Any gain from 3 inch header back?

[robrocketanski]

Has anyone found any gain by switching to 3 inch from the header back? I will be full ported blower, 102mm TB, cam, E85, and 38-40% overdrive (10 inch lower and 2.75 inch upper)

The only other bottle neck I have is stock heads.

Also, can anyone verify if any of the aftermarket exhaust kits are lighter than stock? If I save a few pounds that may make it worth while also.

[Can'tHave2MuchHP]

Yes there's gain at that kind of power level IMO. The NPP is very good but no doubt you'll pick up some decent power and flow by going to a 3 inch cat-back like Corsa's.

I'd definitely get those heads done. Your car is going to be crazy loud

[RocknZL!]

Had the car mod before with all the typical engine bolt on's everyone does and tuned etc...just added Kooks 1 7/8, off road mid pipe and Corsa Sportsman 3" cat back exhaust, gains were 20 hp and 56 ft lbs torque after the dyno re-tune by LSXperts!

[robrocketanski]

Nice. Hard to know if that is all from headers or not but could be some from the 3 inch.

I found this statement in a random forum-

Vizard's rules of thumb: A pipe will flow 115cfm per square inch of cross-sectional area. You need 2.2cfm of flow capacity per horsepower.

Based on that the 2.5 inch is a restriction but it can't be hurting people as much as the math suggests. The math does match the factory 580 hp to the factory 2.5 inch though, or close enough.

1000hpx2.2cfm=2200
2200/115=19 cfm needed
1.5x1.5x3.14=7x2=14 cfm capable
So 3 inch is still a bit under based on that formula.

[RocknZL!]

I have both dyno sheets and loved the results I got, and this is a custom street tune...it's not pushing the motor to the max, it's all fine tuning all the mods to get peak performance not maximum...and we are thrilled with the results! Torque is what it's about!

[winterboy8]

3" all the way.

[kmkalkhoff]

What size is the factory ZL1 system?

[robrocketanski]

factory is 2.5 inch

[MarylandSpeed]

Keep MarylandSpeed in mind we sell a ton of Kooks & JBA & BB etc. at crazy low prices. We can get you great deals on your mod needs just ask for Holly or you can check out the link below.



http://marylandspeed.com/getingear-i-24.html



But if you give us a call you can get an even better deal then what we list on our site.

[SamHouseIII]

If we go with bigger pipes, 3in vs. 2.5in, do we loose boost? I know we do for header swaps, so why wouldn't this drop the pressure too?

[HOJO]

Originally Posted by SamHouseIII

If we go with bigger pipes, 3in vs. 2.5in, do we loose boost? I know we do for header swaps, so why wouldn't this drop the pressure too?

Even if you drop a little boost, which you will a tad bit, you will not loose power. A car runnng 14psi and one running 12 psi could still make the same power. A less restrictive air system will show a little lower boost but make the same power on an identical engine.

[SamHouseIII]

Originally Posted by HOJO

Even if you drop a little boost, which you will a tad bit, you will not loose power. A car runnng 14psi and one running 12 psi could still make the same power. A less restrictive air system will show a little lower boost but make the same power on an identical engine.

Yes, I removed my Billy Boats 3in and NoWeeds because I was told I was loosing to much pressure (The was by Ted J, well respected here and I'll take his word any day). Not saying the flow was a factor, just the loss of pressure.

[ZO6 Bryan]

Originally Posted by SamHouseIII

Yes, I removed my Billy Boats 3in and NoWeeds because I was told I was loosing to much pressure (The was by Ted J, well respected here and I'll take his word any day). Not saying the flow was a factor, just the loss of pressure.

Once again, improved flow resulting in lower boost pressure is a good thing. It does not drop your actual power output. People need to STOP equating boost numbers to power output.

Too make it very clear.
If you do a mod that drops you boost pressure, you just increased you power output. You did not lose power.

[winterboy8]