Valve springs, camshafts, and power-adders, oh my!

[zeeboost]

So I finally have my lsx drivetrain picked and almost ready for completion. The engine is a forged 370ci with a 9:1 CR,

 

 

the transmission is a built t56 (not pictured), and the rear is an R-230.

 

 

I have 3 main questions:

 

1) I currently have a Magnacharger mp122 in my garage, but after doing a lot of research, it seems that 650rwhp will probably be my limit with the blower, so I began looking for a Kenne Bell 2.8 to use instead. I spoke to a user on ls1tech who was selling his KB 2.8 to ask why, and he said that the IATs were rediculous at 15psi, seeing 258* even on meth. He (as well as almost everyone else) also complained about how bad Kenne Bell's customer service, so he'd finally had enough and was going a different route. I was planning on having two "settings" on the power levels, so to speak. The street friendly setting, which would put me around 600rwhp, and the hardcore setting, at around 750-800+ rwhp. With the 2.8 KB, I figured I would have a "street" pulley and a "hardcore" pulley. Since that fellow seemed to be having a lot of problems from the KB, I've been thinking about keeping the mp122 that I currently have, and adding a 150 shot of nitrous. That seems to make a lot more sense to me, since I'm sure I'd rarely use that much horsepower, but how risky is it? I would have it professionally tuned on a dyno if I decide to go this route, btw. I'm curious, is there any more strain on the engine if I have 650hp + 150hp shot of nitrous to make 800hp versus simply making the 800hp from all boost (and most likely meth)? I believe I read that nitrous works well with boost because it helps cool the charge, but I never really researched it that much before.

 

2) An extra set of LSx 241 heads came with the engine that I bought, because the guy I bought it from (who owns an LSx performance shop) recommended that I take the double springs off the 241 heads and install them on the engine I bought, which have single springs. I do not know the spring rates of either spring, but after removing them, it really feels like there was a noticeable difference in compressing the double spring versus the single (duh). It's a distant shot, but you can see the two springs side-by-side here.

 

 

Well anyways, the heads on the engine that I bought have been completely worked over, and that included new valve stem seals. Compared to the seals on the 241 heads, these things are beefy and look like they'd be high-performance. I'm assuming the 241 seals are OEM seals - here's more pics:

 

Beefy seals on the new heads:

 

 

And the OEM (I'm guessing) seals:

 

 

 

Now here's the problem, the inner-spring on the heavy-duty springs that I'm trying to install on the new heads rubs agains the valve stem seal, and I'm pretty sure it would result in destruction of the seal. So, if I want to use the heavier springs, is my only option here to swap out to thinner, OEM-style seals?

 

3) Couple of cam questions: I'm assuming that I should have more than enough low-end torque for the Z to be happy, so I'm looking for a camshaft that will have a power range from approx. 3k - 7k since the blower supposedly falls off in the higher rpms - any problems with this logic? Also, if I end up going the nitrous/blower route, should I buy a nitrous cam or blower cam? I would assume a blower cam since that would be 95% of my driving anyways, but then I was thinking that even with a nitrous cam, the supercharged 370 should still make more than enough power to be happy on the street, and then when I hit the juice, having a nitrous cam would optimize every bit of horsepower. This is all theoretical to me, I have no experience to back it up.

 

Sorry for the long post fellas, but these three things have me at a stand-still with the project. And Braap, after that huge discussion we had about the 408, I felt kinda bad buying this one, but figured it would be for the best (and the price was unbeatable!); I still appreciate your help, nonetheless.

[zeeboost]

I'm a bit more sober now, and I'd like to apologize for the awkward, overly-cheesy thread title. BUT, the questions are still valid and important, so please help. Thanks!

[dr_hunt]

The teflon seals are considered better AFAIK. Beefier is not always better. having new seals is about all you need although the rubber ones are more forgiving when the guides wear out than the teflon seals. Also the teflon don't take high temps very well.

[zeeboost]

If there's not much of a trade-off between the two, I'll stick with the OEM seals. I'm pretty sure I'll be using nitrous on top of the boost...I just hope it won't be too much for the engine. Any advice on which cam I should use?