Im starting to gather the parts and info I need to build my motor.

Ive been searching and cant find some answers so I figured I would start a thread so I can post questions as I come across them.

First couple have to do with the pistons.

Will be running JE 10:1 .040" over pistons.

1.) I believe I read piston clearance should be .0035" correct?

2.) Ive also read that the pistons come with oversize wrist pins, I assume the rods need to be bored out for this? I will probably be running Eagle rods as I have always had good luck with them.

3.) What is everyone running for ring gap for boost use? Ive been searching for the past week and cant find an answer.

next one has to do with the 2.3 oil pump swap.

4.) Where do you get the 9/16" x 2" sleeve that gets installed in the block where the hole is drilled into the galley?


Thanks in advance for the help,
Want to get as much detailed info as possible to provide to the machinist doing the block work.

"Oil Leak ? What oil Leak ? Oh, Thats Just The Sweat From All The HorsePower!!"

1.) whatever the spec sheet for the pistons says clearance should be, do that.

2.) i will assume they mean oversized is the the inner diameter, not the outer.

3.) no idea.

4.) talk to tim at mantapart.



Edited 1 time(s). Last edited Monday, September 13, 2010 5:13 AM


I feel like taking a tinkle on an ecNOtec...

2. Even if it is the outer diameter the rod would need bored. I'll have to check with je directly. I also found specs earlier for piston ring gap, I'm on my phone and don't have my notes by me. Ill post tomorrow after work.

"Oil Leak ? What oil Leak ? Oh, Thats Just The Sweat From All The HorsePower!!"

2.) fixed LOL worded it wrong.

make sure you order them with the LD9 pin diameter, problem solved.

and when you say "10.1" compression, you mean they will have a dome, right?



I feel like taking a tinkle on an ecNOtec...

The JE pistons are flat top. The wrist pins fit in my eagle rods perfectly so there shouldn't be issues.

Sounds good. Thanks for the info.


"Oil Leak ? What oil Leak ? Oh, Thats Just The Sweat From All The HorsePower!!"

if they are flat tops then they are stock LD9 compression ratio.



I feel like taking a tinkle on an ecNOtec...

I'm in no way trying to argue and clutter up the thread but doesn't the 0.040" overbore raise compression?

Not really, you can get .040" oversized in stock cr. Piston height may be different. Doesn't take much to go from 9.7:1 to 10:1.


"Oil Leak ? What oil Leak ? Oh, Thats Just The Sweat From All The HorsePower!!"

well yes dc, it does but i meant strickly std sizes for my statement.

the only true way to know ur cr is to cc everything and use a bunch of math.



I feel like taking a tinkle on an ecNOtec...

DSMskyline wrote:Not really, you can get .040" oversized in stock cr. Piston height may be different. Doesn't take much to go from 9.7:1 to 10:1.

To bad you are starting with 9.5:1. Unless you mixed and matched pistons with heads before the build.

I know I've read somewhere that the 99.5+ ld9s were 9.7 not 9.5.


"Oil Leak ? What oil Leak ? Oh, Thats Just The Sweat From All The HorsePower!!"

z yaaaa wrote:well yes dc, it does but i meant strickly std sizes for my statement.

the only true way to know ur cr is to cc everything and use a bunch of math.

I know what you mean Brad, just trying to figure out why JE claims 10:1 for these as I have the same pistons.

if they have valve reliefs, technically they will have less compression. do yours?

maybe if you have flat tops with a 96-98 head it MIGHT be closer to 10:1, i dont know.



I feel like taking a tinkle on an ecNOtec...

DSMskyline wrote:I know I've read somewhere that the 99.5+ ld9s were 9.7 not 9.5.

AAccording to GM they are all 9.5:1. Also aggording to GM when the small dish in the piston went away (would raise compression) the combustion chamber grew in size (would lower compression). If you use the 96-99 head on 00-02 pistons you would probably have close to 9.7:1. However, if you match heads and pistons together you will have 9.5:1 regardless of the year.

The JE pistons are flat top, no valve reliefs. Well I guess without checking volume on everything we won't know, sorry DSM for cluttering your thread.

It's cool, clarification is always welcome.

I've read 2 or 3 places that show 99.5+ are 9.7:1.
[Here, click.url=gaownersclub.com/forum/showthread.php?t=1978]Your text to link here...



"Oil Leak ? What oil Leak ? Oh, Thats Just The Sweat From All The HorsePower!!"

GM Service Information says that it is 9.5:1. I will trust what GM told its technicians over what a car forum says. I never bothered to do the math but I am sure that it works out to 99.5+ having 9.5:1 if you use the 99.5+ head with its slightly larger combustion chamber.

just because its on the internet does not mean its fact. If every source of information gets its information from one incorrect source then they are still all wrong. Its the tell a lie enough times and it becomes truth theory.

this place is a river of bad information.

i agree, all LD9's are 9.5:1. you really wont fully understand til you've torn down each generation of the engine and closely examined the parts. believe me, the proof is in the pudding.



I feel like taking a tinkle on an ecNOtec...

my old wieseco .040 pistons were left with some nice valve reliefs

z yaaaa wrote:this place is a river of bad information.

i agree, all LD9's are 9.5:1. you really wont fully understand til you've torn down each generation of the engine and closely examined the parts. believe me, the proof is in the pudding.

I'm not going to doubt any one on here. All I know is what I read.

I do in fact have both generations in my possession. The motor I'm using for my build is the factory 99.5 from the car. the motor in the car is from a 97.

Once I get the 99.5 torn apart ill measure everything. Once it goes in the car I will tear apart the 97 motor and take the same measurements and see what I find out. I may even do a simple head chamber measurement between the heads to see what I find out.

So far I'm glad this thread is full of win......... lol


"Oil Leak ? What oil Leak ? Oh, Thats Just The Sweat From All The HorsePower!!"

You will find about a 2cc (if my memory serves me right) difference between chamber volumes. the 96-99 head will have a small protrusion into the chamber that the newer head will not have.

I would trust car forums before what GM told techs, because half of them do not know what they are doing. Sorry no faith in GM and their tech's. I also I have seen the difference in how a 99+ LD9 runs compared to a 96-98 LD9. 99+ stock for stock are stronger, so something is different.



FU Tuning

^^^ i dont see how... the head has smaller exhaust ports AND the intake manifold tb opening is smaller so... maybe more torquey, that i could see...



I feel like taking a tinkle on an ecNOtec...

I know I felt a difference between the stock 99.5 and the 97 I put in. Just doesnt seem that the 97 has the power the stock motor did.


"Oil Leak ? What oil Leak ? Oh, Thats Just The Sweat From All The HorsePower!!"