Z06zak

Had my car tuned last week after getting the long tubes and the intake installed. Overall I'm very happy with the numbers considering the conditions and the conservative tune, the car feels and sounds amazing. Shout out to Powertech Performance in St. Pete. If any of you guys are in the Pinellas/St. Pete/Tampa area I highly recommend you check them out. Joe (owner & tuner) is an awesome guy and the LS platform is his expertise. He walked me through the tune while it was on the dyno and explained what changes he was making as he went along.

Car: 04 c5 z06, 40k miles

Mods: American Racing 1 3/4" long tubes, off-road x-pipe no cats connected to stock Ti axle-backs. Vararam B2 intake w/ power duct.

Conditions: 92F outside/114F in dyno room, 85% humidity, approx 15ft above sea level.

Stock Baseline: 351hp & 329tq

Final Pull: 388hp & 370tq at only 20 degrees of timing.

HCI2000SS

iTrader: (2)

Looks good man!

Z06zak

Thanks!

thunderstruck507

iTrader: (18)

Just curious why they left the timing that low unless your particular car showed no gains with a more normal amount (23-28*)?

Toes

iTrader: (1)

20 degrees is really low. To low

ddnspider

iTrader: (26)

Ls6 engines are more efficient and don't need as much timing. I believe Scottysc5 was the same deal.

ZNix

iTrader: (1)

Curious why you went with 1 3/4 and not the 1 7/8? Is there space constraints?

Z06zak

I asked him the same thing, I was a little surprised by how low he kept the timing too but the more timing he added the more knock he would start to see. Very minimal knock but still knock. He said the heat and humidity was really holding him back from squeezing the last few degrees of timing out. We agreed to leave it conservative because it is my daily driver.

Z06zak

I just felt the 1 3/4" was better suited for a stock 346ci daily driving in the city. I might have picked up a couple peak hp with 1 7/8" but I didn't want to sacrifice any mid range torque so I played it safe.

thunderstruck507

iTrader: (18)

That's strange. Even in dead of summer I've been able to get 27.5* out of my LS1 with LS6 heads and now the LS2 which has even more compression (approx 11.2:1).

That humidity is pretty insane though.

Either way, good numbers.

Z06zak

Yeah it is a little unusual that we couldn't go past 20 degrees without seeing some knock. Most likely some combination of variables like heat/humidity, heat soak, bad gas, blow-bye in intake (I don't have a catch can yet and he mentioned that the intake manifold was very dirty) etc... who knows.

KW Baraka

iTrader: (7)

I would pretty much guarantee that if you went to 1 7/8" headers, you'd gain HP.....and.....torque throughout the entire RPM range.

'Back pressure' be damned.

Jus' sayin'.....

KW

HCI2000SS

iTrader: (2)

A buddy of mine just switched from 1 3/4" to 1 7/8" headers (both Speed Engineering as well) and picked up exactly 5 rwhp. It was the same dyno before and after. He has a heads and cam LS1 to boot.

G Atsma

5HP from 1 7/8" headers over 1 3/4"; a gain, yes. Cost effective, no.

HCI2000SS

iTrader: (2)

Exactly!

Z06zak

How did the curves compare? Everyone but my tuner seems to recommend 1 7/8" but I have yet to see a good back to back comparison. I find it hard to believe that going up in primary size will have zero effect on the low/mid range and will only extend peak torque to gain a couple hp. Either way the difference is not nearly significant enough to make the switch.

HCI2000SS

iTrader: (2)

I don't remember exactly to be honest. I wanna say he said they were pretty much the same all the way through, or the bigger headers started gaining after 3500 rpm. I'll have to ask

ironmanLS1

iTrader: (9)

I was going to ask a similar question. We always look at peak HP for comparison sake, but in reality acceleration happens under the curve.

ZNix

iTrader: (1)

The 1 7/8 headers would have been the better choice imo. I think they would pick up everywhere on the LS6.

KW Baraka

iTrader: (7)

1. Gains will depend on the setup...... ;

2. Sell the old headers to defray the cost of the new headers;

3. For you next build......just go big!

KW