jumper5836

Anyone know what the bore linings are?

Serge944

It should be alusil, since that's what all the other 9A1 DFI engines use. All the previous GT3s (and turbos and GT2s) had cylinder liners which were nikasil coated. 991 GT3 does not use liners.

I don't think it matters though. All the 996/997.1 throw-away engines (non-mezger) had a Lokasil coating, which was a disaster and Porsche has since abandoned it.

Serge944

http://photos.stuttcars.info/upload/...1-gt3-1303.pdf

Their promotional literature confirms alusil.

jumper5836

Thanks

tmg57

Maybe the reason the 9A1 is not racing yet? Mezger easier to rebuild/repair?

jumper5836

There would be no reason they couldn't use it in the 9A1. The Cayenne V8 was alusil but they made the Turbo and S with Nikasil. Alusil engines are suffering from premature cylinder wear now in them. 9A1 engine will follow suit once they get up to the same mileage as what the DD Cayennes see.

tmg57

I didn't mean Nikasil, I meant cylinder liners. Is that an advantage for a race motor, or not?

911rox

Yes... replacing them returns bore to OEM rather than being bored out and oversized....

tmg57

Right, so are we getting closer to explaining why the Mezger block is still the race motor?

Maybe the 9A1 is not a suspect design as many people have implied, but it would make sense that the engine that is cheaper to rebuild might be the choice for that reason alone.

911rox

The mezger is by no means cheaper to rebuild... Not sure what the new GT3 motor is worth but as a crate motor the GT1 motor used to cost about 3 times that of a Carrera/S motor...

tmg57

I don't know the cost of Mezger vs. a GT3, either. But I can't imagine that it would be cheaper to toss a GT3 motor every 40 hours, or so, than to rebuild a Mezger. I say toss the GT3 motor because I'm assuming that it would be very difficult (expensive) to rebuild a GT3 motor given the block design and the need to rebore and recoat the cylinders. I'm not an engine builder or race mechanic, so maybe I'm overlooking something?

911rox

The cost of a large volume mass produced engine block would be less than the labour and parts to refresh the mezger engine block... Labour would be a contributing factor... And the greater number of parts that make up the older engine...

Serge944

It is NOT Alusil that is causing failures - it's Locasil.

Even if it was, I think it's a moot point. The components in a 991 GT3 engine will reach their endurance limit and require rebuild before the coating becomes an issue, especially with the kind of use most cars will be subject to.

Serge944

It would be no more difficult to rebuild the 991 GT3 9A1 than a Mezger. Now you're replacing the case vs the liners. No big deal. No race team would ever rebore it.

In fact, I'll say it will be easier because the way the cylinder liners and water jackets are configured in the watercooled Mezger make engine assembly slow and tedious.

tmg57

Thanks, Serge, makes sense. I'm still trying to figure out why Porsche won't race the 9A1 when it's obvious that they are causing so much consternation among the faithful.