80# Fast injector data

[LSX944]

Hey guys, Brand new to this forum I have been reading over posts and the stickies for hours trying to think of the best way to pose my question... I am having issues getting my 4.8 turbo truck to run properly I can get it to idle but if I try to drive anywhere it lugs and doesnt have power or sometimes it will rev followed by a ton of backfiring. Now, I know thats super broad and not really going to help you guys help me but after much of my own troubleshooting coupled with what I am reading here I have determined that my injector data is not exactly correct. I ordered a base email tune from a local tuner but havent had much luck reaching him since he delivered my order... so here is my question. I get how to scale my IFR on my injectors but what is a mystery to me is getting the offset and pulse correction tables set. I was told that the manufacturer would have a detailed list of their offsets but when I called FAST they didnt have any such info. Does anyone out there know correct information regarding these injectors? I want to tune this right VS. just raping the VE table as its referred to around here. boost tune 3 bar2016410.hpt Here is my current tune I am using the rest of my setup is 4.8 stock motor 78/75 turbo holley efi rails 80# fast injectors. I am using a magnafuel boost reference fuel pressure regulator set at 58 PSI and a 3 bar map. When I asked my tuner why did I come up with different numbers on my IFR than he had plugged in to the table he said they didnt matter that you could compensate with the VE table and thats NOT how I want to tune... thanks for any help you guys can provide.

[matty b]

Send one of the injectors to http://www.deatschwerks.com and for $75, you will get a characterization sheet with all the info you need for your particular injectors. Or you can build an injector flow bench with adjustable fuel pressure regulator, adjustable voltage supply and a microcontroller that can pulse your injectors at a precise rate for a given amount of time. You gotta use a proper test fluid and accurate measuring equipment, but you can extrapolate all data using that equipment. Its probably cheaper to pay $75 though.

[mowton]

At that price, I would send 2 to get a handle on variability......

And you could sell the data for $5 to 10 and get your investment back in no time :-)....good injector data is priceless and the key to any tune/driveability....

Make sure you get all the GM Characteristic parameters...

Ed M

[LSX944]

Send one of the injectors to http://www.deatschwerks.com and for $75, you will get a characterization sheet with all the info you need for your particular injectors. Or you can build an injector flow bench with adjustable fuel pressure regulator, adjustable voltage supply and a microcontroller that can pulse your injectors at a precise rate for a given amount of time. You gotta use a proper test fluid and accurate measuring equipment, but you can extrapolate all data using that equipment. Its probably cheaper to pay $75 though.

Sweet! Ill do that thank you ! I hope this helps get it where I need to be...

[matty b]

No problem, contact them first and tell them what you need, they should get you where you need to go. Believe me, small motors with big injectors are way more sensitive to this data than what could be considered better matched injectors ie; small motor/small injector or big motor/big injectors. Short pulse will make or break you idle tune and offset tables will get you much more precise AFR's under boost.

[LSX944]

No problem, contact them first and tell them what you need, they should get you where you need to go. Believe me, small motors with big injectors are way more sensitive to this data than what could be considered better matched injectors ie; small motor/small injector or big motor/big injectors. Short pulse will make or break you idle tune and offset tables will get you much more precise AFR's under boost.

Ive had a couple of local guys say the FAST injectors gave them constant issues and they got rid of them and went with Siemens Deka 80's but I just figured FAST was a more reputable brand.... Anyone else ever had issues out of these? I was trying to not be cheap and paid more for that name...

I have a 4.8 but have a 5.3 on the engine stand awaiting on me to save some dollars and get building. I bought the 80's to be used in the 5.3 in which I hope to break 800 HP with... I was trying to "future proof" myself with my supporting mods like ford 9 inch 80e trans and good 10an feed lines 8an returns and ditching the stock rails so that I could transfer this stuff over to the 5.3 once it was built.... have I maybe gone too big for my small 4.8 which Im hoping to run about 12 PSI and make 490-525 HP out of....? ive heard some people say on this forum that turning my fuel pressure down could help with my daily Driving ability ???

[matty b]

Id say the same thing as others, some of the FAST injectors are just re branded factory injectors, but their modified stuff leaves a lot to be desired. You can try to "future proof" your setup, but until you are utilizing the injectors at the range they are good for, you are gonna have tons of tuning headaches. Bosch and Siemens are very consistent across batches and their curves are very linear. Lets put it this way, I'd probably not use those injectors if I had a choice and maybe see if I couuld find a better matched set for this motor.

[LSX944]

So would you suggest with what I want out of this 4.8 would the 60# be closer to the range I want ?

[LSX944]

Like these ? https://www.ebay.com/ulk/itm/281319569181

[matty b]

Yep. You may even be able to go slightly smaller, but I wouldn't really recommend it.

[LSX944]

Yep. You may even be able to go slightly smaller, but I wouldn't really recommend it.

Sorry not to make you have to repeat yourself but ill be able to make 500ish HP outta the 60's ?

[matty b]

Lets back up, I see 500hp I think Brake Horsepower. Do you want 500 BHP or Wheel HP? We could be talking about a 100hp difference based on nomenclature.

[LSX944]

Lets back up, I see 500hp I think Brake Horsepower. Do you want 500 BHP or Wheel HP? We could be talking about a 100hp difference based on nomenclature.

Im talking wheel horse power as in dyno numbers... I guess that is to say I want the max my 4.8 can put down out of its stock platform at 10-12 pounds of boost.

[matty b]

That clears it up. I don't like chassis dyno numbers even for goals as they are all over the place even when drivetrain losses are considered. So you wanna make somewhere between 575-625 BHP? 60's will get you there and give you good headroom.

[LSX944]

That clears it up. I don't like chassis dyno numbers even for goals as they are all over the place even when drivetrain losses are considered. So you wanna make somewhere between 575-625 BHP? 60's will get you there and give you good headroom.

I found a set of 60's and they are on the way hope this fixes all my backfire no power AFR all over the place issues.. Thanks for all your help! sorry I guess you are right BHP is a more constant number... but since most of my friends race on the street and spray the dope on stock LS motors till they pop their definition of tuning is by a standalone fuel system and pull a little timing lol you guys have been a ton of help !

[bryanwood74]

Sweet! Ill do that thank you ! I hope this helps get it where I need to be...

Hey if you or anyone else does this I would be glad to shoot you some money for the data.