850 Cylinder head question
 

Is there a difference between an 850 N/A head vs an 850 Turbo head? I am planning on snagging a cylinder head from the local Pull-A-Part for a rebuild-able core. Other than the obvious of looking for cracks and straight valves, any other advice or common problems to look for? What kind/size are the head bolts? Im used to Volkswagen using 12mm triple square headbolts and dont want to show up to the yard unprepared.

Thanks in advance guys. :)

turbo blocks are plumbed for the turbo oil return line, NAs are not. Also, if I remember correctly, NAs and Turbos use different valves, but if you're rebuilding it, it shouldn't matter. Also, different compression numbers.

From my experience of forced induction VWs, the oil feed line is plumbed externally using a fitting that is shared with a oil pressure sensor(for a higher feed pressure). Then the return line is through the bottom of the block. The return line being routed from the turbocharger back to the block was usually a bottom end thing very close to the oil pan. Is the oil feed line integrated into the turbo cylinder head and there is not the same plumbing on the N/A head? Are the journals there to tap for the feed line? Are the valves different in diameter, stem size, or are the exhaust valves sodium filled or anything crazy like that? Compression ratio numbers, I would assume, would differ in the cc's of the piston dish instead of the cc's in the cylinder head. But I am still a newb when it comes to these cars.

The heads for the NA and turbo look very close to me. I'm also pretty sure the exhaust valves are sodium filled. My NA head I sent to the machine shop so I didn't get too up close and personal but my turbo head was in good shape so I just hand lapped the valves to clean them up and get the best seal possible.

The blocks are totally different. The turbo block has piston cooling jets and the NA does not.

Bring a big breaker bar the head bolts can be difficult to break lose. I started outside and worked my way in with only 1/4 turn increments. It takes time but assures a true (if it was true to start) head in the end.

Thanks for the replies guys.

The great thing about these cars for me is they are NEVER touched at the junkyard(with the exception of the turbochargers), so if there is a turbo car there Ill snag the head. I am going to compare the heads while im there, maybe take some pics. Just wanted to make sure that the head bolts were not triple squares or anything weird like that.

Also I did a little research about the bore and stroke of the two engines. From what I read, the 2.3L and 2.4L were built as modular engines. So I am assuming that the water/oil jackets should be the same between them even with the difference in displacement. So it "should" bolt up. Im going to try and get a head gasket from a N/A block and a turbo block to see if atleast the jackets line up while Im at the junkyard. Its kinda tough finding the info on if the cubic volume of the chambers in cylinder heads are different or not. I guess I will eyeball the chambers to see if they appear different, but without a way to measure, it will be a guess.

I've got a problem with my 95 Volvo 850 Turbo. The car is emitting white smoke from the tailpipe. I took it to a mechanic who suggested that it was a head gasket problem after doing a compression test and finding one cylinder firing below 33% below capacity. He admitted it could also be a turbo problem, however. What do you think? Should I buy a new cylinder head gasket set already? Thanks for the input.

Cylinder Head Engine Blocks
 

NAs not for plumbed for turbo oil return line but turbo blocks are. There is much difference between an 850 N/A head vs and 850 Turbo Head.

and the valves are sodium filled on the turbo.

With my experiences with my other turbo cars. The heads are the same. There is usually a small plug in the na for plumbing, but the cams and valves maybe completely different. I maybe wrong but that's how it is on my dsm.

Cams are definitely different between the turbo and non turbo. So are the valves.

Just got an idea take that colorful kid clay stuff, and use it as a measuring device to see if the concave part of the head where the valves seat is the same shape and depth. Then make sure the head gasket part number is the same if so send the head off do all the valves, get your turbo cams polished and make sure the head isn't cracked. This is a gutsey move all you can do is hope for the best or find a turbo head. I'd make sure everything lines up also make sure the cams will even fit in the head they could possibly be bigger or smaller in diameter(cam bearings) make sure the lobes line up with the valves. Basically all the obvious things before you spend money on something that might not work.

N/A cams fit fine in the turbo head. They're actually a performance upgrade. I've been running N/A cams in my turbo head for 6 months now, and lots of other folks have too.

I'm pulling my head off here soon to do a valve job, and thinking while it's off to consider N/A cams. What do N/A cams help performance wise?

Compression is generally lower on forced induction also fwiw.

Which is why pistons are usually concave on forced induction. Now on a Volvo idk because I just bought my first a month ago.