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Turbo Engine Rebuild

Thanks lads.

The needle bearings and guide tube were replaced when clutch last done about 60 or 70k ago. The guide tube still looks brand new, won't hurt to replace the needle bearings again.

Will check the pin as well.

Guys, quick q, I remember being advised to buy new clutch bolts last time I did the clutch. Is there anything special about them, are they stretch bolts or what? I'm sure they were about a tenner from Frazer Part last time.


Not stretch and fully reusable, probably advised to get new ones if they are ZXN heads and made of Philly cheese
Don’t bother replacing the needle bearings with the same, get some oilite bushings of the same dimensions - got mine off eBay.
Cheers Dave, will do.

Spoke to AMAC yesterday, Westwood haven't had any liners in stock, another 2 weeks before they come. Alastair also confirmed the guides need done. Other than that zero progress!

So it looks very much like 2022 before I'm back on the road. Funnily enough had to take my Tag watch for repair yesterday, won't see that till 2022 now either!! Might just hibernate....

With regards to using oilite bushes in a place which can't be reached soak them in oil first. Yes they are oil imprenegated but that doesn't last forever. SAE 30 or 40 will do, mineral, not synthetic.

So we are finally making some progress, the liners have arrived after being on back order, and it was time to get the pistons out the box. Wossner have supplied a set of pistons for a non-alusil 2.5s 16v NA sadly! This is despite being told not once, but twice, by me and the engineers, that we needed a turbo piston coated for non-alusil application. Turns out they supply a 2.5s 16v piston with alusil and non-alusil versions. Only one version for the turbo though, coated for alusil! If I wasn't laughing I'd be crying!! K9477DA for anybody interested.

So we have 2 options. Request an uncoated set (they outsource for coating) but this could take 6 months depending on when they next make a batch..............or else get a coated set, and have them aqua blasted to remove the coating and a light polish. This has been done before and worked with no issue by one of Eldavo's friends. My engine builder will discuss options with Wossner. I await a further update. Nobody said this would be easy...............:ROFLMAO:

Thanks today to Eldavo for his info and for calling the engineers to discuss potential options.

Does the coating matter, if the pistons are going into a ferrous liner? The valve reliefs are the issue I'd have thought. You may as well use JE pistons.
Uncoated are fine for ferrous liners. Negligible thermal transfer properties between coated and uncoated. Coated for alusil is a no no for my application. Yes JE would be fine, as will uncoated or coating removed Wossners. Just a pain in the butt all round really, especially as these pistons were ordered 4 months ago.


scam75 said:
Uncoated are fine for ferrous liners. Negligible thermal transfer properties between coated and uncoated. Coated for alusil is a no no for my application. Yes JE would be fine, as will uncoated or coating removed Wossners. Just a pain in the butt all round really, especially as these pistons were ordered 4 months ago.


Are you sure about that? The Wossner Alusil coating doesn't seem to work now anyway. What the coating was supposed to do, is stop the similar piston and bore materials galling. I'd be more concerned about what ring profile those Wossners have.

To be honest I am no expert but I know that uncoated Wossners will work, either coming uncoated or having coating removed. I also know they won't work alusil coated. This info is all from recent case studies. I also have faith in my engine builder so can only go on what he says and what folk with recent experience have said.

I know exactly zero about JE Pistons and from what I gather Wossner are superior. So I'll be happy to get some uncoated Wossners one way or another!!

And I know even less about ring profiles but whatever they come with they seem to work fine with ferrous liners when uncoated when built by the guy who's building my engine.

Is it too late to go the offset crank grind, mitsubishi rod, JE piston route? If I was rebuilding a 2.5 engine I'd do that, for the extra capacity.
It's not too late for anything really. It will just add more time and expense to the build and would go over what I've earmarked for total cost most likely. I get the point about extra capacity but I can't see me having any need for it. The car won't be driven hard about from the odd wee blast and the 300 ish horses that should be on tap will be more than adequate for me with a freshly rebuilt engine.

The clutch has already been as expense that wasn't originally budgeted for.

The capacity increase would increase the torque, and help to spin up earlier whatever turbo you're using. And apparently the available big end bearings are a better quality with the reduced crank diameter.
Well we are still no further forward with Wossner. AMAC going to try them again today. On the bright side I'm saving a fortune in petrol although sadly I had to miss out on a free £1 of V Power that Shell kindly tried to bribe me with as they've seen I've not been filling up much of late!! :ROFLMAO:

I think JMG and EMC have used JMC pistons in liners for years. I'd contact one of those companies. Wossner seem to have had a bit of a wobble recently, who knows what spec their dealers have in stock now.
Thanks Blade. It's certainly getting to the SOS stage, seek other supplier!! Work a plan out on Friday if no joy.


I think there's a chance you're going to hear piston slap from cold, with forged pistons though.

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