Compression Test Pressures

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February 3, 200224 yr

I'm confused about the minimum "on-spec" compression pressure for a UK spec TT. PAge EF & EC-70 of my UK workshop manual say 142 psi whereas postings elsewhere say 127 psi.

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February 3, 200224 yr

The higher pressure is for NA.

Compression pressure:

Standard: 12,85 bar (186 psi) for NA ; 11,79 bar (171 psi) for TT

Minimum: 9,81 bar (142 psi) for NA ; 8,83 bar (128 psi) for TT

Maximum difference between cylinders: 0,98 bar (14 psi)

Maciej

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Project 1547 - Out of the Blue

Awesome Z.

By Gaz 300 · 6 hours ago6 hr
My daughter calls it Toothless the Dragon: My ‘95 TT Z

After many hours research and consulting OCS, I decided to try something somewhat new with my piston rings.

I have decided to run Total Seal Gapless pistons rings. The setup includes a gapless top ring, with conventional second and oil control rings. To my knowledge I’m the only person in the UK to be running gapless rings on a VG30, but I know of at least one other in the states that have shown very positive results.

The term gapless is a bit of a misnomer. It’s a 2 piece ring, with their individual ring gaps rotated 180 degrees from each other, effectively making the area around the ring gapless. The positives include virtually 0 blowby (so a 0-1% leakdown vs 5% on a conventional ring), increased vacuum and reduced oil fuel dilution. The other benefit is you can run a larger ring gap on the 2 pieces, allowing the a wider margin for thermal expansion without the downside of increased blow by
The only real downside that I can see is the cost, at around 30% more than a CP Piston ring pack.

Hopefully this will help with slightly improving my idle vacuum (due to my cam profile) and a generally more efficient engine.

By nickz32 · 18 hours ago18 hr
My daughter calls it Toothless the Dragon: My ‘95 TT Z

Also spent a bit of time with the burrs to clear out the casting debris and stress risers from around the bottom of the block around the crank journals.
This casting debris is from the imperfect casting mould that leave small sections of iron/sand mix still attached to the main casting. In certain situations, harmonics can release bits of this debris which then has the potential to destroy the bearings, an engine, by being circulated by the oil system.

Stress risers are similar. They’re very fine ridges in the casting that can form a weak point. Simple remedy is grind them back flush.

By nickz32 · 18 hours ago18 hr
My daughter calls it Toothless the Dragon: My ‘95 TT Z

Well I got my block back from OCS last week and have started on the block prep for deep clean and assembly
first job was to clear the excessive casting flash in the centre coolant channel and smooth the entry point out. Out came the long shank tungsten carbide burrs. A small but positive improvement

By nickz32 · 18 hours ago18 hr
Project 1547 - Out of the Blue

Nice to see all those upgrades make it onto the car, congrats!

By nickz32 · 18 hours ago18 hr

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Compression Test Pressures

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Project 1547 - Out of the Blue

My daughter calls it Toothless the Dragon: My ‘95 TT Z

My daughter calls it Toothless the Dragon: My ‘95 TT Z

My daughter calls it Toothless the Dragon: My ‘95 TT Z

Project 1547 - Out of the Blue

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