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Re: XJS V12 twin turbo
Posted: Mon Jul 28, 2014 8:13 am
by jenko
starting to take shape. Before you go too far think about changing spark plugs ,injector placement ,my runners are 100mm from flange to opening and just leaves enough room to change plugs .
Re: XJS V12 twin turbo
Posted: Wed Aug 20, 2014 2:22 am
by Flint Ironstag
Sweet. Any more news? There are lots of people following this with great interest
Re: XJS V12 twin turbo
Posted: Wed Feb 25, 2015 4:52 pm
by Flint Ironstag
Any updates on this project?
Re: XJS V12 twin turbo
Posted: Wed Mar 25, 2015 2:48 pm
by CHEQUERED TUNING
Dont swap out the pistons to the 6l ones 6.5:1 is waay to low, anything even on pump to 10.5:1 is fine when tuned right. the factory comp on the early ones was around 9.5:1 which is perfect for response / power.
If its the 12.5:1 version run it on e85 and limit it to 15 odd psi.
Re: XJS V12 twin turbo
Posted: Mon Mar 30, 2015 8:46 am
by jenko
piston mod for v12 to stop detonation eating head gasket opposite spark plug and allow higher valve lift
Re: XJS V12 twin turbo
Posted: Mon Mar 30, 2015 5:48 pm
by Charlescrown
Love the size of the gudgeon pin on the right. Heavy as. IT looks deceptive with compression ratio. How much difference is there? The one on the left looks like it has a bigger squish area so probably wont need as much timing.
Re: XJS V12 twin turbo
Posted: Mon Mar 30, 2015 8:10 pm
by jenko
the one on the right is 9:1 the one with squish is 10.6:1 runs max timing at 32 deg btdc and 200 grams lighter
Re: XJS V12 twin turbo
Posted: Tue Mar 31, 2015 12:26 pm
by Holden202T
yeah and look at the difference in the ring grooves! probably half as much drag there! and the shorter skirts and removed sections on the side of the pin all helps to reduce weight and drag!
I should take a photo of the stock pre efi buick pistons I have, they are very old school looking like the one above on the right, you can just see the weight in them!