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Cylinder Heads - What Matters Most?

 
Old 06-13-2019, 12:41 AM
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Darth i c to much....
The Darin CID stuff was the new LT1 still 5k
https://www.performancetrucks.net/fo...nifold-550882/

It was Chris Frank with the 5k CID heads
https://frankensteined.net/shop/cid-...-solid-roller/
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Old 06-13-2019, 12:43 AM
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We have definitely learned that people have varying opinions on which heads are best for 400+ci 7,000+rpm applications. And have been shown beautiful examples of both LS3 and LS7 heads.

But that brings us back to the original question of what matters most in your choice of heads... intentions for usage, being the agreed upon number one.

In my theoretical example, I actually found that the smallest heads on the market were perfectly adequate for the engine I want to build. And, CSA played a large part in figuring that out.

I have learned quite a bit from this particular discussion, but I definitely believe that any differences in opinion should be settled on the track, not the internet.
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Old 06-13-2019, 12:53 AM
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Here's one i learned....no matter the port size cam it for the intended rpm...GM ports get larger by the yr. More air and fuel in makes more hp = Area. Look at the LT1 port size from the factory...300+ with minor porting. A good intake makes everything better....we can get more .....in.

John's heads are a good example 302 cc = + 3.1 mcsa with a 427...yet has good port speed and cylinder filling isn't a problem with his intake choice.

Last edited by Smokey B; 06-13-2019 at 01:14 AM.
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Old 06-13-2019, 01:29 AM
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Originally Posted by Smokey B View Post
Here's one i learned....no matter the port size cam it for the intended rpm...GM ports get larger by the yr. More air and fuel in makes more hp = Area. Look at the LT1 port size from the factory...300+ with minor porting. A good intake makes everything better....we can get more .....in.

John's heads are a good example 302 cc = + 3.1 mcsa with a 427...yet has good port speed and cylinder filling isn't a problem with his intake choice.
Depends on combo smokey.
You can make almost anything work with the right parts.
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Old 06-13-2019, 07:58 AM
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B, the funniest thing.....Ls3 heads are a good example. Cam and intake choice makes or breaks this head, unless you've got CID.
Kinda like that..got milk?

Got CID?
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Old 06-13-2019, 08:03 AM
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Originally Posted by Smokey B View Post
B, the funniest thing.....Ls3 heads are a good example. Cam and intake choice makes or breaks this head, unless you've got CID.
Kinda like that..got milk?

Got CID?
Indeed
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Old 06-13-2019, 08:16 AM
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Originally Posted by Smokey B View Post
B, the funniest thing.....Ls3 heads are a good example. Cam and intake choice makes or breaks this head, unless you've got CID.
Kinda like that..got milk?

Got CID?
But if you don't want or need excessive displacement, then the LS3 heads probably won't be the proper head. Not everyone sets out to build a 400+ci engine. Not everyone is chasing the rpms to make use of the rectangle ports, or single plane intakes.

Displacement and rpms are not the answers for every build. Plenty of people will achieve exactly what they are looking for with ported Cathedrals and plastic intakes.

It seems that a lot of the back and forth in this thread is arguing about these gnarly all-out options that very few people are actually building towards. There have been some beautiful heads brought up in here, but it is not worth arguing about because only 5-10% of the people building cars are looking for that level of commitment. And that doesn't mean that everyone else is in any way wrong. To each their own.

It really comes down to what your intentions are, and what your budget allows. And there is really no reason to argue about anything, since everyone has a different preferences and budgets.
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Old 06-13-2019, 08:29 AM
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That's right.
Everyone has different preferences and goals.
You need to be a bit more diverse smokey.
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Old 06-13-2019, 09:47 AM
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Nope...avg HP, I have typical cars. Also I'd just use a shorter cam and fill the runner with more lift. With a good intake choice. 540 + with a stock ls3 and ported heads. Luv me some SR cam
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Old 06-13-2019, 09:54 AM
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No one's arguing.
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Old 06-13-2019, 09:59 AM
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Originally Posted by Smokey B View Post
No one's arguing.
Right. Because you don't listen anyway.
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Old 06-13-2019, 01:51 PM
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Originally Posted by Smokey B View Post
Nope...avg HP, I have typical cars. Also I'd just use a shorter cam and fill the runner with more lift. With a good intake choice. 540 + with a stock ls3 and ported heads. Luv me some SR cam
I proved with stock cube LS3, 560 RWHP was repeatable with no special parts and off the shelf H/C/I. The ported LS3 heads made less gain then the proper intake choice IMO...... A lot to be said in a combination. You slap brodix heads on my car with a stock LS3 intake and you would be lucky to crest 500.

Last edited by lazerlemonta; 06-13-2019 at 02:13 PM.
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Old 06-13-2019, 04:13 PM
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Originally Posted by lazerlemonta View Post
A lot to be said in a combination. You slap brodix heads on my car with a stock LS3 intake and you would be lucky to crest 500.
I quote your build a lot. very true statement here.
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Old 06-13-2019, 04:26 PM
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Originally Posted by DavidBoren View Post
But that brings us back to the original question of what matters most in your choice of heads... intentions for usage, being the agreed upon number one.

In my theoretical example, I actually found that the smallest heads on the market were perfectly adequate for the engine I want to build. And, CSA played a large part in figuring that out.
This is where I've ended up also. The smallest CSA with the most flow. All things being equal, the best port shape, valve shrouding, everything will come into play with this being the sum total. The smallest port with the best flow has the best shape, essentially.

I feel like if I am stuck between options such as a 400 cfm at 260cc or a 400 cfm at 290cc, to me it is very obvious the 260cc is the better bet. And I know cc does not necessarily indicate CSA, but at least with inline heads, the runner lengths are going to be close enough to the same for a potential buyer to deduce that the larger runner has more area. The only exception I would think is if one is pursuing very high RPM, the need for more CSA takes over the port velocity at slower engine speeds.
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Old 06-13-2019, 04:36 PM
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If you're looking for power and extended rpm some of these intakes are worth more than the heads.

And if you're camming it and not looking to extend the rpm range then you likely did it wrong.
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Old 06-13-2019, 05:01 PM
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Originally Posted by JakeFusion View Post
LQ block has terrible windage.

One reason I've looked at LSX vs a 5.3 with a Darton Sleeve. LSX is built like the LS7...
They arent holding the tsp TT 5th gen car back or Agent Orange so id imagine more attention somewhere else would be better spent.
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Old 06-13-2019, 05:05 PM
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Lets compare apples to apples Smokey. If you wanna talk big blocks etc go to that section. This is LS1tech for good reason.
FED is a great place also and their heads are immaculate and make power as well.

You didnt prove me wrong though just decided to argue about something else.
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Old 06-13-2019, 05:06 PM
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The entire debate boils down to usage. Street or race. Intended application. Two different average hp categories. You can only get away with so much on the street, meaning noise, RPM, speed, safety (gasp) etc. Driveability is far too much of a debate concerning what one deems acceptable, so that’s not what I’m talking about concerning street usage.
This discussion always drifts over to the race category, as it always does and probably always will. I live in NASCAR country, and the local popo here might allow us a little more room as far as foolishness goes, but even still, street is street, and laws are laws. 7k is doable in short bursts at times. You talk 8k on the street, and you will be heard for blocks, I’m talking 3/4 of a mile. Hard to hide from cops with a vehicle like that.
Race track on other hand, is a totally different build, cam spec, induction setup and chassis setup. No matter what you believe, those guys on Street Outlaws are not driving street cars. The show is staged and nothing about street racing is actually happening. I smell a new debate coming on shortly...
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Old 06-13-2019, 05:24 PM
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Noticed smokeys grammar & punctuation is on another level now. Nice! Still, as he stated himself he doesn't think he should be more diverse. He must think he is right all the time, with any car, in any situation, anywhere, no matter what. To another statement, who do you think is really LS1Tech limited? Everyone except you? Just so you know smokey.. think that there are many people, you have probably never heard of, that have been faster than you.

Carry on.
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Old 06-13-2019, 05:46 PM
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Originally Posted by Darth_V8r View Post
This is where I've ended up also. The smallest CSA with the most flow. All things being equal, the best port shape, valve shrouding, everything will come into play with this being the sum total. The smallest port with the best flow has the best shape, essentially.

I feel like if I am stuck between options such as a 400 cfm at 260cc or a 400 cfm at 290cc, to me it is very obvious the 260cc is the better bet. And I know cc does not necessarily indicate CSA, but at least with inline heads, the runner lengths are going to be close enough to the same for a potential buyer to deduce that the larger runner has more area. The only exception I would think is if one is pursuing very high RPM, the need for more CSA takes over the port velocity at slower engine speeds.
Originally Posted by HioSSilver View Post
If you're looking for power and extended rpm some of these intakes are worth more than the heads.

And if you're camming it and not looking to extend the rpm range then you likely did it wrong.
I agree that you should have the valvetrain and intake and enough cam to get you there. But there is a point of diminishing returns. And I don't believe the answer is to always get bigger heads. I would way rather see more sensible goals.

If you have essentially maxed out the heads' CSA, then there really isn't any camming it to extend the rpm range. With any more rpm the port velocity goes past .6 mach, and starts working against you, right?

In my theoretical 373ci example 7,200rpms is all you get. Having the intake to get you there is important, yes. Having the cam to get you there is important. But there is nothing to chase after that point... the piston speed and displacement are using everything the heads have to offer before the airspeed becomes unusable according to the Wallace Racing Calculators.

I really like Darth's cfm/cc ratio efficiency scale, as I am a big fan of efficiency. Coefficient of discharge and exhaust ratio are other things that I highly value, even more so than chasing rpms. Obviously, everyone has different opinions on what they value most.

Smokey likes the biggest intake valve he can get, because it comes with a high CSA, which allows for more rpms... coefficient of discharge and exhaust ratio be damned. I'm sure that theory works for some, it's just not my cup of tea.
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