philping

Hi everybody ! I'm in France (sorry for my english !).
I'm the (un)happy owner of a 1994 928GTS, and sad to discover TBF on my engine...
crankshaft is OK and can be saved, ...but my block is dead....
I'd like to know if S4 or GT blocks are the same than GTS ....I know that GTS cranckshaft adds stroke, that pistons are differents ....but what about the block ? Can I find a S4 block, and fit my GTS crankshaft, pistons and heads ?
Thanks !!!!

Black Sea RD

Hi Philping,

First my condolences on your predicament!

Short answer is that it will take an engine builder familiar with the 928 engine and it's Alusil composition to make this work.

It will not be inexpensive since you will need the block to be bored to fit GTS pistons and then transfer the rest of the engine internals that are still usable and find the rest. GTS connecting rods were not known to be that strong and alternatives are available.

I'm surprised that some here who have done engine build projects have not chimed in yet that are much more knowledgable than me about this subject. Hopefully they will shortly!

Best regards,

blown 87

Another nice car done in by TBF.

Constintine is right, very few folks have the skills to make a GTS engine starting from a 5.0 block.

It is going to be very expensive any way you go about it, all for the lack of a SuperClamp.

Froggy shark

Hello Philping,

Sorry for this bad news, why don't you try to get in touch with local sharksters in your area?

Here's our web-tank, please join us, I'm pretty sure you'd meet skilled people that would help

http://www.amicale928.org/forums/index.php

Cheers,

Michel (dans le Nord)
http://culte928.monsite-orange.fr/

philping

Salut Michel ! J'ai déjà contacté des membres de l'amicale à ce sujet, mais personne n'a pu me répondre...le seul à le faire veux me vendre un moteur GTS complet à un prix ...trés complet !
Thanks !!! ....why should the S4 block need to be bored to fit GTS piston ? ...bore is the same, ...no ?
Is the GTS block longer than S4 (for the +7mm stroker) ?
Do I simply have to fit all GTS moving parts in a S4 block to make it run ?

john gill

Hello Philping

Yes you are right if you source a good s4 or GT block all the GTS reciprocating gear will bolt straight in ,if you order a new block from Porsche you get a universal block for the later engines , 1 block fits all .
DOnt know about the earlier engines
THE GTS is a stroked s4 , have done this to 2 here locally in Australia

namasgt

make sure the piston tolerance group number (0, 1 or 2) matches the numbers on the S4/GT block your getting. So if your GTS engine came with group one pistons you need a block thats honed for that size from factory. usually group 1 is easier to find than group 2 blocks, hopefully your GTS engine is a group 1. you can find the group number on your block if you have your intake off, its stamped right next to the deck surface were the heads and block meet.
And about the rods if you do have 2R rods and not the supposedly weak 1R rods, I would just reuse the original rods. If your car is not an early 94 it should have the 2R rods. "2R" is forged on both sides of the small end and big end of the rod, since the oil pan is off, its easy to check.
Before you assemble the engine and have the rotating assembly balanced, don't forget to drill the oil holes for the piston oiling ring and the 2 extra holes on the bottom of both sides the piston where the piston pin (gudgeon pin )goes trough. Porsche or Mahle did not drill the holes behind the oil ring, which is causing most GTS's if not all to burn oil.

john gill

If the engine is a 94 GTS then the oil holes will already be there , dont know about the states but that year and beyond is an easy transition, here locally

john gill

oh and please check that when you strip the blcok down , to check whether the blcok has been sleeved , as the with the GTS there are quite a few around .
If this is so then the tolerance of the pistons will need to be checked as previously mentioned.

ANyway this is good chence to modify .

Black Sea RD

Hi Philping,

You are correct! Was thinking about strokers, excuse.

However you still will need a mechanic who understands these blocks due mainly to their composition and the 928 GTS differences through the model years.

From the responses it looks like you will be in good hands. Just make sure to ask questions and check with your local 928 club to find a good engine builder.

Keep us advised as to your engine build up. We like to hear of success stories!

By the way, we understand Porsche no longer has blocks for sale. Have not confirmed this but was told by a good source who also suffered TBF.

Cheers,

Froggy shark

Hi Philping,

I've tried to find your post on the french forum, but I'm not sure of the result : are you also swapping your gear box from auto to manual on your GTS?

Anyway, feel free to write a new post about your quest, now you know a plain S4 or GT short block would work fine for your project, there's no reason that you can't find this kind of help down here

Just have a look on this thread, not in the south of France but no doubt Lionel (among others) can help : http://forums.amicale928.org/viewtopic.php?f=13&t=4809

Cheers,

Michel
http://culte928.monsite-orange.fr/

philping

Thanks for all these informations ! I'm so happy to know thas S4 block can be use !
My rods are "2R" models ....what does it mean ? My block is group 1 tolerance ..... I'm lucky !
...where can I see these holes ? ...they seems to be important !
My pistons are about 150.000 miles ...should I choose a smaller tolerance group to balance wear...? (is it stupid ? ).
Michel, j'ai parlé de cela en privé avec plusieurs membres de l'amicale ...qui n'ont pas su me répondre, et avec un magasinier de Porsche Nantes ...qui n'a rien su non plus ! Je vais éditer un post là dessus sur le forum ...le TBF est encore en France une donnée peu traitée par rapport aux US, et je savais que outre atlantique les réponses allaient être trés fournies et précises.... à priori j'ai eu toutes les réponses en temps record !
....reste à trouver le block !

namasgt

John

I don't think the 94 and 95 GTS's have those holes drilled in them. Last year I helped a good friend in changing his 94 GTS's rod bearings. We looked and there were no holes. His GTS is one of the last 94s brought to US. Greg Brown can definitely confirm if some of the GTS's have the holes or not, I don't think any of them do, unless you have opened up a GTS engine and the holes were actually drilled all the way trough from factory??

Philping

If you have 2R rods then just reuse them, 1R rods are known to let go in some cases.



Ali

blown 87

The problem you are going to have is finding some one with the skills to match pistons and block.
This is not a job for a first time 928 engine builder, not sure if I would tackle it.

Vilhuer

There are differencees between S4/GT and GTS block but nothing prevents modifying earlier block so that it works with GTS moving parts.

https://rennlist.com/forums/928-foru...fferances.html