24v head vs 12v head

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Diesel92

New member
Say you take both heads and fully port them both sides cut plenum of ec. Which would flow more which would take heat cycles better be more stout handle more rpm? Loved to see some flow charts on both ported heads too. Yes I know there is a lot on it but this is some of the info I had a hard time finding a straight answer for. So any info would be awesome thanks anyone who chimes in
 
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iirc, stock for stock the 24v head flows a tad more. Both maxxed out, the 12v head outflows the 24v by a fairly large margin
 
Just do some searching.

A lot of pullers like 12V heads for less moving parts. It's simpler and cheaper.

A 24V head always has more flow potential than a 12V though. And the valves are smaller which means less load per valve and less stress because of it.

If you're not convinced, draw a circle, then draw the two largest circles inside of it that you can.
Draw another circle and draw the four largest circles you can in it.
You'll always cover more area with the four circles, which means you have more area to move air, which means less restriction.


DirtyMaxx03 said:
iirc, stock for stock the 24v head flows a tad more. Both maxxed out, the 12v head outflows the 24v by a fairly large margin
Click to expand...

A CR head flows a Lot more than a 12V head stock vs stock.
I don't think your facts are right on the second bit either.
 
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I have been but I don't have much time and most stuff I have found seem to be opinion I was just looking for someone who has experience with both. But thanks for the info makes sense I knew that the 24v would flow more but I wasn't sure if it could be ported has heavily as a 12v?
 
CorneliusRox said:
Just do some searching.
Click to expand...

Diesel92 said:
I have been but I don't have much time
Click to expand...

Sorry, just rereading. I didn't mean that in a dick way.





I suppose that's true that the injectors are in the center now, so maybe you could port more in that area, but maybe you can post some flow number comparisons? I would be surprised if a fully ported 12v head can flow more than a fully ported 24v head (not including custom cast 12v heads).
 
CorneliusRox said:
Just do some searching.

A lot of pullers like 12V heads for less moving parts. It's simpler and cheaper.

A 24V head always has more flow potential than a 12V though. And the valves are smaller which means less load per valve and less stress because of it.

If you're not convinced, draw a circle, then draw the two largest circles inside of it that you can.
Draw another circle and draw the four largest circles you can in it.
You'll always cover more area with the four circles, which means you have more area to move air, which means less restriction.




A CR head flows a Lot more than a 12V head stock vs stock.
I don't think your facts are right on the second bit either.
Click to expand...


That's the reason everyone used a 24 valve head for a mod truck right ? O wait......
 
CorneliusRox said:
Sorry, just rereading. I didn't mean that in a dick way.











I suppose that's true that the injectors are in the center now, so maybe you could port more in that area, but maybe you can post some flow number comparisons? I would be surprised if a fully ported 12v head can flow more than a fully ported 24v head (not including custom cast 12v heads).
Click to expand...


So you don't actually know but your giving advise ?
 
4v 1.340 valves=5.64 sq in of valve.
2v 1.87/1.75 valves=5.15 sq in of valve.

.5 total sq inch difference, if you look at the intake only, they are nearly identical.

Deciding which head is better based off valve size when they're that close is a bit, well, wrong.
 
97rada said:
That's the reason everyone used a 24 valve head for a mod truck right ? O wait......
Click to expand...

Calm down internet tough guy.

97rada said:
So you don't actually know but your giving advise ?
Click to expand...

If you actual read, you'll see that I was saying sorry for when I reread my post and I thought it sounded dick-ish. That's not how I meant it to sound.

9724VF350 said:
4v 1.340 valves=5.64 sq in of valve.
2v 1.87/1.75 valves=5.15 sq in of valve.

.5 total sq inch difference, if you look at the intake only, they are nearly identical.

Deciding which head is better based off valve size when they're that close is a bit, well, wrong.
Click to expand...

That's stock vs stock.
If you take a circle (lets say 100mm diameter) and fit the biggest circles you can in it for a 2 valve setup and a 4 valve setup, you get a diameter of 25mm for the 2 valve and 22.71mm on the 4 valve.
Cross sectional area comes out to:
2 valve = 1347.4 in^2
4 valve = 981.7 in^2

That give the 24v a 37% increase max vs max.

Capture_zpsnw68f9l2.jpg
 
CorneliusRox said:
Calm down internet tough guy.







If you actual read, you'll see that I was saying sorry for when I reread my post and I thought it sounded dick-ish. That's not how I meant it to sound.







That's stock vs stock.

If you take a circle (lets say 100mm diameter) and fit the biggest circles you can in it for a 2 valve setup and a 4 valve setup, you get a diameter of 25mm for the 2 valve and 22.71mm on the 4 valve.

Cross sectional area comes out to:

2 valve = 1347.4 in^2

4 valve = 981.7 in^2



That give the 24v a 37% increase max vs max.



Capture_zpsnw68f9l2.jpg
Click to expand...


Don't worry I sounded like an ass without intending to do so
 
No, it's not stock. Those are the biggest valves you can put in stock bores with stock valve locations.

You're drawing has some flaws. You put the valves wherever the biggest valves fit, you made the 2v valves the same diameter, you made no allowances for clearance and seats.

These are factors that come into play when you put the paper down and start making things out of metal that need to last more than 30 seconds.
 
9724VF350 said:
No, it's not stock. Those are the biggest valves you can put in stock bores with stock valve locations.

You're drawing has some flaws. You put the valves wherever the biggest valves fit, you made the 2v valves the same diameter, you made no allowances for clearance and seats.

These are factors that come into play when you put the paper down and start making things out of metal that need to last more than 30 seconds.
Click to expand...

Ah. Good call. I didn't think about that!
I know valves aren't the same diameter, but for the ease of a quick calculation, I thought I'd run with that.

I would still think that you could count the perimeter and the lift to find a difference though. That's realistically the area you're worried about.
 
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Is the amount of air a valve will allow past it really the limiting factor on these heads? I thought the real limiting factor was how thin the water jackets can get when porting.
 
I know valve wise they are close but I was wondering on flow rate volume of a fully quality ported 12 and 24 v head which is superior better heat transfer etc. Are the walls thinner then the other one weaker ?
 
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How much pressure are they tested at? To a point, more pressure would flow more air. Does either setup favor higher pressure more?
 
I've read that even though the 12 valve can flow more. For street trucks, the 24 valve has better manners and is more responsive. Is that accurate?
 
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