Blackbird

1 vote for non-whack <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Only time you would want to make it flat is when you have a vacum/boost referenced fp regulator because then and only then fp at the rail is a constant value.

at least thats how I understand it.

Black LS1 T/A

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Blackbird:
<strong> 1 vote for non-whack <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Only time you would want to make it flat is when you have a vacum/boost referenced fp regulator because then and only then fp at the rail is a constant value.

at least thats how I understand it. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">So, there's one opinion that says Blown Hawk use the scaled constants UNLESS he switches to a vacuum/boost referenced fuel pressure regulator... then he would use flat values per kpa.

BLMONGOOSE, do you buy that, or do you feel he should make all the values the same even if he is not using a vacuum/boost referenced fuel pressure regulator?

MIGHTYMOUSE

iTrader: (59)

the only time you can use a flat flowrate table is when you have a 1;1 fpr that works for vaccum and boost.

the reason the table goes up is because its vs MAP which DROPS as you apply more load. manifold pressure air pressure inside the manifold, same place you'd have the afpr.

the pressure that the map drops and the rate that the flowrate rises IS linear... look at the graph.. all you are doing is raising the pulsewitdth with load outside the computer with the fpr, not inside it with the flowrate table..

mine is flatlined at 5.51 right now and my ltrims are -3% up until PE


if you flatline the flowrate without a afpr then you will have fits re adjusting the fueling in the maf table eew!

MIGHTYMOUSE

iTrader: (59)

i'm going to assume stock fp of 58, 42# svos tested at 43.15#

go here:

http://www.speeddemonmotorsports.com...ectorscale.xls


and you get this as your final new STARTING flowrate values

Injector Flow (g/sec) 6.135407774 6.173645496 6.211647839 6.249419096 6.286963432 6.324284889 6.361387389 6.398274742 6.434950648 6.471418701 6.507682396 6.54374513 6.579610208 6.615280844 6.650760168 6.686051224 6.721156979

there you go!

*note* the fuel pressure and flowrate input boxes are labeled backward on that link so you have to put them in the opposite labeled text box.

Blown Hawk

You guys are great. Right or wrong I appreciate all your opinions and the fact that you took time out to try and help a newbie out. No offense to the other sections, but FI seems to be a really tight knit group and go out of there way to help each other out. Really glad to be one of you guys. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

BH

Blown Hawk

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by MIGHTYMOUSE:
<strong> *note* the fuel pressure and flowrate input boxes are labeled backward on that link so you have to put them in the opposite labeled text box. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">So glad you mentioned that. I was getting wierd numbers and wasn't sure what was going on. Thanks bro.

BH

cablebandit

iTrader: (37)

the reason for the "curve" in the stock flow rate is that under vacuum (like while cruising), the motor literally sucks some of the fuel out of the injector. Of course under boost the injector has some pressure to overcome. I know most of you know this but when I started with FI, I never thought about the intake vaccum/boost affecting the injectors flow rate.

Black LS1 T/A

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by cablebandit:
<strong> the reason for the "curve" in the stock flow rate is that under vacuum (like while cruising), the motor literally sucks some of the fuel out of the injector. Of course under boost the injector has some pressure to overcome. I know most of you know this but when I started with FI, I never thought about the intake vaccum/boost affecting the injectors flow rate. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Now, THAT'S an interesting observation. It makes sense, but I've never heard or read actually data stating that or proving that.

Assuming that is the case, are you saying that alone justifies a flat IFR table, even without the boost-referenced Fuel Pressure Regulator?

I'm just asking, because I don't really know.

cablebandit

iTrader: (37)

it is the reason that the stock fuel map is not flat......to account for the amount of vacuum (or lack of) on the injectors at different engine loads. Think about your stock engine idleing and you under the hood monkeying with vacuum hoses. At idle you have a good strong vacuum. Jump in the car for a spin ang go WOT. The throttle body butterfly is no longer causing a restriction and now you have no vacuum. GM calculates how long the injectors need to be open to get the air fuel to the optimum mixture at idle/cruise/WOT. They also have to account for that vacuum(or lack of) because it literally sucks some fuel out of the injectors. So, they use the "curve" method with the pcm to account for this since the fp is always expected to be 58psi to the injectors. The old way was to just lower the fuel pressure under vacuum conditions to account for vacuum. The buick GN crowd uses the old vacuum/boost regulator way and that worked well for me.

JAS

Been getting email requests for the injector calc. You guys can download it direct now

http://www.tech-ls1.com/extras/injectorcalc.zip
~800k zip file

MIGHTYMOUSE

iTrader: (59)

black ls1 ta: the stock table is on an incline BECAUSE the regulator is not manifold pressure reference.. that is the ONLY reason


if you dont have a pressure referenced regulator, the numbers have to be on the same slope as the stock ''curve''

if you are vaccum referenced (not stock) then you're flowrate table definitely can be flat... the regulator is trimming the fuel for you.

Blown Hawk

Well in my attempts to get the right numbers I got some wierd info. You guys seem to think the 43.15 is the test psi for Ford SVO 42#ers. I'm not disagreeing with you. But I spoke to tbyrne who sent me to Vortec. Vortec didn't know and sent me to a company in Texas, who sent me to another company in Texas. Those guys told me that the Test psi is either 39.1 or 38.4. I guess I just don't understand where all these different numbers are coming from. If I'm a little off how bad will that be? Will it just throw off my AFR? How would I know if I plugged in the wrong numbers?

Mike

Black LS1 T/A

My understanding is that the SVO's are tested at 39.1 or 39.6 (those are the two numbers I've seen thrown around).

MIGHTYMOUSE

iTrader: (59)

if you input the lower psi rating, then you will just be overall slightly richer than the 43 psi rating.

maybe call ford motorsports or bosch.. they make em.

eboggs_jkvl

A novice here but I read SVO were tested at 3 bar and GM were using 4 bar.

3 bar = 43.5
4 bar = 58


ITT

Procharged LM7

so are you guys saying, if I don't have a rising rate regulator(I don't) to use, or not use a flat table on the flow rate?
I tried the table listed, and it gives me a varied flow rate.
Also, once you get the Ltrims close to zero, will your PE get enough fuel to the motor as long as you have large enough injectors?
I just put in SDM 370 injectors today which are drop ins for my truck. I have the initial flow rate at 5.22 all the way across, and it is way too rivh. I am gettign Ltrims of -10, etc.
Alos, there are 4 Ltrims listed in Atap. Are you supposed to be looking at all 4, or just 2? I notice they vary.
I will try putting close to those #'s I see in the table, and see how it does.
I can't get to a wideband for at least a week or so, as they are the one on town and swamped Thanks for the help, guys! Sam

buschman

I'm sorta glad this thread came back up. Now that I've gone the boost referenced fuel pressure regulator route, I have a question about the flat curve. Do you guys mean a linear rise in the IFR table? Or do you mean pick a number(like for instance 25kpa=6.30) and put that in every field 0-80? (ie 0kpa=6.30, 5kpa=6.30, 10kpa=6.30, etc.)?

Mike

Procharged LM7

I am confused. I was getting -10 and mostly - Ltrims with a 5.22 flow rate table flat. I went all over on the flow rate table, and Ataped it and way + Ltrims. I even went to 5.23 and was high +'s.
I put it back at 5.22 and I'm sure it is still rich(- Ltrims) but better than lean, cause I haven't widebanded it yet.
Are you supposed to look at all 4 Ltrims in Atap or just two of them? I notice the second Ltrims of each bank is always lower #'s, than the first in each bank.Can someone give me some light on this? Thanks! Sam

SDM 370 RC Engineering injectors(I believe 42 lbs for my fuel pressure or close) just put them in today

EDIT- Well to update, I guess the PCM was still learning the injectors because now I am back to about where I was with the stock ones, some - Ltrims, some +, but no more than 3-5 cruising or idle(usually hot idle I run a little positive)

AzzHauler

iTrader: (3)

The reason the flow rate table has a slope is because the injector flow is affected by vacuum/boost. If you have a vacuum-referenced regulator then that handles adjusting rail pressure to account for the vacuum/boost in the intake. So you use the flat line if you have one of those style regulators, and a sloped line if you are using the stock, or non-referenced regulator.

Sam, how are you reading the 'second LLtrims of each bank is always lower than the first in each bank'? There is only 1 ltrim for each bank. Strims are different from ltrims and we don't look at those for anything.

Blown Hawk

So in other words, using the example above, 6.30 across the board?

Why was everyone telling me that I needed a one way valve on my Boost Referenced FPR? If it's now adjusting the fuel manually and I'm taking the computer out of the loop, then wouldn't a one-way valve screw it up? Causing me to run very rich at idle and part throttle.

BH