ZPaul2Fresh8

I have a 93 Z28 and someone correct me if I wrong, but I think they come with 22# injectors. Now I have a Hotcam Kit, Longtube Headers, Borla Exhaust, !CaT, !EGR, TB Bypass, Mildly Ported Heads.

Now, I read online many times that the 94-97 24# injectors would be maxxing out around 400hp(fw or rw?), Ok, here's where my questions come in:

1. I read that I'd want to stay around 80-85% duty cycle when finding the right size injector, so with those mods and approx. 350rwhp in my Z, do you think my 22#'rs are being overworked and running out at top end? The power seems to gradually drop at high range...

2. I'm thinking of buying a set of 28# LS6 injectors(assuming they fit), what would be your guys' opinion on those with my current modifications? Would a 52mm TB be of some help after the injectors are input?

Is there an online injector calculator I could use? Even though I don't have any flow numbers?...

Thanks Guys! Let me know what you think...

93formula

we have batchfire in our 93s i think youll be fine with your injectors with just a hot cam. if you have a m6 the 52 mm would not be worth it, id say 58mm. but most would say you dont need a tb. do you have data master? or knwo anyone that has it in your local area? scan your car first to see where your duty cycle is. youll also need reprogamming if you add bigger injectors.

ZPaul2Fresh8

Thanks, I was wondering that. I have CATS, but my laptop is on it's way, just need to buy a EEPROM flasher. Then I'll be tuning....or atleast trying to tune

Would like to hit the dyno soon with a wideband to see what's actually going on... $80 for a run with WB!

93formula

where are you getting this eeprom flasher? and how much? heres something you m ay be interested in if you wanna do tuning and dont want to spend the dyno money everytime:

http://www.techedge.com.au/vehicle/wbo2/wbo2.htm

ZPaul2Fresh8

Thanks for the link, it's pretty cheap, but now cheap enough for me. It looked good, but after reading it I found out your have to buy the Display, Unit, Cable, 2 connectors, + O2 sensor seperately, so the price is still high for me.

$495.90 without shipping or their 3% paypal fee for currency conversion!?! I would maybe do it for $350 shipped.

LWillmann

I think that LS1 inejctors are the wrong impedence, or at least I have heard that somewhere... Just thought I'd throw that out there. It's something to consider.

ZPaul2Fresh8

I'm unsure, I don't know much about injectors... that's why I'm asking... anyone know for sure?

Injuneer

Not exactly... LS1 and LT1 injectors are both high impedance. But they are flow rated at different pressures. LT1's use 3bar (43.5psi) flow rating pressure, LS1's operate at 4bar (58psi). If you run a 28# LS6 injector at 43.5psi, it will only flow 24.3#/HR.

ZPaul2Fresh8

Thanks Injuneer, that's what I was looking for. So buying those injectors would be a waste of money, unless I bumped up the fuel pressure.... is that possible? Wouldn't my fuel pump go out in the near future from over hauling it?

Anyone have a cheap set of injectors they might recoomend that would flow 28 lbs or equivalent?

Injuneer

If you raise the pressure to 58psi, your stock 22# injectors will flow 25.4#/HR (or maybe even more... I suspect they use a number higher than 22 as the flow constant in the ECM). The stock RP's shouldn't have a problem with that pressure, although anything much higher might be a problem.

As far as calculating injector size, check the other thread from today on injectors.... a couple of us posted the formula there.

ZPaul2Fresh8

Ok thanks, I read that a AFPR is a waste, but that is the only way to adjust fuel pressure, no? Also what are "RP's"?

Thanks, I'll be trying to tune in a short while so I wanna get this fuel stuff down. One quick power, optimum power (A/F) should be around 13.7:1? Thanks again,...

Injuneer

An adjustable FPR will have little value unless you reprogram the PCM (although people will argue that this is not applicable to the speed-denstiy 93's). If you raise the pressure, AND calculate the new flow rating, and enter that as the flow constant in the ECM tables, it will work just fine.

Where the AFPR is of limited value is using it to reduce fuel pressure and hopefully lean out the overly rich WOT A/F ratios programmed into the stock LT1 PCM. The PCM adjusts the pulse widths to compensate. But again, this is a "fact" for 94-97, and sort of debatable on the 93's. But that's not your purpose in adjusting the fuel pressure.... the purpose is to change the injector flow rating, AND to tell the ECM what you did.

Rochester Products (RP) made the injectors for the LT1's. They are a "ball and seat" design, and do not like excessively high pressures. That is why people using dry nitrous, and huge fuel pressures will change to a pintle style injector.

ZPaul2Fresh8

Excellent, you're loaded with information! I knew about the PCM compensating the fuel by shortening/lengthening the pulses, I just never knew there was a difference in 93s, is it because of the batch fire method? 94+ Have Sequential firing, right?

Could someone explain how they both work?