Andrew77 wrote:Hi,
Doing my home work on a potential new engine for my GD Galant Rally Car. I am required by CAMS PRC (Production Rally Car) regs to run a engine variant fitted to my model at production. information I've found says the biggest engine fitted was the 4G52 Aston in the Japanese models. Therefore I must use this engine.
My Question is can you fit the 2.6L 4G54 internals into a 4G52, therefore taking it from 2.0l to 2.6l? Also seen a 2.6 taken out to around 3.0l does that mean that potentially you could take a 2l to around 3l or am I being extremely optimistic!!!
Are the blocks the same just machined differently to fit different internals?
Has any body done this?
If this is not possible what capacity can the 4G52 be maxed out to?
the 4G54 2.6l heads can be fitted to the 4G52, which series would be best considering that its going to get a lot of head work done and be coupled up to a set of twin 45 DCOE Webers?
Do not know much about the internals of these engines only have previous experience with Saturn engines.
Any info would be appreciated
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I had a quick read through the PFC regs just to see what they said before posting
first you wont bore a 4g52 to a 2.6 --- thats a 7 mm difference and there wont be any bore left
as metioned there was a 2.384 (4G53 ) vertion but it was and eng with a 98 mm stroke same as the 4G54 with an 88mm bore
you have to stay with the astron 1 head both the 4G52/54 astron 1 heads are the same and realy the biggest down fall if you wont to make the engine bigger
staying with the 2 lt will give you a wider spead of power with this head even ported
I built a 2 lt when I first ran my sigma at hillclimb it had a modest 84 Kw atw but had a good spread of power over a wide range
I also didn't know a lot about the astron back then
some off the spec at the time - the head was ported with most of the work to improve the inner radis on the inlet port and lifting the port a bit doing so - the guides were knocked out and most of the lump around the guide was taken out and bleaded before the guides went back in I tapered the section that was inside the port
I still used std valves but the seats were cut to the outside edge and the valve were back cut
I used a 35/75 cam with Crow double valve springs
I decked the block and sat the pistons prowd of the block by a couple of mm then machined a taper on the outside of the piston to deck height
then by fitting the head on a mill put the same taper in the head giving a tight squish band around the outside edge
the comp ran at 10.5:1
twin 45 mm DCOE13 webers with 37 mm chokes ( sorry cant remember what jetting I had )
the bottom end stayed stock apart from a little weight off the flywheel and the balance shafts removed
Knowing what I do now days I would pull more weight out of the moving parts - the crank with a bit of knife edging and fit a crank scaper
a lighter custom steel flywheel - a tilton race cluch ( or something that doen't explode - I had a presure plate explode so dont like cast things spinning at high speed any more )
I hope some of that could be helpfull even if its only food for thought