Oh yeah, I forgot that one

 

Agreed, use ALL the tuning tools at your disposal and let them tell you where to stop boosting.
I think Parish and 4.8carazy dumped huge amounts of boost and/or nitrous thru a stock 4.8/5.3 without tuning and the motor held. Not that pumping 15+psi thru a stock lower end would make me sleep soundly at night but proper tuning should be the limiting factor IMHO.

 

I can't say I totally agree... If all it depended on was the "Tune/Gas" we would all be able to run more boost. There are so many other factors. kbracing96 has a 4.8, I have a 6.0. Can the 6.0 run more boost than a 4.8? How much can a 4.8 handle? He doesn't have a fuel pump, so for him it's obviously less. Is weight a factor? How about the fact that with the stock springs I couldn't run more than 7psi without terrible valve float? With the springs, 10psi doesn't have any issues. Maybe others have found that with a 6.0 and springs, 15psi is the limit at 93 Octane.

Maybe others have proven that at, say, 12psi, the motor only lasts so long. But at 10psi, it will last forever. I know, wishful thinking...

I'm just giving examples as to why there is so much more than the Tune/Gas. I see your point, but when someone specifically asks, I think it's better to look at exactly what they have, rather than a basic "how much money do you have". It's funny though...

 

And compression ratio and octane and ...

 

there are much more factors involved than just adding more boost to making good power. Every forced induction application is different. Some cars/trucks run better on less boost and more timing for example... others it's the other way around or a combination of both.

"Boost" in all actuality is a measurement of the built up pressure between the turbine and the intake. If you think about it, it basically shows you how much power your motor ISN'T making from the blower/turbo.

With the meth kit and higher octane, you can run Much more boost and much more timing. Tubos like to have more timing. Basically, the only way to see what method is going to work for your truck is going to be to put it on the dyno, log it, and while using a good wideband, tune the truck for optimum AFR and to have zero KR... once you hit KR, you want to back down a little bit... make sense?

there are still many more factors involved, so a good tuner is what you want to have a good tune dialed in and setup for your ride.

 

I know my question was pretty general and I was looking to get some more info, before I did anything. As far as boosting a 4.8 to around 12 lbs to make up for the small displacement, my thinking is this. The 4.8 is basically the same bottom end as a 6.0 but with a smaller bore= less cubes. So, with that said, why couldn't I run a few more pounds of boost to make up for the smaller "charge" in the combustion chamber? This would help it get closer to the power level of a 6.0 that's running less boost. The bottom end should handle the power, right? It would be seeing the same kind of load as a 6.0 running less boost. From what I've see some people on here, like Parish, 4.8crazy, and Jason 98 TA, have really beat on a 4.8 and not really killed any. I know I have to watch the tune, and I will have a wideband by the end of the week, and I have a way to watch my timing, but no tuning software to change anything yet. I have the stuff to build a home made meth setup with just an on/off kind of trigger, but was looking to try to keep this simple. I've pretty much gone though my toy budget for a while so I can't really afford get Hp tuners for a little bit.

On a side note, I'm needing a stall, but like I said, I'm low in the toy fund right now, How much would a .69 over the .81 A/R exhaust housing help out my low end spool time. I have just the base T 60-1 turbo as it is a small motor. This thing is a real pig off the line. I know it will choke the high end some, but I boost more down low anyway. It would be cheaper then a stall and easier to install. Anyone have one laying around I could try?? Thanks for all your help guys.

 

I can't speak about a limit on the amount of boost one can run but as far as the springs go... it's really no surprise that the springs on a 2002 truck (3-4 years old) gave you problems. My stock springs have no issues running 7.5 psi up to 6000 rpm on a stock cam. After I put the 2.9 pulley on today I expect to see them holding 8.5 psi. Granted I only have 4300 miles on the engine. Your springs inability to hold was a matter of age, use, AND boost. Not just the boost. Now, this is not to say that the stock springs are the best for our boost levels. Changing springs also paves the way for a quicker cam install later

 

Stock springs can easily hold 8.5-9 psi. I just proved it today

 

true. I'm running stock springs at the same boost level.....


Now adding a FI cam to the package would change the whole scenario..

 

We pulled apart F8L Z71's 5.3 today and it was perfect. The reason it broek was from him sucking up water and seizing up a rist pin. Go figure eh?

He ended up running up to 15psi at the track on the stock bottom end with just head studs and MLS gaskets.

The tune has to be spot on. No Knock. And from the looks of his motor, nothing was going to break either. So run it where you feel comfortable, but like others have already said in this thread, go as far as you are willing to take the risk, because when something fails, it happens quick.

And a good bank account helps too...I like that one.