Can I add 100hp (about 450rwhp) to my LS2 with nothing more than bolt-ons and a cam? The anwser is obviously yes but let me add another requirement: Have near stock drivability. Near stock drivability means that other than tailpipe noise and more power, the modifications would be virtually undetectable from the drivers seat. This would also include the ability for the car to be driven at 1000rpms with no bucking/surging etc.

Also, no blowers or nitrous, must be pump gas and have cats.

From the research I have done I have compiled the below list. Feel free to offer any advice you might have.

CAI
Conversion to LS3 style MAF
102mm TB
102mm Fast
160 stat
Cam with hardware (need help here)
1 7/8 or 1 3/4 headers?
X-Pipe
2.5 or 3" Exhaust?
Dyno Tune

A miracle

 

It's very possible but it's not going to be easy with the somewhat docile cam and high flow catted X-pipe (versus off road X-pipe) that you seem to be seeking.

 

Sure. My car is making 400rwhp sae corrected right now through a stalled auto with only boltons. An M6 would easily eclipse that with equal mods and picking up 35-40 rwhp with a non-radical cam is not hard to do.

 

Well that is good to know. I am guessing the only item on my list that would impact the drivability would be the cam. If I can get 410-415rwhp without the cam, I would think I have a shot.

Any advice on headers and exhaust? Will 1 3/4 x 2.5" be enough or do I need to go to 1 7/8 x 3"?

 

It will be tuff to get 450 with a small cam and bolt ons. If you do some port work on the heads with all of those mods your should be able to make it to 450. also you should be ok with the 1 3/4 to 2.5 in headers if your only looking for 450. If you want to go bigger you can but there wont be a huge gain.

 

 

Don't forget a underdrive crank pulley should be good for another 10 whp.

 

My car makes 457 rwhp with a small cam and stock idle. No bucking or surging at any rpm. A cam such ~ 220°/230° at .610" lift would be close also.

You probably will need aftermarket or good ported heads. The stock MAF, throttle body, stock pulley are fine for that power level, so put your money somewhere else. Good set of CNC ported 243 heads, mild cam, FAST intake, and LT headers should get you there. The ported FAST 92 was worth 31 rwhp on my car. Plus a good tune, of course.

See the list of mods in my signature.

Here is a video of my car at a 675 rpm idle. 99% of the people that hear it don't believe it has 100 rwhp than stock.

 

Sounds stcok to me.

I really want to stay with stock heads. Its not a money issue, just a personal goal. Can I build a stock driving LS2 with 450rwhp, the factory long block and no poweradders?

I know you said my money would not be well spent on a MAF or TB, but is there ANY power to be gained? What about porting the FAST 102?

And what about exhaust? I know the rule of thumb is 1 3/4 x 2.5 will be fine for my power level. But is there ANY power to be gained by going with 1 7/8 x 3.

If I don't reach my goal, I would prefer to come up short on power not drivability.

 

It's going to be tough to do, but I believe you could get real close with a 223/227 116. It'd drive like my 218/230 116 in my LS1 as it has close to the same overlap and you have more cubes to soak up duration. The larger exhaust will not inhibit your goals and shouldn't cost much more, so I'd recommend it. An Underdrive pulley is free hp that will help you achieve your goal and so is a lighter weight clutch such as our Level 2 with 18lb flywheel which will free up ~10hp. Feel free to call me if you have any questions.

 

The key to a nice, smooth idle is keep the overlap in the negative range. I like the cam suggested by PRE-Z06. It has a -7° overlap while mine is -12°. I am sure it will idle and drive great. I rode in a G8 last week with a 218°/230° cam , headers and A6 automatic. The idle was dead smooth. However, it put down only 407 rwhp or far less than your target.

In my opinion, a ported throttle body is pretty simple DYI project. Remove the lip before the throttle blade with a Dremel drill and cutter bit then use a 80 grit sanding drum to smooth it out.

An under drive pulley obviously adds power by reducing the power needed to spin all the accessories. I chose not to do it since my idle RPM is near stock and was concerned it may cause a problem with reduced alternator output at idle. But never really seriously considered them.

I have 1 3/4 Dynatech long tuber headers and understand they are the best size for the 6.0 L LS2 with your power target. But you may want to confirm it. I understand the 1 7/8" are better on the 6.2L LS3.

I hear you about stock heads, but the stock LS2 heads only flow about 250 cfm. To get to 450 rwhp, a big cam is needed with the unported 243 heads. An alternative are the unported GM LS3 heads and L76 intake manifold. I recently witnessed a LS2 with these heads, headers, FAST intake and a small cam dyno at 457 rwhp and 428 rwtq. In any case, the OEM LS2 intake manifold is a major constraint. The FAST 102 replaced the discontinued FAST 92, so you will have to go with that if you get an aftermarket intake manifold. If you use the stock as-cast LS3 heads, then you can use the L76 intake manifold.

I also suggest calling Comp Cam to get their input.

 

If you port your FAST102 and pick a perfect cam, you can probably come close -- but my research a few months ago leads me to believe you need new heads to get past about 440WHP on an LS2 unless you want to hate your car at a drive-thru window.

 

Agree with the other guys. You need to make cylinder head improvements or live with a really rumpy cam to get to 450 wheel with an LS2. Finding a suitable set of ported 243's isn't that tough. I found a set on this forum for about 750 bucks. Livernois Stage II's. They flow similar to stock LS3 heads. My LS3, when it was cam only, made 475 wheel with a 226/234 114lsa cam. That cam was a little agressive for my tastes. Get a set of ported 243's, better intake mani, and a cam like PRE-Z06 mentioned and you'll get where you want to be.

 

The cam Chris mentioned should work very well and make good power also, a friend of mine installed a 227/231 112 + 2 in his LS2 GTO and called me today to tell me how much he loves it, said that it drives perfect, idles great and the car hasn't been tuned for the cam yet. He had it tuned a couple months back for all the bolt-ons but didn't think he would have been able to get his cam so soon.

 

I'd say do everything you have listed with the suggested cam specs and if you're not happy get the stage 2 heads. I may do this same thing in the near future.

 

I can vouch for that and this LS2 has some torque.

To the OP, I would do some port work on the heads. If you want 450 rwhp for cam only, that will be a healthy cam and no hiding that

 

You're right about negative overlap equating to a cams docileness, but fwiw I've speced cams with more overlap than the one I mentioned that still work with stock torque converters, so they have to have good manners. Also keep in mind that the G8 has less compression and more drivetrain loss.

 

Its all in the heads.. 450 rwhp isn't a huge task but to have it be docile and stock like is all in the heads.

 

If a full bolt-on LS2 can make over 400rwhp and that cam can pick up 50rwhp, then I don't see why 450rwhp can't be achieved with stock heads...

 

True. But let's not forget that 'very daily drivable' and 'excessive cam lope' are VERY subjective things. One man's opinion of smooth might be another man's 'too choppy'.

Personally, when I hear of someone wanting a totally docile, entirely daily drivable cam for their stock headed LS2, a 227/231 or even a 220/230 along with 114LSA and/or .610+ lift isn't the first thing that comes to mind.
When I hear 'docile', I'm thinking more along the lines of something in the 218/222 116LSA and .590 lift range. And that of course will likely not get a bolt ons/stock headed LS2 to 450rwhp.
But maybe the original poster has a higher tolerance than I think he might.