Series I L67 Fuel Injectors - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 10-29-2003, 09:42 AM   #1
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Default Series I L67 Fuel Injectors

How many lb/hr are the Series I L67 fuel injectors. I know the Series II are 36lb/hr, but what about the Series I???

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Shawn
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Old 10-29-2003, 03:17 PM   #2
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Default Re: Series I L67 Fuel Injectors

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Originally Posted by dbtk2
How many lb/hr are the Series I L67 fuel injectors. I know the Series II are 36lb/hr, but what about the Series I???

Thanks

Shawn
I believe 24...
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Old 10-30-2003, 12:20 AM   #3
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I think 23 or 24, jeffrey knows for sure.
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Old 10-30-2003, 01:52 PM   #4
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Default Series 1 Fuel Injectors

The stock fuel injectors for the Series 1 are 21lb/hr. With any mods to the intake you should really run about 24lb/hr. Accel makes the and Summit Racing sell them for around $180 for a set of 6 ... Part #ACC150624.


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Old 10-30-2003, 08:39 PM   #5
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stock series 1 SC injectors are 21#
series 1 NA injectors are 19#

i replaced mine when i did the SC upgrade to accel matched 24# injectors
now im thinking about going to 30-36#
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Old 11-08-2003, 09:29 PM   #6
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I took this from another post I did, it seems to apply better here anyway:

There is a lot of confusion about these (or is it just me) and I wanna try and clear things up. I'm just going to use basic math and throw this out to try and figure this out but lemme know if I'm way off. Fuel injectors that you see for sale are rated at 100% duty cycle. This isn't, however, what they run at. Generally you shoot for an 80-85% duty cycle. Lemme use this simple formula to explain:
(HP x BSFC) / Injectors x duty cycle
The rough BSFC (Brake Specific Fuel Consumption) for the supercharged engine is about 60. BSFC is how much fuel (in lbs) it would take to make 1hp for 1hour. Using the math (at 100% duty cycle) they work out to 20.5lbs. Close enough to the 21lbs that people are talking about. But wait...thats at the unreachable 100% duty cycle that people selling them rate them as, not people that put them in factory cars designed to last 100,000miles and more. things get hairy when you figure out how big an injector is needed to sustain 205hp with a BSFC of .60 and a duty cycle of a more reasonable 85%. It works out to a reasonably higher 24.1lbs/hr. So lets think about this. We know the injectors in your average engine should run a max around 80-85% duty cycle, why would GM install injectors that could only sustain 205hp if they were CONSTANTLY on (100% duty cycle)? Its common knowledge that you should buy injectors rated at your 80-85%d.c. needs, why would GM sway from this? Of course this doesn't take into account fuel pressure which can make up a few lbs but taking 21lbs and raising the pressure 10psi will only get you 22.5lbs/hr...and thats STILL at 100% duty cycle! Any comments on this?


Since this I wrote to summit racing to ask for clarification, they didn't help much but they suggested that .60 is high for supercharged and it should be more of .50-.55 and 80% DC is max, any larger and they wear out quickly. So using these numbers (.53 BSFC and 80% DC) they should come out to 22.6lbs. But since they are rated at static flow (100% DC) they would be 27.1lb injectors. This is getting really crazy now. I can make the numbers add up using .50 BSFC which will come out to 21.3lb injectors at 80% load but that would mean that since 80% is as high as you wanna go that the fuel system in these things aren't as good as we think. Just for review: 205hp at 80% load and .50 bsfc (most effecient possible) needs 21.3lb injectors, stock is supposed 21lbs which would mean even a 20hp increase would push these things over the 80% mark, require 23.4lb injectors, and begin to wear them out very quickly. I really don't know what to think any more. Since .50 BSFC seems to make things add up we can estimate the top end for the fuel system by adding up 100% dc and an additional 10psi of fuel pressure which is regualted by the supercharger and do some reverse math to see what that could support. So assuming 21lbs is at 80% dc we bump that up to 100% dc and we get 25.2lb injectors, raise the fuel pressure 10psi and we get 27.7lb injectors. Do some math and it comes out to being able to support 332hp tops. This seems more logical but of course these are at the breaking point for the injectors. BTW I typed this out WHILE I was thinking about it so if I contradicted myself a few times don't bother, just kinda keep up. Anyway this is totally up for debate.
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Old 11-08-2003, 09:40 PM   #7
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that sounds like you got it covered, when i went to accel'* application chart, they showed the 3.8NA and the 3.8 SC and the NA was stock 19# and the SC was 21# stock. they didnt say what duty cycle they were rated at though. i just know that im going to go with the ZZP lucus 42.5# injectors so i know i wont be running out of fuel
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Old 11-08-2003, 09:58 PM   #8
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ooohhh me likey. it says they require tuning, do they only mean with the LS1 intake package?
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Old 11-08-2003, 10:04 PM   #9
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i already have a mini afc 2.0 version to calibrate my fuel curve. it works swet. and 13 different points to make a setting through the entire KHz range from 1-13. also im adding a walbro 255 lph pump too. after last weekend and running lean from 300' out , i need a better fuel delivery system. i just wish we had a regulator that we can change out to an adjustible one.
just might be my next project
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Old 11-08-2003, 10:15 PM   #10
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You actualy can adjust the one we have, takes a little modification though. I saw step by step details on a webpage once, I believe they were talking about the chevy 3.8 but the regulator was identical. Basically you drill a hole in the top of it and put a screw in there. Then by tightening the screw you press against the regulator valve and hence you can raise the pressure. There was a little more involved in it but it looked fairly simple. I'll see if I can find it. Anyway, the mini-afc isn't compatable with the '93 is it? Can I just plug and play? I need larger injectors and would like the 40lb range and those look perfect but I don't want to plug in a problem, ya know?
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