Boreing my 2gn need some advise

Darkwing · Post by **Darkwing** » Tue Jun 11, 2013 10:04 am

So my 2000 Highline block is starting to knock in the mornings, im assuming piston slap since its only got 320000miles on it

that being said im trying to figure out a safe boring diameter for the 2.0, i can get up to a 1mm overbore, (which will be kinda cool to do) but i dont want to weaken my block,

so far this car has a r/t head, 01 r/t cam, r/t intake and exhaust, a CAT delete UDP and a 60mm throttle. oh and head has been ported and polished.

after checking the org, I've decided to put in the DOHC pistons, grind off the corners, and possibly get a thinner head gasket, but i've done .02 bore on a intrepid 3.3 before and thats been my max

any other suggestions while im in the bottom end?

Hudson_Neon · Post by **Hudson_Neon** » Tue Jun 11, 2013 10:20 am

well generally piston sizes aren't measured in mm... but .020" is a common size to punch these blocks out at. DOHC pistons aren't gonna be any bigger in diameter, so that will defeat your original intention here. honestly, if you're looking to stay N/A go with this and select "2.0 SOHC", "10.5:1", ".020 Overbore", and "Eagle" and you'll have a pretty nice bottom end in that engine.

https://www.modernperformance.com/produ ... eterebuild

Darkwing · Post by **Darkwing** » Tue Jun 11, 2013 10:35 am

as much as i want to get that kit, this car is a automatic and the wife drives it, that being said im just planning on changing pistons and bearings, oil pump. putting 1200bucks or even the 550bucks for the forged pistons on modern is kinda a big risk for me since the wife just gets in and drives. now on my 2002 ill put the 1200buck in parts in lol.

my budget is basically 500-900bucks and that includes machining, and i know i can do it if i find the right max bore.

1MM is .040inch

Hudson_Neon · Post by **Hudson_Neon** » Tue Jun 11, 2013 10:54 am

500-900 including machining is gonna be pretty tough considering any overbore pistons are gonna cost almost 500 to begin with. if you can find cast pistons that are like .020 over or .030 over for cheap, go for it. i wouldn't recommend doing .039 over though

Post by **occasional demons** » Tue Jun 11, 2013 11:09 am

You can get overbore OEM type DOHC pistons from Rock Auto, for dirt cheap.

Sealed Power, 1.00 mm OS H853CP $175.16 set of 4 plus shipping.

so they aren't some ebay brand...

You will need to have the old pistons pressed off, and the new pressed on tho.

But that is still far cheaper than the full floating style that the performance pistons have.

Darkwing · Post by **Darkwing** » Tue Jun 11, 2013 11:12 am

i can get DOHC pistons for $60 a set thats the 1mm(.040) and rings are like a 100 bucks(also the .040). these are sealed power also. my machinist just did a 4 cylinder 2.4 boring to .020 decking and vat for 178 bucks

im not too sure how i can spend 500 bucks on just pistons.

Hudson_Neon · Post by **Hudson_Neon** » Tue Jun 11, 2013 11:13 am

hmm, that's interesting. guess i never really looked into replacing factory pistons with replacement overbore pistons that aren't performance on anything other than stuff i'm fixing for other people

Darkwing · Post by **Darkwing** » Tue Jun 11, 2013 11:14 am

occasional demons wrote:You can get overbore OEM type DOHC pistons from Rock Auto, for dirt cheap. Sealed Power, 1.00 mm OS H853CP $175.16 set of 4 plus shipping.

so they aren't some ebay brand...

You will need to have the old pistons pressed off, and the new pressed on tho.

But that is still far cheaper than the full floating style that the performance pistons have.

yup im getting my through my machinist, so thats where my prices are coming from

Post by **occasional demons** » Tue Jun 11, 2013 11:23 am

Altho, for ~ $900, if you are lucky, and score a cheap low mileage 2.4, you can have a nice little upgrade, depending on what brackets/misc items you can find used...

But then you don't want your woman pwning your ass on the street.

Darkwing · Post by **Darkwing** » Tue Jun 11, 2013 2:35 pm

occasional demons wrote:Altho, for ~ $900, if you are lucky, and score a cheap low mileage 2.4, you can have a nice little upgrade, depending on what brackets/misc items you can find used...

But then you don't want your woman pwning your ass on the street.

well if that ever happens ill just have to SRT my 2002 LOL!

nerox · Post by **nerox** » Tue Jun 11, 2013 3:27 pm

Hudson_Neon wrote:well generally piston sizes aren't measured in mm...

they are everywhere else in the world

Darkwing · Post by **Darkwing** » Tue Jun 11, 2013 6:43 pm

so has anyone tried .040 over?? LOL or is it not recommended?

Post by **occasional demons** » Wed Jun 12, 2013 7:14 am

I believe 1mm (.0393") is the biggest OS piston they sell. You can go to the max, but once something happens to the cylinder wall, you are looking for a replacement block.

If these were scarce, I would say keep it conservative, but finding another rebuildable 2.0 block isn't too difficult, yet.

Darkwing · Post by **Darkwing** » Wed Jun 12, 2013 9:56 am

occasional demons wrote:I believe 1mm (.0393") is the biggest OS piston they sell. You can go to the max, but once something happens to the cylinder wall, you are looking for a replacement block.

If these were scarce, I would say keep it conservative, but finding another rebuildable 2.0 block isn't too difficult, yet.

as much neons i've done here i believe there are too many 2.0 blocks out there in the world. lol. and i did get my dads (now wifes) 2000 neon to 320K with no problems at all still has the original transmission and original bottom end. obviously its all hiway miles. so i think ill chance the over bore at 1mm MAX size see how it goes, with the dohc and overbore, we should be running a 2.001L at 10.3:1 compression

(its just a guess dont correct me)

timk225 · Post by **timk225** » Wed Jun 12, 2013 9:57 am

Bore it enough to get clean straight cylinder walls and no more. The extra 1 cubic inch you might get from going bigger is not worth the thinner cylinder walls.

jrumann59 · Post by **jrumann59** » Wed Jun 12, 2013 12:13 pm

Hudson_Neon wrote:well generally piston sizes aren't measured in mm... but .020" is a common size to punch these blocks out at. DOHC pistons aren't gonna be any bigger in diameter, so that will defeat your original intention here. honestly, if you're looking to stay N/A go with this and select "2.0 SOHC", "10.5:1", ".020 Overbore", and "Eagle" and you'll have a pretty nice bottom end in that engine.

https://www.modernperformance.com/produ ... eterebuild

DOHC Pistons are higher compression than SOHC pistons that is why SOHC handle boost better than the 2.0 DOHCs did. The Early DOHCs that got boost ran SOHC pistons to lower the compression ratio.

That aside buy once, cry once. IF you are going towards performance save the money by nice forged pistons and do it right instead of spending the money twice.

r/tguy02 · Post by **r/tguy02** » Wed Jun 12, 2013 1:32 pm

i dont believe he's boosting it though james, so the cheaper option in this case wouldnt hurt.

jrumann59 · Post by **jrumann59** » Wed Jun 12, 2013 2:04 pm

r/tguy02 wrote:i dont believe he's boosting it though james, so the cheaper option in this case wouldnt hurt.

I get that he is looking for overbore options and compression options.

Post by **occasional demons** » Wed Jun 12, 2013 5:22 pm

It's just a cheap rebuild for his wife's car. Just looking for a cheap bump in CR. It won't gain much with 10.3:1, but should get better fuel economy. Our '96 SOHC has a DOHC bottom end, and it runs fine on 87 octane, but will also make better use of higher octane than a regular SOHC.

DOHC Pistons are higher compression than SOHC pistons that is why SOHC handle boost better than the 2.0 DOHCs did. The Early DOHCs that got boost ran SOHC pistons to lower the compression ratio.

In an SOHC, DOHC pistons are a higher ratio. In a DOHC, they are lower than a pre 2003 SOHC.

The SOHC engines were 9.8:1 and the DOHC were 9.4 or 9.6:1. The SOHC pistons with the DOHC head probably put it around 9:1 ish.

Hudson_Neon · Post by **Hudson_Neon** » Wed Jun 12, 2013 10:48 pm

jrumann59 wrote:
Hudson_Neon wrote:well generally piston sizes aren't measured in mm... but .020" is a common size to punch these blocks out at. DOHC pistons aren't gonna be any bigger in diameter, so that will defeat your original intention here. honestly, if you're looking to stay N/A go with this and select "2.0 SOHC", "10.5:1", ".020 Overbore", and "Eagle" and you'll have a pretty nice bottom end in that engine.

https://www.modernperformance.com/produ ... eterebuild
DOHC Pistons are higher compression than SOHC pistons that is why SOHC handle boost better than the 2.0 DOHCs did. The Early DOHCs that got boost ran SOHC pistons to lower the compression ratio.

yeah, i know that. but i was just assuming that, like most other people, he was thinking of just running stock DOHC pistons which wouldn't accomplish the overbore needed. but we've moved past all that and i've now learned that you can get cheap stock overbore replacements

wickedgood4684 · Post by **wickedgood4684** » Thu Jun 13, 2013 7:31 am

I say tear the engine down and have your machinist inspect the block to see how out of round the cylinders are. If it is in good shape and just needs a hone then that's money saved on your end. If it needs to be bored to be round again then your machinist will be able to tell you what over-sized piston you will need. Do not buy pistons until your machinist informs you as to which size you need.

Darkwing · Post by **Darkwing** » Fri Jun 14, 2013 10:13 am

i know it wont be in great shape for the miles its got, and i know im going to have to bore it since ive been hearing a piston slap in the mornings on cold starts. so i think ill go a 50mm or the 1mm.