niphilli2

Hello All,

I am thinking of doing some bolt-on modifications to a 2003 Z06 and have some questions about injector duity cycle. The target is 400RWHP with a very conservative tune.

What injector would be reccomended for a safe setup? Are the stock units up to the task?

Please keep in mind that I want this to be conservative, the car is babied but I want it to be built so that I could take it to a roadcourse and have no problems. I want stock reliability out of a 400RWHP setup, or I will just leave it stock. Its a better car than I am a driver anyway
Thanks,
-Nick

travisnd

Leave the car stock. As you progress and start seeing oil temps north of 280 get an oil cooler. Then spend the rest of your money on track time and consumables.

An extra 40 rwhp over stock won't really make you any faster. A 2002+ LS6 can get very close to 400 rwhp with an intake and longtubes w/o cats and a tune, but that will cost you around $2000.

If you do decide to do the horsepower thing then your stock injectors will be fine at that level. Once you open up the motor and install a cam you'll want to think of larger injectors for road course duty. My old Z06 had a G5-X2 cam and made 436 rwhp (stock heads). I was at just over 100% duty cycle so I upgraded to 42s just in case I ever put heads on the car.

My current race car is a 2001 Z06 with a stock 122,000 mile LS6

AU N EGL

Leave it stock.

I did some bolt ons and small cam to my 03 to get just over 400 rwhp.
Each winter I change the springs ( comp 918s) change plugs and wires and change the injectors. Then dyno tune.

MX621

at about 420-430whp the stock ls6 injectors are maxed, i know from experience.. im running ford svo 30lb injectors.. there pretty cheap and they are actually 37lb injectors on our cars via higher fuel rail press.. ford advertizes 30lb @ 42 psi, we run 60 psi or close to it.

RAFTRACER

I would agree with the above....at ~400rwhp you will be running duty cycles in the 90+% area and that is not really safe. One "good" air day and injectors will be maxed and the AFR will be lean. I also use what the gentleman above recommended for the same reasons. 30lb Ford SVO injectors will be perfect for you and are cheap.

niphilli2

Thanks for the input all!

I originally started down this path because my dad bought a pristene Torch red A4Vert that we would like to give a few more ponies. The original thought was for me to buy a FAST102 (donate my LS6 Manifold), and LT headers (Donate my manifolds and midsection) with the supporting boltons. The more I think about it the more I think about it the more I am leaning toward leaving mine stock. Then we will leave his exhaust alone, buy a used LS6 manifold and ported TB, and go with an exhaust manifold freindly camshaft for his car with some upgraded springs.

Travis and Golden~ Thanks for the input My goal is to have stock durability, so I would probably go with the expense of LT headers and a 102 rather than deal with the dual valvesprings or regular valvespring maitenance that come along with aftermarket camshafts. I am so impressed by the durability of the LS6 that I dont want to do anything internal.

Golden~ I see you are close. Is there a tuner you trust for roadrace applications (safe tune)?

MX & Raft~ Thanks for the input. Your posts support the research I have seen so far. I was concerned that 400whp was on the limit of the duity cycle for our stock injectors and would not want to risk that in a roadcourse environment. How difficult is it to tune in the new injectors? Nothing scares me more than some hack screwing up the tune in the car just so I could get 50 more horsepower out a car that is already very capable.

Thanks!
-Nick

travisnd

An aftermarket intake manifold is a huge waste on a stock motor.

Scooter70

SVO 30s are very easy to tune. They're a very popular injector (both of my cars have them) so any competent tuner will know exactly what to do with them.

AU N EGL

Nick there are several dyno tuners in the area. All will tune your car for your needs.

Durham, Raleigh, Garner, Moorsville, Vanceboro out by the coast.

Never ask for the most HP, ask and work with them on flat torque curves, and let them know it is for 3000 to redline, 2-3 times every 2 min for 20-30 min at a time.

a stock C5Z can run very very well with a tune at 365-370 rwhp.

AU N EGL

Fast intakes unless it is a 90 is not needed. the Fast102 will not get any more out of the LS6 so no need.

I use a TPiS PP 78 mm TB on the stock LS6 intake

Jason

After you've had to work on a car with LT headers, you'll swear you'll never own another.

Wicked Weasel

CAI, headers and tune are good upgrades. Heck I did those mods to my TBSS and my wife drives that the most.

niphilli2

Thanks for the information everyone!

Golden~ IF you can send me your expereicnes with local tunders that would be great. I have met a few and read about a few, but due to past expereinces I am leary of some information posted about who is a good tuner and who is not. I am looking for someone to spend a few hours on a street tune, then a few hours on the dyno to tune it in. Not to copy and paste a file while the car is on the dyno from another similar car.

0Louis @ LG Motorsports

Since when did stock 28lb injectors max out on a bolt on LS6? Youll be fine with that power level and stock injectors. They support more than that, as some have said.

niphilli2

Louis, you should know. Do you guys have a lot of 400RWHP cars running on the road course reliabily on the stock 28#ers?

Just wondering, I have read a good amount about duity cycle (rule of thumb to keep at or below 80% for a roadcouse) but the proof is in the puddin'

0Louis @ LG Motorsports

I do know, and thats why I was asking We dont look at injectors on cars with the 1462 28lb LS6 until 430-440 rwhp.

They fuel fine at 400-430 rwhp, and have never ever failed an injector due to duty cycle, only pressure ( 130psi of base fuel pressure will do that )

travisnd

^ That matches my experience. It took 436 rwhp with a G5-X2 cam and LT headers to get to 100% duty cycle on my stockers.

RAFTRACER

I may know of STOCK long block LS6's with bolt ons making in access of 420 rwhp (several) and I am just fine running my duty cycles lower than 90%. Some areas of the country may have a little better air quality and baro during certain times of the year. No one said anything about failing injectors.......Also not talking about running AFR's in the 13's or the affect of ram-air systems ...

30lb SVO injectors are cheap insurance and also provide the ability to expand again later with more power if the need arises.

SouthernSon

Amen to 'dat! Let's not forget raising the RPM limit a little, too.

Bink

the Bosch GTP 39lb/hr injectors are a nice choice for the 450 hp range. They were used in the World Challenge Corvettes and ASA cars. The offset/fueling tables, which are injector specific, are available for your tuner (available in the ASA and WC tunes). Having the correct offset tables cleans up part-throttle fueling.

FWIW - if you take a brand new set of injectors and have them flowed they can vary by a couple percent.