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HybridZ

NA or Turbo engine?


Takumi Trueno

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Hello, Im in the middle of doing L28et engine swap on my 75 Z. I bought the engine ages ago and now finally getting around to it. Its a P90 head and F54 block. It didnt come with a distributor so I had to buy one from someone on here. I found it odd that it didnt match up. So ass Im taking apart the engine, I take off the head and I see flat top pistons.

 

Do I unfortunately have an NA engine? Is there any other changes, other than the pistons and the distributor shaft?

 

Do you all recommend I change the pistons to dished? Is it as simple as that?

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There is a small "adapter housing" that bolts to the front cover which is used on the non-turbo cars.

 

Removing this small housing should allow the proper turbo distributor to fit but you also need the proper turbo distributor/oil pump shaft for it to fit.

 

If the engine is a 1981 it will use crank trigger and an empty distributor as well as the non-turbo style oil pump drive shaft.

 

Don't sweat the flat top pistons as many run them in turbo cars but you will find that 10psi is pretty much the limit with intercooling and a bit less without it.

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Another option is to just add the turbo stuff onto your 75 engine. The 75 engine has dished pistons and 8.3:1 cr. You can drop the compression of the stock 75 engine to the stock turbo level (7.4:1) by putting the P90 head onto the 75 block. Use the head gasket that matches the block year. If you don't, then it will over heat.

 

then add a megasquirt 2 efi system.

 

or you can install a 8:1 fmu ($100 from ebay) and lock out your ignition mechanical advance curve and set the timing to 25 degrees. This will allow you to use all the stock 75 efi stuff (intake, injectors, ecu, ignition, engine, head....) works OK to 8 psi of boost.

 

If you plan on using stock boost, then I would use the 75 engine with the turbo bolt on stuff. A Megasquirt efi system would be best, but a cheap and easy to install FMU would get you boosting much sooner.

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