Hi, i don't know if you know this or not, but I've taken my coupe of the road to sort out a lot of problems she's got, as it happens I'm having to take her engine out... and apart. now, i was thinking on ways to recondition the engine and I had a brain wave! My idea was to have the cylinders bored out. This would be great because it would up the power slightly and bring the business end of the engine back to a practically new condition. My idea is to take 5 new 16VT pistons and fit them to my 20VT, this will mean the cylinders will have to be bored out from 82mm to 84mm and it will result in an extra 100cc. but... i need help... I cant even think about all this until i have prices and to get prices i need to know how much 5X 16VT pistons will set me back. Now, I can phone up the garage and ask them for a quite but if they're to look up the parts their system needs a chassis number, and I've only got a chassis number for a 1998 20VT. i was wondering if someone could let me use their chassis number just so i could get a quote, or better still if someone had access to a fiat parts lookup database type thingy if they could give me a price. I've been thinking about this for a while and it makes a lot of sense and it's not terribly difficult. I know I'll probably have to get the engine remapped at some point and have to play with the turbo boost a little but this is the level of tuning i want to start delving into so i thought I'd start at the top.

I will provide photoes of my progress as i go along if you want.

Jackal/Solouko

I'm pretty sure you wont manage to bore the cylinders out that much! And then 16VT pistons probably wont be correct height etc etc..

I was thinking the same.

Ross

you looking for forged or std pistons? If std i have 7 i can sell you

You have a nice pearl white plus??

please dont do this to it!!

why do you say that? it's only 2mm and the engine can take it as the 16VT has shown, they are the same engine only the 20VT has an extra cylinder almost bolted onto the side.

BTW I'm looking for 5 standard pistons but only if they're in good condition. I'm not looking to go OTT with tuning the engine, it's more to recondition it as she's done over 98ooo hard short trip miles. But I'll need to find somewhere who can supply new piston rings so if anyone knows where i can get them please let me know. But seriously... how much would you want for 5 of them?

and no... i don't have a white plus, I have a standard silver 20VT with a squillion and one little problems including rust... which technically isn't even possible on a galvanised body! she has been a little neglected by previous owners and needs a lot of TLC, time and quite possible money to get her back up to scratch. I don't know why my little 20VT logo has gone white, I'm sure i set it to silver.

Thanks though.

Really? looked so nice when I saw it. but I guess you can't tell from the outside. I wouldn't bore it out mate, sounds like major agg + triple mither!

It's not dude, the engine is quite messed up, oil leaks from blown oil seals (from being over filled with oil), the exhaust manifold has sheared off the head, she's also showing the first signs of the black death and as I'm taking her apart I'm finding more and more problems! 2 weeks ago i knew the engine had to come out so that i could get the sheared studs out of the head, now I've almost got the engine out i might as well do all that i can to put her back together so that she can go on and do another 98000 miles, i know i can do this,. I've done it twice before, just not the boring out bit, but I'll pay someone to do that. It's not going to be a major performance increase, but it will restore the seals between the cylinder and piston, this means less blow-by gasses, healthier longer lasting engine, more performance and better fuel economy, that and it's a good little project.

Dude. Speak to barbz about boring out the head. He bored my engine out to fit gapped down rings, and is very experienced.

http://www.torqueitalia.com

Ross

I think the max is 83mm overbore that will give you 2047cc but Im sure that was with forged pistons ?

I've already seen the website dude and it was my next port of call after the forum, i've seen the 2.5 coupe on there, i'm guessing that's a a fiat silo abarth lump in that monster with 5 16VT cylenders to take it up from 2.4 to 2.5... it's very impressive. thanks for the advice, i'll contact him.

its not, forget the 16vt pistons in the 20v, its newer generation then the 16v. You'll save ntohing with this idea and get into loads of problems, dont forget there's a water jacket around the cylinders its not solid iron! Even if you managed it your wont have a gasket to fit it.

Just rebuild with std oversize pistons else get forged items.

rich

This thread is so wrong!

The 16VT is a COMPLETELY DIFFERENT ENGINE to the 20VT. The 20VT is like the 1.8 16v and 2.0 16v Fiat and alfa units of late but nothing like the 16VT unit.
You cannot bore the block out 2mm as it will become porous and p**s coolant into the bores like Rich says. Aside from which you would require a custom head gasket as the std gasket will not seal and will overhang into the bore.
Next, the 16VT pistons are too long for the 20VT engine, and the gudgeon pin is different - they are totally incompatible. Even the location of the cuts for the valves are in a different place on the piston.
If you want to overbore then Fiat can offer you +0.4mm pistons but for anything else you will need custom forged pistons as none of the engine family are turbocharged so are not usable.

wow, thanks johnS that's really sound advice, just what i was looking for, not speculation and conjecture but good hard solid facts as to why i can't or shouldn't do this, thanks again. but throwing that idea totally in the "131N File" now, what are the alternatives? I'm not concerned about more power more about restoring the engine as best i can. would new piston rings be enough or would the bore have to be honed out and over-sized cylinders fitted, taking up this 0.4mm? or should i just leave it? take it apart, give it a clean then put it back together will all new gaskets? it's done 98,000 miles in it's life will the block be that badly worn?

answers on a postcard to:

Jackal

get the bores checked for oval, wear etc. They'll tell you what you need to do, if it's OK (should be unless engine was really pushed, chipped, wrong fueling, pushed from cold, etc...) just stick an new set of rings on your existing pistons and be done with. Obviously skim the head, check valves, replace valve seals, reseat and regap valves, etc etc...
I've seen engines that were looked after with 100K on the clock half of them with a GT28RS and bores were perfect!

V.

Engine has been pushed, i can pretty much guarantee this.
it's bound to have had the wrong fuel at some point, Tesco 100 or something soft.
Pushed from cold... yeah, it's done that a few times.

how is best to get the bores checked? does it have to be done professionally or would a set of precision callipers work? (can borrow them from work)
When you say re-gap valves do you mean resetting/adjusting the tappets on the rocker arms?

Jackal

I'd say professionally I think they have laser technology machines that do the checking.

Apologies, you're on a 20VT so you have hydraulic tappets no regapping like us 16VT ones.

V.

that's OK, I'm more accustomed to hydraulic tappets anyway, i have not got the pacents for feeler guages , however i can check the lash adjusters make sure they're not worn out like the ones in the risma, soon as the coops roadworthy that's me next task!

Thanks though.

Jackal

I've never seen an ovalised 20VT personally, they are usually near perfect or totally wrecked
Theres a special measuring tool for it which centres itself in the bore.
Check the ring lands on the pistons are ok
If the engine has had a hard life it doesn't mean there'll be any exposure of this. I would say the most likely problem would be the shells or wearing on the crank journals

Some engines do not have piston sets that are all the same. There is a code on top of the pistons which define the tolerance the pistons conform to and therefore the bore measurement.

John

Let me send you one! Managed to get the bores in the last engine I broke all oval. After the big enbds went, the pistons hit the head and with the oval bores as well all we salvaged was the cams

But almost certainly due to bore wash from running far too rich

ok, fair point But on a relatively stock engine I've never seen any ovality. On the N/A version of the engine even after 25k miles the bores will be oval on the other hand (which is why a lot of the turbo conversions for fiat/alfa/lancia engines specify low mileages

Why is it the bores go oval on the NA

I wonder as well, worse metals maybe, or different quality rings???

John, help us!


V.