ls1 machine work and piston size question
08-04-2007, 07:43 AM
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ls1 machine work and piston size question So I tore down my 90k ls1 today and it really doesn't look to bad for 90k. The guy I bought it from said it smoked, hence the reason for the tear down. There is slight scoring in the number 4 piston. I sending the block to be cleaned up. How far can these things be honed and still use the stock pistons (or should they not be re-used at all)? Also, I have heard the rods are strong as long as you change over to ARP bolts so are they good to reuse too? Finally, do you want to cross-hatch the ls1's for oil retention purposes like the old SBC's or are they a smooth bore?
Sorry for the dumb questions just trying to get a feel for these babies.
Goal is a 400-450 summer driver, all engine
Sorry for the dumb questions just trying to get a feel for these babies.
Goal is a 400-450 summer driver, all engine
08-04-2007, 03:44 PM
#2
Your engine builder should know all the answers to these questions.
But.
You should probably buy aftermarket rods if you ever intend to spray on the motor with it having 400-450hp n/a.
Stock pistons are definitely not going to be the best choice. I personally went with Diamonds.
The crosshatch should still be visible on the motor, but yes you do need to cross hatch for oil retention.
ARP rod bolts should be more than sufficient unless you plan to spin it wicked high, get some upgraded ARPs (theyre like 25$ more). The stock bolts are TTY (torque to yield) and should never be reused.
If your engine builder(machine shop) doesn't have a torque plate already for lsX motors, I would suggest finding one which does.
But.
You should probably buy aftermarket rods if you ever intend to spray on the motor with it having 400-450hp n/a.
Stock pistons are definitely not going to be the best choice. I personally went with Diamonds.
The crosshatch should still be visible on the motor, but yes you do need to cross hatch for oil retention.
ARP rod bolts should be more than sufficient unless you plan to spin it wicked high, get some upgraded ARPs (theyre like 25$ more). The stock bolts are TTY (torque to yield) and should never be reused.
If your engine builder(machine shop) doesn't have a torque plate already for lsX motors, I would suggest finding one which does.
08-04-2007, 07:13 PM
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Its a 99 block and this is the only reputable engine shop in the area. I know the guy and he builds racing engines for a living but does have limited experience with the ls1 motors. I on the other hand have no experience with these. I don't have plans of spraying it and the >400 horse mark will not be for a long time. Its going back together basically stock topend for now (read poor ha).
This is going to sound bad but what is a torque plate and what should I look for to make sure they have the right one.
Once again sorry for these questions but I want to be able to intelligently talk to my builder so we can properly plan out this build
This is going to sound bad but what is a torque plate and what should I look for to make sure they have the right one.
Once again sorry for these questions but I want to be able to intelligently talk to my builder so we can properly plan out this build
08-04-2007, 11:28 PM
#5
If you ask the guy and he gives you a look like he has no idea whatsoever, turn around and walk out the door. Don't mess around when building a motor, pay even a little bit more and get it done CORRECTLY.
I would think that he's going to need to go to 3.907 at least because if the pistons are forged, theyre going to expand more than stock hypereutectics.
Lets put it this way. Im getting my block freshened up, rings filed to fit/spec'd for n2o, crank/entire rotating assembly balanced, and then theyre going to cc my heads for me and cc the cylinder so I can figure out my exact compression ratio.
All of this is less than 500$. With the right people doing the right work.
I would think that he's going to need to go to 3.907 at least because if the pistons are forged, theyre going to expand more than stock hypereutectics.
Lets put it this way. Im getting my block freshened up, rings filed to fit/spec'd for n2o, crank/entire rotating assembly balanced, and then theyre going to cc my heads for me and cc the cylinder so I can figure out my exact compression ratio.
All of this is less than 500$. With the right people doing the right work.
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08-05-2007, 08:50 PM
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bit pricey? What are its ranges. All I need is some block machining. How much would it be for a decent shop to assemble a short block? I could do it but, would rather not since you guys make it sound like the ls1 is unlike any other engine as far as build up. What makes this thing so finicky?
08-05-2007, 08:52 PM
#9
If you want it done right- go to W2W. Those guys are bar none.
Its not like its extremely hard- Im going to be assembling my whole motor myself- but I will have the whole rotating assembly balanced before I do assemble it so I dont have any weird harmonics that I could have prevented.
Its not like its extremely hard- Im going to be assembling my whole motor myself- but I will have the whole rotating assembly balanced before I do assemble it so I dont have any weird harmonics that I could have prevented.
08-06-2007, 07:18 AM
#11
Actually, no. The forged pistons are 3.989 for the forged when cold. The bore needs to be 3.905.
Originally Posted by 2000TurboVert
Arent most forged ls1 stock pistons right at 3.905?
08-06-2007, 08:05 AM
#12
We build in .004 clearance into the pistons. We have some that are for a 3.903 bore and some for a 3.905 bore. You won't have to run them looser than that. If you're running a stock rod, keep in mind the pin diameter is .945 instead of the commonly used .927 that most of the aftermarket rods use.
08-06-2007, 11:33 AM
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I'm looking at the forged ring and piston kit from SDPC now thats around 500. What bore size will work? isn't 3.906 too large? If not what should the engine be bored or honed to for the 3.906 pistons to work?
08-07-2007, 07:01 PM
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Oh great this dang day just keeps getting better. Sure am glad I didn't drop off my engine to W2W cuz they would have charged an arm and a leg to tell me that my block is cracked in every last one of the passenger side water jackets. So now I'm screwed, basically. And I def. will not trust buying things like that anymore unless I can see them. Just my luck I guess.
08-07-2007, 08:46 PM
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that would have been perfect. Thanks for the info I'll keep it in mind for future reference. any one know where I can find a complete new stock shortblock for sale?
