Building a Z24 Discussion

[gryffinwings]

So I've been comparing specs between the Z24 and the KA24E or DE, seeing what would be the best option, note that my Nissan 720 is registered in Washington State, so I don't have to mess with smog.  I was looking at the CR spec on the Z24 and I found it's 8.3:1 fairly low in my opinion, I was thinking about raising the compression ratio to 9.0 or 9.5, however if I want to do that I would require either custom pistons, which can be pricey or I could get the deck and head shaved, how much material to shave off is the question here. My plans are the following:

 

Z24:

-Basic Rebuild. Gaskets, Pistons, bearings, water and oil pump.

-Weber 32/36 - Most likely needing a rejet do to mods, prefer this one because I prefer good low and mid range torque which is what the Z24 is all about.

-Comp Cam that improves the powerband

-Increase CR.

 

My goal is to get up to around 120-130 HP and 150 ft lbs of torque, What do you guys think about this? Obviously there are some other things I probably would need to do to realize my power goals.

 

Z24 Pros:

-Decent Amount of Torque

-I have it already

-Cheap to rebuild

 

Cons:

-Not a lot of power.

-Not a lot of aftermarket parts, but some.

 

KA24E/DE Pros:

-Has a bit more power.

-Modern, possibly more reliable.

-Less miles on block

 

Cons:

-Cost, I don't have it.

-Cost of other parts I need.

 

[Dolomite]

There's a reason you've probably never seen a built z24. A ka24de has tons more power stock and way more potential, the e is quite superior to the z24 as well in my opinion. For the price of building the z24 you could probably buy a ka24de and install it and still have a few bucks left.

[Draker]

Naw.. Z24 is crap and the head flows like turds.

[flatcat19]

Money spent rebuilding a Z24 will go further sourcing a KA. Nothing wrong with the E or DE. 

 

Aftermarket support is greater. More sources as the engine was available in more models for a longer period of time. 

[_chiefjt]

Putting ka24e pistons in a z24 will raise the compression to 9.52 and they go right in. If your gonna run a cam I'd suggest relief cuts and stiffer valve springs.

[gryffinwings]

Putting ka24e pistons in a z24 will raise the compression to 9.52 and they go right in. If your gonna run a cam I'd suggest relief cuts and stiffer valve springs.

Thanks for that info. I'll have to look into valve springs. Not sure I'm going to need them since I'm not revving past stock levels. However getting valve relief cut into those Pistons sounds good.

[Z-train]

Z-24 has limits no matter the size of your wallet.The KA's only limit IS your wallet.ZERO point in building a Z as if you ever want to go faster-you can't.

[gryffinwings]

Z-24 has limits no matter the size of your wallet.The KA's only limit IS your wallet.ZERO point in building a Z as if you ever want to go faster-you can't.

 

This is true, however there come a time when the limiting factor isn't just the wallet, I can't build up a KA24 anyway I like but then after that I have to consider what the platform can handle, which this being a 720 pickup mean I have to do more for it to be able to handle and also the drive train being able to handle the extra power. You can't expect the platform to handle all the extra power without upgrades. However, I have been convinced that the KA motor while technically superior, I still want to know more about the limits and what kind of power output I should expect if I were to do the upgrades to the engine that I specify, personally I think if the engine is modified in the confines of the rev limit, meaning increasing low end grunt, I think I could get a decent amount of power out of it.

[DISLEXICDIME]

A stock healthy dual cam ka will dyno around 130 to 160 horses if you want to build a Z24 stick a l series head on it with port work and bigger valves and a cam and dual carbs . But if you do a lz it will cost at least twice as much as a ka . As far as drive Train is concerned the rear end will hold both

[datzenmike]

KA24E pistons give a Z24 a 9.52 compression. The KA24DE piston has a larger dish and the compression will be less than the E. I would recommend you not use a stock 89mm piston as your Z24 block cylinders almost certainly worn and are tapered or oval. Go 0.5 or 1.0mm over size and have the block bored to match.

 

There are limits to how much lift a Z24 cam can be ground. The intake and exhaust valves will hit each other if too opened too much. But they are never open together except for a short time during the overlap period. Even then they are not at full lift. During overlap, the exhaust is closing while the intake is staring to open. The longer the overlap the more open the valves will be at the same time. I haven't seen any Z series cam specs with total valve opening duration over 265 degrees and maybe for a good reason. L series can go above 310 degrees and the valves can never touch. There shouldn't be a clearance problem between pistons and the larger diameter intake valve.  At the same time the piston is just at TDC. 

[gryffinwings]

KA24E pistons give a Z24 a 9.52 compression. The KA24DE piston has a larger dish and the compression will be less than the E. I would recommend you not use a stock 89mm piston as your Z24 block cylinders almost certainly worn and are tapered or oval. Go 0.5 or 1.0mm over size and have the block bored to match.

 

There are limits to how much lift a Z24 cam can be ground. The intake and exhaust valves will hit each other if too opened too much. But they are never open together except for a short time during the overlap period. Even then they are not at full lift. During overlap, the exhaust is closing while the intake is staring to open. The longer the overlap the more open the valves will be at the same time. I haven't seen any Z series cam specs with total valve opening duration over 265 degrees and maybe for a good reason. L series can go above 310 degrees and the valves can never touch. There shouldn't be a clearance problem between pistons and the larger diameter intake valve.  At the same time the piston is just at TDC. 

 

I've been looking at these 2 cams from COMP cams, they look like what I'm looking for, should bump up my torque decently. And at the moment, my engine is working great, it's not exaclty slugish and doesn't feel worn out, so I think I have plenty of life left in it, considering the hauling I did with this truck probably should have killed the engine or something else considering I've hauled over 500 lbs in the back. Either way, I was planning on overboring anyways, probably 30 over, or whatever my machine shop recommends, I've rebuilt an engine before a toyota 3TC, so doing the work isn't a problem for me.

 

 

Brand:COMP Cams

Manufacturer's Part Number:88-119-6

Part Type:Camshafts

Product Line:COMP Cams High Energy Camshafts

Summit Racing Part Number:CCA-88-119-6

 

UPC:036584191117

Cam Style:Mechanical flat tappet

Basic Operating RPM Range:800-4,500

Intake Duration at 050 inch Lift:208

Exhaust Duration at 050 inch Lift:208

Duration at 050 inch Lift:208 int./208 exh.

Advertised Intake Duration:252

Advertised Exhaust Duration:252

Advertised Duration:252 int./252 exh.

Intake Valve Lift with Factory Rocker Arm Ratio:0.422 in.

Exhaust Valve Lift with Factory Rocker Arm Ratio:0.422 in.

Valve Lift with Factory Rocker Arm Ratio:0.422 int./0.422 exh.

Lobe Separation (degrees):110

Intake Valve Lash:0.010 in.

Exhaust Valve Lash:0.010 in.

 

and

 

 

 

Brand:COMP Cams

Manufacturer's Part Number:88-123-6

Part Type:Camshafts

Product Line:COMP Cams High Energy Camshafts

Summit Racing Part Number:CCA-88-123-6

 

UPC:036584191124

Cam Style:Mechanical flat tappet

Basic Operating RPM Range:1,000-4,800

Intake Duration at 050 inch Lift:214

Exhaust Duration at 050 inch Lift:214

Duration at 050 inch Lift:214 int./214 exh.

Advertised Intake Duration:260

Advertised Exhaust Duration:260

Advertised Duration:260 int./260 exh.

Intake Valve Lift with Factory Rocker Arm Ratio:0.420 in.

Exhaust Valve Lift with Factory Rocker Arm Ratio:0.420 in.

Valve Lift with Factory Rocker Arm Ratio:0.420 int./0.420 exh.

Lobe Separation (degrees):110

 

 

[datzenmike]

Factory cam is 248 duration and .413" lift at the valves.

[gryffinwings]

Factory cam is 248 duration and .413" lift at the valves.

 

So either cam is going to be a big difference from the stock cam. Because that thing feels like it loses breath at around 4000 RPM give or take. Thanks for that little bit of info :).

[_chiefjt]

Wow, 248/.413".........and the Nismo cam is a 272/.406". Hmmmmm

[datzenmike]

So either cam is going to be a big difference from the stock cam. Because that thing feels like it loses breath at around 4000 RPM give or take. Thanks for that little bit of info :).

 

Not really much of an increase.

 

The running out of breath at 4K is mostly the port design of the head. Both intake and exhaust and low on the head and close to the block. This means a very tight bend right at the valves that is restrictive to good flow. Take a look at an L series intake. It's much higher on the head and flows downward towards a slight bend at the valve.

 

Not enough room for larger diameter valves and the lift and duration are limited. This will not overcome the poor breathing on this head. The engine has to work to pull air in, and this kills the power. 

 

It is very efficient at under 4K and what it was designed for. Huge torque and pulling power for a truck. Minimal emissions.

[_chiefjt]

I wish someone would just build one already with pics and details. I know a couple guys who have dual mikunis. This one guy I know has a ported head with Schneider springs, cam (I forget what cam he has), Doug Thorleys, stage 2 center force and dual 44s. He was still working on getting the exhaust and clutch done but he said it got up quick. I'm sure his clutch and header is done now.

 

It's another "I know a guy" story but I've seen it in person. Anyways, what I'm saying is someone should just build a z24 with progress pics like I see L motors built.

[Draker]

Then dyno it, overlayed with a stock KA-[DE|E]

[flatcat19]

I wish someone would just build one already with pics and details. I know a couple guys who have dual mikunis. This one guy I know has a ported head with Schneider springs, cam (I forget what cam he has), Doug Thorleys, stage 2 center force and dual 44s. He was still working on getting the exhaust and clutch done but he said it got up quick. I'm sure his clutch and header is done now.

 

It's another "I know a guy" story but I've seen it in person. Anyways, what I'm saying is someone should just build a z24 with progress pics like I see L motors built.

 

Dyno sheet? I'd be willing to bet it was a toque monster, but still would stumble to it's knees around 4,500. 

 

 

Sounds like a lot of money spent to build a stump-puller. 

[_chiefjt]

That's the thing, he just wants to cruise around and have a little fun with the gang when we cruise. Don't think it'd stumble at 4,500 though. It'd be a nice Honda puller. lol

[Z-train]

So either cam is going to be a big difference from the stock cam. Because that thing feels like it loses breath at around 4000 RPM give or take. Thanks for that little bit of info :).

That is the head running out of flow.

 

 

By DatsunMike from another topic:

 

Peak torque is 150 @ 4,400 for the E and 160 @ 4,400 for the DE.

 

In comparison the Z24 is 134 @ 2,800 rpms.

 

The torque increase with the KA will be a noticeable thing.

[Twoeightythreezdatsun]

If you like the power characteristics of the Z24 but want more powa, Just get a nice low mile KA24DE from a 1998-2004 4cyl Frontier! 
 

heck it doesn't even have to be low-mile, these KAs are known to do over 400,000 miles.

 

some food for thought: The only area where a Z24 might have a chance at competing is at IDLE SPEED and I doubt even that.
 

The Z24i had 134ft-lb peak at 2800rpm

The KA24DE had 154ft-lb peak at 4400rpm

 

Nissan advertised that the Frontier Ka had 90% of peak torque at 1200rpm.

 

So, that means at just above idle, the Frontier's KA24DE has more torque than the Z24i had at ANY rpm.

 

The KA will pull harder at ANY RPM than the Z24. The KA has more torque at REDLINE than the Z24 has at ANY RPM. 

 

The Frontier Ka had 142hp peak as well. Thats a 36hp gain. This means the stock KA will deliver TO THE WHEELS what the Z24 manages at THE CRANKSHAFT. 
 

Yeah, you could probably build up the Z24 to have similar output to a STOCK KA24DE, but remember that the KA is STOCK. 
 

Add in the fact that the D22 application KA24 is very similar in appearance to a Z24, with a very carburetor-esque throttle body (but still is MPFI) down to the distributor in the timing cover  and the externally mounted oil pump! Only your emissions guy would probably be able to tell it wasnt the OE motor, and hey, can't argue with 24-26 MPG average fuel economy (and thats in a substantially larger and heavier FRONTIER truck) 

 

Wait, theres more! KA24s arent plagued with the head gasket issues the Z24 suffered from. 

 

Its really a no brainer, just use a Ka :)