N/A head on turbo motor?

[superstroke17]

Just wondering who has done this and with what success and what needs to be done. I found out my head is cracked (big surprise) from my 87 tc. My bottom end is ready and my machine man found a crack in the head when he magna-fluxed it. Apparently that head no longer exists around here so I'm guessing i gotta find another route. I seen that it was possible to use a N/a head with some machine work. Just wondering who has done this and how. Thanks

 

[Boost-Gobbler]

Just wondering who has done this and with what success and what needs to be done. I found out my head is cracked (big surprise) from my 87 tc. My bottom end is ready and my machine man found a crack in the head when he magna-fluxed it. Apparently that head no longer exists around here so I'm guessing i gotta find another route. I seen that it was possible to use a N/a head with some machine work. Just wondering who has done this and how. Thanks

i havent done it but and i wouldnt try it, thats just my opinion. if i where in your shoes id search every where i could (forums junk yards exc.) for a uncraked head (forums would probably be teh best bet though) from what i understand most of these 2.3 heads are going to be cracked.. due to my recent expirence id send it to bo port, what did you have done to your bottom end? are you just doing a standard rebuild or are you doing a power rebuild? if your going for power id call bo port. they should able to help you out, they stock uncracked heads i beleve so maybe you could buy one from them.

 

[stykthyn]

the n/a head will choke on a turbo application. they were never designed to flow well, much less with boost

 

[Anlushac11]

You can use a normally aspirated head, just use the turbo motors exhaust valves which IIRC are made from a high temp material (Stellite?). Turbo motors I think also had a more hear shaped combustion chamber to try and reduce detonation.

I know of no difference in the port size or design between a turbo or normally aspirated head. Between a early oval port head and a D-port head yes but not between say a D-port normally aspirated head and a turbo head of the same style.

 

[65ShelbyClone]

the n/a head will choke on a turbo application. they were never designed to flow well, much less with boost

The only difference between turbo and N/A D-port head castings is the chamber shape. They both have induction hardened seats and if not cracked already, durability will be improved with machining ans installation of separate hardened seats.

The N/A head will raise the compression on a turbo engine, but not a tremendous amount; maybe to 8.5:1 or so. It still requires a little more caution with respect to the tune and octane sensitivity.

Regarding the turbo exhaust valves, the most commonly referenced material I have seen is Nimonic 80. I have no idea if that is correct, but it is a high-nickel super alloy suitable for the application. Inconel is the only widely available alternative I can think of off-hand that automotive poppet valves are commonly made of. Most big valves that people use in these turbo engines are regular stainless and they seem to work fine.