Z24 Turbo Charging questions and journey

[NicktheMillwright]

Good afternoon gentlemen

I have some questions regarding turbo charging my z24 (Yes I did make a post a while back asling the same thing, but here im planning to update you all as I go) After various back and forth ideas regarding what I'm looking for from this truck, I've come to the conclusion I want to keep the z24.

 

From my research I've gathered a fair bit of information, and that's left me with a few questions. (I'm not an engine builder, I'm just a Millwright)

 

Do I need dished/Lower compression pistons or will running forged KA24E pistons, (which would raised the compression) work fine? I assume raising compression when adding a turbo is the way to go. Running ARP studs should help keep the head on. Im not concerned about having to run higher octane.

 

 

Adding a longer duration cam, from what I understand, will aid in fuel air flow. However stiffer valve springs are required due to said longer duration. How would I go about figuring out which springs I need to order?

 

 

*If I want to exceed 7psi of boost, would I need to run a EFI style carb (Like a Holley Sniper) to prevent complications with the fuel delivery? Beyond 7psi of boost I assume it would overcome the fuel pump and starve the engine of fuel.

 

If I have to run an efi system, I assume I also will need a crank position sensor. I know the Z24i had one, so finding where that's located shouldn't be too difficult.

 

Would it be worth running an intercooler alongside the turbo? And I assume running an oil cooler would be a wise idea.

 

Thats all I can think of at the moment, I'll update this thread with progress and questions as I go.

 

Nick

[datzenmike]

 As air is compressed the ambient air temperatures are also compressed into a smaller volume and go up. A diesel with a 22 to 1 compression reaches well over 1,000 degrees and will ignite the fuel without the need for spark plugs. Gasoline needs even less heat to spontaneously ignite. A turbo charger is basically a compressor and added to the normal engine's compression will easily exceed the gasoline's auto ignition point. Adding compression makes this even more likely to explode before it's intended time There are way to tame this but it does add complexity, just be aware of it. If not exceeding 6-8 PSI boost then you can get around this by using high octane gas.

 

The fuel pump produces 3-4 PSI. A boost of even 5 PSI will push the fuel back into the pump and the carburetor will run dry. What you would need is a fuel pressure that adjusts and keeps 3-4 PSI above the boost. There are boost reference fuel pumps. A lot cheaper than going EFI. EFI would be better for several reasons.

 

Yes longer duration allows more valve opening time for air to get in but as the turbo increases the air pressure it's even more likely to pack itself in there even with a stock cam. The problem is does the overlap also increase? Overlap is the time when intake and exhaust are both open. Too much increase and the intake air under pressure can blow right through and some of it goes right out the open exhaust. Stock cams or moderate overlap are better for turbo.

 

If running a blow through carburetor or EFI an inter cooler removes some of the heat which reduces self ignition and makes the air denser so more will fit. More volume equals more power. For 6-7 PSI it may not be worth the bother but the higher the boost the more the heat of compression.

 

The turbo does need an oil supply and as the turbo is going to be the hottest part it will absorb heat. An oil cooler is a good idea as heat in a forced induction engine is your enemy. All the other engine parts will make more heat and oil will absorb a lot from, and cool them also. I would also get a KA oil pump from a D21 Hardbody. They are a much higher volume output than the L and Z series engines.

[Stoffregen Motorsports]

I would run forged pistons. Yes, many OEM turbo engines come with modern cast pistons, but they are also using EFI which manages things a lot more efficiently. FWIW, the KA24DE pistons have a built-in "reverse dome" or dish. I believe they are 11cc, but I really can't remember.

 

Just know that if you plan on trying for anything more than just a couple pounds of boost, you will need lots of research before the build and hours of tuning once it is running.

[datzenmike]

Hyper-eutectec pistons in production engines were limited to 6-8 PSI and that helps a lot. Proper ring gap would also be crucial.

 

I have 9cc for the DE pistons. The stock Z24 has 15cc dish so this would raise the compression up to near 8.8

[NicktheMillwright]

So here's what I have noted down:

- Find some forged DE pistons

- Stock or moderate cam to avoid overlap

- KA oil pump, that will be easy to find

- EFI for more control over fuel delivery, maybe a Holley Sniper EFI 2GC Large Bore (Holleys website they are good for up to 14.7 psi of boost.

- An intercooler beyond 7psi of boost (which is what I want) and this will also in theory help control pre-det

 

If I'm going this far down the rabbit hole, maybe not a bad idea to machine a adjustable cam pully/gear? I could machine that myself if none are avaliable

 

If I understand correctly, generally the static compression for turbo engines is around 8.0:1 to run 93 octane, while NA is 9.0:1 (Generally speaking)

Pre det could be micromanaged with head gasket thickness and timing if knock becomes a problem. It would probably be in my best interest to getting touch with an engine tuner...

 

[Stoffregen Motorsports]

Best to set the CR with piston dish and cylinder head chamber volume. Adjusting compression with head gasket means the tension on the timing chain will change.

 

Forged pistons are custom and come from custom piston manufacturers, like JE, Wiseco, Cosworth, Arias and more. All of these guys have Datsun/Nissan pistons designs already, so getting a custom set won't be difficult.

[NicktheMillwright]

Ok so I followed up and talked with a local engine tuner. So he's saying around 9:1 is the sweet spot for L20B motors and given how similar the Z and L are, forged DE pistons would be ideal. As Mike mentioned it would keep the compression around 8.8:1, so that's perfect. I did look around on Cosworth and Wiseco and both have good options available.

 

A 3in exhaust for extra flow and a fresh source of cold air will help with pre-det. Another suggestion was to fit the largest possible intercooler I can, either air to air or air to water. For the cold air, I might take a page from Dodge's book and make a intake in place of a high beam light.

 

Rockauto has Melling oil pumps for sale for KA motors, so I'll grab one of those.

[datzenmike]

Pre ignition/pinging/detonation can also be reduced with...

 

Definitely ambient air from in front of the radiator. 'Cold air intake' and an inter cooler.

 

Another way to cool the intake air is... alcohol/water injection under maximum boost. Intake air is cooled by evaporation of the alcohol and the water can directly absorb heat in the combustion chamber by turning to steam and carrying the heat out the exhaust.

 

 

Some kind of ignition retard set up. Reduces maximum combustion chamber pressures till definitely after TDC.

 

 

[Stoffregen Motorsports]

Back in the old days, Melling aftermarket pumps were cast iron. Yuck. That would be sacrilege on a Datsun motor.

[NicktheMillwright]

6 hours ago, Stoffregen Motorsports said:

Back in the old days, Melling aftermarket pumps were cast iron. Yuck. That would be sacrilege on a Datsun motor.

 

What would you recommend I look for? I haven't bought anything just yet

[datzenmike]

Go to NAPA and ask for a mid '90s D21 Hardbody KA 4 cylinder oil pump. They are identical to the L and Z series but the internal rotors are 13% longer thus moving more oil. Yhe oil pressure al low speeds is higher.

 

 

My tired L20B had a hot oil pressure of 17 PSI. I put a used wrecking yard KA oil pump on and hot idle pressure climbed to 29 PSI.

 

You'll need more oil for the feed for the turbo.

[NicktheMillwright]

23 minutes ago, datzenmike said:

Go to NAPA and ask for a mid '90s D21 Hardbody KA 4 cylinder oil pump. They are identical to the L and Z series but the internal rotors are 13% longer thus moving more oil. Yhe oil pressure al low speeds is higher.

 

 

My tired L20B had a hot oil pressure of 17 PSI. I put a used wrecking yard KA oil pump on and hot idle pressure climbed to 29 PSI.

Alright, I'll get right on that. An oil cooler would also be a good idea. Do you happen to know where the stock oil pressure sensor went on the z24? Can't remember if it was an oil pressure or oil temp gauge the ST trucks came with.

[Stoffregen Motorsports]

As long as the pump is aluminum, it's probably good enough quality.

 

Oil PSI is taken off the side of the block, near the oil filter. A cooler will be nice. There were factory Nissan oil cooler adapters, but most likely, you'll have to use an aftermarket sandwich plate or remote filter kit.

[NicktheMillwright]

New question

 

Need the carburetor flange size on a stock Z24 intake manifold. I think its 2GC Small bore, but I'm not sure.

 

The carb I want to fit is a Holley Super Sniper which uses the 2300 2-BBL. Wondering if there's another ""Bolt on"" option or if it's easier to just modify my existing one.

 

Point being that Holley doesn't make an EFI carb that can handle over 14.7psi of boost other than the super sniper.

Edited May 26, 2023 by NicktheMillwright

[datzenmike]

It's not the same as the earlier rectangle bolt pattern Hitachi carbs. The pair of bolts on the secondary (closest to the valve cover) are farther apart than the two on the primary. It's an isosceles trapezoid. Hope I got that right. 

[NicktheMillwright]

Oh... fuck.

 

So needless to say, I'm going to have to modify it... fantastic 

 

Attached is all the mounts that Holley sells and adapter plates exist. Maybe a laser cut adapter could work?

 

carburetor_flange_guide-Copy.pdf

Edited May 26, 2023 by NicktheMillwright

[Stoffregen Motorsports]

CAn you make your own flange? Most of those adapters are likely made out of crap aluminum.

[Stoffregen Motorsports]

I made this a few months ago.

 

 

 

Edited May 26, 2023 by Stoffregen Motorsports

[NicktheMillwright]

1 hour ago, Stoffregen Motorsports said:

CAn you make your own flange? Most of those adapters are likely made out of crap aluminum.

 

Yeah I have the knowledge to make my own. I figured I'd have to anyway. No biggie.

 

Is that an LS manifold set up for 3 2300? 

[Stoffregen Motorsports]

35 minutes ago, NicktheMillwright said:

 

Yeah I have the knowledge to make my own. I figured I'd have to anyway. No biggie.

 

Is that an LS manifold set up for 3 2300? 

Use at least 1/2" thick material.

 

Yes, that's a dual quad LS2 intake modified to use three 2300 EFI throttle bodies. The throttle bodies will be anodized gold and they look just like carbs. We're also using a Corvette 3x2 air cleaner for a factory look.

 

If you're interested in the 2300 EFI setup, let me know and I'll get you the info. The guy is local to me , but I can't remember his name.

[NicktheMillwright]

1 hour ago, Stoffregen Motorsports said:

Use at least 1/2" thick material.

 

Yes, that's a dual quad LS2 intake modified to use three 2300 EFI throttle bodies. The throttle bodies will be anodized gold and they look just like carbs. We're also using a Corvette 3x2 air cleaner for a factory look.

 

If you're interested in the 2300 EFI setup, let me know and I'll get you the info. The guy is local to me , but I can't remember his name.

 

 

I'm planning to use a Holley Super Sniper 2300 2 Barrel. So I'll have to most likely TIG a 2300 flange onto the intake manifold, or make my own manifold (That will be a learning curve). Going to pull a used manifold from a scrap z24 in town and mock it up first.

 

If not make it myself, where abouts are you located?

 

 

https://www.holley.com/products/fuel_systems/fuel_injection/sniper_efi/sniper_2300_2bbl/super_sniper_2300/parts/550-853