boring 1g rod to fit 2g piston

[1988talon22]

Originally Posted by 1988talon22
Hi guys, I brought my 1g rod and 2g piston into the shop. I got the rod bored but they said the piston freeplay is too tight and they need to do something to it to give it more space.

When you already got a 1g Rod & stock 1g piston, it would move side to side. But for the 2g piston u can't move it side to side, you can just wiggle it a little bit. They wanted to charge me $270 for that, so I got it back. They already bored out the rods for me. Anything will help. Do you have any advice on what I can do with the rods since they already bored the small end?? Thanks

 

[grdsm]

wtf?????

 

[Jeff99GS]

Dude, your post is almost UN-Readable?!?!!

You need to Narrow the rod like in the picture below.

 

[My1GLaser]

Hi guys, I brought my 1g rod and 2g piston into the shop. I got the rod bored but they said the piston freeplay is too tight and they need to do something to it to give it more space.

When you already got a 1g Rod & stock 1g piston, it would move side to side. But for the 2g piston u can't move it side to side, you can just wiggle it a little bit. They wanted to charge me $270 for that, so I got it back. They already bored out the rods for me. Anything will help. Do you have any advice on what I can do with the rods since they already bored the small end?? Thanks

I mostly fixed your post for you. Holy f_ck man. You have to do better than that or you aren't going to make it long on this site.

The 1g wrist pin is 21mm and the 2g wrist pin is 22mm. So if you try to jam a 22mm pin into a 21mm hole it will be tight. Do you know what wrist pin is being used? The 1g rod hole is only 21mm and will need to be bored to 22mm to work correctly. What size is the hole in the small end of the rod right now and did you actually pay them for anything?

Edit: Thank Jeff for the help. I didn't know about the narrowing part.

 

[1988talon22]

well what they did was bore the rod smaller end but for the piston they have to bore it too cause when u put in the pins there not enough space for the rod to move cause usually wen u install them they should have room . but for the piston there no room so doesnt matter if the rod were bored they need to bored out the piston too so that what i meant . because when u stick in the rod there a hole about 1inch long where it goes that hole space is to tight its not the hole where the pin goes i think i got some nippo 2g jdm piston let see if i can get a picture for u guy sorry about my english never went to highschool only elementry so its kinda sucks

 

[Jeff99GS]

WOW is my post Invisible? You need to NARROW THE ROD end .100 as well as boring the opening of the rod.

Absolutely NOOOO Machine work should be done to the piston to fit it on a 1g big rod.

Print out the picture that I posted and take it to your machinist...If he can't figure that out then take it somewhere else.

 

[johnboy1065]

how did you get new rings for the 2g pistons? can you just order them from mitsubishi?

thanks,
John

 

[95eclipser]

why would you want a 7 bolt piston instead of a 6 bolt on.. its dish is deeper then the 7 so it can hold more boost and the ratio is also small for better boost... i would rethink it man and you will prob end up ruining the rod in the end gl tho

 

[johnboy1065]

why would you want a 7 bolt piston instead of a 6 bolt on.. its dish is deeper then the 7 so it can hold more boost and the ratio is also small for better boost... i would rethink it man and you will prob end up ruining the rod in the end gl tho

I'm a newbie too DSM's

but from what I've read, the 1G "big rods" are stronger than the 2G rods. BUT the 2G piston's are stronger than the 1G pistons.

So basically your pairing them together to get a stronger rotating assembly

 

[95eclipser]

i dont know if that is completely true or not.. im not a guru but i have seen then up close an personal and i feel like the 1g piston would be the better choice through visual difference even befor we get down to the math

but here are some pics of why im saying that

1st pis is the rods 6bolt on top,7 on bottom
2nd pic is the pistons left is the 7 right is the 6

 

[95eclipser]

hope this helps..

 

[juanpac0]

why would you want a 7 bolt piston instead of a 6 bolt on.. its dish is deeper then the 7 so it can hold more boost and the ratio is also small for better boost... i would rethink it man and you will prob end up ruining the rod in the end gl tho

Higher CR.

 

[whe3ls]

1g pistons are 7.8:1 2g pistons are 8.5:1

 

[95eclipser]

ya those are the ratios i just looked them up again... higher cr is one way of looking at ...
i just like to be safe and would rather have lower just my opinion

 

[whe3ls]

i wouldn't start worrying about detonation problems @ 8.5:1. you really wouldnt start to see problems till 10.5:1 and higher, under higher boost lvl's.

 

[95eclipser]

i don't think you would have a tough time with detonation at that CF along as the fuel supply is free and you have a good spark.. and a cop would help too..

drew

 

[grimdsm]

Well.. to start 2g pistons are ok.... I personally recommend the evo 9 piston.
its kind of the poor mans forged pitson. They are forged aluminum, have a 22mm press wrist pin (which means no full floating rods), they have the skirt coating just like wiseco, they machine thetop surface, thicker wrist pin, 20% lighter than a 2g piston, and they have better heat transfer as well. sourced from dsm grave yard

 

[JayRolla]

i wouldn't start worrying about detonation problems @ 8.5:1. you really wouldnt start to see problems till 10.5:1 and higher, under higher boost lvl's.

Actually a 1g with a stock ecu and timing will have huge issues. I had all kinds of knock issues because of 2g pistons and stock 1g timing map. You can always get a way with more boost on lower compression. 8.5-8.8:1 is perfect for a boosted pump gas car. If running race gas, meth injection, e85.... than 9.0-10.5:1 would be more suited.

 

[JayRolla]

Well.. to start 2g pistons are ok.... I personally recommend the evo 9 piston.
its kind of the poor mans forged pitson. They are forged aluminum, have a 22mm press wrist pin (which means no full floating rods), they have the skirt coating just like wiseco, they machine thetop surface, thicker wrist pin, 20% lighter than a 2g piston, and they have better heat transfer as well. sourced from dsm grave yard

Not to mention they are 8.8:1

Man I remember years ago when I talked with two machine shops, slowboy racing, buschur, RRE and a few others. All said the same thing that I was an idiot and could not run evo pistons in my car. Now its all over the place. I had a set of evo 8's for like $50 and went with 2g pistons instead.

If I did it again I would have used some of those pistons. Next motor will be a forged stroker so I probably wont use those ever.

 

[grimdsm]

Yeah the 8.8:1 is tha shiot! I just dropped my motor off to dsm grave yard to have them build a Frankenstein with the evo 9's... I cant wait to get that sucker back

 

[dsm-onster]

i wouldn't start worrying about detonation problems @ 8.5:1. you really wouldnt start to see problems till 10.5:1 and higher, under higher boost lvl's.

I've so far cracked 8 1g pistons due too detonation from sweepign tunes and other small tests, tweeks and otherwize experiments

The 1g piston does have a distinct advantage. As pictured, the top ringland is much farther down the bore. Of course that helps with cracking. But the space between the 1st and 2nd compression ring cracked on every single 1g piston that I've ever damaged. No other damage. The 2g piston has a larger gap here.

It's my guess, but I say the 2g piston has plenty of meat between the crown and the first ring for anyone ever wanting to run a stock piston. And then it has a thicker/stronger gap between the 1st and 2nd ring. I still think 1g pistons are VERY durable considering they are stock cast pistons. But I think the redesigne of the 2g piston better balances the separation of the rings between the crown and wristpin.

 

[johnboy1065]

I don't think my question got answered above.....can you get new rings to put on the 2g or evo 8-9 pistons???

thanks,
John

 

[gettingwop]

why would you want a 7 bolt piston instead of a 6 bolt on.. its dish is deeper then the 7 so it can hold more boost and the ratio is also small for better boost... i would rethink it man and you will prob end up ruining the rod in the end gl tho

Welllllll...I mean if your considering pushing like 30 psi I would want lower CR. Most people are only using 15-20 psi which would make more power with a higher CR piston. The 2g piston, and slightly higher stock boost made the 2g the higher hp of the DSM's.

You won't be ruining rods if you do this, it's been done by many people with successful results. This will not be an experiment, unless the shop your at is a chop shop...Which it sounds like they aren't sure what is going on.

 

[grimdsm]

I don't think my question got answered above.....can you get new rings to put on the 2g or evo 8-9 pistons???

thanks,
John

dsm graveyard has em
DSM Graveyard - Your #1 Source for Used DSM Parts!

 

[Colt4G63 also]

Awesome pictures 95eclipser! Thanks! I've always heard about the 2g pistons massive superior ringlands, and discussed it here and there, but now conclusive proof. I feel like I've just seen a unicorn, or an extra terrestrial. I knew it was real, but now there's pictures and everything.

It's like you just pulled out some papers from your briefcase and said, "What you mean these dead sea scrolls? Why didn't you just ask? I've had them right here all along... next to the holy grail."

Where were you during all those thread discussions about the advantages of the 1g rod-2g piston combo?