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[kterkkila]

Just noticed that Spesso really make racing gaskets for 2.0 Nord engines? What are the differences compared to TS gaskets? I have been understood that it's possible to use TS heads on Nord bottom ends, so there can't be big differences?

[Micke]

You can use Nord gasket on a TS engine. A part in front doesn't match so there's some cutting to do.
I don't see any reason to do it even if it's possible.

Anyway, so far I successfully used std head gaskest without any problems. As you won't be boosting it should work for you as well.

[kterkkila]

My piston problem is finally solved. I have found lot of good experiences via this forum, so I would like to share mine in this topic.

All available choices I found, were whether too heavy or too expensive, so had to go on custom pistons. I had long conversations with Finnish speed shop who sells Venolias, and with Paul Spruell who have 85mm JE option for TS engines.

Venolias list pistons for TS are quite heavy due to original like basic design. The valve reliefs and top bulge seems to be improved when compared to TS std pistons (see Mickes picture earlier). Venolia could make them lighter, or pistons could be machined lighter on speed shop, but that's long way to go. If I was choosing Venolias, the complete new design would be the way. That's a bit costly but also somewhat risky way due to lack of experiments.

What comes to JE's, Paul already have almost the right pistons for these needs, so JE's were much better start for this customing process.

Things to be changed were the bore and valve reliefs. 85mm goes over 2000 cc which would mean 60kg higher minimum weight on the racing class. That can't be tolerated in any point of view. The choices were done between std 84mm and 84.8mm bores. I ended up to std bore in few reasons. The std liners have hardened surface, which might be gone if reboring them to 84.8. Secondly new liners would not cost much more than reboring. There is also more head gaskets available for std bore.

Because I wan't try different cams in future, there must be enough valve to piston clearance. Even with stock cams, the valve to piston clearance was the limiting factor when dynoing the car. I use nord rods, stock valve reliefs on pistons, 46mm intake valves and VVT operates on opposite direction (advancing cam timing at mid rpm range with reduced travel..).

Paul offered his help on this and will design needed modifications. The plan is to have pistons with std 84mm bore, 5mm deeper valve relief on intake side and 3mm on exhaust (compared to stock TS pistons). The compression ratio is going to be 11:1 (or 12.1 with nord rods).

The 85mm versio weights 336g, so the 84mm can't be far from that. I also desided to go with light 70g pins

Now I feel quite confident with this piston issue and just keep waiting for them

Kimmo

[Mats]

Sounds really sweet.

Does the bores have a hardened surface? That sounds wrong, should be regular cast iron, I have successfully honed mine with regular tools and that would have been impossible with a hardened surface.

[Maurizio]

Nice info, when my machine shop saga not will end soon, I will be shoping for other pistons also...

Things to be changed were the bore and valve reliefs. 85mm goes over 2000 cc which would mean 60kg higher minimum weight on the racing class. That can't be tolerated in any point of view. The choices were done between std 84mm and 84.8mm bores. I ended up to std bore in few reasons. The std liners have hardened surface, which might be gone if reboring them to 84.8. Secondly new liners would not cost much more than reboring. There is also more head gaskets available for std bore.

Std gasket have a bore of 85 mm if I remember correct. I know it is not legal but how is the difference checked , who can tell using 85 mm instead of 84.8 mm pistons.... and there is no substitude for cc's

[kterkkila]

Does the bores have a hardened surface? That sounds wrong, should be regular cast iron, I have successfully honed mine with regular tools and that would have been impossible with a hardened surface.

I've been told so, but not really sure about it? Does anybody have other opinions? I may be wrong with that. That wasn't only reason for going with std bore, but one favourable aspect.

[kterkkila]

Std gasket have a bore of 85 mm if I remember correct. I know it is not legal but how is the difference checked , who can tell using 85 mm instead of 84.8 mm pistons.... and there is no substitude for cc's

That's correct, the std gasket have 85mm rings. I guess that's true for other replacement gaskets too, when offering them for 84mm bore. If having 85mm gasket perfectly positioned with 85mm bore, I guess there isn't any problem.

How many mm's the fire rings of the gasket can go over the cylinder bore edge? I don't have right answer for that, but have had failures with too small fire rings in past..

I also asked from Spesso if their Nord race gaskets were good for 85mm bore, and the answer was negative, only for 84mm. Of cource can't be 100% sure if the e-mail handler knew everything about the topic.

Opening of engines is very uncommon in our class, but it's possible. Probably you never got caught from that reason, but the real displacement of race cars is one hot topic. I may loose two hp's here

Kimmo

[Micke]

So I've heard too.

For sure the TS has harder sleeves than the old Nord.
This you can see as the TS with 200 tkm doesn't have a "blue car in the mirror" like the old ones. Durability is way better.

[Mats]

Blue car in the mirror?

You mean burning oil? I have seen a lot of blue smoking TS engines...

[Zamani]

I thought the problem with Nords and blue smoke is poorly tuned carbs causing some oil wash down of the liners particularly on the intake valve side of the liner.

[Micke]

The old liners tend to be totally shot after 150-200 tkm.

Of course there are TS engines smoking as well.
In my experience they last much better. Even my father's 164 doesn't smoke with 336 on the odo. My bro's 75 was shot but didn't yet smoke bad with >400 on the clock. I opened two of my 75 TS engines and both have liners in mint conditions. Unknown mileage but enough for sure.

[Zamani]

Probably just like why Alfasud rust more than 75s. Quality of materials during the production period.

[Mats]

Have anyone ever opened a TS engine and found the Pistons not scuffed on the intake side?
The cars I have seen (ts and turbo) have all ran very rich during WOT. Remapping without even touching the hardware usually is very good for power and economy.

[kterkkila]

Have anyone ever opened a TS engine and found the Pistons not scuffed on the intake side?
The cars I have seen (ts and turbo) have all ran very rich during WOT. Remapping without even touching the hardware usually is very good for power and economy.

Never seen one.

My TS pistons have some scuff marks on the exhaust side too. Because intake side is the pressure side there should be always more wearing than at exhaust side, but could it really be mostly caused by being too rich at WOT? Maybe high throttle opening at low rpm's could be one big reason as it selves? Shame that there isn't oil spraying holes or nozzles..

[TS_turbo]

... Shame that there isn't oil spraying holes or nozzles..

alfa 155 2,0 TS block have oil spray nozzles but any one know is it the same block as 75 TS?