batmanntexas

iTrader: (1)

I need some help from all you knowledgeable turbo folks out there. I need some advice on which of these three cams that I have, on hand, would be the best choice for a twin turbo build on my Avalanche.

Engine details: 383ci, ported 243 heads, forged bottom end, ported TBSS intake, ported 90mm TB, currently about 12:1 CR (will be lowering to 11:1 or so).
Turbo details: T3/T4 hybrid, 60mm, 1.15 A/R, journal bearings. I bought these off eBay about 14 years ago, they are still new in the box, so I figured I might as well put them to use.

Current cam in 383:
239/247/.629/.629 @112LSA

Cam option 1: stock GM LS9 cam (211/230/.558/.552 lift @122.5 LSA)

Cam option 2: 216/223/.556/.556 @114 LSA

My goal for this truck is daily driver duties & towing. Probably only looking to do about 8-10psi max.

So, I'm thinking the LS9 cam is the better choice, but I have no experience with turbo cam selection.

Thanks,
Scott

truckdoug

iTrader: (25)

cam 2 looks pretty tasty.

liketowork

iTrader: (4)

The less overlap, the less of the boost that you are making will go out the exhaust before the valve closes. the ls9 cam of the 3 has less overlap

JoeNova

I'd pitch the 14 year old ebay turbos. Those things were still exploding 10 years ago. They have come a LONG way since then.

rpturbo

iTrader: (47)

I agree on the less overlap statement, however thats not the only thing to consider for cam selection. If it were mine, I also would pick the 2nd cam over the LS9.

1CAMWNDR

iTrader: (21)

2nd cam for sure. The LS9 cam does not work too well with a turbo truck....the way wide LSA sort of kills off boost torque. But with the ported heads I would take advantage of the airflow above .550". I think buying a specific one for you r cubes and head flow would be a better idea. Just sell the 3 cams you currently have to help with the cost.

batmanntexas

iTrader: (1)

Thanks for the responses. I guess I'll try and sell the 2 that are on the shelf now (LS9 and 216/223) and order a custom one. Thanks again for the info/advice, I really appreciate it!

As for just ditching the eBay turbos to buy something else, can't see doing that since they are brand new. I'm not going to be pushing these things very hard, so I don't think they'll be blowing up on me.....and if they do......guess it'll be time to build a bigger, badder LS for the truck.

-Scott

1CAMWNDR

iTrader: (21)

Oh yeah, use the turbos you have and see how it drives for sure.

Bazman

Cam # 2 is the pick of what you have for torque. Yes it could be improved on, but it will really wake the motor up at all normal driving rpms compared to the LS9 cam, and will wake it up significantly compared to the one you are now running at lower rpms and off boost. With a bit of advance on the intake to further boost low end torque I think you'd be pretty happy with it. That cam has zero overlap @ 050

JakeFusion

iTrader: (7)

I'd pick a different cam all together? 227/235 .600/.600 114+4... or so.

sbcgenII

iTrader: (1)

Go with #2

jmac636

iTrader: (8)

When those Turbo's start smoking I'd buy a couple Borg S366 turbo's or Vs Racing S366's. They sell them with T4 housings though.

gametech

iTrader: (1)

I am not intentionally picking on you, but I quoted your comment as an example. How the **** can anybody pick a cam without knowing any details of the heads? He said they were ported, but what do they flow? Where in the lift range do they flow? These questions need to be answered before a cam can be chosen. If he had stock parts the answer would be much easier to figure out.

JakeFusion

iTrader: (7)

They are ported 243s. They all fall within a general range. Had he LS3s or LS7s, it'd be different. Stock, not really. The I/E ratio stays about the same whether ported or unported.

You want to cam a twin turbo setup close to a usable NA cam usually. I usually recommend something like a 227/235 for most street driven vehicles with 243s. Being that it's a 383, he could go with a little more. But seeing that it's a truck, it's a decent compromise cam.

gametech

iTrader: (1)

Asked and answered. Fair enough.

batmanntexas

iTrader: (1)

@JakeFusion - Thanks for the information and advice! I will definitely just get a custom camshaft rather than use any of the three that I currently own. Thanks again for all of the advice. I'll post back in here when I start the build process.

-Scott

Kfxguy

iTrader: (1)

i do have a cam Id swap you for your smaller cam. I have a brian tooley 227/234 on a 113+2
works excellent with my single 7875 on a 5.7. spools almost instant. I just want something a little less rowdy. It would be perfect in a bigger motor like yours.