C20xe oversized pistons

[benton101]

Im looking for some info before embark on boring my c20xe bigger.
Am I correct in saying it has a ratio of 10.8.1 and pistons of 86.5mm?

I'm looking at set of pistons and rods on eBay and there is to sets
1. Is 87mm with a comp ratio of 8.5.1
2. Is 87mm with comp ratio of 10.5.1

I'm thinking number 2 but any suggestions please guys would be great.
Cheers

[Mike]

Standard 20XE pistons are 86mm Ø (with rings fitted)

[benton101]

Cheers mike.

Anyone else with any info on which would be best?

[Old man Jimbo]

The ones with a ratio of 8.5 to 1 are for turbo applications..

[philip]

10.5:! cr on standard pistons
11:1 cr on flat top pistons

then anything up to 12.5:1 cr with likes of omegas, wossners, accralites, cp etc, those figures tend to be based on a un skimmed head too.

stock bores are as said 86mm

what do you want from the engine, how much you got to spend on your build? can suggest few parts thats all.

[benton101]

10.5:! cr on standard pistons
11:1 cr on flat top pistons

then anything up to 12.5:1 cr with likes of omegas, wossners, accralites, cp etc, those figures tend to be based on a un skimmed head too.

stock bores are as said 86.5mm

what do you want from the engine, how much you got to spend on your build? can suggest few parts thats all.


cool, so i would would be best with the 10.5.1 87mm rods and pistons then.

im trying to get a 2100cc block with steel internals. iv not got a budget but trying to keeps the costs reasonable mate.

can i use the standard crank with the steel internals? how much power can the crank hold?

any help is appreciated?

[philip]

need 88mm pistons to go to about 2090or so cc. is the car going on tbs? spec of head etc? how much power? i can write a full list of parts needed, but need to know abit more about what your building thats all

standard early crank is what you'll ideally need, lighter and capable of about 9k rpm in bursts, but will do 8.5k all day balanced.

[Old man Jimbo]

stock bores are as said 86.5mm



Are they? I thought they're 86mm standard?

[Mike]

Are they? I thought they're 86mm standard?

This^

Mine measured 86 Ø before a rebore as its now got Omega 86.5s in which didnt fit in before (obviously). The orignal MAHLE's Ive still got here are 86 Ø.

[Andy]

standard pistons are 85.95,bores are 86mm

[philip]

doh! ment to put 86mm haha, well thats the finished bore size, pistons tend to be about 85.95-97mm from the ones ive seen

[benton101]

need 88mm pistons to go to about 2090or so cc. is the car going on tbs? spec of head etc? how much power? i can write a full list of parts needed, but need to know abit more about what your building thats all

standard early crank is what you'll ideally need, lighter and capable of about 9k rpm in bursts, but will do 8.5k all day balanced.
Cool. I have 45mm tbs the highest lift cams for hydraulic lifters, tbt exhaust manifold. No head work done, I've still to remap the ecu but I think I should have about 200bhp. Do you now where to get and how much 88mm pistons? How much power do you think that the bigger pistons will gain

[philip]

bigger pistons id only suggest if were going for an all out race engine as after 88mm if you have a meltdown ur blocks scrap, if went with 87mm or 87.5mm you have another overbore that may salvage the block.

pistons i can supply. omega, accralite, cosworths, i tend to use omegas as there one of the best/proven pistons about but are £460 +postage a set, can also supply rods, and any other part you would need tbh.

what spec are the cams and what ecu have you got?

[Gareth_C]

Cool. I have 45mm tbs the highest lift cams for hydraulic lifters, tbt exhaust manifold. No head work done, I've still to remap the ecu but I think I should have about 200bhp. Do you now where to get and how much 88mm pistons? How much power do you think that the bigger pistons will gain

Hi mate sounds like you have a good base there I’m running 88mm pistons and as Philip said the block is a one shot pony so if your wanting a bit more longevity out of the engine then drop to the 87-87.5mm pistons. The other thing I would suggest is looking at doing something with the head as you have a good intake system and if you mean BTB exhaust a good exhaust but the head will restrict it a little. Take a look at my engine build on my project thread for some it ads on the engine spec you want:

http://www.pngclub.com/forum/showthread.php?145354-My-XE-nova-on-throttle-bodies-(Project-275-bhp (http://www.pngclub.com/forum/showthread.php?145354-My-XE-nova-on-throttle-bodies-(Project-275-bhp))

All my engine work was undertaken by Steve (AKA steveboyslim on here, migweb & Vauxsport) give him a pm and he will point you the right direction.
Cheers Gareth

[benton101]

bigger pistons id only suggest if were going for an all out race engine as after 88mm if you have a meltdown ur blocks scrap, if went with 87mm or 87.5mm you have another overbore that may salvage the block.

pistons i can supply. omega, accralite, cosworths, i tend to use omegas as there one of the best/proven pistons about but are £460 +postage a set, can also supply rods, and any other part you would need tbh.

what spec are the cams and what ecu have you got?

i see what your saying phill. il stick with the 87mm pistons and rods i was going to put in.
cheers phill but iv looked at ebay in america and there is a company that sells pistons and rods for $575.

my cams are made by kent but i cant remember the number. im running a DTA pro 40 ecu with a brand new dta wiring loom made by them on order.

[benton101]

Hi mate sounds like you have a good base there I’m running 88mm pistons and as Philip said the block is a one shot pony so if your wanting a bit more longevity out of the engine then drop to the 87-87.5mm pistons. The other thing I would suggest is looking at doing something with the head as you have a good intake system and if you mean BTB exhaust a good exhaust but the head will restrict it a little. Take a look at my engine build on my project thread for some it ads on the engine spec you want:

http://www.pngclub.com/forum/showthread.php?145354-My-XE-nova-on-throttle-bodies-(Project-275-bhp (http://www.pngclub.com/forum/showthread.php?145354-My-XE-nova-on-throttle-bodies-(Project-275-bhp))

All my engine work was undertaken by Steve (AKA steveboyslim on here, migweb & Vauxsport) give him a pm and he will point you the right direction.
Cheers Gareth


thats a good build you got there gareth, i had a little nosey. whats the piston size sitting at now? is it still road legal with the plastic windows? is it a pain to change your documents for the MOT?

[philip]

have you got a link for the rods/pistons matey? dont forget import duty, tax etc with importing

[Gareth_C]

thats a good build you got there gareth, i had a little nosey. whats the piston size sitting at now? is it still road legal with the plastic windows? is it a pain to change your documents for the MOT?

I run the cosworth pistons which with the rings are bang on 88mm iirc, yes the car is fully road legal the side and rear windows can be plastic, but the windscreen has to stay glass for an mot. the documents are ok you fill in the change of engine on the V5 log book and most likely the dvla will ask for an engineers report. I can mine done at a mot station and it cost £15

[benton101]

Yeh I'm remembering about the duty. The owner of the shop he is giving a lower value so it helps on the tax haha

[yingxuy]

A car on TBS? Head and other specifications? How much power? I can write a complete list of required parts, Wedding Cufflinks (http://www.meritline.com/Cufflinks---c-13571.aspx) but you need to know all of the building is abit more.