tompugh

Hello, I need some guidelines for selecting the injectors for my set up. I am bolting together a H/C combination starting with a 99 LS1, 6 sp. with a Blackwing and catback. Adding a Z06 manifold, LTs, 'stage 2' cnc'd 243 heads (2.05 int./1.57 exh. 62ccs), Comp Cams XER-224/230, .581/588 lift. Can I get by with the stock LS1 injectors or should I move up to Z06 or larger size? Thanks, Tom

jmzvet

The Ford SVO 30lb injectors are a good upgrade for a modded C5. They flow at about 36lbs in the C5. They are a direct replacement and are a good value. About $200 for a set of 8.

triblk6spd

and with the addition of the racetronix fuel pump you would be in good shape fuel wise.

6Speeder

You probably won't need to go as big as SVO 30#'s. If you have the peashooter 26's, you should move to the stock for 97,98, and 2001 and up 28.8's and be fine. They will support nearly 450rwhp. There's usually a set or two for sale on this forum, at a good price.

I actually ran my 26's for a while at my power level and was OK, but the duty cycle was high.

JR_VET

place SVO 30lb because my 26lb duty cycle were at 115% 28.8 are good but it all based on the duty cyle. I rather be safe than sorry.

boosted_z06

If going to stock 28 lb injectors would handle 500 HP at the flywheel then how come the LS2 with 400 HP uses 32 lb and the 500 HP C6 Z06 uses 40 lbs ?

Ikester

Dirty Howie

I have 420 RWHP and stock 04 injectors. I was going to go 30 and Andy at A&A said I would be wasting my money. I had Charlie, tuner over there check my duty cycle at my last dyno session and all was good.


DH

6Speeder

Because they anticapate morons running the car, never cleaning the injectors or monitoring how it's running.

Proofs in the pudding guys. As I said I actually ran mine, making 413rwhp (at sea level, CF 1.0) on the 26.6# injectors, and it didn't run out of fuel, the injectors kept up just fine. The 28.8 injectors will support nearly 450 rwhp, some others here are doing it.

Running 36# injectors on most heads/cam 346 cube LS1/6 engines is overkill. The GM fuel maps are very well developed for 28's, why spend the extra grickles for SVO 30's and then have to reinvent a good fuel map, including offsets and pulse widths? That's crazy

boosted_z06

You need to go to basic 101 engine school. If the only reason was because injectors could might dirty then they would just use 28s on all the models and save the costs of what the higher flow injectors cost.
At 80% duty cycle even 28s would not properly support 450 HP at the flywheel
That is like saying sparkplugs are good for 100,000 miles but injectors get so plugged up in short time and somehow when they do they flow more if they are bigger.

Yes you can use 28s but that also means they fall behind and cause ping and forced to use lower timing at WOT.

I guess when installing a maggie supercharger with only 6 PSI the kit comes with 42 lb injectors and they do that because injectors get dirty

If the GM stock fuel map was so perfect for higher volume fuel flow then why is its require to remap for best performance ?

Why is it the C5R even used 40 Lb injectors, surely not because they are worried the injectors would get dirty in a 1 hour race

boosted_z06

I suggest those two guys are the last ones to listen to. Spinning the tires on a dyno for 30 seconds when engine barely gets to 100 percent engine load says nothing about real world driving and if your duty cycle was not over 80% then they better use a better method for finding what the duty cycle really is.

Some shops do not sell just the injectors since they are only about $240 a set and there is no profit margin to sell them

Larger injectors just do not allow making more HP but also are used to prevent ping and allow more timing, they also help cool the cylinder/pistons and cats.

Pumba

Tom,

Here is a formula that you can use to safely determine the correct size of injector you should have:

Crankshaft Horsepower DIVIDED by Number of Cylinders x Intended Brake Specific Fuel Consumption (.45 is suggested for Fuel Injected N.A. Engines) DIVIDED by Injector Duty Cycle (80% is recommended) = Injector size


For example:

500 Crankshaft HP DIVIDED by 8 x .45 BSFC DIVIDED by .8 Duty Cycle = 37 lb. Injectors

.

fdxpilot

Yeah, since Andy and Charlie work so hard to screw the Corvette community. They probably know more about tuning vettes than you and the rest of the members here, combined. You obviously don't know who Andy is.

6Speeder

The formula Pumba gave is a good GENERAL rule, and will give safety for dirty injectors, etc., and racing at high loads/rpm's ALL THE TIME. The problems with it are: 1. The figure used for BSFC is for ALL fuel injected engines us to high for LS6 engines. The heads/ports/injector location allows these engines to be more efficient in converting gas to HP. 2. It won't hurt an injector to go do high duty cycles occasionally. Constant 90 to 100% duty cycles could cause it to heatlock but really, on the street or drag strip, how often or long is our engine at WOT, 4th or 5th gear, max rpm? THAT'S the ONLY time your injectors will see potentially high duty cycles.

Andy is right, throw your money away if you want, but you don't need to.

tompugh

Wow, lots of controversy here. It sounds like I should definitely change out the stock 26 lber's. Pumba, thanks for the formula and to others for your suggestions. Tom

Bink

He knows who Andy and Charlie are.

Here's a link for an excellent reference ->http://www.rceng.com/technical.htm

DSOM Z06

Vette Doctors told me that at my current 401 RWHP, I'd be wasting my money upgrading my injectors. If I was constantly drag racing or autocrossing I might have to change but for a weekend warrior it is not necessary. Now if you say that The Vette Doctors don't know what they are talking about go page this guy Quimbo and tell him how you feel.

FixedRoof

I went with SVO 42's. They are slight overkill, but thats ok for me. I like that..lol. I'm only at 65% Duty Cycle going full ***** out. The stock 26's would have been maxxxed out for sure.

Diferent injectors are rated at different PSI... so make sure what you are looking at. It is like comparing apples to oranges...

30's should be fine.

steve

phils C5 vette

I have 28.8 and Ill keep them after my AFRs go on

taaz024

OK, "the bottom line is" that it is safe to say:
1. In '99 and '00, GM installed 26lb injectors.'97, '98. '01-'04 are 28lb?
2. No need to upgrade 26lb until you modify.
3. No need to upgrade 28lb until you reach 450RWHP often.
4. Don't go higher than 30lb unless you have one bad %&@ vette.
5. Everyone is entitled to their own opinion, but the above 4 are accurate.

Who agrees with these stats?