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Old 12-29-2012, 11:52 AM
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Circle Track 406 top end questions

New rules for our track came out and have opened up our rules greatly. We run a 3/8 mile ASPHALT oval street stock weighing 3000 lb, turning 6800-7000 every night. SBC 406...the question I have is on the top end. I have thought about running the vortec bowtie heads and edelbrock 2814 intake, but without shaving the heads alot we would lose alot of compression. Or, I considered running our current sportsman II heads with large dome pistons to bump compression up closer to 14.5-1 and high rise intake for normal heads. Is the vortec bowtie set up worth losing the compression to or is it smarter to go for more compression? Any questions or comments just let me know

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Old 12-29-2012, 01:10 PM
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what size chambers are you looking for? The large port Vortecs can take some angle milling and you may be worried over nothing. For a cast iron head they're damn hard to beat.
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Old 12-29-2012, 11:00 PM
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Well I guess i'm not sure. What size should I be going for? I know they come stock at 66cc correct? The plan was not to shave the vortec bowties very much if that is that route I chose. I guess what I am trying to ask is, for my application, is it smarter to go with the dome pistons and sportsman II heads for the shear purpose of more compression, or is it smarter to go for the better flowing vortec bowties and flat top pistons with less compression?
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Old 12-30-2012, 12:29 AM
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clarky06 what were the rule changes? from what to what? we have a few good roundie rounders here.Is there also a displacement rule?
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Old 12-30-2012, 12:55 AM
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Is this information correct about the 206 cc vortec head?

Large-Port Vortec Cylinder Head Flow
INTAKE
EXHAUST
Lift Volume Lift Volume
0.200 128.6 0.200 100.8
0.300 188.4 0.300 138.6
0.400 234.8 0.400 154.4
0.500 257.2 0.500 152.5
0.600 263.2 0.600 163.8
0.700 269.1 0.700 167.0
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Old 12-30-2012, 02:32 AM
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Quote:
Originally Posted by clarky06 View Post
Well I guess i'm not sure. What size should I be going for? I know they come stock at 66cc correct? The plan was not to shave the vortec bowties very much if that is that route I chose. I guess what I am trying to ask is, for my application, is it smarter to go with the dome pistons and sportsman II heads for the shear purpose of more compression, or is it smarter to go for the better flowing vortec bowties and flat top pistons with less compression?
I'm guessing race gas is no problem.

A lot depends on the cam. More flow trumps more compression as long as the CR is within reason for the cam. If you NEED the compression, I would mill the Bow Tie Vortec heads to get the chamber volume I needed, and I would run either FT or as small a dome as possible.

I was told it's possible to flat mill them about 0.090" before getting into the intake seat. They can go down to 48cc, but it takes welding the plug cooling holes and angle milling. I'd rather use a FT piston and a smaller chamber than a bigger chamber and a dome.

But if the cam can work as intended w/less CR, there's no great advantage in running more CR.
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Old 12-30-2012, 08:18 AM
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Originally Posted by vinniekq2 View Post
clarky06 what were the rule changes? from what to what? we have a few good roundie rounders here.Is there also a displacement rule?
We can now run ANY steal head, headers, any cast iron or aluminum intake, but if we run an aluminum intake or headers it is a 50 lb penalty. We can run roller cams, but can take off 50 lbs if we don't run one. We are still on the Holley 4412 though, it does not state it must be stock though. No displacement rule. Last year we were on stock intake and exhaust manifolds.

Cobalt- No we can any racing gasoline. I guess I would need to speak to the cam grinder and see what he thinks now.
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Old 12-30-2012, 09:53 AM
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I would run the headers and aluminum intake.an ASA type cam. That carb is going to take a lot of effort.I think 670 CFM or more is possible.\You will need to have the carb custom built( I bet that has been done already)
I think my math (after carb flow testing) would be with a short stroke 400.A detuned high 650 plus horse power engine?is that enough?
The budget can be destroyed by high tech engines that have to use certain parts,,,example may cost $1200.oo to build a 670 CFM 2 bbl where you could buy a 750 4 bbl for $500
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Old 12-30-2012, 12:27 PM
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Look at the Enginequest cast iron heads with 50cc chambers. On engine like yours, I use 12:1 compression to allow the use of only $8/gallon fuel. I would probably go for the flat tappet cam if your car can make use of the 50lb break. If you have to run the car heavy to get the correct percentages, then go roller cam.
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Old 12-30-2012, 12:51 PM
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Quote:
Originally Posted by clarky06 View Post
New rules for our track came out and have opened up our rules greatly. We run a 3/8 mile ASPHALT oval street stock weighing 3000 lb, turning 6800-7000 every night. SBC 406...the question I have is on the top end. I have thought about running the vortec bowtie heads and edelbrock 2814 intake, but without shaving the heads alot we would lose alot of compression. Or, I considered running our current sportsman II heads with large dome pistons to bump compression up closer to 14.5-1 and high rise intake for normal heads. Is the vortec bowtie set up worth losing the compression to or is it smarter to go for more compression? Any questions or comments just let me know

Thanks
Can you run 18 degree heads. If so better take a look. They make so big power over all 23 degree heads. Chances are everyone has upgraded to these haeds if possible by rules. They are the step before sb2 engine.

The new bowtie head is the best 23 degree head gm has ever made for there sbc. These will work well and make lots of power also the gm ones are very well built. Brodix and dart also have max effort 23 degree heads. I wouldnt go any less unless more tq is needed at your track.

What is everyone else running? Its always good to offer help and make friends so you can find out what they are building in the off season.

Hope this helps.
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Old 12-30-2012, 03:44 PM
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Quote:
Originally Posted by lmsport View Post
Look at the Enginequest cast iron heads with 50cc chambers. On engine like yours, I use 12:1 compression to allow the use of only $8/gallon fuel. I would probably go for the flat tappet cam if your car can make use of the 50lb break. If you have to run the car heavy to get the correct percentages, then go roller cam.
Find some Enginequest heads, part number CC220AA. They're 50cc chambers, 220 intake runner, and will flow up to about 290cfm without porting. Lane Automotive has them for about $375 each for the bare casting.
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Old 12-30-2012, 06:32 PM
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290 cfm intake side,what about exhaust side?re imsport
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