Forged Replacement Pistons for the LN3
#1
Junior Member
Thread Starter
Join Date: May 2006
Location: BonnevilleHell
Posts: 0
Likes: 0
Received 0 Likes
on
0 Posts
Forged Replacement Pistons for the LN3
Just thinking out loud again, and thinking ahead to the first overbore.
Anyone given any thought to replacement pistons for the 3800. So far, I've found the one that has been discussed here before, Diamond. All the rest of the manufacturers seem to focus on the older Buick GN 231cid. I imagine JE, Wiseco, and others would make anykind of piston ya want for a price.
But, what about using GN 5.960" rods and GN pistons in a LN3? Seems like that would kill two birds with one stone: forged pistons with thicker wrist pins and stronger rods to go with them. The selection of piston crows is pretty good too..dished, flattops, and domes depending on who'* 231 piston you are looking at. Rod choices are the stock I beams and H-beams.
I guess the question would be will it fit in the block and what is the stock diameter of a GN rod journal (3800 is 2.250")
Thoughts anyone?
Anyone given any thought to replacement pistons for the 3800. So far, I've found the one that has been discussed here before, Diamond. All the rest of the manufacturers seem to focus on the older Buick GN 231cid. I imagine JE, Wiseco, and others would make anykind of piston ya want for a price.
But, what about using GN 5.960" rods and GN pistons in a LN3? Seems like that would kill two birds with one stone: forged pistons with thicker wrist pins and stronger rods to go with them. The selection of piston crows is pretty good too..dished, flattops, and domes depending on who'* 231 piston you are looking at. Rod choices are the stock I beams and H-beams.
I guess the question would be will it fit in the block and what is the stock diameter of a GN rod journal (3800 is 2.250")
Thoughts anyone?
#2
Junior Member
Posts like a Ricer Type-R
The first question I'd ask is how many cars here (including those with high boost and high power) have ever broken a piston, wrist pin, or rod?
The second question after that answer comes back as Zero, is why spend the money on more durability when you don't need it?
The second question after that answer comes back as Zero, is why spend the money on more durability when you don't need it?
#3
Guest
Posts: n/a
Not sure how to answer this one...
The 3800 SC from 91-95 Used the Same crank as my 91'*... From what we have seen on the rods, the SC uses a floating pin, and the pistons are supposedly hardened...
I have only seen 1 3800 LN3 pop a rod( Owner ran it low on oil ... )
The rods in the 3800 seem to be pretty beefy when you compare them to say a Ford 4.0 60* V6...
But I am sure there are items out there for them... Maybe someone with an 88 service manual could tell us what the Rod journals were on the Old LG3 3.8 V6
__________________
Best Car Insurance | Auto Protection Today | FREE Trade-In Quote
The 3800 SC from 91-95 Used the Same crank as my 91'*... From what we have seen on the rods, the SC uses a floating pin, and the pistons are supposedly hardened...
I have only seen 1 3800 LN3 pop a rod( Owner ran it low on oil ... )
The rods in the 3800 seem to be pretty beefy when you compare them to say a Ford 4.0 60* V6...
But I am sure there are items out there for them... Maybe someone with an 88 service manual could tell us what the Rod journals were on the Old LG3 3.8 V6
__________________
Best Car Insurance | Auto Protection Today | FREE Trade-In Quote
#4
Junior Member
Thread Starter
Join Date: May 2006
Location: BonnevilleHell
Posts: 0
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by willwren
The first question I'd ask is how many cars here (including those with high boost and high power) have ever broken a piston, wrist pin, or rod?
The second question after that answer comes back as Zero, is why spend the money on more durability when you don't need it?
The second question after that answer comes back as Zero, is why spend the money on more durability when you don't need it?
That'* the train of thought...after the pop, what can I use to rebuild it with to increase the likelyhood of it surviving the next round. First thought that comes to mind is the rotating assembly...hence the question what is available that is stronger than stock.
#5
Guest
Posts: n/a
Curt you make wme wonder how much of a diffrence there are in the pistons between the LG3 and LN3... Both of them have the identical 3.40 in stroke and 3.80 in bore, I don't think the deck heigth shrank any in the LN3 over the LG3... Almost makes me wonder if the same rods were used, and possibly could the LG3 pistons be used in the 3800 LN3 application... If I remember right there are pistons galore for the old 3.8
__________________
Best Car Insurance | Auto Protection Today | FREE Trade-In Quote
__________________
Best Car Insurance | Auto Protection Today | FREE Trade-In Quote
#6
Junior Member
Thread Starter
Join Date: May 2006
Location: BonnevilleHell
Posts: 0
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by jr's3800
Curt you make wme wonder how much of a diffrence there are in the pistons between the LG3 and LN3... Both of them have the identical 3.40 in stroke and 3.80 in bore, I don't think the deck heigth shrank any in the LN3 over the LG3... Almost makes me wonder if the same rods were used, and possibly could the LG3 pistons be used in the 3800 LN3 application... If I remember right there are pistons galore for the old 3.8
Is the rod journal on the L67 the same as the LN3? Over in one of the forced induction threads, as an argument against putting a blower on the LN3, was the comment that the L67 pistons and rods were stronger than their normally aspirated brethren. But are they also interchangable? (i.e. do they share the same 2.250" journal diameter) Based on your comment that the L67 crank was the same as your 91, then they must be interchangable...and that would open up another option of using just better stock replacement pistons (or forged copies) with L67 rods.
#7
Junior Member
Posts like a Ricer Type-R
Originally Posted by clm2112
Is the rod journal on the L67 the same as the LN3? Over in one of the forced induction threads, as an argument against putting a blower on the LN3, was the comment that the L67 pistons and rods were stronger than their normally aspirated brethren. But are they also interchangable? (i.e. do they share the same 2.250" journal diameter) Based on your comment that the L67 crank was the same as your 91, then they must be interchangable...and that would open up another option of using just better stock replacement pistons (or forged copies) with L67 rods.
#8
I would only replace them if you were doing an engine overhaul.
If you HAVE to replace them, yes, then go forged for insurance against failure and that extra reliability when you wind it out to 6500 rpm.
If you HAVE to replace them, yes, then go forged for insurance against failure and that extra reliability when you wind it out to 6500 rpm.
#9
Junior Member
Posts like a Ricer Type-R
Originally Posted by 2000SilverBullet
I would only replace them if you were doing an engine overhaul.
If you HAVE to replace them, yes, then go forged for insurance against failure and that extra reliability when you wind it out to 6500 rpm.
If you HAVE to replace them, yes, then go forged for insurance against failure and that extra reliability when you wind it out to 6500 rpm.
#10
Guest
Posts: n/a
Originally Posted by clm2112
Originally Posted by jr's3800
Curt you make wme wonder how much of a diffrence there are in the pistons between the LG3 and LN3... Both of them have the identical 3.40 in stroke and 3.80 in bore, I don't think the deck heigth shrank any in the LN3 over the LG3... Almost makes me wonder if the same rods were used, and possibly could the LG3 pistons be used in the 3800 LN3 application... If I remember right there are pistons galore for the old 3.8
Is the rod journal on the L67 the same as the LN3? Over in one of the forced induction threads, as an argument against putting a blower on the LN3, was the comment that the L67 pistons and rods were stronger than their normally aspirated brethren. But are they also interchangable? (i.e. do they share the same 2.250" journal diameter) Based on your comment that the L67 crank was the same as your 91, then they must be interchangable...and that would open up another option of using just better stock replacement pistons (or forged copies) with L67 rods.
Piston Pin Diameter for the 91 LN3 is 0.9053-0.9055 in
Connecting rod journal 2.2487-2.2499
I am not 100% here... But when GM went from the 87-88 Vin 3 3.8 V6 to the 3800 Vin C V6, there were changes in the piston design... I believe that the pistons got shorter, and the rings were moved up to help aid in reduced emissions... So there may be some diffrences there... As for the heigth and location of the Piston Pin within the piston I couldn't say...
__________________
Best Car Insurance | Auto Protection Today | FREE Trade-In Quote