stroked LS3 question

**98TransAmWs-6** · 10-13-2010, 11:47 AM

I am hoping to be able to do an engine build by this time next year. I am looking at stroking a LS3 block and I was wondering what is the biggest you can stroke it out to? I read some where it was 4.10 or 4.25 but I am not totally sure. My other question is what is the biggest bore you can have on the LS3? The reason I ask this is I want to know if you can get it to over 427 without re-sleeving it. I know on the LS1 sleeving it can cause some drivibility issues so if it is possible I would prefer not to do that unless it won't cause any problems. Also if there is another block that would be better please let me know.

**shady milkman** · 10-13-2010, 12:12 PM

Originally Posted by 98TransAmWs-6

I am hoping to be able to do an engine build by this time next year. I am looking at stroking a LS3 block and I was wondering what is the biggest you can stroke it out to? I read some where it was 4.10 or 4.25 but I am not totally sure. My other question is what is the biggest bore you can have on the LS3? The reason I ask this is I want to know if you can get it to over 427 without re-sleeving it. I know on the LS1 sleeving it can cause some drivibility issues so if it is possible I would prefer not to do that unless it won't cause any problems. Also if there is another block that would be better please let me know.

while i see where you are coming from i must tell you..dont ..a ls3 with a 4.1" stroke will be a 427....boring any of the lsx aluminum cylinders is very limited as in .05" ...so it is basically enough for a hone. There is also concerns with a long stroke on engines not intended for that long of stoke...especially in terms of piston wobble and oiling/sealing concerns.... here are two really good options imho..a stock ci ls3 or a stock ci ls7. the ls3 is a great platform and has great power potential. The ls7 should go without saying that it is top dog in ci and potential. If money was no issue i would imho run a c56 block then a ls7 then a ls3....however for me money is a issue

so i want to drop in a ls3 with a fast 102, some touched heads..preferably ls7 heads and a nice cam so i can have great drive-ability and reliability

**98TransAmWs-6** · 10-13-2010, 12:25 PM

Isn't the c56 the race block that gm makes, I thought it was called the C5R? well I want at least 427 ci so I am guessing the ls7 would be the way to go since you said there would be problems with doing what I want to do with the block. I can't find any ls7 blocks so I have no clue how much they cost. I am guessing in the 6k range. Another question as for as heads/intake/cam go for the ls3 and ls7 what would be the best to use? I was thinking for the ls3 doing l92 ported heads and either the l76 or ls3 intake and perhaps the gm hot cam because I wan't to still be able to drive this car if I want to everyday. For the ls7 I haven't done much research so I don't know what fits yet. Are the ls7 and ls3 similar at all in the head and intake department? Input would be great.

**shady milkman** · 10-13-2010, 12:30 PM

Originally Posted by 98TransAmWs-6

Isn't the c56 the race block that gm makes, I thought it was called the C5R? well I want at least 427 ci so I am guessing the ls7 would be the way to go since you said there would be problems with doing what I want to do with the block. I can't find any ls7 blocks so I have no clue how much they cost. I am guessing in the 6k range. Another question as for as heads/intake/cam go for the ls3 and ls7 what would be the best to use? I was thinking for the ls3 doing l92 ported heads and either the l76 or ls3 intake and perhaps the gm hot cam because I wan't to still be able to drive this car if I want to everyday. For the ls7 I haven't done much research so I don't know what fits yet. Are the ls7 and ls3 similar at all in the head and intake department? Input would be great.

the ls7 heads are leaps and bounds better than the ls3 heads for several reasons ...why do you want a 427 by the way ? when it comes down to it..you will be forking over quite a bit of money for a small gain ..but it is your decision ..if you want 427...imho it is a ls7 or a lsx block period ...that way you keep the drive-ability and reliability

**98TransAmWs-6** · 10-13-2010, 12:35 PM

Originally Posted by shady milkman

the ls7 heads are leaps and bounds better than the ls3 heads for several reasons ...why do you want a 427 by the way ? when it comes down to it..you will be forking over quite a bit of money for a small gain ..but it is your decision ..if you want 427...imho it is a ls7 or a lsx block period ...that way you keep the drive-ability and reliability

I actually don't know why I want a 427 besides just wanting the most cubes I can get out of a small block but if it isn't worth the extra money and I could build a ls3 just as powerful then I'd do that instead since ls3 blocks are a lot cheaper like half the price. I am new at this engine build thing what other things would I need besides heads,intake,cam, crank, drive accessories, push rods, motor mounts, etc. Is there anywhere I can find a list? Also would any stuff from my ls1 hookup like my ac and other components or would I basically have to buy everything for the ls3?

**shady milkman** · 10-13-2010, 12:37 PM

Originally Posted by 98TransAmWs-6

I actually don't know why I want a 427 besides just wanting the most cubes I can get out of a small block but if it isn't worth the extra money and I could build a ls3 just as powerful then I'd do that instead since ls3 blocks are a lot cheaper like half the price.

x2 now you are thinking .. plus get a used ls3 long block for 3-4k and eventually sell the top end and upgrade to ls7 style heads and fast intake and a cam and you will be in the nasty 5xx range

**98TransAmWs-6** · 10-13-2010, 12:41 PM

Originally Posted by shady milkman

x2 now you are thinking .. plus get a used ls3 long block for 3-4k and eventually sell the top end and upgrade to ls7 style heads and fast intake and a cam and you will be in the nasty 5xx range

what do you mean by sell the top end? will my radiator, fuel lines, ac and other stuff my my ls1 work on the ls3 long block or will I have to get new stuff? Also will I need to get a new computer and wiring harness for the ls3? Oh yea and I'll probably need to get new headers right? Or will they fit? One other thing TSP sells this LSX bowtie block that only costs $2,099 and it says it can be bored up to 4.25 and stroked up to 4.50 and can handle 2,500 hp do you think that would be worth buying or would you still do the LS3 long block over that?

**shady milkman** · 10-14-2010, 04:19 AM

if you want more out of the ls3..i said you could sell the top end...stock heads,intake to get some money to buy aftermarket heads and intake.

yes you need a newer computer..since you are a 98..you really need a newer computer anyways ... besides that for the most part..everything else will bolt right up..headers included. i like the ls3 over the lsx simply for weight...60-100 pounds on the front end over the ls3 does not sound good to me...and for my plans with my car..a lsx would be overkill

**98TransAmWs-6** · 10-14-2010, 06:53 AM

Originally Posted by shady milkman

if you want more out of the ls3..i said you could sell the top end...stock heads,intake to get some money to buy aftermarket heads and intake.

yes you need a newer computer..since you are a 98..you really need a newer computer anyways ... besides that for the most part..everything else will bolt right up..headers included. i like the ls3 over the lsx simply for weight...60-100 pounds on the front end over the ls3 does not sound good to me...and for my plans with my car..a lsx would be overkill

Ok I figured that's what you meant by top end but wasn't totally sure. Right now I am trying to decide on whether to just buy a ls3 crate engine and sell my ls1 as well as the parts I want to sell so I can put performance parts on it. Or just buy the ls3 block, forged internals, and performance parts straight up and bolt the rest of the ls1 parts on it and sell the parts I ditch. Need to decide which one would be better, with the crate engine I get totally new parts and everything but its more expensive and with just buying the parts I need it will end up being cheaper over all. I am definately going to put in a new rear end too for sure.

**shady milkman** · 10-14-2010, 06:59 AM

Originally Posted by 98TransAmWs-6

Ok I figured that's what you meant by top end but wasn't totally sure. Right now I am trying to decide on whether to just buy a ls3 crate engine and sell my ls1 as well as the parts I want to sell so I can put performance parts on it. Or just buy the ls3 block, forged internals, and performance parts straight up and bolt the rest of the ls1 parts on it and sell the parts I ditch. Need to decide which one would be better, with the crate engine I get totally new parts and everything but its more expensive and with just buying the parts I need it will end up being cheaper over all. I am definately going to put in a new rear end too for sure.

how is a crate more expensive than a built longblock ? remember some of that cost will be recouped when you sell the parts you dont need..i doubt they will be for sale for long either

**98TransAmWs-6** · 10-14-2010, 10:08 AM

Originally Posted by shady milkman

how is a crate more expensive than a built longblock ? remember some of that cost will be recouped when you sell the parts you dont need..i doubt they will be for sale for long either

Well I was more of assuming since I wouldn't be buying every single part for a complete long block engine ( I would be using a lot of parts from my ls1) the crate ls3s I have found are from 8k-12k. But so far for everything I have priced out for the long block it's cheaper. One question what is the difference between the ls3 short block and long block besides the obvious?

**shady milkman** · 10-14-2010, 10:24 AM

Originally Posted by 98TransAmWs-6

Well I was more of assuming since I wouldn't be buying every single part for a complete long block engine ( I would be using a lot of parts from my ls1) the crate ls3s I have found are from 8k-12k. But so far for everything I have priced out for the long block it's cheaper. One question what is the difference between the ls3 short block and long block besides the obvious?

that is it..a shotblock is the rotating assymbly and the block...a longblock is top end + shortblock....i believe the difference between a long block and a crate is accessory drives and oiling system come with a crate..not always with a long-block.............for the ls3 what are you thinking of using from the ls1 ? the heads/intake and even the cam will be ill suited for a ls3. this is unless you have some really good heads and intake

**98TransAmWs-6** · 10-14-2010, 06:55 PM

Originally Posted by shady milkman

that is it..a shotblock is the rotating assymbly and the block...a longblock is top end + shortblock....i believe the difference between a long block and a crate is accessory drives and oiling system come with a crate..not always with a long-block.............for the ls3 what are you thinking of using from the ls1 ? the heads/intake and even the cam will be ill suited for a ls3. this is unless you have some really good heads and intake

Ah ok that makes more sense. What I am going to use from my ls1 is more of accessories if possible, I am going to get new heads/cam/intake. The ls1 timing chain won't work right? I was thinking of using my alternator, ac, power steering pump, under drive pulleys, etc. This is of course if it will all work with the ls3 if not I might as well just buy the crate engine. Wonder if gm will make a custom crate engine for me to so I can have ls7 heads on it vs the ls3.

**shady milkman** · 10-15-2010, 08:26 AM

the ls3 timing chain is better..as is the ls2..so you wont want to keep the ls1 timing chain...i high highly doubt gm would do that for you btw.

**98TransAmWs-6** · 10-15-2010, 11:01 AM

Originally Posted by shady milkman

the ls3 timing chain is better..as is the ls2..so you wont want to keep the ls1 timing chain...i high highly doubt gm would do that for you btw.

I figured not but you never know if you don't ask. I probably should also get a new rear end and drive shaft when I do this since I'd rather not rip my right off once I put the engine in and start it up for the first time. Another question will my a4 work with a ls3, I have heard they do but would there be a better one to go with?

**shady milkman** · 10-15-2010, 11:29 AM

Originally Posted by 98TransAmWs-6

I figured not but you never know if you don't ask. I probably should also get a new rear end and drive shaft when I do this since I'd rather not rip my right off once I put the engine in and start it up for the first time. Another question will my a4 work with a ls3, I have heard they do but would there be a better one to go with?

yes i am 99% sure it will..gm doesnt change their bellhousing bolt locations extra very oftem .....i dont think your rear end and driveshaft will go right off the bat with a stock ls3....if you DR it or slick it ...i am sure you will

**98TransAmWs-6** · 10-15-2010, 01:10 PM

Originally Posted by shady milkman

yes i am 99% sure it will..gm doesnt change their bellhousing bolt locations extra very oftem .....i dont think your rear end and driveshaft will go right off the bat with a stock ls3....if you DR it or slick it ...i am sure you will

Well it's not going to be stock when I put it in my car it will have ls7 heads, fast tb/intake, some sort of cam whether it is the gm hot cam or something else. Although I might just put it in and later change that stuff out. So I'd think at the very minimum I would be pushing the high 500s if not low 600s since with the stock ls3 with a hot cam you are pushing around 480. That is going to be a huge difference from at ls1 with 330-350 hp (never gotten a dyno done before).