g4cn bore ### help

[suprasalas]

What's up you guys i need help with my G4CN. I know that the g4cn and the 4g67 are the same blocks with an 81.5mm bore (1.8). I've been reading some threads that you can bore out the 4g67 to an 85.5mm bore same as the 4g63? That is a 4mm (.157) difference.

Does the block have enough clearance to bore it out to an 85.5mm? I have a 4g63 and the only difference I can find is that the g4cn doesn't have Oil squirter and the bore is smaller. I mean the crank and rods look the same from the 4g63 (6bolt) please help me I am really confused.

PS the 4g63 block doesn't work!!!

 

[BogusSVO]

I have not bored a 1.8l block.

But from what I have bored, I just do not see any block going .157 over with out having paper thin cylinder walls.

The only way I can think of finding out if the block will bore that far is to have it sonic checked for thickness.

 

[suprasalas]

From what I've been reading the g4cn is the same block as the 4g63 but under bored.
Check this site out 4g67 turbo.. - Page 2 - Zerotohundred.com
Do you know a estimate price for getting my block sonic checked?

 

[JayB12]

I have both a g4cn(4g67) and 4g63 block lying around. I have also heard that they both from the same casting but different machine work for each. Also, the stock bore for a 4g63 is 85mm, 85.5mm (.020" over) is the usual overbore. I took a quick measurement and the 63 has ~8.3mm between each cyl while the g4cn has ~11.3 (took measurements with old digi calipers and didn't clean any carbon before measuring.)

 

[suprasalas]

I have both a g4cn(4g67) and 4g63 block lying around. I have also heard that they both from the same casting but different machine work for each. Also, the stock bore for a 4g63 is 85mm, 85.5mm (.020" over) is the usual overbore. I took a quick measurement and the 63 has ~8.3mm between each cyl while the g4cn has ~11.3 (took measurements with old digi calipers and didn't clean any carbon before measuring.)

thanks
so it is a 4g63 but just under bored??

 

[JayB12]

thanks
so it is a 4g63 but just under bored??

As far as I know, that seems to be the case. Only differences are bore/pistons/rods/no oil squirters/no knock sensor. I also sold the crank from the g4cn and my friend is using it in his 6bolt 4g63 motor with no issues.

Also in your first post what do you mean by the 4g63 won't work?

 

[suprasalas]

Yeah I saw that my crank had an 88mm stroke same as my 6bolt. So the g4cn rods are not the same as in the 63. I'm assuming that the g4cn are weaker??
I said that because there is always a smart a$$ out there that is going to reply me with "why don't you just use your 4g63". My 4g63 is warp so bad I can't even bore it enough to fix it due to lean a/f mixture.

 

[JayB12]

So the g4cn rods are not the same as in the 63. I'm assuming that the g4cn are weaker??

The g4cn rods have an oil hole in the big end while 1g rods don't (probably because of oil squirters). That's the only difference I can SEE. I do have a feeling there would be a difference in length or pin size that you couldn't just use it in a turbo car. I could be wrong though. The rods are big and forged just like the 1g rods are so they are likely not weak.

 

[suprasalas]

Well I'm going to take my g4cn apart this week so I can start taking measurements and see the difference between the rods. Hopefully there the same so I can reuse them with 7bolt pistons or other aftermarket pistons. I'll post the measurements with pictures so everybody can see the difference between the both g4cn and 63 rods if there is any difference between both of them besides the oil hole on the big rod end.

 

[BogusSVO]

Just beacuse both blocks share the same diamentions, does not mean that when the block was cast they pourd the cylinder sleeves thicker.

Most factorys would not do this, for 2 reasons, cost and weight.

Look at the Chevy 305 and 350, both run the same crank and rods, but the 305 has a smaller bore 305 = 3.736 and the 350 has 4.00

But you can not bore a 305 out to a 350 bore

For this logic, I feel you will not be able to bore the 1.8 to the 2.0

As far as having the block sonic checked, I would say between $60-$100

 

[suprasalas]

I've been really wondering about the bore but first thing is to get my block sonic tested to make sure I have enough material to bore it out that wide and not have a paper thin cylindered wall.

 

[suprasalas]

i was looking through more forums and found this..

is it safe to bore 4g67 block to 86mm to fit 2g pistons??
i've heard so many pros n cons..
how about its reliability on long distance??

 

[BogusSVO]

What thread was that in?

 

[suprasalas]

i found it here..http://www.zerotohundred.com/newforums/tech-forced-induction/197322-4g67-turbo-6.html sorry it said 2j not 2g pistons

 

[BogusSVO]

WOW thats some horrid reading ....

I still doubt the block will go .157 over for what you want to do.

Most engines will go .060 or 1.5mm in a non performance NA

302/5.0 Fords go .040 max for a HI-po build
350 Chevy is .060 ( I saw a .080 once from a mass rebuilder)
2.3 Ford turbo .030/.040

I have personally cracked the cylinder bores on .060 NA builds

If you were closer, Id tell you to load up the block and come to the shop and bore it.......

 

[suprasalas]

jaja thats what i was thinking but theres some good info on it heres a little more info..

is it safe to bore 4g67 block to 86mm to fit 2j pistons??
i've heard so many pros n cons..
how about its reliability on long distance??

hi, its safe to bore from 81.5 till 86mm
till 87mm i'm not very sure as i had not tried it and don't know anyone does.

i myself also using 4g67 block, but i only bore till 85mm to fit in vr4 piston.

actually seeing is believing
if u had seen the 4g67 block, u will have definite confident that it will be able to bore till 86mm..

### the cylinder wall is so thick.. it actually looks alot like a debored VR4 block.

but many things u need to buy first to build a 4G67 block.

you need:
VR4 oil pump
VR4/Evo oil squirter
VR4 flywheel.
everything else can use back evo 1/2/3 ones.

these are really the hard to find loorrr.
especially the flywheel, most are condeem flywheel. crack and unusable, i found 2 last time. but both are unusable. the seller also lari already. cannot get my money refund. haih haih.
so i resort using a new JUN forge flywheel, cost me a bomb, about RM1000 per piece. ;(

But then if u already got the stuff ready, then you can start to play 4G67 block hehe...
else, your project could hang a long long time.

the other good about about 4G67 block is, its 100% compatible wif VR4 parts or the mat salleh call DSM parts. so u can absolutely change every single part of the engine with performance parts.
cool huh~~ hehe

 

[BogusSVO]

Who knows how nutty those guys are....

Thats still alot to bore, 4.5mm-5.5mm

At this point, all I will say is try it and see how it goes.

 

[suprasalas]

wow i found out that you can stroke them out to 2.3
http://www.zerotohundred.com/newforums/car-modification/228048-2-3-stroker-kit-on-4g67.html

I'm thinking of taking my block to get bore sometime after december due to christmas and new years.

ill upload the photo I took, everything looks the same as the 4g63 6 bolt

hey are the photo

 

[suprasalas]

So my measurements here they are for the rods and pistons.
Rod wrist pin-21mm
Rod length- 150mm
Piston top to piston pin- 35mm
Piston width 81.5mm
Same head gasket no differences at all

 

[whe3ls]

weight the crank it might be like 5 pounds lighter if its like the 4g67

 

[suprasalas]

will do tomarrow..

 

[suprasalas]

So today I was taking some measurements and found out that there is enough metal. The walls are 6.21mm thick. So if I bore it out from 81.5mm to 85mm there would be leave me about 2mm left over.
I was thinking about using my evo pistons with it. What would be a good ptw clearance?

 

[suprasalas]

good news you guys i got the block back from the machine shop bore out to 85mm. ill post up some pictures later on today.. all i need back from the machine shop are my rods and pistons.

 

[suprasalas]

Heres the block with arp bolts

 

[arrowhead]

Any news as to how this worked out, I imagine you should have the engine running by now unless you ran into a problem.