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Old 03-07-2009, 07:15 PM
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dart heads vs vortec heads

this motor will be run on the street and track occassionaly.But i'm up in the air on what to do as far as heads. I know that i at lest want 2.02 and 1.60 and around a 64cc chamber.I have dish piston right now in the motor and plan to keep it that way for the pump gas.I plan to stay with cast iron heads.I'm in need of some real actual advice here.Proven testimony's would be good. Thanks for any good advice or guidance.

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Old 03-07-2009, 09:33 PM
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another one

to get good answers you have to give good information. you should think about listing information about your motor if you are going to post. what size engine,what size cam,what intake manifold,what is your compression ratio all of this is required information to answer a question to its fullest answer.
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Old 03-07-2009, 09:46 PM
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I would have to say Dart if you an afford either... Darts are a performance aftermarket head and vortecs a performance stock head. Big difference.
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Old 03-07-2009, 11:15 PM
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Compare airflow head to head. Don't be swayed by fantastic flow figures at 0.600", 0.650" and 0.700" valve lift. This is not the type of cam you would use in a street motor that will see occasional drag strip duty. Concentrate on the airflow achieved with lifts 0.100" through 0.500" where your valves will spend the bulk of their time. Here, for instance is the flow, intake and exhaust, of the L31 Vortec GM head, part number 12558060, casting number 12558062....
0.100 70 48
0.200 139 101
0.300 190 129
0.400 227 140
0.500 239 147
These production heads will outflow any other production Chevy small block head and will also outflow many aftermarket heads.
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Old 03-08-2009, 07:19 AM
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Quote:
Originally Posted by techinspector1
Compare airflow head to head. Don't be swayed by fantastic flow figures at 0.600", 0.650" and 0.700" valve lift. This is not the type of cam you would use in a street motor that will see occasional drag strip duty. Concentrate on the airflow achieved with lifts 0.100" through 0.500" where your valves will spend the bulk of their time. Here, for instance is the flow, intake and exhaust, of the L31 Vortec GM head, part number 12558060, casting number 12558062....
0.100 70 48
0.200 139 101
0.300 190 129
0.400 227 140
0.500 239 147
These production heads will outflow any other production Chevy small block head and will also outflow many aftermarket heads.
Excellent advice. I would not get all tied up in airflow either. It is not the single determining factor of how a head will perform, only part of the story. Engineers, engine builders, and people who REALLY know heads will support that.
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Old 03-08-2009, 08:38 AM
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Darts are perhaps a more durable head, which means a lot in some cases. Vortecs are perhaps a more efficent head, which can also mean a lot in some cases. Being designed as a stock head they have really good flow Vortecs, in a strip only viehicle I'd go with the Darts because they can be ported to flow really well and have better more durable castings.

Why you NEED those valve sizes is beyond me though... How did you come to that conclusion? Valve sizes have a lot less to do with power than a LOT of other head aspects like even plug location, which very few people think to notice.
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Old 03-08-2009, 01:51 PM
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Quote:
Originally Posted by Jsup
Excellent advice. I would not get all tied up in airflow either. It is not the single determining factor of how a head will perform, only part of the story. Engineers, engine builders, and people who REALLY know heads will support that.
Jsup, I know we've been over this before and I can appreciate your remarks, but I contend that airflow is the main value that a consumer has available to him in determination of which head to buy. Ideally of course, each head purchaser would have access to a flow bench and would make an arrangement with each of the manufacturers to send him a head to flow. That is the only way a person is going to be absolutely certain that he's going to get the head that flows the best for his application, to flow all heads on ONE flow bench. Otherwise, we just have to trust the manufacturer and his flow figures to make the purchase.

All of us have seen evidence that different manufacturers use different pipe bore sizes to flow their heads, so it's never going to be an apples to apples comparison using the published figures. I noted one manufacturer uses a 4.200" pipe to flow SBC heads. Now tell me, when's the last time you saw a production block with a 4.200" bore? I'd venture to say that 95% of the SBC's out there have a 4.030" or 4.060" bore. They also have no standard for humidity, temperature or the pressure drop used. Of course, the standard we all of us hot rodders use is 28" of water, but we can't be sure that's the drop used by the manufacturer of the heads we're considering. We also don't know if the flow was wet or dry. What flow bench did they use? What valve sizes did they use for testing? Was it the same size they use in the production head you're considering buying? What about the valve/seat angles. One angle, three angle, five angle, 40-eleven-umpteen angle? Were the valve stems full size tip to head or was the valve stem turned to a smaller diameter in the port area for testing? Also, as you noted in an earlier thread, static compression ratio plays into the mix, but not all manufacturers are going to publish that. They may not even tell you if you call and inquire.

Again, all we can do without flowing the heads ourselves is to trust the published figures from the manufacturer after we have satisfied ourselves as to the chamber size and shape and as noted by ap72, the plug location.

Last edited by techinspector1; 03-08-2009 at 02:36 PM.
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Old 03-08-2009, 03:12 PM
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Quote:
Originally Posted by techinspector1
Jsup, I know we've been over this before and I can appreciate your remarks, but I contend that airflow is the main value that a consumer has available to him in determination of which head to buy. .
I agree... unfortunately. Buying heads on flow alone is a tough gamble, but that's what they shove down our throats. Kinda like buying a car based on its advertised HP. There's so much more involved.

When I'm buying heads I make a little graph of the flow to get a visual idea of the flow "under the curve." Then I visualize a reasonable lift and look only at those sections of the curve. More average flow is better than more peak flow. That's one of the reasons I keep coming back to Vortecs. They make as much (if not more) flow than many aftermarket heads and do it with smaller valves and ports; PLUS, most of their flow occurs at lower lifts.

OP, don't focus on valve size, focus on quality of flow, average flow, and mid/low lift flow. Pick a flow that will support your HP goals, then find a head that provides that flow using the smallest possible runner. The nice thing about Vortecs is that they make all their good numbers using a 170cc port and small valves. They do really well with bigger valves and a little bowl work, so you could easily be ahead of the game on flow compared to some of Dart's offerings while still having the same valve size, smaller ports, and much cheaper investment if you're careful.

But most importantly, look at published dyno figures and timeslips. Just like we always say, "we don't race dynos," I also say "head flow figures don't prove it will make power." Assuming a car will make a certain ET based on the engine dyno isn't accurate since there are a million chassis factors that are involved. Assuming head flow will make a certain power level is equally inaccurate.

Last edited by curtis73; 03-08-2009 at 03:18 PM.
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Old 03-08-2009, 05:33 PM
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Quote:
Originally Posted by techinspector1
Compare airflow head to head. Don't be swayed by fantastic flow figures at 0.600", 0.650" and 0.700" valve lift. This is not the type of cam you would use in a street motor that will see occasional drag strip duty. Concentrate on the airflow achieved with lifts 0.100" through 0.500" where your valves will spend the bulk of their time. Here, for instance is the flow, intake and exhaust, of the L31 Vortec GM head, part number 12558060, casting number 12558062....
0.100 70 48
0.200 139 101
0.300 190 129
0.400 227 140
0.500 239 147
These production heads will outflow any other production Chevy small block head and will also outflow many aftermarket heads.

Where do these flow numbers come from ? Most of the results I have seen when tested at 28" of water show the Vortec heads flowing at 200-210 cfm on the intake.
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Old 03-08-2009, 05:46 PM
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CHP, srweiss, and several other sources confirm the 239cfm. Where did you hear 210cfm? That's no better than 70s smog heads?
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Old 03-08-2009, 05:49 PM
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from the testimonials and research I have come across the vortecs are great for street and mild racing. If you want to rev pass 5000-5500 or have more than .470 lift go with the darts.
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Old 03-08-2009, 08:10 PM
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Not that is might help much but World Product Sportsman 2 heads and as well the RHS Pro action heads are also some options to choose as well. The World, Dart, and RHS heads are made of a higher density cast iron and are a little better to work with wise then Vortec but for money wise and value with a little work Vortec's can't be beat but I went after market heads for my next build just because of the cost factor to use a roller cam setup.
Eric
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Old 03-08-2009, 11:09 PM
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Quote:
Originally Posted by RustoRod
Where do these flow numbers come from ? Most of the results I have seen when tested at 28" of water show the Vortec heads flowing at 200-210 cfm on the intake.
Came out of my Scoggin-Dickey Chevrolet catalog. I have to assume the numbers are published by GM. Like curtis, I have seen these numbers in several places.
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Old 03-08-2009, 11:11 PM
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Quote:
Originally Posted by techinspector1
Jsup, I know we've been over this before and I can appreciate your remarks, but I contend that airflow is the main value that a consumer has available to him in determination of which head to buy. Ideally of course, each head purchaser would have access to a flow bench and would make an arrangement with each of the manufacturers to send him a head to flow. That is the only way a person is going to be absolutely certain that he's going to get the head that flows the best for his application, to flow all heads on ONE flow bench. Otherwise, we just have to trust the manufacturer and his flow figures to make the purchase.

All of us have seen evidence that different manufacturers use different pipe bore sizes to flow their heads, so it's never going to be an apples to apples comparison using the published figures. I noted one manufacturer uses a 4.200" pipe to flow SBC heads. Now tell me, when's the last time you saw a production block with a 4.200" bore? I'd venture to say that 95% of the SBC's out there have a 4.030" or 4.060" bore. They also have no standard for humidity, temperature or the pressure drop used. Of course, the standard we all of us hot rodders use is 28" of water, but we can't be sure that's the drop used by the manufacturer of the heads we're considering. We also don't know if the flow was wet or dry. What flow bench did they use? What valve sizes did they use for testing? Was it the same size they use in the production head you're considering buying? What about the valve/seat angles. One angle, three angle, five angle, 40-eleven-umpteen angle? Were the valve stems full size tip to head or was the valve stem turned to a smaller diameter in the port area for testing? Also, as you noted in an earlier thread, static compression ratio plays into the mix, but not all manufacturers are going to publish that. They may not even tell you if you call and inquire.

Again, all we can do without flowing the heads ourselves is to trust the published figures from the manufacturer after we have satisfied ourselves as to the chamber size and shape and as noted by ap72, the plug location.
While I do agree as an industry "standard" it's out there. However, we'll have to agree to disagree on its value. Dry flow numbers only tell part of the story and is not in and of itself a criteria to pick a head. They are inaccurate many times as benches just blocks apart can vary by as many as 15 CFM and are effected by barometric pressure and such. Additionally, ADVERTISED flow numbers come from a manufacturer and well, put the best spin on things.

Go look at RFD, they know heads inside out and I will defer to their comments:
http://www.raceflowdevelopment.com/RFD-heads.htm


I don't think there's a whole lot of difference in our position. I will note however BRODIX does say right on their website that compression ratio does matter, and they recommend heads based on that.

http://brodix.com/heads/compression.html

Every manufacturer has deviations on chamber sizes from time to time as well as port volume and flow.
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Old 03-08-2009, 11:18 PM
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Quote:
Originally Posted by curtis73
I agree... unfortunately. Buying heads on flow alone is a tough gamble, but that's what they shove down our throats. Kinda like buying a car based on its advertised HP. There's so much more involved.

When I'm buying heads I make a little graph of the flow to get a visual idea of the flow "under the curve." Then I visualize a reasonable lift and look only at those sections of the curve. More average flow is better than more peak flow. That's one of the reasons I keep coming back to Vortecs. They make as much (if not more) flow than many aftermarket heads and do it with smaller valves and ports; PLUS, most of their flow occurs at lower lifts.

OP, don't focus on valve size, focus on quality of flow, average flow, and mid/low lift flow. Pick a flow that will support your HP goals, then find a head that provides that flow using the smallest possible runner. The nice thing about Vortecs is that they make all their good numbers using a 170cc port and small valves. They do really well with bigger valves and a little bowl work, so you could easily be ahead of the game on flow compared to some of Dart's offerings while still having the same valve size, smaller ports, and much cheaper investment if you're careful.

But most importantly, look at published dyno figures and timeslips. Just like we always say, "we don't race dynos," I also say "head flow figures don't prove it will make power." Assuming a car will make a certain ET based on the engine dyno isn't accurate since there are a million chassis factors that are involved. Assuming head flow will make a certain power level is equally inaccurate.
I will defer to a friend of mine who posted this on another forum, he posts here so may see it:

Quote:
Originally Posted by guru View Post
Hey guys,
I have been pouring over the dyno mania article on the 2007 engine masters challenge and I have come up with the following tale of 2 327s.

1 is a ported stock casting head with a mild solid cam, and the other is an AFR headed 327 with a larger solid cam. I dont really care about the variation in camshafts because different heads should have different cams. Different heads have different strengths and weaknesses. In any case lets continue.



As we can see the ported stock head combo was dramatically superior to the AFR head under 5000 rpm and at a noticable disadvantage above 5000rpm.

I will let you draw your own conclusions. Mine are as follows:

The AFR headed 327 is a really good high RPM combo and would tear it up if it was never forced to compete below 5000rpm. Probably given our M21s close ratio probably wouldnt spend to much time below 5000 rpm anyway down a 1/4 mile track. If I were a drag racer it would be my engine of choice. The other 327 would probably be a better street engine, and maybe better in other forms of racing like road racing or autocrossing. The ported stockers also scored better on the 2007 Jegs engine masters challenge.

So the major lesson to take away - the best combo is the one that meets your intended purpose. Before you pick up a catalog and buy the most expensive shiniest part with all the right brand names, and be lauded by the interweb fanbois ask yourself is it right for your intended application? Who knows maybe some ported stockers IS right for what you are doing.

An AFR 195 CNC ported head was in the top 5 on a 302, and made a ridiculous amount of power and torque. The winners used some raised runner racer pro heads from australia.

Well matched components are well matched components no matter what. But well matched to what?
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