Smoke !! - 3.2 rebuild advice

[Nathan]

Well, it looks like the dreaded premature valve guide wear may have caught up with me. In a blink of an eye my cars gone from never using any oil to smoking like a chimney. It happened so quickly I still can't believe it - on the dyno, 2 runs clean as a whistle, after third run it starts bellowing smoke. I'm hoping it may just be a dislodge valve stem seal but doubt it somehow.

Anyway, I'm planning on pulling it down myself. As mine's a US spec low comp motor can anyone give me advice on upgrading to Euro spec compression? If I swap for some Euro pistons am I likely to need new cylinders too? I guess this will only be the case if the ring position relative to the piston pin is different (anyone know??).

What other options do I have? Would a capacity increase pay off and what is available? I understand this will require new P's & C's - is anything else needed?

Thanks for any advice.

Nathan


Migration info. Legacy thread was 2587

 

[nick-moss]

What colour is the smoke and does it happen under power or on the overrun?

The US spec motor has a 9.5 CR and produces 207 bhp (217 bhp '87 on). The euro spec is 10.3 CR and 231 bhp, so depending on what year your car is, it is possibly a worthwile upgrade. The cylinders are Nikasil, so you will need to look at the state of them to decide whether they need replacing as well.You can probably get the same power hike with a chip upgrade, which you may need anyway when changing the CR.

Good luck.


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[Nathan]

Nick, smoke's blue and happens on over-run e.g. cruise down a big hill, no throttle, open throttle at bottom of hill and a big blue cloud exits the rear. Mine's an '89 car and before this happened I was already going to have it chipped. AMD reckoned 235 with one of their chips and a cat pipe (which I've got). However, the same on a Euro spec motor would be even better!!

The car's only covered 113000 kms so I'm not expecting any real bore wear. I know nikasil cyls are very hard but I'm still concerned about wear-ridge problems if Euro spec pistons have a higher ring position. I don't want to go hunting a set if it's going to be more trouble than it's worth. As things stand now I've hopefully got a set of rings, guides and maybe even valves lined up FOC, so will already have saved a bob or two. Do you know of any reputable machine shops/Porsche engine builders in the Yorkshire area? I understand nikasil bores require specialist honing tools and are not the sort of thing to give to your average reconditioner.

Thanks, Nathan


Migration info. Legacy thread was 2621

 

[Nathan]

Nick, is it possible to change the stem seals with the engine in the car? Yesterday I took her out for a real good thrashing and the smoke stopped! (and no, it didn't run out of oil!). The speed at which this started always seemed strange so I'm suspecting a moving stem seal. Wishful thinking?


Migration info. Legacy thread was 2703

 

[nick-moss]

Blue smoke? That is fuel isn't it rather than oil. Pale blue, grey, dark blue or black?

it's not worth the hassle of trying to do the job with the engine in even if it can be done. You will get the motor out in less than 4 hours if it's you first one, the last one I did was 2 hours.

As far as I know if the Nikasyl needs honing, it needs replating, which is a real specialist job.

Try
http://www.rlracing.co.uk


Migration info. Legacy thread was 2705

 

[Nathan]

Pale blue & smells like burning oil.

Red Line could well be worth a look. I've not come across them before. Not too far from me either (and they do chips). Thanks for the link.


Migration info. Legacy thread was 2706

 

[nick-moss]

pale blue after zero throttle or on the over-run is valve guides or seals as you have already worked out.

I have no experience of Redline, but the fact that they run 7 race cars says something. Let us know how it works out


Migration info. Legacy thread was 2707