deecount

I have an LS3 A6 with the LPE TVS2300 package installed. I went ahead and had the American Racing Headers 1 7/8" with catted x-pipe installed and the car retuned. The end result was a zero increase in peak power. 509 rwhp before and 509 rwhp after. I picked up 10 or so hp/tq in the midrange. Is this normal?

PowerLabs

I saw zero gain from going from 1 3/4" headers to 1 7/8", but this was from headers to different headers. I'd expect to see some gain from a car that had stock manifolds.
Did your boost change at all?

deecount

They didn't provide that information to me. I would have to assume it did drop a little due to less restriction, but just how much I don't know.

TrenAman

you probably lost boost and the headers made up for the difference.. just a theory.. 509rwhp is on the low side for a A6 LS3 + tvs2300 IMO.. pulley it down and get your 600rwhp 580tq..

m R g S r

i'd say boost dropped, and you are most likely making the same exact power at a lower PSI, so the efficiency of your setup went up. bring the boost back up to where it was before, or turn it up higher and enjoy more power!!

blaine123

+1 Boost goes down when you add headers. Your power stays the same, but instead of doing 509 rwhp at say 11 lbs of boost... ur now doing 509 rwhp at 10 lbs of boost.

deecount

That's kind of what I was thinking. I'm already running the 3.1" pulley. Both shops seem to think that I'll run into belt slip issues if I go any smaller.

So if I was at 8lbs boost originally with no belt slip and now I'm at lets say 7lbs boost, would a smaller pulley slip because of lack of belt wrap even though I'd only be back at 8lbs boost?
Is there a boost threshold that causes slip or is it belt wrap or both?

Drewstein

^^^ this.

If boost were the same you would see the increase. With FI, the air is static unless you affect it like spinning the thing faster.

3 Z06ZR1

Can you post up a dyno showing before and after the switch?

old motorhead

Are you sure of the 3.1" pulley? They usually ship with a bigger pulley. Pulley size is usually painted on the back side of the pulley. If you do have a 3.1 now, I wouldn't go any smaller 'till you find out where you are boost wise. I have a 2.9" pulley and see a little over 8psi, but that is with LT's, blower cam, no cats, and NPP exhaust. If I close the NPP's, boost goes up to 9+, but power is off. I think about 9.5 to 10psi is about it before you get into belt slip with the 6rib belt.

deecount

Lingenfelter told me that they used the 3.1" pulley. I guess I need to contact the shop and see if they monitored the boost pressure when they were tuning for the headers.

old motorhead

Tried to answer your PM, but your in box is full.....

deecount

Sorry about that - just cleaned it up.

deecount

Here's the final dyno. It runs great and feels really strong. I just thought I might see some more peak power with the headers.

Drewstein

Once again they should have told you (I'm assuming they know) that the airflow didn't change as your blower is set to move a specific CFM regardless of headers or not. You have to move more air/fuel through the motor to create more power and you're not doing that yet.

I surprised they sold you headers without telling you that.

deecount

I guess on the positive side of things I'll be all set if I want to go with a cam and boost upgrade

Drewstein

Yes you will pick up a bunch because of the headers when you put more air through the motor.

Also, you picked up power under the curve which makes for a damn quick car.