Peugeot 1.9 8V wet liner honing and clearances

benlilly · Post by **benlilly** » February 14th, 2007, 9:35 am

Hi Guy,

I measured my liners last night and found them to in fairly good condition other than one that had some fine scores in the thrust face.

Their nominal dimension is 83mm. My liners averaged 83.02mm. Smallest measurement being 83.00, largest 83.03mm. I was very surprised at this given the engine has done 100,000 miles. The measurements might not be spot on as it was the first time I had used a bore guage (tricky!) so I'm going to get a friend to check them later.

How much can I expect this to increase during a typical honing process?

Also, my Haynes manual specs max ovality and taper as 0.1mm. Is this a sensible tolerance to work to for a fast road engine?

The engine is a Peugeot 1.9 8v. Cast pistons and wet liners.

Kind Regards,

Ben Lilly

Post by **Guy Croft** » February 14th, 2007, 10:12 am

Ben, hi

best to buy a Flex Hone for that, the dimensional change will be 'unmeasureable'. I imagine you'd have chrome faced/plated top rings so use 180 grit silicone carbide.

Contact my friend and honing guru Bob Spilsby at PaceHigh Ltd tel: 01707 327788

If you hone by rigid stones it could throw your good liners way oversize. That Haynes limit is a bit er, generous but is probably taken from OE data. Not that the liners may be size classed to pistons so don't mix them up. 83 would be a class A and 83.03 could easily be a not-very-worn class D or E. There is an article on piston/bore sizing in GC V/W.

GC

benlilly · Post by **benlilly** » February 14th, 2007, 6:42 pm

Hi Guy,

Thanks for the tips and the article helps alot.

Is 0.05mm a typical bore to skirt clearance for a cast piston in a performance engine?

One other thing, in the Vizzard book I own it recommends to run bearing clearances at top limit when an engine is being built for performance (doesn't state 'race'). To minimise friction I imagine. Is this the way you would work?

My head tells me to go half way between bottom and top limit.

Thanks for the help, kind regards,

Ben

Post by **Guy Croft** » February 14th, 2007, 8:00 pm

Ben, hi

yes, for your bore size 0.05mm will be fine.

As for bearing clearances, let me simply say 'beggars cannot be choosers', in the sense that most of us have to make the best of what we have in front of use. I won't comment on Vizard, but state that if your clearances are within OE limits, you'll be fine. I often have to certify 'fit for duty' on things that are some way outside OE spec, in those cases I'll advise the client that we can or cannot use - that needs my direct experience.

GC

benlilly · Post by **benlilly** » February 21st, 2007, 11:23 pm

Hi Guy,

Thanks for the help.

Have measured my skirt to bore as clearances as 0.032mm to 0.038mm.

Ben

Post by **Guy Croft** » February 22nd, 2007, 2:54 pm

That is way too tight I think! Only 1.2-1.4 thousandths of an inch. Does not sound enough to me..

Check again?

GC

benlilly · Post by **benlilly** » February 22nd, 2007, 5:13 pm

I thought they might be on the tight side.

But, this means the pistons I have been supplied must be the wrong size. They are 82.95mm nominal and all seem to be exactly that size. I have checked they are the right part.

My bores are 83.0mm nominal.

So, if bores and pistons are all at nominal size that gives me 0.05/2=0.025mm clearance. Just under 1 thou!

I'll make some more checks...

Post by **Guy Croft** » February 23rd, 2007, 9:02 am

Pistons 82.95mm nominal and all seem to be exactly that size. I have checked they are the right part. My bores are 83.0mm nominal.

Ben, maybe a measurement error on your part? If the box says pistons are 82.95 they will be. And if the bores are 83 or over then the running clearance will be 0.05mm/fractionally more which is typical/OK in that bore size range for cast pistons.

GC

benlilly · Post by **benlilly** » February 23rd, 2007, 9:14 am

Ok, I see where I have gone wrong. I thought quoting clearance on one side rather than total clearance was the norm.
Doh!
Thanks,
Ben

benlilly · Post by **benlilly** » April 13th, 2007, 3:06 pm

Hi Guy,

I ended up buying all new liners for my 1.9 8v Peugeot engine.

They are made by Kolben Schmidt and come honed with what looks like (to my eye) a decent finish.

I also have new pistons and rings from the same manufacturer.

Do you consider the factory finish to be a good standard?

I think they are good but I'm being cautious having read chapters in various books discussing the importance the bore/liner finish to ring bed in.

Thanks,

Ben

Post by **Guy Croft** » April 13th, 2007, 3:40 pm

Sorry, KS wet liners ready to run or they need honing? I don't know, I've never even seen them, far less the ring pack.

Anyone else know the answer? No guesswork please.. even I can say give them 30 seconds with a 180 grit FlexHone...

GC

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Peugeot 1.9 8V wet liner honing and clearances

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