another vote for turbo

 

If you the 6.0(VHO)it already makes good power down low-you ever floored it at 20-25 i jumped the hell out of my buddys lightning but we need more mid range and top end power on these things. Personally im going with a radix setup b/c ive always wanted a s/c truck. Just me though the turbos are sweet and will do the truck and also the STS is cheaper. Depends on how much you wanna spend and where you wanna make power. My vote is for the radix.

 

Questions about turbo.... err, STS 6.0 driveability...

Say I'm cruising on the interstate and I come up to hill. I'm at 2,000rpm. How easily is it to build boost? Do I need to really feed a lot of pedal, or does it come pretty easy with the added load from the incline?

What about if I've got a trailer in tow...same story, but it's even easier to get into boost because of the load?

Are the STS's lightly spooled at cruise at 65-70mph? How does cruise control work with them? The last thing I'd want is a flat spot or lag in that area.

 

I find that there is zero lag on the highway. In fact boost almost comes on too soon, I now need to use cruise more often just to keep the mph's down. I wouldn't worry about flat spots on the highway, it is just less "exciting" off the line (less so considering it's a 6000+lb truck).

Ed

 

Awesome. Is that an STS you have?

 

No, I have a custom made setup built by turbo dynamics in NY- It is intercooled and mounted next to the engine.

ED

 

I may need to PM you on that...

 

Marc,

My setup may abit different than the lower boost guys because of the way my timing is set up so low boost is not as helpful on my truck as it is for those 5-7psi guys.

At cruising speeds I am not int boost but give it a tad bit of throttle and it will see a couple pounds. Floor it at anything above 35mph and it downshifts and just rips, I don't really notice any lag, it may take aprox. 1 second to hit full boost from that point but my definition of lag is the time it takes to see boost, not go from 1psi to 13psi.

On inclines boost is already there on my truck. In fact I am actually at full 5psi (low boost mode) solid all the way up steep inclines. My truck isn't set up for that though so I am continually shifting back and forth between OD and 3rd so I have to manually stick it in 3rd and lay off the pedal or else I'll be doing 100mph up the hill passing people and in the Bay Area you DON'T wanna be the fastest guy up the hill.

In essense I think any turbo will react favorably in the conditions you mentioned. You just have your tuner set it up the way you like it. I have mine set up for flat land driving with no real hills and so on the freeway I don't have to give it much throttle % to have it downshift to the next gear, therfore enabling me to pass very easily without #1 luggin the motor in a high gear (bad on your OD band) and #2 flooring it. Flooring it with 500+rwhp and no muffler is kind of rediculous in morning traffic. LOL

 

Thanks F8L...

Yeah, I'm pretty happy with the torque I'm making with the little cam and headers here. I can very lightly roll into the throttle at 65mph/2,000rpm, and pick up 5mph in about 5 seconds. (doesn't sound like much, but that's better than stock and a lot better than the bigger cam I had in here). Any more than that, and it kicks down to 3rd.

I guess what I'm worried about is feeding some pedal on, only to have the motor continue to fall flat until it downshifts... where it'll scream. I hate that. I had an old tired V6 truck that ran like that - it put me in a bad mood.

Do you happen to know what the recommended turbo size for a 6.0, for "all around" or street/tow use? I understand the GT67 you have there is pretty nasty for a 5.3, right? (but it's an easier spooling, more efficient turbo, than it's size suggests?) I'm guessing I'd look at the STS kit's base turbo, or maybe something smaller in general? I'm not sure.

After doing a lot of reading here about tuning for PSI, I see what you mean about the 5psi setting not being setup for you. I figure I'd ideally like to see a healthy but "safe" amount of boost, and stick with it. Maybe 6-7, maybe a little higher. If I went turbo, I can't push it as hard as some of you are. Not now anyway.

 

The GT67 is perfect for the 6.0L. It spools great on an LS1 and even better on the LQ4. You could also check out the GT35 but I think it's a bit small for a 6.0 but I'll be damned if it wouldn't spool like a ****!!

If you tune for 5-7psi and that's all you plan on running then you can have awesome part throttle repsonse. Kinda like you mentioned above about lightly rolling into the throttle and the truck just starts really moving. I can do that now even with my oversized turbo and not being tuned for low boost. The only time I have problems is on onramps for some reason. I'll get that figured out later when I get the truck back

The beauty of custom tuning is you can have it set up anyway you like. I can easily pass people without downshifting. I kinda pick at what throttle % I want it to downshift so that I can pass those ******** that start speeding up to block you off and not have to floor it to get it to downshift. If that makes any sense. In this way I can more accurately control how much boost I am seeing. At 5psi it's no biggy but at 13psi I don't want it to downshift and slam up to 13psi just to pass some retard. LOL