KA head, Napz Z head for Z L6

[agentalpha]

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.

 

I don't think the valves are a problem.

A KA24de twin cam conversion has been done.

How do you "know" the Napz head will swap?

Do you mean as far as bore spacing, oil/coolant passages?

Care to elaborate?

Shaving a timing cover isn't a big deal...

I've considered it as a good possiblility, as how cheap they are,

and how simple I have thought it would be (as if making a head from 3 is simple, lol).

At least as far as the timing chain, ect.

 

A bigger cam would cure most of why people knock the Naps z engine.

 

I know lots of fabbing is necessary for making a head from three.

But, I am looking at keeping things as simple and low cost as possible.

Right off the bat, I have to buy 3 heads.

And, the KA single cam has the best valve cover as well, lol.

 

And I'm not loaded.

 

And THIS is the kind of input I'm looking for.

 

THANKS!

Edited February 20, 2009 by agentalpha

[72240z]

I really doubt the napz head will work as easy as the ka if at all because the gallies are different on the napz head to l block, no? Even if they just have to be slightly altered its one more step for less result. Not to mention the piston/deck/valve clearances being WAY off. I don't think you can do much more lift with a cam although duration would help, there are clearance issues already stock. That said what cam would you use? With the ka rt a stock set of nissan cams works. What dizzy would you use? v12 dizzy? lol If only using one set of plugs I'd say whats the point then. Cross flow isn't worth all that.

 

As for the non de ka option I have to ask why? Your going to go through the exact same process so why not dohc? The heads are just about the same price even. The only benefit I can see is the timing chain set up would be a tad easier but with this kind of project does that really matter? Again too what cam are you going to use?

 

I mean when you come down to brass tacks the L6 has the P90 head available which hands down does or can flow better then any sohc 2 valve head ever produced by datsun/nissan so really dohc is the only thing that makes sense in my opinion. I venture to say a properly worked p90 would give the 3 valve ka a run for it's money too. All that work for MAYBE a slight increase? Not worth it to me.

 

I have been going ape shit thinking about this since it was 1st uttered on hbz. The ka rt is the cheapest, easiest, most sensible rt with the highest return there is.

Edited February 20, 2009 by 72240z

[philip1]

wow I misread the title on this one I thought it was an L16 damn I need to not reply at 1AM

[datzenmike]

L28, L26, L24, L18, L16 motors are all 207.85 tall. The closest matching valve cover is the Z20/ Z22 at 227.45.

 

There's a reason people swap L heads onto Z engines and not the other way round.

 

Ignition is easy... get an EDIS system with 6 coils each coil fires both plugs on each cylinder.

 

KA24E head will beat the P-90 I think. Getting enough compression will be the thing.

[datzenmike]

L28 motor with flat top pistons and Z series head gives 8.1 compression.

Same as above but with KA24E head... 7.34

 

L28 motor with 10.9cc dished pistons and Z series head.... 7.1

Same as above but with KA24E head.... 6.5

 

The L, Z and KA all have different head volumes. The KA24DE IS very close to the open chamber L head. I can now see why it was used.

[philip1]

what would happen if the block was bored to fit KA pistons? I know its a stretch.

[datzenmike]

From 86mm to 89mm? Besides the KA pistons have a 4.1mm different pin height so the closest longer rod would be L16/L24 at 133mm. The 1.1mm negative deck height equates to almost 7cc of extra combustion chamber. I'll work it out

 

L28 bored to 89mm with KA24E pistons and L16 rods= 7.8 The motor would now be 2948cc Nor do able I think anyway.

[philip1]

I thought the L28 was 87mm bore? anyway the pin height is an issue but could a LD28 crank fix that with it's 4mm longer stroke

[72240z]

Ignition is easy... get an EDIS system with 6 coils each coil fires both plugs on each cylinder.

Ya that would be a easy way to do it, but again imo it defeats one of the main purposes for using the napz.

 

KA24E head will beat the P-90 I think. Getting enough compression will be the thing.

It may, odds are in its favor. My point was that it would be a minor gain or in any event way less then the 4 valve head. To do all that work I personally want max gain.

 

L28 motor with flat top pistons and Z series head gives 8.1 compression.

Same as above but with KA24E head... 7.34

 

L28 motor with 10.9cc dished pistons and Z series head.... 7.1

Same as above but with KA24E head.... 6.5

 

The L, Z and KA all have different head volumes. The KA24DE IS very close to the open chamber L head. I can now see why it was used.

 

You think it was used because of the head volume? Look at the alternatives, I can't see how it could be any kind of choice. I really don't think the head volume matters. There are 3 dif stock stroke cranks avail, 3con rods, 4+ stock pistons and like what 50 after market pistons in any comp anyone could ever need? Just about any comp desirable can be achieved with any of the options, regardless of head volume of the choice.

I thought the L28 was 87mm bore? anyway the pin height is an issue but could a LD28 crank fix that with it's 4mm longer stroke

Stock bore is 86 and the ka's have actually been used already, some shave them to solve the height issue, or hg, dif rod etc. I don't like the geometry it equates to though, I think 3.0L is ideal. ka24e for flat tops and ka24de for dished. I believe that's close to the limit though. 87mm, ld crank, l24 rods is a true 3L, I'm pretty sure at 89 its 3.1L, 90 is a true 3.2L. Edited February 20, 2009 by 72240z

[datzenmike]

....

There's a reason people swap L heads onto Z engines and not the other way round.

 

Ignition is easy... get an EDIS system with 6 coils each coil fires both plugs on each cylinder.

 

Ya that would be a easy way to do it, but again imo it defeats one of the main purposes for using the napz.

 

Not following. Maybe I wasn't clear... six coils, one for each 2 plug cylinder. The coil is used as in the 'wasted spark' set up but instead of wasting the spark it fires the second plug.

 

 

KA24E head will beat the P-90 I think. Getting enough compression will be the thing.

 

It may, odds are in its favor. My point was that it would be a minor gain or in any event way less then the 4 valve head. To do all that work I personally want max gain.

 

Well the E is only 10-15 hp behind the DE so I expect it to be better than the L head which only has to flow enough to fill an L18 size cylinder. If the E head was easier to do I would do it all things equal otherwise, yes 4 valve for sure.

 

L28 motor with flat top pistons and Z series head gives 8.1 compression.

Same as above but with KA24E head... 7.34

 

L28 motor with 10.9cc dished pistons and Z series head.... 7.1

Same as above but with KA24E head.... 6.5

 

The L, Z and KA all have different head volumes. The KA24DE IS very close to the open chamber L head. I can now see why it was used.

 

 

You think it was used because of the head volume? Look at the alternatives, I can't see how it could be any kind of choice. I really don't think the head volume matters. There are 3 dif stock stroke cranks avail, 3con rods, 4+ stock pistons and like what 50 after market pistons in any comp anyone could ever need? Just about any comp desirable can be achieved with any of the options, regardless of head volume of the choice.

Stock bore is 86 and the ka's have actually been used already, some shave them to solve the height issue, or hg, dif rod etc. I don't like the geometry it equates to though, I think 3.0L is ideal. ka24e for flat tops and ka24de for dished. I believe that's close to the limit though. 87mm, ld crank, l24 rods is a true 3L, I'm pretty sure at 89 its 3.1L, 90 is a true 3.2L.

 

The Z head has a much larger combustion chamber than the L head.. bigger by 12cc. The KA24E is bigger than that. Fitting either of those heads on a much smaller volume cylinder is going to drop the compression.

 

L28 motor, flat tops and Z head = 8.1

L28 motor, flat tops and E head = 7.34

 

 

L28 with 89mm KA 2.8cc dish pistons ZERO deck and Z head = 8.28

L28 with 89mm KA 2.8cc dish pistons ZERO deck and E head = 7.52

 

Same as above but flat tops

Z head = 8.6

E head = 7.77

 

To bring the E compression up to that of the Z head you will need a piston with an 8cc dome on it. Nissan doesn't make them. As noted this is a zero deck height so 1.1mm has to be milled off the block!

 

OK on to the LD28 crank:

L28, KA'E' pistons, LD28 crank (3.1L) with Z head = 8.67

L28, KA'E' pistons, LD28 crank (3.1L) with E head = 7.85

 

 

Even at 3.1 liters with flat tops it's a struggle to get 7.85 compression. Head volume does indeed make a big difference. Z heads are bigger... KAs are even bigger.

Edited February 21, 2009 by datzenmike

[philip1]

this may be way out in left field but what if you welded together a couple KA blocks to be a 6 and then used a L6 crank. This would get the bore size up but the stroke may not work still.

 

 

I say go RB30e and call it good LOL

 

 

Edited February 21, 2009 by philip1

[datzenmike]

Sort of a KA36E? Hmmm you would need 173.95 rod length ... the largest is 165 from the Z24 and KA24e/de

 

Why stop at welding blocks together, weld up a few cranks too. lol

 

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[philip1]

if the OP was wanting a cross flow head and good flow an RB series engine is the easiest solution. an RB30e is a cross flow 3.0 I6 sohc and is easily mated to the twin cam head. I don't know why I didn't think of this earlier.

[72240z]

Idk why anyone would go rb30e and not rb30de. Lots of people have mentioned it, its expensive as all hell to get a block and head here. Plus then you have to go through all the trouble. None of the original mounts or parts work at that point. So why bother? 2JZ-GE Makes 220hp/tq out of the box and has a 6 speed available in this country= THE END.

 

The only reason I see to do this is to keep the L in there. Once other engines come in to play its game over.

Edited February 21, 2009 by 72240z

[72240z]

Not following. Maybe I wasn't clear... six coils, one for each 2 plug cylinder. The coil is used as in the 'wasted spark' set up but instead of wasting the spark it fires the second plug.

Maybe I'm wrong but I thought the 2 plugs on the z didn't fire at the same time and that's why it needed 8 separate plugs not just 4 split.

 

 

 

 

 

Well the E is only 10-15 hp behind the DE so I expect it to be better than the L head which only has to flow enough to fill an L18 size cylinder. If the E head was easier to do I would do it all things equal otherwise, yes 4 valve for sure.

Idk we are on the same page in the end but you really need to check the flow charts on all 3 to see what I mean.

 

 

 

 

 

 

The Z head has a much larger combustion chamber than the L head.. bigger by 12cc. The KA24E is bigger than that. Fitting either of those heads on a much smaller volume cylinder is going to drop the compression.

 

L28 motor, flat tops and Z head = 8.1

L28 motor, flat tops and E head = 7.34

 

 

L28 with 89mm KA 2.8cc dish pistons ZERO deck and Z head = 8.28

L28 with 89mm KA 2.8cc dish pistons ZERO deck and E head = 7.52

 

Same as above but flat tops

Z head = 8.6

E head = 7.77

 

To bring the E compression up to that of the Z head you will need a piston with an 8cc dome on it. Nissan doesn't make them. As noted this is a zero deck height so 1.1mm has to be milled off the block!

 

OK on to the LD28 crank:

L28, KA'E' pistons, LD28 crank (3.1L) with Z head = 8.67

L28, KA'E' pistons, LD28 crank (3.1L) with E head = 7.85

 

 

Even at 3.1 liters with flat tops it's a struggle to get 7.85 compression. Head volume does indeed make a big difference. Z heads are bigger... KAs are even bigger.

None of that changes that it can be done with normal methods lol. It doesn't matter which nissan makes, the L series has so many after market pistons available and even companies like ross that will make any you like. Beyond that with the right stroke/rod you COULD use a stock piston and just machine valve reliefs. More over you could just weld the head so it's not hemi...... A slew of options, I feel volume was last on the lists of reasons is my point.

 

All that aside the one and only one of this made so far was for a turbo application so I doubt low comp was a concern.

[72240z]

Sort of a KA36E? Hmmm you would need 173.95 rod length ... the largest is 165 from the Z24 and KA24e/de

 

Why stop at welding blocks together, weld up a few cranks too. lol

 

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Just weld 2 together, 4.8 dohc I8 :lol::lol::lol:

[datzenmike]

Yeah the NAPS fires both plugs together in the 1342 order same as most 4 cyl.

[72240z]

Yeah the NAPS fires both plugs together in the 1342 order same as most 4 cyl.

 

Hmmm I see. Wonder why they don't just use one plug on the dizzy end to 2 on the plug side, clean it up a bit.

[agentalpha]

Wow.

I leave a day, and the thread goes haywire.

:lol:

 

The KA pistons are a very, very common swap in the 3.0 and 3.1 L6 motors.

 

For the most part, the coolant/oil holes are all in the same location, from the L 4's, to the KA...

It's just a continuation of the same motor design.

 

The twin cam is WAY too much fabbing/engineering for the timing drive.

I'd like to hear about that guy making it past 10-20,000 miles.

 

The P90 is the best L6 stock head, but you have to destroy a vintage turbo head for it's original purpose,

and still is not a crossflow head, so the exhaust flow will always suffer, no matter how much work goes into it.

AND, even the best ported P90 STILL flows less than a STOCK single cam KA port.

And once the P90's are all gone, or destroyed, that's it, no more.

We are speaking of a 30 year old part from Japan, remember?;)

 

Dunno where you are getting your info, but there is a thread @ Hybridz on porting you should to read.

 

NOT interested in Fuel Injection. For the third time I think, 3 sidedraft CARBS.

 

And NOT interested in an overpriced, over hyped, heavy motors that is hard to get over priced parts for here,

ie. any newer skyline motor.

Have you priced one, or notice how freaking over-complicated they are?

For 200-250HP stock?:lol:

Again, NO F/I, No turbo,

so don't tell me about how some get 750HP out of 'em, please.

I know, and that's 20 Grand later.

You paying for it?:D

 

L6's are fairly cheap, and plentiful.

I can get cheap parts almost anywhere.

 

The head design is just antique.

Edited February 21, 2009 by agentalpha

[philip1]

or one centrally placed plug

[72240z]

Seriously, and no offense intended at all.... if the timing gears on the dohc are your concern as they will be too hard then non of this section heads shit is going to happen. That's just what it is. The timing chain is the "lazy afternoon" of the entire project. Doweling the sections making sure all is true and sealed and braced is VERY hard I don't care what the head choice is. The person who did it is a pro with access to an entire machine shop.

 

 

Seriously 500 buys you a 7mge(WITH 5 speed) 3.0 dohc 24valve cross flow 200hp/tq stock at a low 9.1:1 comp and they even make a webber mani for it. Call it a day....

 

If it has to stay in the family? rb20de $800 with the 5 speed, less stock power, same potential, also have webber mani in japan. Change the valve cover one day and its a s20 clone.

[agentalpha]

And as far as C/R goes, a good deck surface shave does wonders...

 

Not too hard, too complicated.

RELIABLE.

 

NOT putting a Yota motor in it, or a 4 cyl.

 

Where'd you buy your crystal ball, this ain't gunna happen?

[72240z]

Because like 100 more knowledgeable people have been on it and there is still only one. There is a reason(s) for that. It's nothing against you personally at all, hope you don't take it that way and feel free to prove me wrong but I'll play the odds and say not happening.

 

It also makes no sense to use the sohc or the napz heads for the MANY aforementioned reasons. ka24de is best gain, same trouble, same cost, already been done etc.... Those are the facts.

[datzenmike]

Hmmm I see. Wonder why they don't just use one plug on the dizzy end to 2 on the plug side, clean it up a bit.

 

One plug wire going to two plugs? Won't work, electricity always, always, looks for the shortest/easiest path to ground. One of those plugs will always be easier to fire than the other. Once it finds a path it will take it and not split into two.

 

 

or one centrally placed plug

 

 

One plug will work but there was a reason for two. Two ignition sources means the fuel burns faster. Shorter burn time means the ignition advance can be retarded so that the hot expanding gasses are at maximum pressure at just the right time after TDC. This reduces the time when oxides of nitrogen are produced so lower emissions.

 

The L20B single plug timing is 12 BTDC, the Z24 dual plug is 3-5 BTDC. Big difference. Dual plugs perform at least as well as single, better actually. The head is almost a HEMI shape, efficient and detonation resistant because of cross flow turbulence and no hidden corners.

[agentalpha]

Because like 100 more knowledgeable people have been on it and there is still only one. There is a reason(s) for that. It's nothing against you personally at all, hope you don't take it that way and feel free to prove me wrong but I'll play the odds and say not happening.

 

It also makes no sense to use the sohc or the napz heads for the MANY aforementioned reasons. ka24de is best gain, same trouble, same cost, already been done etc.... Those are the facts.

100 more? You know me THAT well huh? Didn't say it was being started next week, or even this year.

I wouldn't hold your breath, but it WILL be done.

Maybe because it's a huge undertaking, LOTS of fabbing, and people don't want to invest time and money into R+D for a head that can't even be used for vintage racing?

 

People LOVE to whip out a catalog and a credit card, THAT'S why.

 

And as I mentioned(feels like 10x now),

the de is over complicated(MUCH more trouble, a LOT more) for the very slight gains over an existing single cam head.

The single cam KA head will flat smoke a P90(3 valves, cross flow, ect).

End of story.

 

Ever wonder if I was maybe asking input for the community's sake, not my own?

Or actually HOPING someone might mention something I hadn't thought of?

Edited February 23, 2009 by agentalpha