I'm compiling a list of C5 and Z06 Dyno modifications. I hope this saves
someone time and money. Half the stuff I get turns out to be crap. If you
would like to contribute, have questions or have other modification and/or
vendor information, please email feedback. The modifications listed were
performed on a 2000 Coupe, 2001 Z06 and 2003 Z06. Some things that worked on the C5 don't work as well on the Z06's. All HP ratings are RWHP in
cronolgical order. I'm experimenting with LS1 Edit. Does anyone have tables and/or dyno numbers? Does anyone have dyno info on Aftermarket Heads?

2000 C5 - 307 HP stock, 22,000 miles, July 2001
K&N Filter in stock box +4 HP, Z06 Airbox +3 HP
Throttle body coolant by-pass tube 0 HP
Remove MAF screen -1 Hp @ 2800 RPM, +2 @ 5900 RPM
IAT relocation +2 HP @ 2800 RPM, -1 HP @ 5700 RPM (knock detect)
Random Technology Cats +6 HP, +2 HP @ 2900 RPM
Flowmaster mufflers +5 HP
JBA headers +4 HP
Modified 322 Peak RWHP @ 5400 RPM

2001 Z06 - 334 HP @ 5700 RPM stock, 7150 miles, Aug 2003
K&N Filter +6 HP, cut Z06 Airbox opening -1 HP @ 2400, +1 @ 5900 RPM
WCC Airbridge -2 HP @ 3000 RPM, +4 HP @ 5800 RPM
Ported throttle body +3 HP
Port matched exhaust manifolds, no pup-cats, new Random cats, Xpipe +14
Modified 358 RWHP @ 5900 RPM

2003 Z06 - 356 HP @ 5800 RPM stock, 2000 miles, April 2003
K&N filter +3 HP, Removed and installed Blackwing +6 HP @ 4200 RPM
WCC Airbridge +2 HP 3300 RPM, +4 HP 6200 RPM
BBK Throttle Body +5 HP @ 6100 RPM
Hypertech 180 thermostat -3 HP, @ 200 F. 8 degrees hotter than stock 192 F.
Hypertech 160 thermostat +2 HP, @ 178 F. 14 degrees cooler
JBA headers -4 HP @ 3400 RPM, -7 HP @ 6000 RPM
SLP headers hit passenger side frame, no dyno test
B&B Z06 headers +3 HP @3700 RPM, +6 HP @ 5700RPM
Random 3" Cats, 3" tubing, Hedman 3" X-Pipe +8 @ 4600 RPM, +5 @ 6100
GM HD Plug wires +1 HP
Crane 1.8 Roller Rockers +8 HP
Predator Programmer -3 HP @ 3200 RPM, -9 HP @ 6200 RPM
Modifed RWHP 388 @ 6000 RPM

(Temp, Knock, Spark and Fuel were monitored using AutoTap GM Extended Software. I will be testing TPIS, LPE and Stainless Works full length headers on the 2003 Z06)

Parts Winners
Shifters: Kirban vs. B&M = B&M
Headlamps: MidAmerica HiIntensity Blue vs. WCC Hyperwhite = Hyperwhite
Speakers: MB Quart vs. Infinity Kappa = Infinity
Shocks: Stock 2003 Z06 vs. Edelbrock IAS = Edelbrock

Best Mods
Baer Eradispeed Rotors
Fichtner Chevrolet CD Changer
Bel Remote detector with hidden Controls where the ashtray goes
Fosgate amp under seat using factory Bose deck/woofers/wiring

Vendors that Rock:
Mid America Corvettes
Eckler's
Jeg's
Exit28Motorsports
RockAuto GM Parts
West Coast Corvette (WCC)
Martel Brothers
LMPerformance

Vendors to Avoid:
GMPartsDirect
RPM Outlet


[Modified by ACELRNT, 10:55 PM 5/15/2003]

 

:D

 

:rolleyes: Please add "This is of course just my opinion" to your post. I have lots of disagreements with your post, but I will just name one. T Byrne Motorsports has been an excellent vendor for me.

 

You are right. My bad. It is just my opinion. I ordered several items from the guys you mentioned. Everything was great, fast ship, good prices... until the one time I needed customer service on a defective item and got into a great big hassle.

 

I weighed my 03Z with 119 miles and it came in at 3140lbs with a FULL tank of gas...I know J-rod weighed his 02Z...(not sure of the mileage) with a FULL tank and it came in at 3150lbs

A little something to add to your data base

BTW, my weighing machine had a +/- degree of 30lbs ( meaning the car could've have actually been 30 pounds lighter or heavier)

Good luck ! :)

David In Indy

 

With respect to the Crane roller rockers on the Z06; what was the rocker ratio?

Also, do you have any information on the Granatelli or other MAF for the Z06?

By the way, great project, I wish I could contribute more!! :D

Thanks, Mike

 

On my car, removing the airbox cover and replacing it with two wire ties neeted me a 15.8HP gain and aaproximately 11.2 lb/Ft tq...

Before 356
After 372

 

Crane 1.8 Ratio Roller Rockers. The HP gain was noticeable, but the best part is the crisp throttle response from 3500 to 5500 RPM. I've seen 1.85 rockers, but the springs would need to be changed to prevent coil bind. .040 clearance hot is the minimum recommended coil clearance at full valve lift. My 2003 Z06 was .055 - .065 inches. I also used Titanium clips and retainers.

 

The 2003 Z06 MAF really rocks! They come screenless from the factory, are calibrated for the screenless airflow and have the IAT sensor built in. Any MAF changes made will eventually be negated by O2 driven fuel trim tables. The GM mechanic that I take my cars to reasoned that he would rather spend the money on EFILive5 Pro and change the fuel trim and spark tables on his 2002 Z06.

 

Were you using the stock filter?
Are you using the stock air-bridge?
What year and how many miles?
15.8 HP is AMAZING.

 

How is it possible on the 03 Z06 that it loses horse power with headers, also on the same 03 Z06, it loses horse power after using the pred tuning. :confused: :confused: :confused:

 

The 2002-2003 Z06 exhaust manifold is actually a 4 into 2 into 1 Tri-Y design. The JBA is a 4 into 1, and the runners are a bit shorter than the factory manifolds. Everyone I talk to says it is difficult to get better HP than the stock exhaust without going to full length headers. The B&B Z06 headers are a Tri-Y design with slightly larger and longer runners. The advantage is that these bolt up to the stock exhaust without cutting or welding.

The Predator caused the engine to run real rough. The data logging showed knock detection was limiting the spark advance and WOT operation was enabling COT (converter over temp). Rather than dick with it, I bailed. If it's not good out of the box, it's better off staying in the box. I tried it because RPM Outlet had a 30 day money back guarantee. I sent it back two days after I received it. The problem is they wouldn't honor the guarantee, saying it was a typo. RPM Outlet ended up charging me a 30% restock fee of $125.30. One of the worst vendors I've dealt with. What a f***in' nightmare. :rant: :mad :nopity

 

The Z06 exhaust manifolds are not "tyi-wye", but they are more efficient than fabricated shorty headers because the exhaust passages are smoother and constant cross section. With fabricated shorties the bends lose cross section area, and the welded joints can have weld splatter and other discontinuities in the flow path. That's why GM went back to CI manifolds from the fabricated stainless steel manifolds on C4s.

Even long tube headers don't do much with the OEM cams because they have very little overlap.

Sometimes it's hard to beat the OEM stuff at any price.

Duke

 

:rolleyes:
The 2003 Z06 cast iron manifolds are 4 into 2 into 1. If you look inside the drivers side bank, there is a divider between the 1-3 runners and the 5-7 runners. 1 and 3 merge together before they merge with 5 and 7. The same is true for the passenger side. On my 2001 Z06, they all merge simultaneously. When I spoke to B&B about the FCOR-0257 Z06 Tri-Y headers, they explained they were made in similar fashion to the stock units. The previous B&B offerings are not Tri-Y.

 

:flag So then I take it long tube headers will give a little boost in HP's over the stock setup. Is the gain even worth the money? :confused:

 

Guess not....for a stock C5 w/ headers. I'd say do heads/cam then get new headers along with that. Or if you SC, you should most def. get new headers. But for a stock vette it just doesn't seem like its worth $1000-$1500, first spend 3-4K on cam/headers.

 

It's only tough to beat the stock manifolds while retaining the stock collector mounting locations. The B&B Tri-Y headers cost $1000 and showed a 6-8 HP gain. The stock exhaust tubing from the collectors to the cats looks to be nearly 3 inch, but is in fact 2-1/2 inch tubing inside 3" to reduce heat radiation. Eliminating this section by installing full length headers added 15 HP and 16 Ft/lbs using TPIS units on a 2002 Z06, according to Dave McDonald (MCNASTY), and he spent $950 including welding.

 

"Headers" implies that wave dynamics are captured to enhance exhaust scavenging, and to take advantage of wave dynamics in a typical automotive engine, the total passage length before the final collector must be in the range 30-40 inches.

On a conventional automotive V-8 with a cruciform crankshaft, two cylinders on each bank fire at 90 degree intervals. If the exhaust exits into a conventional "log" manifold there will be interference on the lead cylinder of this sequence because the trailing cylinder will blow down as the lead cylinder completes the exhaust stroke.

The Z06 manifolds are designed to mitigate this interference, so they might be properly called a "branched manifold" as opposed to a "log manifold", but they are not equivalent to a conventional tri-wye header.

Notwithstanding the above, the '02-'03 Z06 manifolds perform very well and only a well designed set of long tube headers is likely to outperform them. Though most headers on the market are four-into-one, tri-wye headers are better for street engines because they produce favorable wave dynamics over a broader rev band, but they are more expensive to manufacture and most header customers want them to look like "race headers", which are normally four-into-one because racing engines only need to capture wave dynamics over a fairly narrow rev band.

If you look at the exhaust manifold on older four cylinder engines, they often have two isolated outlets, which group 1-4 and 2-3 into separate down pipes that merge to a single pipe two to three feet beyond the manifold. This type of system functions as a true tri-wye header. Mercedes V-8s from seventies also have branched manifolds with two isolated outlets and long down pipes that function as tri-wye headers.

Unfortunately, most of these systems have been replaced by conventional manifolds in order to get the converters and O2 sensors closer to the exhaust source for quicker lightoff, since quick warmup is critical to passing current emission certification standards.

Though the current Z06 manifolds can be (loosely) considered to be branched, they merge into a single outlet, which precludes the use of two isolated downpipes to obtain a true "header" effect by taking advantage of wave dynamics to aid exhaust scavenging.

Duke




[Modified by SWCDuke, 11:30 AM 5/11/2003]

 

I like your "branched manifold" description. I also think this better describes the B&B 'headers'. The Tri-Y descriptor is better left to a design like the Belangers. I was using and repeating loose descriptive terminology instead of scientific. Now if we could only get B&B to change their Tri-Y advertising...
:flag