Generation IV Internal Engine - LS3 Build Questions




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McAllister513
04-21-2012, 10:42 PM
Ok well my rings in the Vette have managed to take a dump on me and now its smoking like a freight train. So now I have decided to build a forged LS3 and drop it in. This car is a weekend street beater and I really just want to make about 500RWHP off spray and then spray a 200 shot on it. I know some of you don't agree with nitrous but thats what I prefer.

I will be picking up a 60K Mile LS3 Block next week and thats about as far as I am right now. :confused:

I have few questions.

What kind of power can I make with a big cam LS3 off spray? It will most likely stock ported heads with forged rods and forged pistons.

I have a been told I can use a stock LS1 crank that way I don't have to mess with anything on the reluctor wheel? Is their anything special I have to do in order to run that crank?

What rods & pistons do you guys recommend?

Thanks :cheers:


bww3588
04-22-2012, 12:06 AM
To run the 24x crank is fine, but the ls3 block does not have provisions for the ls1 cam sensor, so you would have to run an ls2 style front cover and cam sensor. Or you could just run ls3 crank and cam sensor and get the conversion box. It would make it simpler I would think.

McAllister513
04-22-2012, 08:17 PM
Bump. Still need some answers.


Tainted
04-22-2012, 09:21 PM
Are you going to bore it out any? Bigger cubes is a great thing, and the price between rotating assemblies is nothing.

Juicedh22
04-23-2012, 01:15 PM
What kind of power can I make with a big cam LS3 off spray? It will most likely stock ported heads with forged rods and forged pistons.

If you're using stock LS3 heads, I wouldnt even suggest porting them, unless you have the extra funding anyway; most people with ported heads are not seeing a lot of power over stock heads. So unless you get a great deal, or have hte money to spend for minimal power/tq gains; I personally dont recommend it. Especially, if you're just looking to get close to that 500whp number.

You CAN get close to that 500whp number with just a cam. For example many people seem to be reaching/crossing 480whp with just an LG Motorsports G6X3 cam. A local shop here (CincySpeed) has their own cam (BooSSt), that I just saw make 482whp on a stingy DynoJet dyno on an ls3 c6 (with intake/exhaust) (and the cam is less agressive than the G6x3, and is actually designed for boost/n2o - I can give you further info on it if you want).

I have a been told I can use a stock LS1 crank that way I don't have to mess with anything on the reluctor wheel? Is their anything special I have to do in order to run that crank?

You CAN use the ls1 crank, but it is not much more difficult to get a 24x reluctor wheel and swap it onto the ls3 crank; I had a shop do this for me and it was less than $200 to have them swap the reluctor wheel, and inspect the engine while they did it (I took them the short block).

I suggest getting a 24x reluctor setup as opposed to running one of the conversion boxes, i have heard of those having issues.

As stated, you will need an ls2 front cover w/ cam sensor, along with an early 3 bolt ls2 2x cam gear. I also recommend swapping the ls3 chain tensioner with an ls2 style chain damper. Too many stories i have seen with the tensioners breaking.

You will also need to drill/tap a couple of the un-used threaded bosses on the side of hte ls3 block, to mount your knock sensors.

Finally you will need a couple conversion harnesses from racetronix; the cam sensor relocation harness, the knock sensor relocation harness, and if you have an ls1/6 car you will want the ls2 throttle body conversion harness (MAKE SURE YOUR THROTTLE BODY IS AN LS2, or PRE 2010 ls3 TB, the 2010+ TBs have a different resistance and will cause fits for your ecm).

If you want more detail, let me know. I just got done swapping a heads/cam ls3 into my c5z.

LSHUNT
04-23-2012, 05:48 PM
If you build a forged stroked LS3 and throw a cam in it, you won't even need ported heads to get 500hp assuming you have full bolt ons to support it.

Johnnystock
04-23-2012, 10:21 PM
I'd be curious to see a back to back dyno with stock VS ported LS3 heads. My money is on the ported set, especially with a cam and full boltons!

McAllister513
04-23-2012, 10:25 PM
As stated, you will need an ls2 front cover w/ cam sensor, along with an early 3 bolt ls2 2x cam gear. I also recommend swapping the ls3 chain tensioner with an ls2 style chain damper. Too many stories i have seen with the tensioners breaking.

Thank you for all the advise:cheers:and I'll definitely prolly be in contact with you if I have any issues.

So I need the LS2 Timing Set Correct? With LS2 chain and damper?

Which cam do I use? One for a LS1? LS2? Or LS3?

If you build a forged stroked LS3 and throw a cam in it, you won't even need ported heads to get 500hp assuming you have full bolt ons to support it.

It will be a full bolt on with a large cam for sure. I am running the VRX5 cam in my LS1 right now and I plan on either getting a little bigger than it. A buddy has the Vindicator cam of Vengeance and I love it so I might go with it. Never know though. Still just buying basic stuff right now so I can take it all the machine shop who is going to assemble it all.

Juicedh22
04-24-2012, 08:17 AM
So I need the LS2 Timing Set Correct? With LS2 chain and damper?

Which cam do I use? One for a LS1? LS2? Or LS3?


Just need the cam gear, the timing gear on the crank are all the same. LS2/3/7/9 chain are all the same, which is what most people run. I upgraded to the Katech C5R chain for the extra piece of mind in my investment (ls3s are known for harmonics issues at top RPMs)

You want a 3-bolt camshaft (LS1/2/6 style), which is pretty straight forward, since you're getting an aftermarket camshaft.

Here is my build thread, though I didnt go into as much detail as I should have (left out the harness stuff, and the knock sensor stuff)
http://forums.corvetteforum.com/c5-z06-discussion/3015780-ls3-engine-build-pics-and-such.html


It will be a full bolt on with a large cam for sure. I am running the VRX5 cam in my LS1 right now and I plan on either getting a little bigger than it. A buddy has the Vindicator cam of Vengeance and I love it so I might go with it. Never know though. Still just buying basic stuff right now so I can take it all the machine shop who is going to assemble it all.
Our step change is very similar. I also had the VRX5 in my ls6. Very streetable cam! I think the G6X3 is also a great street cam, a small amount of surge at 1600 rpm, but nothing to write home about.

Once again, I do want to throw out the recommendation for Cincy Speed's BooSSt cam. The numbers I have seen off of it are great N/A, and it is designed with boost in mind. Give them a call, talk to Craig, or Tracey (who designed the cam) 513-821-2221.