Top-End Rebuild - Essential Upgrades?

[mcgc0]

Hi,

I have a '89 engine that I believe might require a top-end rebuild. Naturally, since '89 Porsche made a few essential changes in combating or curing known problems (generally associated with the often mentioned oil leaks). I have below a list of essential additions/upgrades collected from various readings and articles that should be included with a top-end rebuild (some may be obvious and part of a rebuild anyway?). Anyone aware of any other obvious additions/upgrades that I may have missed out? Also, I've made a secondary list of (performance?) improvements that would be nice-to-haves as part of any re-build. Any suggestions there too?

Essential:
- Distributor vent pipe kit
- Replacement distributor drive belt
- '91> cylinder heads and barrels (with the O ring seal head/barrel interface)
- Viton (green replacing black) O ring seals between barrels and crankcase
- Mandatory new valve guides
- Rocker shaft RS type seals?
- Steel (993 Turbo) barrel/head retaining studs?

Upgrades (optional):
- Post-'91 plastic air intakes (replacing alloy version)
- Single-flap throttle body
- Hot-film mass airflow sensor (replacing flap-type airflow meter)
- Performance chip (DIY)
- K&N/PowerFlow induction ((DIY)

Please correct or advise if any of the options above are incorrect, any other useful information also welcome.

Thanks..

 

[Steve Brookes]

With the engine out it would be advisable to have any engine tins that are OK sandblasted and powder coated and those that have rusted away replaced with new.

 

[38F3E1]

If your cylinder heads and barrels are OK I believe you can have them machined to take the head/barrel seal rather then throwing them away and replacing with new.

Ian.

 

[mcgc0]

Thanks Steve and Ian. Suggestions and advice taken on board.

Had an interesting thought too; a potential upgrade of pistons, barrels (and heads?) to 3.8! No idea of costs. Know any suppliers of these parts (UK or elsewhere?). Might, or probably should, make this suggestion a new topic.

Thanks again..

 

[Steve Brookes]

I'm no expert on engine rebuilds/upgrades but I believe moving to a 3.8 displacement is a whole new can of very expensive worms. I think you're into having the bottom end rebuilt too (to ensure it can take the strain), new conrods, new cams and bigger injectors. Ninemeister in the Northwest are known for their expertise in these types of upgrade.

Just to get a flavour of what can be done on 964 engines I would suggest you browse Rennlist. Here's a nice thread on a full engine rebuild to get you started:

http://forums.rennlist.com/rennforums/964-forum/487983-my-engine-rebuild.html

You'll find many of us on there too []

 

[mcgc0]

Excellent Steve - and thanks for the prompt response. In the back of my mind I had thought that if I'm not careful what is supposed to be a regular rebuild will turn out to be a project sucking up cash! Indeed, I imagine adding the extra capacity/power increase will need other items along the delivery line upgraded or replaced (from remapping to maybe stopping power!).

Thanks also for the Renlist suggestion and I will call Ninemeister for more background..

Cheers..

 

[madmoog]

AFASK the bottom end is fine for 3.8 and more (as it is shared between various models), Rennlist is a great sorrce of info in this respect as Steve said, and there are quite a few 3.8's out there (although only aware of mine and Christer's -now sold - in the UK). As for how expensive, depends on what else you do and with cams and a good remap they can produce the power and torque of an early 3.3 turbo If I were to do it myself (mine was already a 3.8 when I got it) I would probably consider 4.0

 

[MrMoots]

Hi mcgc0 (doubt that's your real name)

The link that Steve posted is regarding my engine rebuild. I thought about going along the line of 3.8, but for a first time rebuild, I felt it to be too much of a headache. There is lots to consider, some of which is not obvious until you start to put together a standard 3.6.

I intend to update my rennlist post soon on the finishing off of the engine and summarising where stuff came from, who did what, time scales etc. I have not sat down and added up the incredibly large folder of receipts I have gathered, but have rough figure in my head that its cost about 7k. That includes gearbox rebuild, tools, two lots of head rebuilds, new cylinders and pistons and an RS flywheel. If a garage did that all, I recon I would be well over 10K.

Is it worth it? I thought yes and still think that, but you have to be sure. Remember I had no problems with camshafts, crankshaft, rockers. big gearbox parts etc. You soon get carried away with things.

I now (hopefully) have a good solid engine with weight-matched internals, new cylinders and pistons, fully rebuilt quality heads and an RS flywheel. Its crying out now for throttle bodies and a aftermarket ECU. That's the way I will go when I get time and money to do it.

If you need any thing let me know.

Regards

 

[mcgc0]

Seems that very quickly I can find myself in a whole world of more decision making; how far should one actually go? If doing the barrels and pistons, then why not Carrillo con rods. It would be a shame not to do the whole thing properly.

For sure I don't think my budget for a full-on 3.6 > 3.8 upgrade would be justifiable for the amount of limited mileage I would realistically manage. I can see that if I did just the barrels and pistons I would regret in the back of my mind that I should have done it all.

If then sticking to the normal top-end rebuild as originally planned, I guess my original 'Essential' list would still be advisable? If then thinking more 'bang for bucks' the £/bhp for value would be (in cost order?) PowerFlow air induction, performance chip, plastic air induction pipe and then larger throttle bodies (and hot-film MAS?). Seems to me that maybe a large proportion of the perfomance increase can be delivered lower down the budget, and chasing that last 20% becomes a bit of an exponential power/pound curve.

MrMoots, your rebuild story on Renlist I followed up - top man, I'm envious. Used to rebuild V8'and 12's many years ago and your progress story updates really comes over brilliantly.

SP_CS, thanks for the FVD link. A veritable sweetshop of bits 'n pieces I'm adding to my list!

 

[mcgc0]

Thanks Steve, had a chat with Ninemeister (very helpful guys indeed). Full set of 3.8 barrels and pistons offered at £2k. Had a trawl around PelicanParts and others too and not much in it. Very excited now as I've just agreed the purchase of my first ever 964 (C4) and should really get used to it first before major upgrades. Besides, being sensible and can't really afford straight off an expensive upgrade like that just yet - but one I've added to my list along with KW variant 3, RS front anti-roll bar... does it ever stop?!

 

[Steve Brookes]

Being one of a number of 964 owners that have recently had KW V3 installed, I would agree that this is one of the best performance upgrades that you can do. It transforms the handling and makes the bhp you have much more useable. Don't forget to have the wishbone bushes changed at the same time.

 

[mcgc0]

Thanks Steve, maybe a better upgrade than out 'n out power?

The wishbone bushes are the Powerflex ones often referred to? Specialist job to fit, and a ball park cost all in?

 

[Steve Brookes]

ORIGINAL: mcgc0

Thanks Steve, maybe a better upgrade than out 'n out power?

The wishbone bushes are the Powerflex ones often referred to? Specialist job to fit, and a ball park cost all in?

Mine were superflex bushes (pretty much the same) and cost £270 + VAT fitted which is the same as buying ONE new wishbone (you can't buy the original Porsche bushes on their own). Cost of the superflex bushes to fit yourself if you have the time are £135 + VAT. I had these done at the same time as the KW V3 which was £1450 + VAT fully fitted. Since the latter included full geo, I effectively got the geo for the new bushes free (i.e. doing bushes alone would have also needed a geo in addition to the fitting costs).

As trackdays are a big factor in using my car, I felt that the suspension was a bigger upgrade than adding power because going round corners quickly is where the real enjoyment is. []