jacksonrw

guys like the title states I have some spares that I want to build my backup race engine with

What do i need to do to an NA block to make it applicable for a 951?

Can i use an NA head on a turbo application

Can i use an NA cam for Turbo?

what do i need to do?

xsboost90

n/a block will work for a 951- you need the balance shaft mount on the ds w/ the turbo oil feed.

n/a head is not coated w/ ceramic although they have been used before- i think the valves are smaller slightly - exhaust valves on turbo are sodium filled and stainless.

i think that the early cams were same as turbo..or late cant remember.

hosrom_951

I have not used any NA engine parts myself, but i do have a complete NA parts car (full engine with internals) that i did ask around what would work for a turbo, here is what i got:

-Block is fine to use, need to unplug upper balance shaft housing cover to use for turbo oil feed line (note my block is from an 88 NA and it is already tapped from the factory but just plugged with an allen bolt)

-The NA head does not have ceramic liners in the exhaust port, which is good and bad because you can have it ported & polished and gain more, bad because no ceramic liners. But those guys running 2.7L heads have no problems to report running w/o ceramic liners.

-I would not use the NA cam, some say there is a tiny advantage, but i would go ahead and get a better cam.

-Need 951 or better internals for block (pistons, rings & rod while the crankshaft is the same), need 951 or better valves (both intake and exhaust). You would also require to use the 951 oil pan, unless you plan on a dry sump system. You would also need to swap the oil cooler housings (the one which the oil filter sits on), im not sure which OPRV would be used, someone here would shed more light into that.

-Need to use 951 driver's side engine mount support for the turbo (mounting & oil return).

I guess that pretty much covers it, at least that is what i understood and the route i would be going for when the time comes to use that spare engine.

Guys here would add or adjust anything that i may have missed out.

schwank

From all the reading I've done, the turbo cam is the same as the early NA cam. Some 951 guys go to the late NA cam as it has a touch of overlap IIRC.

cruise98

OPRV's are the same between NA & turbo, but are specific to early and late blocks.

MY '86 and later oil pans are interchangeable between the NA & turbo as they have the turbo drain connection, it is just plugged on the NA's. Be sure you keep the oil pan and the oil pump pickups together along with the dipstick and guide tube for whatever year you have. If you are adding pan baffles and modifying the pickup anyway, there is no reason I can see to source a late pan and associated parts.

The oil pans and associated baffles, pickup etc. all changed with model year '87 and are the same for the NA, turbo, and turbo "S".

turbo cam is the same at the NA '83 - 85.5

Flywheel, clutch, clutch cover and fork are all different

reno808

yeah mostly likely i am going to be using a 2.5 na head.

Olli Snellman

Yes you can use NA block, head & cam.
Original 951 cam is an early NA cam. Late NA cam is almost the same, it only have 1mm more lift on exhaust side. You can identify these cams from stamping which can be found from cam. Early NA & 951 have 05R and late NA cam have 09R stampings. NA block is almost identical to 951 one, you just need make a hole to balance saft cover for a oil line. Some blocks have a bolt/screw there which can be take off. At least my S2 and 924S blocks have it. You can use also NA head, in some cases it is even better because it does not have those ceramic coatings installed to exhaust ports. I am going to use a new 2,7L head with S2 block with late NA cam, so only NA stuff.
You only need to have 951 pistons and rods, otherwise you can use NA stuff.

According to factory 951 information Technik manual, the ceramic coatings are more or less there to ensure the possible catalytic converter will heat up as soon as possible...

reno808

Interesting

hosrom_951

What?????

i hear different things from different people, but the bottom line is you can use a NA head (be it a 2.5 or 2.7) without problems.

jacksonrw

ok the NA head (no mod) - cam (no mod) and block (minor mod) is good to go on the turbo block pairing wise- do i use which valves on it?

can someone send me a picture on where the NA block has this bolt that has to be removed or is it on the balance shaft cover?

hosrom_951

Here you go:

jacksonrw

perfect Thank you
It isn't on the block ...so the blocks must be identical...it comes off the DS bakance shaft cover

Thanks

hosrom_951

Thing is, i know that the balance shaft covers (both passenger and driver's side) are machined per block and are not interchangeable.....

Then again, i could be wrong on this!!

jacksonrw

wow now that's something
you are saying that adding a turbo balance shaft cover to an NA block can't be done?

Olli Snellman

Hussam is right. Do not mix covers & blocks which are not the same pair. Blocks and covers are machined together. Even tough there is not a plug which can be removed, the cover can be easily modify.

Check out the pictures:

The first one is a 944 NA (1987) with plug. The second one is a 944 S2 (1991) wthout plug