ARCTICWHITE98Z28

iTrader: (1)

Before anyone asks, yes I have searched. The reason I am posting this question is because I spoke with reputable dyno tuner today who told me that my injectors and fuel pump are way too small to run a 100 dry shot. I was under the impression that a smaller shot like that should be fine with my stock injectors (28.6#) and stock fuel pump..

I decided to go with a dyno tune because I had a mail order tune done and my car ran very lean (14:1 - 15:1 from 4,000 - 6,000 RPM) on a dyno earlier this week. The reason I didn't get a dyno tune at that dyno is because they did not have an onsite tuner and I do not have any tuning software myself. I just wanted an air/fuel reading.

So after searching for a reputable dyno tuner in Michigan I came across the guy that told me I need to upgrade my injectors and fuel pump in order to run a 100 dry shot. Has anyone else needed to upgrade there injectors or fuel pump just to run a 100 shot? If so, would a 75 shot be ok with a dyno tune?

I really want to start spraying, but I don't want to have to upgrade my whole fuel system just to run a small shot, along with paying $400+ for the dyno tune. Any feedback is appreciated. THANKS.

SS6ixSpeed

You have nothing to worry about. Those injectors and your fuel pump can easily handle a 100 shot. All you NEED is a step colder plug.

caliswangin916

iTrader: (3)

i had the 26lb injectors and was at 86% duty cycle on an NOS dry 50(fwhp). so i never went to higher shot. it was running good til i went and got 36lb injectors and tuning software. since then i've been trying to figure out how to use HPT to decrease my rich decel for the past 3 weeks. i sprayed the 50 again last week and my afr was 13.1 so i stopped until i can figure out what to tune. it's been a hassle trying to figure out what to do in the tuning software. might just take it to a tuner if i can't get these issues resolved in the next couple of weeks.

i suggest you get a wideband with a gauge like an lm1 1st. then injectors, tune for the injectors, fuel pump too. but that's me and i want to stay as safe as possible. pretty much for me to run a $400 kit has cost about another $1500 to "TRY" to reach a comfortable level. and i have another $250(pump), $120(heater), and maybe a tune($450) to go. it's still much, much, much less than going turbo so i don't have any regrets.

i thought " injectors...everyone's got larger than stock injectors, no problem, i got tuning software, ls1tech's got lots of people who can help, i'll get these dialed in within a couple of hours and can spray my 100." NOPE!!!


if i end up taking it to get tuned, at least i got a $700 scanner.

btw i need some help with these 36lb injectors if anyone can help with an hpt tune file for 36 or 42lb injectors.

bad6as

iTrader: (17)

for a dry 100 shot him and i want to do. for fuel would injectors be needed 1st? or a pump?

caliswangin916

iTrader: (3)

i say injectors and a tune for them before the pump. given that the stock pump is working fine, i wouldn't get a pump til i'm around 450 from reading the threads but that's my opinion. i know others on here have gone past that 450 on a stock pump. better to pay for injectors, pump and tune that's set up for a 150+ shot and a total whp of 500 or so and just spray less to be safe.
this is just from my reading and paranoid attitude. you are going to have to decide what you are comfortable with, better to be safe than sorry if you don't have another engine ready to drop in like myself.

Beer99C5

iTrader: (21)

If you did a search I am sure you came across my issues.

I have sprayed to 466 HP with a 175 combined shot (50 Dry/125 Wet) on the stock fuel pump no problems (Stock LS1/ Catback/CAI).

The F-body pump I believe is not the same as the Corvette pump, and Vettes have a little more room on spray; based on what I have read and learned from the various forums. Perhaps your tuner is basing this on his F-Body expierence.

As for a 100 shot on the larger injectors I would say likey you can probably do it. Start w/ a 75 check the AFR and if it safe go for the 100.

Your duty cycle will likely be above 85% for both, and this may be another reason the tuner advises larger injectors.

This being said when the injectors were identified as the reason why I could not get a safe AFR w/ a 75 Dry (99-00 have the 26# injectors) upgrading them was pretty easy, HSW hooked me up w/ Delphi 42's and used EFI to change the IFR.

Now that I am looking for 500 at the wheels I am changing out my pump just to be safe.

Beer99C5

iTrader: (21)

Did you use the TAQuickness/redhardsupra spreedsheet to calc the new IFR? I am traveling tomorrow, hit me up w/ a PM and I will run the numbers on the HPT sheet and get them to ya if you have not already done it that way.

sprayin'99ss

iTrader: (2)

Hey man I think I have the exact same problem as you, but I just ordered my HPTuners and will have it by early next week. My 42# injectors are already in and car runs terrible...as expected. i had a Diablo sport tuner and just got my money back for it(long story). anyway I have a few friends that are really good at tuning and will upload a tune or something for you asap...if I get mine worked out!


To orig poster I have a 99 with the 26# injectors and have sprayed a 125 shot for a while and have had no problems. I was rich with my 100 so I bumped to a 125 and started to go a little lean on the higer RPM range I would stay around a 100 shot and you should be ok if your car is stock. keep in mind I don't even have an aftermarket muffler on my car so I didn't really push those injectors too hard. Just slap it on a dyno (if you don't have a wideband) when you get the system put on and see where you are at!!

Robert56

iTrader: (2)

I made 480rwhp on stock 28lb'ers and stock vette pump (125/135rwhp shot). I have sinced upped the shot and added 42lb SVOs and pump. Also, used redhardsupra's spreed sheet to rescale the injectors, it's a step by step and a breeze on HPT.

The one thing I would point out, if your running as lean as you state n/a, then you could also be lean on the spray. You need a good base tune, and this is fact for a wet or dry hit. Now will you be able to support a 100rwhp shot, imo, yes. However, for ulimate safety, you should be logging parameters and/or dyno tuning as every car is a little different. Good luck.

Oh yea the 80% duty cycle rule is just a longevity suggestion and not written in stone. A quick 1/4 mile pass above 80% will hurt nothing. It's when you get around 100% and start seeing a lean condition, then you are out of injectors. Same on pump, watch for fuel pressure drop and/or going lean at highest demand area, as long as injectors aren't maxed then pump is running out.
Robert

caliswangin916

iTrader: (3)

pm sent!!!!!

caliswangin916

iTrader: (3)

please help me please!!!

caliswangin916

iTrader: (3)

suppers Robert,
my na with the 36lb injector's afr is 12-12.6. my stock injectors were about the same too.
stock injectors + 50 shot was 12.5 but 36lb injectors and 50 shot is 13.1.

please help me in this thread.
https://ls1tech.com/forums/pcm-diagnostics-tuning/665636-36lb-injectors-rich-decel.html
my last post in here to not hijack.

Robert56

iTrader: (2)

Just a quick read over on other post. Will check it out tommorrow, have some ideas.
Robert

ARCTICWHITE98Z28

iTrader: (1)

Just a quick update. I am going to a different dyno tomorrow morning to have my AFR verified. This time I am going to have the tech put the AF sensor in the bung before the cat vs. placing it in the cutout after the cat. I also cleaned out my MAF wires this morning with some electronics cleaner just as an added measure. I was not throwing any codes, but I figured it couldn't hurt. When I first bought my car a couple of years ago it ran like crap until I cleaned the MAF. It was running good recently, but I thought I would clean it again just in case it may be affecting the AFR.

Hopefully I will get a better AFR so I can actually start spraying. I will let you guys know the results.