How much over standard piston can I go

[2Lgalant]

Hey guys what's the biggest you can bore a 4g52 out to was thinking of 40' thou oversive is that to much or is that ok

[Superscan811]

1mm over is fine but an extra 7.1mm + 8mm stroke would be better...


Cheers.

[2Lgalant]

Ok then so 40 thou is no where near max

[Superscan811]

an extra 7.1mm + 8mm stroke

=2.6L

[81GL]

but an extra 7.1mm + 8mm stroke would be better...

...Nothing wrong with the 2lt ya cheeky bugger!

& yeah, think you'll find 1mm over size is about it for off the shelf pistons. Not sure if the come in .5mm ? may do, ask who ever is doing the boring if they can get them in that increment.

[2Lgalant]

Lol fair deal I'll ask

[krohny]

our 4g32 is bored 2.6mm.. if you can find pistons the right size id say your pretty safe with 1mm over

[Scorpma82]

4g32 is now a 2.6L??

Aren't they are 1.6L to begin with??

What did you do get THAT sort of difference??

[A112H]

Bored 2.6mm oversize not taken out to 2.6lt, lol
Too early for ya Scorpma82??

[Scorpma82]

oh yeah.....ur right lol

i was gonna say....how the hell was that done!!!!! lol

[A112H]

lol, would be a few quick old Galants around if it was possible thats for sure.
I did read on here somewhere that someone is trying to get 3.0 out of his 2.6 I think 2.8 is as far as I have ever seen one go. If he does it I will be very interested in how

EDIT; just realised that was you, lmao

How are you planning on getting it out to 3.0

[Scorpma82]

none the less, 2.6mm oversize is quite an achievement

and that person trying to get 3.0L out of the astron is me

i havent worked out how to do it yet but reading alot of useful (and useless) information on piston sizes and crank stroke on carbuddy.com.au

[cheaterparts]

but an extra 7.1mm + 8mm stroke would be better...

...Nothing wrong with the 2lt ya cheeky bugger!

true but there can a huge difference in performance between the two

[Scorpma82]

Hey cheater,

You got raceing GE of yours running yet?

[cheaterparts]

Hey cheater,

You got raceing GE of yours running yet?

No - but scott the ebay junky is taking away his scorps and I will be able to move some stuff around and get back in my shed
I wont to get it going again

it will take up fishing time though

[Scorpma82]

fark fishing!!!! not exactly an exciting sport IMO lol

I wanna see a serious Astron in serious Anger!!!!!



In all seriousness, be great to see a Sigma actually racing....i'd do it myself just its just too damn expensive for me....i'll have to stick with a serious streeter (not that there anything wrong with that)

[cheaterparts]

fark fishing!!!! not exactly an exciting sport IMO lol
be great to see a Sigma actually racing....i'd do it myself just its just too damn expensive for me..

dont worry fishing has its moments I caught 6 gummy sharks yesterday on a kayak and am now targeting toothies
wonting to catch a bronzie this year in the kayak

as for the cost thats another reason the sigma has been parked up - I've had the parts to do the rebuild for some time
but if I fixed it I would have wonted to play with it

[Scorpma82]

yeah i know how u feel

i quoted on entry fees to race in the 2L Sports Sedans and was told $500 at Sandown

Just about dropped dead when i heard that !!!!!!!!!

[Rally_2.6LC]

our 4g32 is bored 2.6mm.. if you can find pistons the right size id say your pretty safe with 1mm over

So what pistons do you use to get a 4G32 out 2.6mm? What size does that make it?
Very interested


Matt

[krohny]

They are .5mm oversize 4g35 high comp pistons.
Don't remember the rest of the exact numbers, I think it makes it about 1850 or so? Don't quote me on that though

[DanTurboLancer]

Correct me if im wrong here folks..
Usually 60+ is the most off the shelf pistons goto.
40+ is fine.
Are you boring out because you want larger capacity?
Or rebuilding and bores are crook?

Either way, you should get the block crack tested then get them to measure up your bores so they can recommend the minumum amount you need it bored.
If its a decent machine shop they will ask you to buy the pistons, and then measure the pistons to make sure they are all ok.
Then machine the bores to suit the accurate clearances for the pistons and rings

[BAD-SIG]

I've been talking to a local highly experienced engine builder and he advised me it's impossible to bore an Aston 2000 block from stock 84mm to the 2600's 91.1mm. He said the largest I can make it is either 2223cc with 2.6 crank and 85mm bore, or 2275cc with 2.6 crank and 86mm bore. I want to keep the 2 litre block so all numbers match. Unless anyone can give me or sell me a cheap narrow block 2.6 so I can recondition it and bore that out instead

[Rally_2.6LC]

If you want numbers to match, get a 2.6, shave it until no numbers are left and re stamp it.......not unheard of.
I know of a "1.6" litre that looked a lot like a 4g54 once upon a time.

Cheers Matt