Question... On a 75 wet... Does there tend to be problems with maintaining fuel pressure throughout the run with the stock fuel pump?

I know the base is 62psi for the pressure but what is the fuel pressure at WOT? I am looking for the right jets to buy but when I use the jetting calculator online and base it on 62psi those jets seem to make me run way lean.. Makes me think I'm losing fuel pressure?

Calculator seems more accurate when basing it on 30 psi which is a huge difference.. More accurate in the sense that the jets and shot size match with what people here are running on their cobalts..

I will be connecting a friends wideband today and running a shot but I'm not sure what jets to test it out with..

Should I be basing my jets on this 30psi of fuel pressure? Or get a new pump.... Help if you have any ideas. Thanks.



P.S. 75 shot.. 91 octane.. Would it work? (That's what I've been trying)

Bump..


What is the fuel pressure at when WOT on a 75 shot? ANYONE?

 

Fuel pump would be fine for a 75 shot would only put u around 300-315 whp what's the commanded a/f set at.... No miss fires any cylinder

 

I'm just really wondering what the pressure is at WOT on spray.. I cant figure out which jet to get. People here use what seems to be jets based on 30-35psi...

Idle psi is at 60-62

 

Be cause of the type of fuel system in our car I think it always looses psi I remember reading bout that

 

Really? Will upgrading the pump keep it at a constant psi?

 

that weird do you have a fuel pressure guage installed...you should check to see if maybe your pump is going bad...cuz i keep a constant 60 psi at all times...its not until i hit around about 5.5krpm that it starts dropping a lil to about 58psi...you should check that your pressure is good

maybe your fuel filter is clogged...how many miles you got on your car? have you changed the fuel filter at all?

 

I've got a little over 30k miles.. Havent changed the fuel filter..

How much is a FP guage?

 

well i bought one from autozone for 30 bucks...but now i have an electronic one installed in the cabin...with the sending unit installed on fuel rail that i got from glow shift for 50 bucks from ebay

 

When my fuel line is being used for my wet shot I can't monitor fuel pressure right?

 

when should fuel filters be changed?

 

^ Good question.

I wonder if my fuel filter is clogged.. And I wonder if getting a new fuel pump would maintain my flow at 60psi @ WOT... Cuz if it maintains a constant fuel pressure.. And I know what it is.. I think I can get it to work right when tuning with the wideband and what not..

 

You can, you need to buy a t fitting. Not sure who makes/sells them, but i've seen it before.

JW, is your kit used or new?

 

My kit is used..

I wonder what my FP is aw WOT on a 75.. **** haha.

It would make sense to me if the FP was not consistent and if it was losing pressure.. Cuz the jets people use are based on a much lower FP based on the jetting calculators.. damien what jets do you use and how did you choose them? What shot are you running and what's your FP @ WOT?

 

I run a 42/26. ItalianJoe told me what to use and that was that.

I never relied on the jet calculators cause thats what I did the first time I set my kit up and 5 sprays later it blew.

 

should be changed about every 20k-30k

 

Hm.. Yeah see a 42/26 is right when setting the fuel pressure to 30 in the calculator..

And every other combo people run matches with 30psi of fuel pressure.. So I should just base my jets on 30psi? That's what I don't get.. Why is it like that? I thought we had a consistent 60ish...

 

I have been running a 44/28 set for about 2 weeks now and everything has been great, afr's at 11.2 WOT

 

^ Good to know.. You wouldn't go any higher on the AFRs right? What shot is that? Like 80?

And also.. What's your setup (All your mods?) I'm curious about what you did for your tune man.. I need some help with mine if possible.

Also, what fuel pressure do you base your jets off of?

 

Fuel Filters should be changed every 30k is what I have been told, I have stuck with this, Im almost to my 4th fuel filter.

DO NOT BUY THEM FROM GM, go to Autozone, I paid $64 for my 1st one from GM, then i went to autozone the 2nd time I changed it and they had one for $14

l8r,
PD

 

http://www.harrisspeedworks.com/prod...cat=136&page=1

that is the kit i am running and it supose to be for an LS1 but works fine for my balt.
My mods are 2.9 pulley, 42lb injectors, Gmpp header, ZZP cattless DP, Gmpp exhaust, ZZP S3 heat exchanger, and a custom ZZP nitrous tune.

As far as jetting goes i just used what the manufacturer told me to use after i told them what fuel pressure i was at (62psi) and they recomended a 44/28 set up for a 75 shot and it has been working great. AFR's have not gone past 11.4 and usualy hang around 11.2 but as long as i stay under 11.5 i will be fine.

IMO i would get a different tune. I ran this same set up with the stage 2 tune and the timing retarded and it was prety good, but with the ZZP tune it makes a world of a difference with the same shot. My 50 shot on my zzp tune feels like a 75 on stage 2 tune.

 

Wait.. You just ordered a custom ZZP tune? And told them your mods? How much did that cost you?

Our mods are almost identical.. But my nitrous kit is mix and match with different brands.. Mainly a dynotune nitrous kit though...

 

Yup, its $100 for the tune if ya send them your pcm first or its like $200 something and they will just send you a different pcm and then send yours back and get $100 back. Besides tuning it for nitrous there is also some other stuff done to it that the stage 2 tune doesnt have, and i also got limited boost in first, 70% to be exact, its the **** .
But yea i love the tune and have not had one problem. Here's the link if you're intrested

http://www.zzperformance.com/cobalt_...=755&catid=144

 

How accurate is the canned tune they make you? Pretty decent?

Hm... Tempting...

Maybe I should get my shot actually working right first lol

 

Like i said....ive had great AFR's, no knock, no missfires, and good power gains.

 

How does their tuning process work exactly?

Did you tell them exactly what to tune for? Give me an example.. Please