N/T 1G. Bore over/ piston/ compression ? Selecting size and shopping list

[Dirt Eagle]

I found the set for 125$ on dsm graveyard (which i know everyone hates)
NPR Piston Set w/ Rings - 4g63 6 Bolt - Non Turbo - (9 to 1) comp. rating
w/ 85.75 (.03 OVER) or 85.5 (.02 over)

1g Eagle Talon---- N/T----. Goal of around 160hp. If I went this route I would be running at 2.2L? This would be with a 9:1 compression rating with 91 oct and 275 cc injectors, and bumping up my fuel pump, bore of cylinder, planning to buy a pre burned chip from frozen apps, new gaskets, deep cleaning, for around $300- 400 the budget id like to stay at for this quick build. I'm not being cheep it's my dirt track car and you don't dump much into them. Track is 3/8th mile

Would I be making any real gains?
Should i bore over .03 or .02?
What kind of timing changes would I need to make?
What horsepower and torque would I be pushing? I KNOW EVERYONE ASKS THIS
What other changes to consider?
What size over do you bore the block?
Since I'm not running crazy horsepower do i have to change rods?
Can I run stock crank shaft?

 

[randman2011]

Those pistons are meant to be OEM replacements. The standard 85mm bore and 88mm stroke net 1997.4cc displacement. The 85.75mm bore and 88mm stroke net 2032.8cc displacement. People generally don't overbore for displacement. It's usually because the cylinder walls were destroyed and had to be bored to make them smooth or round again. In my experience, people looking for more displacement get a bigger crankshaft and shorter connecting rods to bump up the stroke. The stock N/T pistons are 9:1 compression, so you're not gaining anything there. I would expect to see no noticeable gains on this setup over stock. You can go lighter so that (along with other mods like stiffer valve springs) you can spin faster, or increase displacement via stroke, but this is not the route to go to get more power.

To answer your other questions, this wouldn't require a change in the crank or conn rods since you're not really changing anything. Same goes for timing.

 

[Dirt Eagle]

Those pistons are meant to be OEM replacements. The standard 85mm bore and 88mm stroke net 1997.4cc displacement. The 85.75mm bore and 88mm stroke net 2032.8cc displacement. People generally don't overbore for displacement. It's usually because the cylinder walls were destroyed and had to be bored to make them smooth or round again. In my experience, people looking for more displacement get a bigger crankshaft and shorter connecting rods to bump up the stroke. The stock N/T pistons are 9:1 compression, so you're not gaining anything there. I would expect to see no noticeable gains on this setup over stock. You can go lighter so that (along with other mods like stiffer valve springs) you can spin faster, or increase displacement via stroke, but this is not the route to go to get more power.
To answer your other questions, this wouldn't require a change in the crank or conn rods since you're not really changing anything. Same goes for timing.

I thought that it was 7.5:1 but I was wrong you are correct. The turbo is the 7.5. I guess I wont be gaining any compression.

If I am increasing the bore size how am i not increasing displacement when I would Honing the cylinder to a smooth surface and creating an .030 of fuel and air space filled with my extra cc's from the injectors and remapping the maf? Do i have the understanding of displacement wrong?

So if we run with what you're saying i need longer stroke? Ok I can not afford to buy a new crank unless anyone has a suggestions of a used one? So that leaves me with rod length. What is a safe added rod length? Can I then use my stock pistons in your opinion? I still am not convinced that the added bore size wouldn't create more power.

 

[randman2011]

The bore increase does increase displacement, but those pistons would increase it from 85mm to 85.75mm, which is not a big increase. Likewise, displacement goes from 1.997L to 2.043cc. That's a 1.7% increase in displacement. 0.045L. The difference is so incredibly negligible that you would probably gain more power from the "deep cleaning" that you talked about earlier. You also cannot change conn rod length without changing either the crankshaft or pistons to compensate. Since the crankshaft alone determines stroke and you wouldn't be changing the crankshaft, your stroke and your displacement would stay the same regardless of what length con rod you have. A longer con rod will push the piston into the head and break everything. A shorter con rod would just decrease compression. Neither are going to give you any gains. The cheapest options for more power on an NT are probably high revving cams or higher compression pistons, since I know that stroker kits are pretty expensive.

If there's nothing wring with your current pistons and you aren't willing to put out more money for high compression ones, if there are any, then don't worry about replacing them. I am both a turbo guy and a 2G guy, so maybe 1GNT drivers might have better suggestions, but those pistons are not the way to go for more power.

Edit: Suggestions for 1GNT upgrades from elsewhere on the web

• Air Intake
  Replace the stock air box with a solid pipe and high-flow cone filter.
• Cat-back Exhaust
  Replace the stock cat-back exhaust with a higher flowing model.
• High-Flow Cat
  Replace the stock catalytic converter with a higher flowing model.
• Exhaust Header
  Replace the factory exhaust manifold with a tubular steel header.

 

[Dirt Eagle]

The bore increase does increase displacement, but those pistons would increase it from 85mm to 85.75mm, which is not a big increase. Likewise, displacement goes from 1.997L to 2.043cc. That's a 1.7% increase in displacement. 0.045L. The difference is so incredibly negligible that you would probably gain more power from the "deep cleaning" that you talked about earlier. You also cannot change conn rod length without changing either the crankshaft or pistons to compensate. Since the crankshaft alone determines stroke and you wouldn't be changing the crankshaft, your stroke and your displacement would stay the same regardless of what length con rod you have. A longer con rod will push the piston into the head and break everything. A shorter con rod would just decrease compression. Neither are going to give you any gains. The cheapest options for more power on an NT are probably high revving cams or higher compression pistons, since I know that stroker kits are pretty expensive.

If there's nothing wring with your current pistons and you aren't willing to put out more money for high compression ones, if there are any, then don't worry about replacing them. I am both a turbo guy and a 2G guy, so maybe 1GNT drivers might have better suggestions, but those pistons are not the way to go for more power.

Edit: Suggestions for 1GNT upgrades from elsewhere on the web

• Air Intake
  Replace the stock air box with a solid pipe and high-flow cone filter.
• Cat-back Exhaust
  Replace the stock cat-back exhaust with a higher flowing model.
• High-Flow Cat
  Replace the stock catalytic converter with a higher flowing model.
• Exhaust Header
  Replace the factory exhaust manifold with a tubular steel header.

Thanks for your input. Makes complete since! That's a problem i'm finding on here that not a lot of people know non turbo! In my class of racing headers are illegal. As far as everything else in your edit, i have stock manifold into dump pipe into 2 feet of exhaust and a turn out under passenger side. Air box is deleted with high flow air filter and the headlight removed to create an almost "RAM" / CAI induction (I know its ghetto but its small town dirt track racing).
SOOOOO.... THEN the money needs to be put into a crank. Are there other cars that i can pull a crank off of to replace (similar blocks or other dsm's that have interchangeable parts, ik the 7 bolt has the gallant )or a reasonably priced crank shaft ? I know nothing about crankshafts ... what am i looking for?

 

[randman2011]

I know you can put the 4G64 crankshaft in to a 7 bolt 4G63 to increase displacement, but I have no idea about the 6 bolt. Can you do cams in your class? The stock ones were designed for drivability and economy, so you could probably get some better ones for pretty cheap. I know the lift and duration changed on the 6 bolts a lot, so between the different years and NT and turbo blocks, you might be able to find some used OEM cams that would give some better high end power. This thread covers a lot of info about 1g cams, but I can't really help you any more than that. 1G Cam Differences

I'm kind of surprised that no one has come in here yelling "SELL THE NT AND GET A TURBO!" because that's usually how these threads go.

 

[Dirt Eagle]

I'm kind of surprised that no one has come in here yelling "SELL THE NT AND GET A TURBO!" because that's usually how these threads go.

I KNOW! Either that or the people that just talk shit! They dont take the time to read why I'm asking these questions. Yea ill have to look into cams ... i know there are a lot of interchangeables with the 7 bolt but i havent found any help on the 6! Thanks for the help hopefully i get some 6 bolt techs soon

 

[lasthope05]

Do some research on g4js huyndai pistons. They can be made to work with a .060" over bore(which is close to the limit of the block) and rod work to fit 7 bolt pistons. The -3 cc dish pistons would raise compression to 10:1 with a .051 head gasket thickness, zero deck, and stock 47cc dohc head. Using a huyndai 43cc head would raise compression up to 10.7:1.

I would also clean the intake manifold out really good and give it an acid port. It's and old cheater trick to open up the runners while keeping the factory cast look.

 

[Dirt Eagle]

Do some research on g4js huyndai pistons. They can be made to work with a .060" over bore(which is close to the limit of the block) and rod work to fit 7 bolt pistons. The -3 cc dish pistons would raise compression to 10:1 with a .051 head gasket thickness, zero deck, and stock 47cc dohc head. Using a huyndai 43cc head would raise compression up to 10.7:1.

I would also clean the intake manifold out really good and give it an acid port. It's and old cheater trick to open up the runners while keeping the factory cast look.

The 91 Hyundai Sonata had the 6 bolt 4g64 motor with a 100mm stroke so it seems to be the obvious choice. I dont want to bore more than .03 but the increase in crank will stroke me to 2.3. Will this be a direct fit? I know if i was to use the whole long block I would have to change trannys so im trying to avoid that and the motor mount issue

 

[Dirt Eagle]

I know you can put the 4G64 crankshaft in to a 7 bolt 4G63 to increase displacement, but I have no idea about the 6 bolt. Can you do cams in your class? The stock ones were designed for drivability and economy, so you could probably get some better ones for pretty cheap. I know the lift and duration changed on the 6 bolts a lot, so between the different years and NT and turbo blocks, you might be able to find some used OEM cams that would give some better high end power. This thread covers a lot of info about 1g cams, but I can't really help you any more than that. 1G Cam Differences

I'm kind of surprised that no one has come in here yelling "SELL THE NT AND GET A TURBO!" because that's usually how these threads go.

CAMS would be a no and too obvious of a change. Maybe do turbo cams

 

[lasthope05]

It is the obvious choice to stroke the motor but you said in your previous post you dont have to money for a new crank or motor, but can do an overbore with pistons.

 

[mean4g]

bore size doesn't really matter in your case. If you were boosted I would stay as small as possible in order to leave as much material around the cylinders as possible and ensure block flex stays to a minimum. As far as compression goes, if it stays N/A I would look into much higher compression. 9 to 1 is really short changing yourself. You can quite easily run 10.5-11 to 1 on 93 octane fuel without touching the head or doing anything extensive. The great thing about compression is you will gain power through the entire power curve. 1.5 of compression will be a very noticeable difference in power.


Also you can choose a very mild cam. Wouldn't be obvious at all. ;-)

 

[mean4g]

It is the obvious choice to stroke the motor but you said in your previous post you dont have to money for a new crank or motor, but can do an overbore with pistons.

If he over bores a significant amount the head will have to be reworked to match the chambers. Not enough material and cost efficient enough to warrant an overbore in his case.

 

[lasthope05]

If he over bores a significant amount the head will have to be reworked to match the chambers. Not enough material and cost efficient enough to warrant an overbore in his case.

The cylinder head does not have to be reworked at all. You dont rework/match the chambers when you overbore an engine. A .060" overbore in a 4g63(85mm) is the standard bore in a 4g64( 86.5mm) which is basically the same castings with a taller deck height. That coupled with the fact that for one year the galant came from the factory with a dohc 4g64.

Also, there is no weaknesss in the cylinder walls of the 4g64. The only issue is headgaskets (fire ring) when making huge power and high boost.

 

[mean4g]

The cylinder head does not have to be reworked at all. You dont rework/match the chambers when you overbore an engine. A .060" overbore in a 4g63(85mm) is the standard bore in a 4g64( 86.5mm) which is basically the same castings with a taller deck height. That coupled with the fact that for one year the galant came from the factory with a dohc 4g64.

Also, there is no weaknesss in the cylinder walls of the 4g64. The only issue is headgaskets (fire ring) when making huge power and high boost.

if using a 4g63 head on a 86.5-87MM bore you "should" re-work the quench/squish area of the head...but you can do without I guess. Like I said not enough material to warrant doing an overbore....1.5MM isn't going to be any significant difference.

 

[Dirt Eagle]

It is the obvious choice to stroke the motor but you said in your previous post you dont have to money for a new crank or motor, but can do an overbore with pistons.

If I was to stroke a way to save money that I've been seeing all over this forum and you spoke of is the galant 100mm crank, rods, and pistons. This can be pulled from a low mileage junk. Since hp wont be that high this would hold, but how is the fit? I understand machining will have to be done but I have not yet seen a build of someone doing this. I want to stick with my 4g63 block.

bore size doesn't really matter in your case. If you were boosted I would stay as small as possible in order to leave as much material around the cylinders as possible and ensure block flex stays to a minimum. As far as compression goes, if it stays N/A I would look into much higher compression. 9 to 1 is really short changing yourself. You can quite easily run 10.5-11 to 1 on 93 octane fuel without touching the head or doing anything extensive. The great thing about compression is you will gain power through the entire power curve. 1.5 of compression will be a very noticeable difference in power.


Also you can choose a very mild cam. Wouldn't be obvious at all. ;-)

What cam would you suggest... I do not understand the differences in cams

 

[Dirt Eagle]

I know you can put the 4G64 crankshaft in to a 7 bolt 4G63 to increase displacement, but I have no idea about the 6 bolt. Can you do cams in your class? The stock ones were designed for drivability and economy, so you could probably get some better ones for pretty cheap. I know the lift and duration changed on the 6 bolts a lot, so between the different years and NT and turbo blocks, you might be able to find some used OEM cams that would give some better high end power. This thread covers a lot of info about 1g cams, but I can't really help you any more than that. 1G Cam Differences

I'm kind of surprised that no one has come in here yelling "SELL THE NT AND GET A TURBO!" because that's usually how these threads go.

I didnt see this until I started to review my old posts... you said the gallant crank, pistons, and rods will fit????? Obviously with machining for clearance but is the general fit there?. Have you seen this build done because I cant find anyone who has actually done it?! This seems to be the most economic route.