KA head, Napz Z head for Z L6

[agentalpha]

Hey guys.

 

Have any of you seen the vids of the twin cam KA24de heads made into a head for a 2.8L L6 on Youtube? I think it's a little over complicated. It also seemed rather slow for all the work/time he invested, considering it was twin turbo.

 

My questions are:

How complicated do you think it would be to get 2-3 single cam KA heads to work on the Z L6?

 

Would it be possible to use a stock Z cam with a few modded NAPS Z heads?

I can't remember the spacing/placement of the rocker arms on M 720 2.4L, in comparison to say a N42.

 

I KNOW it wouldn't be anywhere even close to a bolt on affair, and lots of fabbing would need to be done. I also know anything is possible with enough time and money, but I am looking for a much better breathing alternative than any of the non-crossflow factory heads(N42, P90).

 

Oh, yes. This would be geared towards a N/A application.

 

Thought? Opinions? Ideas?

[Skib]

The KA head made into a DOHC is 1 fast Z's L31ett Fairlady 2+2

 

http://forums.hybridz.org/showthread.php?t=100001

[280zForce]

He did make 489 whp on 17 psi with maxing out stock t3 turbos and using stock KA heads & cams. He now has custom ground cams, ported head work, and bigger turbos, can rev to 8500+ rpm easy and has a shit load more power in waiting, he's aiming for 750+ whp.

 

Now most Z guys make around 270-300 whp on a stock t3 single turbo with 15 psi.

 

Good enough point in his build?

[agentalpha]

Sure.

Hopefully it lasts as well.

I wouldn't think the L6 blocks would handle more than 450 HP or so.

[280zForce]

Sure.

Hopefully it lasts as well.

I wouldn't think the L6 blocks would handle more than 450 HP or so.

There's a few of us over 450 whp... the blocks will handle the power just fine. Heck you could even hit 400-450 whp on stock internals as long as your tune is good.

 

But anything much over that we use beefed up internal parts.

 

I built a 3.0L L6, stroker turbo with efi ITBs, looking to get a good 600 whp or so outta it when my Z gets back on the road.

[datzenmike]

Hey guys.

 

Have any of you seen the vids of the twin cam KA24de heads made into a head for a 2.8L L6 on Youtube? I think it's a little over complicated. It also seemed rather slow for all the work/time he invested, considering it was twin turbo.

 

On a strictly normally aspirated engine the DE head would out flow and hands down out perform the L 6 head no mater how ported it was. Yes it did seem a little slow because a non turbo relies on 14.7 lbs of atmospheric air pressure to fill the cylinders. Any restriction at all will limit how fast it will fill at high RPMs. A turbo can effectively double or more the air pressure so a restriction doesn't matter as much. A turbo will make any head breathe... it has no choice.:D Even an L head will work good with a turbo.

 

 

 

My questions are:

How complicated do you think it would be to get 2-3 single cam KA heads to work on the Z L6?

 

You would have to cut and weld the heads together much like the DE but the timing chain would be easier.

 

 

 

Would it be possible to use a stock Z cam with a few modded NAPS Z heads?

I can't remember the spacing/placement of the rocker arms on M 720 2.4L, in comparison to say a N42.

 

The L cam is totally different from a NAPS. The NAPS looks like a broom stick in comparison. Also the L cam profile is for valves all on one side. The NAPS cam is in the middle and the rockers are on either side. The opening and closing ramps would be reversed on half the valves. It's generally accepted that the NAPS Z head flows less than the L head, so making a 6cyl NAPS head is ... backward movement.

 

 

 

 

I KNOW it wouldn't be anywhere even close to a bolt on affair, and lots of fabbing would need to be done. I also know anything is possible with enough time and money, but I am looking for a much better breathing alternative than any of the non-crossflow factory heads(N42, P90).

 

Oh, yes. This would be geared towards a N/A application.

 

Thought? Opinions? Ideas?

[hughdogz]

...A turbo can effectively double or more the air pressure so a restriction doesn't matter as much. A turbo will make any head breathe... it has no choice.:D Even an L head will work good with a turbo...

 

I agree to an extent. Flow is flow, and it doesn't matter what the air pressure is (atmospheric or above) the head and combustion chamber design will dictate the volumetric efficiency of the engine. As you stated, a KA will always flow better than an L-series head.

 

To say it another way, a properly ported head will flow more whether it is an n/a or turbo application.

[agentalpha]

Thanks for the input, and thanks for trying to explain that to me.

I am well aware how a turbo works, and it's abilities to overcome "bad" head and intake designs/restrictions.

I am also aware of what was/is involved in making the KA head for the L6.

I am a heckuva fabricator, and have almost 30 years working on cars.

Thanks though!:D

 

I didn't think of the fact the opening ramps were on the wrong sides for the intake(or would it be exhausts?) valves. GREAT point!

 

Ok. Maybe I should clarify a bit more.

What I am curious to find out is the TECHNICALITIES involved.

I am curious as to what kind of STREETABLE,

N/A power can be had with a MUCH better head.

 

Bore spacing, camshaft. Tech input.

 

I am rather anti- miles of wiring, and anti- vague(expensive) codes.

Fuck that. Plus, a good Military EM Pulse, and your done.:lol:

 

I know some(ie VERY few) cats are making near 300 Hp on the full blown race L6 motors. But those are nowhere streetable either, and the wear and tear has to be pretty high.

Edited February 16, 2009 by agentalpha

[datzenmike]

That's better said. I guess what I was getting at is that a turbo can make any head flow well.

 

Hypothetical... two motors identical but one head ported to the max the other stock. Both have identical turbos.

 

The ported motor takes 10 lb of boost to fill the cylinder to it's maximum safe amount before detonation prevents any safe increase in boost and hp is say 100.

 

The restrictive head motor approaches 10 lb of boost but because the port is restricted not all the pressure gets to the cylinder so more boost is dialed in to compensate. Eventually the boost reaches 12 lb and the cylinder if filled to it maximum safe amount and detonation prevents any safe increase. The hp output is 100.

 

Of course a good flowing head would be less work for the turbo. I don't know turbo so I realize I may be way out there wrong.

[agentalpha]

One thing to consider: "streetable".

When you "port it to the max", you kill the vacuum signal to the carb boosters.

 

I think it's funny that so many people still think "bigger is better" when it comes to everything. Cams, ports, carbs, exhaust systems. No matter how much they are told, or read it, even though it's been known fact otherwise for 40+ years, they don't listen. Even though they are killing their power, because they HAD to have that 3" exhaust on their 1.8L, or KNOW they are gunna get 400HP outta their Civic, or HAD to put that 750CFM double pumper with mechanical secondaries on their chevy truck 350.

 

That's a big reason I roll my eyes and laugh when I see those 4"+ fart cannon exhaust tips in tiny 4 cyl. cars.

Talk about ricer wannabe.

 

:lol:

 

Not saying YOU think like this, BTW...

Edited February 16, 2009 by agentalpha

[Skib]

I wouldn't think the L6 blocks would handle more than 450 HP or so.

 

a stock bottom end could handle 400 if its tuned right and with aftermarket internals it can go plenty more. I think TimZ is up to like 600hp? I know Johns running at about 454hp. the L6 is tough.

[datzenmike]

One thing to consider: "streetable".

When you "port it to the max", you kill the vacuum signal to the carb boosters.

.

 

I don't think porting will affect vacuum much. High overlap cams at low RPMs are another story. At low speed the vacuum is lost when both the intake and exhaust are open at the same time. Usually the high performance cam has a later closing intake valve so the piston is well on the up swing towards TDC on the compression stroke. At low speeds the piston actually pumps some of the cylinder contents back into the intake. Sort of like taking a bight of apple and then spitting some of it out. As can be imagined low speed with a huge cam is lumpy and rough.

 

Porting a head out to cavernous size will lower the air speed of the air through it though. Good intake speed will offset some of the bad effects of late intake closing and valve overlap because it's inertia keeps it flowing forward into the cylinder and is more difficult to reverse. Of course this smaller port and high velocity becomes a choke point at high RPMs and doesn't allow enough intake air for good breathing.

 

I'm hoping that my Z24 head will benefit from porting, in that making the port larger at the short turn radius will slow the air speed down and allow it to make the bend without separating from the port wall and becoming turbulent. Well, in theory.

[agentalpha]

I don't think porting will affect vacuum much. High overlap cams at low RPMs are another story. At low speed the vacuum is lost when both the intake and exhaust are open at the same time. Usually the high performance cam has a later closing intake valve so the piston is well on the up swing towards TDC on the compression stroke. At low speeds the piston actually pumps some of the cylinder contents back into the intake. Sort of like taking a bight of apple and then spitting some of it out. As can be imagined low speed with a huge cam is lumpy and rough.

 

Porting a head out to cavernous size will lower the air speed of the air through it though. Good intake speed will offset some of the bad effects of late intake closing and valve overlap because it's inertia keeps it flowing forward into the cylinder and is more difficult to reverse. Of course this smaller port and high velocity becomes a choke point at high RPMs and doesn't allow enough intake air for good breathing.

 

I'm hoping that my Z24 head will benefit from porting, in that making the port larger at the short turn radius will slow the air speed down and allow it to make the bend without separating from the port wall and becoming turbulent. Well, in theory.

 

Mild porting, no.

It can, though, very much so. You are close.

If you increase the port diameter very much, you reduce the vacuum signal, Bro.

And reduced signal = reduced fuel atomization.

Like squeezing a garden hose. Which shoots farther?

 

And a "lumpy" cam idles roughly, actually what you describe,

and is aggravated on a shared plenum manifold.

With a IR setup(like Mikunis and Webers) this isn't a factor at all.

That's why I actually bought a "Lumpy" grind for my street car.

 

Most guys knock the Z24. They never rode in my 720, either, and all I did(for the most part) was put a huge(for the engine) Holley on it. The valves are actually good sized 1.76 I, 1.65 E, if memory serves. CANTED valve angle, Hemi combustion chambers, twin plugs. Really doesn't get much better for a 2 valve per cyl head. With minor(careful) work, I'd bet they WOULD flow pretty well.

 

The ONLY problem with them is the short radius side. The port is down low to the seat, and a very small radius. so be VERY, VERY careful about removing ANY material, other than removing that knife edge between the seat and port on the short side. Just blend it from the seat, to the runner floor. I wouldn't do much more there, myself.

If you decrease the radius, you will hurt flow.

Edited February 17, 2009 by agentalpha

[hughdogz]

It can, though, very much so. You are close.

If you increase the port diameter very much, you reduce the vacuum signal, Bro.

 

I see what you mean if you take the vacuum in the runner of the head, but vacuum is usually taken at the intake manifold, so I don't see how porting a head would affect the vaccum at idle. (I could be wrong)

 

 

And reduced signal = reduced fuel atomization.

Like squeezing a garden hose. Which shoots farther?

 

I'm not convinced that is a great analogy. You're not changing the pressure by putting your thumb over the end of a garden hose, just the exit velocity.

Think of it his way...with a gravity fed water works, by putting your thumb over the end of the garden hose, you're not changing the height of the water in the reservoir (i.e. water pressure) any. When the water leaves the end of the garden hose, it is at atmospheric pressure and is no longer at the water pressure...

[datzenmike]

Mild porting, no.

It can, though, very much so. You are close.

If you increase the port diameter very much, you reduce the vacuum signal, Bro.

And reduced signal = reduced fuel atomization.

Like squeezing a garden hose. Which shoots farther?

 

No. I can't see that. The port and intake are sealed with a carb at one end letting in a small amount of idle air and a motor sucking air out through an opening and closing valve at the other. Vacuum builds and is unaffected even if the port were the size of a garbage can. Like the pinched garden hose, a smaller runner or port will force it to move faster... larger, slower. Maybe we are talking about two different things.

 

 

 

Most guys knock the Z24. They never rode in my 720, either, and all I did(for the most part) was put a huge(for the engine) Holley on it. The valves are actually good sized 1.76 I, 1.65 E, if memory serves. CANTED valve angle, Hemi combustion chambers, twin plugs. Really doesn't get much better for a 2 valve per cyl head. With minor(careful) work, I'd bet they WOULD flow pretty well.

 

The ONLY problem with them is the short radius side. The port is down low to the seat, and a very small radius. so be VERY, VERY careful about removing ANY material, other than removing that knife edge between the seat and port on the short side. Just blend it from the seat, to the runner floor. I wouldn't do much more there, myself.

If you decrease the radius, you will hurt flow.

 

The Z24 is quit impressive, and it should be with longer stroke and larger displacement, at least at low to mid range. It quickly runs out of breath so even minor changes will improve it. The carb is very good for what it does, like most Hitachi carbs, good mileage, running and fair performance. It's a bit small for the engine size. Most 720 owners rave about the 32/36 Weber performance increase.

 

I removed a lot of the short radius, intake and exhaust, producing a smoother more gentle curve, even blending the curve well into the valve seat metal. The Z radius is so bad you can't make it worse. Unlike the L, the area directly below the seat is very rough with a casting ridge and burrs from machining the recess for the seats. This means it can be improved on.

 

http://i138.photobucket.com/albums/q251/datzenmike/L%20Z%20Heads%20and%20Motors/headZ20006Large.jpg[/img]"]

 

Here the short radius is lowered into a U or V shape at the bottom of the port. It was much higher and rounded before.

 

http://i138.photobucket.com/albums/q251/datzenmike/L%20Z%20Heads%20and%20Motors/headZ20004Large.jpg[/img]"]

 

Here there was much contouring of the valve seat into the port wall from 4 clock wise around to 1 o'clock. Roughly opposite the short radius. This area has a casting ridge and burrs and did not match the base of the valve seat.

[72240z]

I see what you mean if you take the vacuum in the runner of the head, but vacuum is usually taken at the intake manifold, so I don't see how porting a head would affect the vaccum at idle. (I could be wrong)

how can the vacuum change through the head but not the intake manifold? It can't. At idle it would for the most part be tiny/negligible but different non the less. My father used to call it the pulse of the engine, everything changes it even if just a tiny bit.

 

 

I'm not convinced that is a great analogy. You're not changing the pressure by putting your thumb over the end of a garden hose, just the exit velocity.

Think of it his way...with a gravity fed water works, by putting your thumb over the end of the garden hose, you're not changing the height of the water in the reservoir (i.e. water pressure) any. When the water leaves the end of the garden hose, it is at atmospheric pressure and is no longer at the water pressure...

 

You ARE changing the pressure by putting your thumb over the end. When the valve is off the psi is at w/e the main is at. You open it, then it falls. You partially cover the end and it will come back up. The same applies for your gravity example only instead of artificial pressure from the main its the waters weight creating the back pressure. You can apply it to anything too, pressure washers with different psi tips, does the engine change? No, just the tip. When you change exhaust sizes doesn't the back pressure change? Did the engine itself? No.

 

Vacuum builds and is unaffected even if the port were the size of a garbage can.

How can you say that? Vacuum and velocity are directly related. Isn't that why porting is such an art? You can't just remove max material because you will kill velocity reducing vacuum? Very similar to why back pressure is so imp on the exhaust side. Maybe I'm wrong. Edited February 17, 2009 by 72240z

[agentalpha]

Yeah, it felt like it was smacking a wall @ 5,000 RPM@ 110 MPH.

 

Lets try this analogy.

If you have a coffee can, with a pinhole on either side, lid and bottom. One being the valve seat, the other being the throttle valve, how are you going to get a strong, smooth vacuum signal through the interior?

Yes, you will get a signal. But one that is smooth and strong, keeping the fuel atomized?

No.

This is an extreme version, but apparently the idea wasn't being conveyed.

 

You have actually decreased the radius. Your starting point is the valve seat.

You want a GENTLE radius from parallel to the valve stem, a little past the actual seat, to the port floor.

 

Now, you have a sharp radius from the seat into the port floor.

Made it worse. And, with such a large increase in port area, your airflow will die, and the fuel will fall out of suspension...

Edited February 17, 2009 by agentalpha

[agentalpha]

OK.

I want to help ya, so I found a pic of what I'm trying to say.

Here is a pic of an LT1(pic A) and a LT4 (pic B) exhaust port.

As you can see, the LT1 has a VERY small short side radius.

And, notice how low it sits in comparison to the valve seat?

BAD for flow.

Edited February 17, 2009 by agentalpha

[hang_510]

 

You can apply it to anything too...

[datzenmike]

OK maybe I wasn't clear: If you measure the intake vacuum that the carburetor feels when idling. Weather the port is stock or ported out won't affect this. The carb hasn't changed and the idle speed is the same. The same amount of air is drawn through the port. The vacuum in the manifold is the same.

 

True, where the air speeds up or slows down the vacuum would increase or decrease slightly, but only at that point.... not at the carb. The same amount of idle air is passing through the carb... the vacuum felt by the carb is the same,. No amount of porting can change that.

 

As for the head, I'm not cutting it open to show you. :D but my short radius is much reduced by removing material. Almost impossible to make it worse. When I felt around the base of the seat, there was a lump where it met the head material much like A:

 

 

When finished the port was parallel with the seat and gently sloped away with less curve than before. It looks more like B now. Without before pictures it's rather moot.

 

Yes the attempt has been made to enlarge the port at the bend to slow the air speed down on purpose. The slower air will go around the bend easier. I am counting on increased flow and less turbulence to offset any slight downside.

Edited February 17, 2009 by datzenmike

[hughdogz]

Bernoulli's principle...

 

Hydrostatic pressure = density * gravitational acceleration * fluid depth. But once the fluid starts moving then Bernoulli's principal takes over.

 

The pressure in a moving fluid is a combination of the static and dynamic pressure. At P2 in the image above, the static (or gage) pressure goes down, but the dynamic pressure goes up.

 

So, for the garden hose analogy, it is true that the static pressure goes down when the fluid is discharging, but the dynamic pressure goes up since it's moving. The total pressure remains the same in the hose whether you have it blocked off or not. I'm almost 100% sure about this, but I could be wrong.

[agentalpha]

I AGREE the vacuum will be the same at Idle.

 

However, off/above idle(where most street driving occurs),

it's moot point, once that throttle is cracked open even slightly.

 

Rgardless, good luck with the port job.

I hope it works as you intend.

 

Bernoulli Rocked.

Are you familiar with the lifting body Aircraft he designed?

He built on that could carry I think 6 tons, in the TWENTIES!

Effin government and bad politics killed his success.

His lifting body designs were WAY safer and HUGELY more efficient

than the fuselage low aspect wing designs you see today.

 

What's funny is he isn't even credited with the design.

NASA is, 40 years later, and their designs are clumsy at best in comparison.

 

OK. Anyone have any ideas in getting a KA head to work on an L6?

Edited February 17, 2009 by agentalpha

[datzenmike]

Take one KA24E head and slice in half. Cut the center two cylinders from a second head and dowel them together and clamp with 4 rods just like the DE hwead:

 

 

Rear 1/3 clamping block:

 

 

 

Just follow the DE build substituting E for DE. Use Z20 or Z22 front timing cover. Will have to shorten 2cm somehow... cut and weld together.

Edited February 18, 2009 by datzenmike

[agentalpha]

If it were only this simple.

 

2 CM? why are you saying this?

 

Use a Z22 cover?

 

Hmmnn...

[philip1]

back to the OP's question I think the limiting factor is wether or not the valves will clear the block. I would go with a KA head if the gaskets line up but I know the NAP-Z will swap over. You will have to have a NAP-Z front cover modified for the shorter deck height but I think it's doable. if you go with EFI you'll probably see the biggest benefit in the torque department.