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Converting 86 z24 to z24i + turbo build tips


Stevo2055

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Hey guys I have a 1986.5 d21 4x4 5 speed

I am currently in the process of rebuild the motor and plan on turboing it 

I bought the truck not running and it had a blown head gasket and sat for awhile with coolant in the #1 cylinder so I’m doing a full tear down, hone, and new pistons and valves. 

 

In the meantime I found a low km z24 with a 5 speed 2x4 out of a 86 720 that was running when pulled out, it’s priced very fair and is close by so I’m thinking of throwing that in for now. 

 

I’ve looked through the forums but haven’t found anyone that’s converted a carbed z24 to tbi, would I be able to bolt my intake and tbi to this head? Would I need to swap oil pump and distributor as well or would an 86 z24 distributor work with z24i ecu? 

 

Or would I be better off just running the carburetor for now untill my other motor is finished? What wiring is required for the carbed units? 

 

Also with future plans of turboing, in the event I blow the z24i block are the z24 blocks and heads the same?  

 

And if you’ve read this far and have any tips for building up the z24i motor to handle the boost for longer I’d greatly appreciate that as well. From what I’ve heard the crank and rods will hold up fine but is there a better option for pistons? Ka pistons possibly? And are ring gaps a concern? 

 

Any info or tips would be greatly appreciated! 

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The Z24i has a high pressure fuel pump so a carburetor Z24 won't work on that. The Z24i also uses a CAS (crank angle sensor) rather than a distributor and this is splined into the oil pump/distributor spindle so if running Z24i you will need this kept together. Yes the Z24i intake will fit the earlier Z24 is you also swap and keep the fuel pump and CAS together.

 

KA pistons are really no different than Z24 pistons for strength, but it will raise the compression to 9.52. Unless going to forged pistons I wouldn't exceed 7 PSI of boost.

 

I also doubt that the Z24i will be able to sense the increase is air flow and react with extra fuel. It was never designed for 50% more air.

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Thanks for the reply datzenmike I was hoping you would chime in as you seem to have a wealth of knowledge on these motor.  

So just to clarify for me. I could run the z24 motor if I swap over my z24i intake, tbi throttle body, oil pump, and crank position sensor/distributor?  

 

I chatted with a fellow that boosted a z24i using all stock internals, Ecu, and injector and he claims he got 3 years out of it running on 12 psi! Till it popped, and says it ran just happy the whole time.  I don’t plan on dailying this truck or anything, more of just a toy around the acreage and out in the bush but would like more power to turn bigger tires without regearing it and it’s a cheap unit for my first turbo project so if it blows it blows I’m not to concerned about that, especially if I have a back up motor but would like to get it working as best as it can for as long as it can. I would only run about 6 psi I’m thinking as to not blow back fuel or lean out.  More or less just doing it as a learning experience for future bigger better builds. 

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8 hours ago, Stevo2055 said:

Thanks for the reply datzenmike I was hoping you would chime in as you seem to have a wealth of knowledge on these motor.  

So just to clarify for me. I could run the z24 motor if I swap over my z24i intake, tbi throttle body, oil pump, and crank position sensor/distributor?  

 

I chatted with a fellow that boosted a z24i using all stock internals, Ecu, and injector and he claims he got 3 years out of it running on 12 psi! Till it popped, and says it ran just happy the whole time.  I don’t plan on dailying this truck or anything, more of just a toy around the acreage and out in the bush but would like more power to turn bigger tires without regearing it and it’s a cheap unit for my first turbo project so if it blows it blows I’m not to concerned about that, especially if I have a back up motor but would like to get it working as best as it can for as long as it can. I would only run about 6 psi I’m thinking as to not blow back fuel or lean out.  More or less just doing it as a learning experience for future bigger better builds. 

 

You would also need  the ECU under the driver's seat? to run everything and probably any wiring in between. Don't need to swap the oil pump but you do need to swap the drive spindle and CAS. Don't forget the high pressure fuel pump and the exhaust manifold with the O2 sensor. Seems like a lot of bother....

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1 minute ago, datzenmike said:

 

You would also need  the ECU under the driver's seat? to run everything and probably any wiring in between. Don't need to swap the oil pump but you do need to swap the drive spindle and CAS. Don't forget the high pressure fuel pump and the exhaust manifold with the O2 sensor. Seems like a lot of bother....

 

Sorry I may not have been clear in my post. I would be putting a z24 motor into a 1986.5 d21 that was originally a z24i that I pulled the motor out of to rebuild so all the wiring, ecu, exhaust manifold, and fuel pump are already in the truck, I just want to make sure the z24i intake, tbi, and CAS would bolt up and work on a z24 motor out of a wrecked 86 720 that I would be putting into the d21. The 720 it came out of only had 120,000kms and still ran like a top when he pulled it and he’s only asking 250$ for it, which is cheaper than I can buy a master rebuild kit and valves for my z24i motor, which is why I’m considering going this route. 

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6 minutes ago, datzenmike said:

You probably were clear, I wasn't seeing it. Spindle and CAS, intake and EFi and you're good. This'll be easy.

 

I have the tendency to over explain things and make it more confusing than it needs to be sometime haha. 

Perfect, that’s exactly what I was hoping the hear! I will likely go grab that motor this weekend. 

So far I really enjoy working on this truck, everything is quite simple, easy to understand, and easy to work on, besides the rusty bits haha I’m up in Canada so it’s rare to find one of these that are manual, 4x4, and not completely rotted out so I’m pretty excited just to get this one running and moving on it’s own power. 

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Haha all good I got the answer I was looking for in the end.  It looks like the previous owner of this d21 “deleted” the O2 sensor and decided to just jam a bolt in the bung on the front of the exhaust manifold and weld it up....I’m assuming that’s where it went anyway as there’s no other bungs within reach of the O2 wire plug, should I go through the effort and cut it back off and install one?  I know it’s probably been asked a million times and I’ve read a lot of contradicting posts on this topic but what emissions systems can I remove without hurting performance? 

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O2 is not on that list if running efi and turbo.

 

Pretty much all the other emissions stuff can be deleted without affecting overall engine performance.

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The ECU needs O2 sensor input to generate the proper mixtures for the EFI. Without it and some other sensors the ECU defaults to an over rich 'limp home' mode that is safe to run but intended to be temporary and fixed right away. Only at WOT is the O2 ignored. Mileage is terrible in 'limp home'.

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3 hours ago, datzenmike said:

The ECU needs O2 sensor input to generate the proper mixtures for the EFI. Without it and some other sensors the ECU defaults to an over rich 'limp home' mode that is safe to run but intended to be temporary and fixed right away. Only at WOT is the O2 ignored. Mileage is terrible in 'limp home'.

 

In wondering if that’s how that one guy I mentioned previously was able to pull off running 12psi of boost. By having it run supper rich and counteracting this with more air. He was saying that 12psi was the sweet spot for him for air fuel ratio if he went higher it was too lean, lower it was too rich and with the low rpm range on these maybe it would be alright, obviously it would be super rich when the turbos not spooling though...but better than super lean 

I’m not concerned about economy when I do the turbo set up as this truck is just a toy and won’t be de a daily driver or even really see the highway. 

But I will install one for the meantime just to keep it happy untill I get all the turbo parts built/bought. 

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You will need an air fuel meter to warn against too lean.

 

Most EFI are set to the size of the engine and the max amount of air it will ingest..... and a bit more to be safe. There's no sense in designing the EFI to ever use 50% more.  Why would it?  

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6 hours ago, datzenmike said:

You will need an air fuel meter to warn against too lean.

 

Most EFI are set to the size of the engine and the max amount of air it will ingest..... and a bit more to be safe. There's no sense in designing the EFI to ever use 50% more.  Why would it?  

 

So guys like us can slap turbos on it hahaha 

 

 

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