Ok I want some clarification on issues about turbo boost vs blower boost. for the most part in general I have always seen people run Blower boost within a range of 5psi to 8psi. Anything major than that it seems that you really need to be careful on your setup so you dont hurt anything. You hardly ever see anyone running that much boost with a blower.

Now in a turbo (in our trucks) generally 5psi is also the norm to run at, anything greater than that requires one to also be careful. But it also seems that there is much more flexibilty when you run at a higher boost with a turbo. Take for example FL8 he is running a believe 13.5 psi (something like that) yeah I know that he has mods to handle that but could he run 13.5 psi with a radix and his reliability issue still be the same? And Parish running 22 psi of boost on the 4.8, hell with that kind of boost you can power NASA Challenger!!

Generally this is what I see:

1) It seems that turbo boost is a bit safer at high psi. For what reason I do not know!!

2) Maybe it is not safer, its just that with a turbo you tend to see a higher psi range because its an easier option of turning up the boost on a turbo. Rather than with a blower you have to change the pully.

Please clarify lets get a good discussion on this!

 

there is more to the equation.
Turbos use controllers that alow more boost with the turn of a ****; no belt slip
S/C use belts and require pulley swaps.
F8L has a larger turbo, FMIC, and meth. His system is setup to make more boost and do it more efficiently.
The Radix rusn out of steam or hits the blowers maximum impeller speed before alot of the turbos.
Boost is boost for the most part. You need to have a good fuel system as well as some sort of intercooling. Tuning also plays a huge role. Some motors hold together better than others, but no stock bottem end will hold 15+ psi from any form of FI indefinately.

 

green tahoe to the rescue again great answer and i know that running 12 psi on a bottom end 6.0 is possible i have seen it done before as far as how long dunno he tried to tune it to a 15 pound and roasted it before longevity could be established and this was on an ATI and like green said people running higher boost turbos also have the setup for it just like you will need running high boost superchargers but again you do not have to deal with belt slippage....

now they do make pulleys that hold on a bit better as well so something to think about and another thing running the 12 psi on that ATI required an intercooler upgrade pound for pound you cant argue the fact that top fuel cars use SC but also not near the same application

i am partial to the SC over turbo because i like the sound better but in the end again like was already said boost is boost be careful TUNE . TUNE. TUNE and you will be ok

 

Boost is boost. This is the way that I see it as well. It is just that I always see turbos running at higher psi. So if I understood you correctly if F8L was to run a S/C at the same psi that he is running at it would be the same... no problems. It is all up to the S/C being able to run at that high psi.

 

1) It seems that turbo boost is a bit safer at high psi. For what reason I do not know!!

Boost is only as safe as you make it. Usually anything over 5-6 psi generates higher IAT's (intake temps) and is more prone to detonation. Cool air is always more dense allowing more fuel to be mixed with it.

Many people including myself are using the Radix kit and the max that system can put out is about 10 psi with pump gas on a 5.3 without significant diminishing returns. The dimishing returns are a result of overspinning the blower and generating excessive heat. People with ProChargers (ie F1's) are running more boost, sometime up to 15-20 psi. These units usually have massive intercoolers to keep intake temps down.

The same applies to turbos. Turbos can run tons of boost, but how much is dependent on the turbo size and housing as well as the effeciency of the intercooler. Turbos are said to be more effecient as they uses the engines exhaust to power them and there is no parastatic loss. (sp) Since the turbos dont generate any type of loss, boost can usually equate to more rwhp.

The fuel injection system is also a limiting factor when running higher boost levels. Bigger injectors and larger fuel pump or inline boost-a-pump are usually necessary for more than 5-6 pounds of boost. Insufficient fueling can create a lean condition and kill the motor as well, regardless of the whether a blower or turbo.

2) Maybe it is not safer, its just that with a turbo you tend to see a higher psi range because its an easier option of turning up the boost on a turbo. Rather than with a blower you have to change the pully.

Turning up the boost is easier with a turbo, but precautions are still there. You still need an intercooler, injectors, and fuel pump for higher boost levels. A tune is also necessary



Well, here is a start. I know there are people with more knowledge than me, so let it flow. This will be a good topic to discuss.

 

Thanks.
Do you know who makes the different pulleys for our apps? I would think that it would be the same as any other LSX motor, but cant seem to get confirmation on that. Id like an 8 rib setup for my new setup.

 

He would have to step up to a pretty good sized head unit to make that kind of boost as well as a better tensioner system as well. Once again though, we enter into the efficiency equation. When you overspin a blower you decrease its efficiency and increase the air discharge temp which makes less power. Theres alot to it. I believe the base kit comes with a 60-1 turbo which F8L would be operating out of its efficiency range. So he stepped up to a larger turbo and a different exhaust housing. There is ALOT to it and I sure dont know all that much!

 

I dont think boost is boost. A supercharger generates a parasitic loss when it makes boost. The supercharger is driven off of the crankshaft and reduces rwhp. To make 7 pounds of boost, the engine has to overcome the energy it takes to make that 7 pounds of boost.

A turbo is spun by the exhaust gases and doesn't create a parasitic loss like a supercharger does. Therefore it can generate more rwhp with less energy.

 

im not going to get into an arguement like also your going to prolly get a response sooner out of the SC because like you put it is belt driven so is directly related with engine speed where as with the turbo you have to build the exhaust to turn it there is pros and cons either way i am partial to SC that is all my post was about do not make it more than it was please i gave an opinion which is what this site is for people to come and get opinions on matters about there trucks and cars once again he asked what we thought this is what i though (OPINION)

so destrucktive take these posts for what you will and understand they are just opinions and that mine maybe different but i like the SC (especially the ATI for performance and again i just like the way they sound )

and if you are so into turbos why is it that you have a SC ...???

thanks again all for your time

 

Great responses so far

I'll add that I agree boost is not boost when it comes to how well a motor can handle it. On a centrifugal system you wont have near the same avg. HP that you would on a turbo. A turbo setup has the potential to create lots more heat due to it making more power over a longer RPM range. This could easily lead to detonation. Also look how fast and hard some turbo setups can come into power, this is why tuning is very critical. A high powered Radix/KB setup could be similar because of it's broad powerband.

For what it's worth I would never use me as a GOOD example of what boost levels are safe. My goal in life is to blow **** up and I do a damn good job of it.

I ran fine with my setup for awhile at 13psi with occational 14psi spikes. It wasn't until I ran 14-15psi that I started to have trouble and part of that could have been from the water ingestion thing. All I know is at 15psi I now have this nice rattle in the bottom end, kinda like a spun bearing. LOL