rpm ranges. If you look at the volumetric Eff column you will see that this combination never even gets above 90%. Heads and correct camming can exceed 100 %. I would expect 700+ foot pounds out of 580 ci. I was also guessing at 1000 cfm

Ask Steve 542 what kind of compressions he was able to run with his mountian motors


[Modified by gkull, 8:41 AM 3/3/2004]

 

I usually dont come to this fside of the forum but this is unreal. A monster 9.5L Big Block for a street/track car? That is insane, how can you guys ever hook up with that much power? Do you have a solid axel and slicks or something? :confused:

side exit headers with 2 1/8” primaries, 4” collectors and JCL baffles for mufflers. :eek: :eek:

 

HI You need a minimum of dart 355 or brodix m2 xtra or even m2 -4xtra heads with that many cubes.All the cam in the world isnt going to help that peanut head on that big an engine.It will feel the same at 2000 as 6000 like a steady freight train.With the larger heads you will still have locomotive torque but hp with rpm will be in the 100 plus range per 1000 rpm as you go up.Then it will feel like a turbo sensation.The other advantage with bigger heads is you dont need as much lift to flow the same or better than with smaller heads and bigger cams.Much less strain on your valvetrain. Put more duration in it and dont go so high on lift ,not that the cam your looking at is that big. I would put more duration in it.My engine combo is here http://temp.corvetteforum.net/c3/hotrod12

 

632CID :eek: :eek: + a 14x71 blower :eek: :eek: Running 7's :crazy:

How much power do you estimate you have there? How hard does it pin you into the seat when you launch? Is that blower running 1:1 or is it overdriven or underdriven?? PLus do they displace that much per revolution or for every two revolutions?

 

HI I have hit 1600 hp and 1200lbs of torque.The supercharger displaces 526 cu in for every crank revolution when set at 1to1. Mine is 20 percent overdrive for race ,and 5 over for cruising.Accelaration is instant with a 1.06 60 ft and 0 to 100mph in 2.1 sec,redline is 7400rpm with either a 4.10 or 3.70 gear eighth or quarter mile .After the eighth your just there for the ride.This car took 14 years to get here.Not an overnite project,I kept wanting to go to the next level.Now I want a Pro mod,it never ends does it. mike

 

Mike your car is awesome, please don't tell me it never ends. I was hoping my little 572 would finally satisfy my need for speed.

Welcome to the forum, your obvious expertise will be greatly appreciated.

 

Hi John Thanks Im sure your 572 Will be awesome. That was my last engine 4.5 x4.5 It ran 8.0s in this same car at 3000lb s. My car is maxed out . I cant make it any lighter and the car wants to lift at the big end.I have added a wing and chutes with now stainless pipes on the outside.Those pics are a couple of years old but will be putting new ones up soon as weather permits. I have some full drag race video s I need to learn how to get them posted.What some dont know is every time you get a bigger engine it tames down everything else.It is actually easier to launch a big motor than a smaller one as long as you got the right set up. regards mike