My current setup is running about 7psi @ 6k. I was wondering if I replace the engine with a 5.3 what would happen to the boost? Im inclined to think it would go up because of the smaller cubes and if the cam specs arent what the 99ls engine is. Am I right? If so then how about if a 02 ls6 cam was used on the 5.3? The reason I ask is because my current setup is verry close to max rpm according to vortech. I didnt know about upgrading to a smaller pulley and was told the 5.3 is a dog down low compared to a LS1 or a 6.0 even in a mild blown setup like mine. More up top is what Im after but I dont wanna loose any midrange torque either. What do yall think?

 

Changing your engine at this point isn't going to change the power much. Sure, going to the smaller motor might make more boost, but that's just showing the backup of air in the intake manifold due to the motor not being able to 'ingest' more air due to the smaller displacement. Think about it this way. Air flow is power, and if you're spinning your blower at nearly the max rpm, you're not going to get anymore airflow out of it by going smaller.

You need a bigger blower, not a smaller motor.

What would you rather have? A mustang gt making 15psi of boost and 400hp, or a ls1 making 7lbs of boost and 450hp?

Again, if your blower is at max rpm, you need a bigger blower to get more hp.

 

Agreed, and good point. I might have worded this wrong. I know my stock engine wont last forever' when I replace it I will probably get a 5.3 or a 6.0 stock engine fron a wrecked truck or something like that. My ? is: should I get the cheapo 5.3 or opt for the hard to find double priced 6.0. What would be the pros and or cons of each and why or why not should I choose one or the other, make sense??? Im retarded, my bad .

 

6.0 will need more air to make the same amount of boost due to a slightly higher CI. Both the 5.3 and 6.0 can take alot of boost though. A 6.0 at 6psi will make about the same as a 5.3 with 7psi, although I dont think the air consumption will be a whole extra psi.

If you put a turbo on there it wouldnt be a problem

 

Don't fixate on the boost pressure. A 6.0l motor with a decent set of heads will make more power with a blower than a 5.3 with less efficient heads and the same blower speed. The smaller motor will make more 'boost' pressure, but will result in more heat generated, which means you have to cut timing.

 

^^ +1
Don't obsess about the boost pressure, focus on what it puts down to the rear wheels.

Which head unit pulley are you running? I have the 3.12" on my V9G equipped car.

 

I should have added theoretically lol. All parts equal aside from the CI, they would make relatively the same power at the given blower speed

 

Me too. I was told that the blower is already past optimal efficiency and to put a meth kit on it with dual nozzles rether than up the boost for higher hp. BTW what is your setup and #'s???

 

to all others that responded: I was just curious what engine would be the better choice for the setup I have now as Im probably not changing out the vortech for a turbo as money dosent grow like that where I live. I also understand not to get caught up in the boost # game as its just un used air for the most part.

 

I say go with the more cubes because when you're not in boost, you'll have more power for better drivability.

 

My 10 to 1 5.3 moves my car around just as good as my 6.0 with ls3 heads. Actually feels stronger around town.

 

Mine is a very mild build, basically the blower kit and little else on a 2001 Camaro SS M6. Put down 465/440 on 9# on a Dynojet. This is with stock exhaust manifolds and factory cats (!). I have an SLP Y pipe after the cats and the muffler in the SLP dual dual has been removed and replaced with piping. It has the original Spectacle Solutions Lid, a BBK throttle body, and a ZO6 MAF. Brian Reckart retuned the PCM for me after I did the additional mods above and beyond the Vortech kit. It also has a Spec III clutch and McLeod adjustable master.

 

How do you get 10 to 1 outta a 5.3? LS6 heads? What did it make and on how many #'s, thanks for the tip.

 

Um, I'll take that lid good sir. Im guessing that your making 9#'s because of the stock mani's n cats. Mine barely makes 7 #'s @6000rpm. What rpm did you make the 9#'s at? Nice #'s BTW.

 

haha. I've had offers on the lid.

Yes, if I put some longtubes on the car, the boost would drop. I can't tell you boost versus RPM as car no longer has a boost gauge on it. Was only temporarily mounted after install for verification. Also the dyno I used didn't have a vacuum line to connect to measure and record psi.

 

I run an l33 5.3 HO motor, its an aluminum block version of the lm7 5.3, has flat top pistons and the ls6 heads. With the 04 ls6 cam its a nice runner. no dyno numbers but if you run my 1/8th mile time and weight it comes out to about 450 rwhp, 500 at the motor at 5-6psi