XU10 8v Head corrosion

[DamirGTI 345]

Picking bits for building 2.0 T engine .

 

I have one head cracked between the valves , and seems like the second spare head is kinda questionable too ..

 

Thoughts on this one please ?

[DamirGTI 345]

.... pitting on this area seems very close to the head gasket fire ring .

 

Not sure if it needs welding , or juts a skim to clear up a bit .

[petert 607]

Dig out the tooth decay and weld it. You can save just about anything these days.

[DamirGTI 345]

Welded up , skimmed ..

 

But now measuring the combustion chambers i'm down 5cc on this head compared to my other 2.0 T head .

 

This welded head is now 28cc , and my other scrap head measures 33cc (seems like virgin aka non skimmed) .

 

Roughly how much of a CR increase does 5cc makes out on XU10 8v ?

 

I've option of making either RGY or RGX engine (that's if i can save/press out RGX pistons as two of them seized up in the block) .

Would prefer RGX because of better squish clearance by using RGX pistons , but with this 28cc head in combination me thinks CR will be bit too high for turbo engine ?!?

 

Anyone knows how much cc is in the piston dish volume on RGX piston , and how deep down the bore is RGY flat top piston at TDC please ?

 

D

[SRDT 198]

I can only find the same compression height of 40mm for both pistons but it's only on one document so there could be an error.

Both types are fine on a stock engine but early flat top RGY pistons are said to be stronger, maybe the lower CR of RGX pistons helped mitigate knock and PSA could get away with a cheaper and weaker alloy.

 

Looking at PSA documents CR with RGY flat top pistons is 8.5:1 vs 7.9:1 with RGX dished pistons.

http://www.ckc.dk/pubs/MAN008930.pdf

Page 299 for RGY and 316 for RGX

[DamirGTI 345]

Strange , i always thought that the early RGY was the low compression engine and the later RGX was the one with higher compression

 

Much of the specs and technical data on the net says it's the opposite too , very confusing engine !

 

I have here only RGY engine in bits and pieces , need to drag the 406 at my place and see what's inside the RGX variant .

 

Now that reminds me , i have an OE PSA book with piston specs for entire XU engine range , need to find it hopefully there's some info there for 2.0 T engine .

 

Was there ever repair manual for this engine ?

I couldn't find any , none in the Haynes books for 406 only some limited info/data about 2.0 T in early blue book for XM .

 

Me thinks they went for different piston design on later RGX engines to lets say "modernize" the engine a bit , to add some engine response off boost , improve overall fuel mixture making it more homogeneous , adding some turbulence to enhance heat transfer , more knock/detonation resistance and more power (yet they only managed around 6hp with comparison to RGY which really isn't much) .

Quite a few positive benefits from improving squish clearance on an engine .

 

D

 

 

[SRDT 198]

Looking at the power and torque curves the early engine looks restricted to ensure constant torque then constant power. The later engine has higher peak values but also more rounded curves.