HOW TO DO AN ADVANCED SEARCH.

Mon Jul 08, 2013 3:56 pm by Admin


For the benefit of 944Hybrids users there are two search functions available for you to use.
The purpose of this sticky is to explain the "Advanced Search" function because it is much more powerful and is the best choice when researching information.

When you log on to the site a list of options is shown in a line at the top of the page. One option is labelled "Search", use this option (NOT the search box lower down on the right).

After you click on the upper search option, a drop down box appears. At the bottom of this box is a radio button marked "Advanced …

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Fuel pump options

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Fuel pump options

Post  yamamtx on Tue Jan 10, 2017 8:57 pm

Hey guys,

I have my Ls swap up and running and I am going to start phase 2 which is a low boost turbo making 500-550 hp.  My question is what are people doing for a fuel pump in this situation?  I see Lindsey racing has one that is good to about 450-500.  Any thoughts?

Thanks

yamamtx

Posts : 44
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Re: Fuel pump options

Post  sharkey on Tue Jan 10, 2017 10:37 pm

the bosche 044 fuel pump would be the way id go, they are good for around 550-600 hp. if your planning to make more, id go with a dual 044 setup. there isnt a lot that will out flow a single 044 and be reliable. the aeromotive a1000 does outflow the 044, but its big and noisy and not that reliable.

sharkey

Posts : 363
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Re: Fuel pump options

Post  yamamtx on Wed Jan 11, 2017 1:43 pm

Thanks Sharkey, I was leaning that way but didn't know if I would be pushing the limits to hard.

yamamtx

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Re: Fuel pump options

Post  sharkey on Wed Jan 11, 2017 3:28 pm

there is another option for a single pump that comes to mind, and thats the AEM 380lph pump. its a higher output version of the bosche 044, should be enough for 700hp. it also uses AN fittings, so plumbing is made easier.

now i will say, i put one on my swap and i have replaced it (with an 044). i was starting to get a lot of noise from it with less than 1000km on it, and it was making me a bit nervous. thinking about it now it likely wasnt the pump failing, it was more likely cavitation i was hearing. im still running the elbow out of the tankinto the pump, i doubt thats good for flow, my post pump fuel filter is fairly small, and im still running the stock 10mm feed and 8mm return line. its likely my fuel system is too small for the pump. for the power levels your planning i would be running a -8 (1/2") feed line at minimum and a -6 (3/8") return line (or use the stock feed line as the return). i plan on doing this in the future when i push my swap past 500hp.

sharkey

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Re: Fuel pump options

Post  yamamtx on Wed Jan 11, 2017 8:55 pm

Thanks for the additional info. I currently have a returnless setup, would there be a reason why I should go to a return setup? Thanks

yamamtx

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Re: Fuel pump options

Post  sharkey on Wed Jan 11, 2017 9:40 pm

really depends on your school of thought. on a stock or mild build, returnless fuel system is fine. once you start putting boost in the mix, tuning can become a little harder with a fixed pressure returnless system.

in a returnless fixed pressure fuel system the rail pressure will always stay the same, however the differential pressure (also known as effective fuel pressure) between the rail and intake manifold changes with manifold vacuum or boost. lets say the fuel pressure is set at 58psi (stock late model gm pressure), on a naturally aspirated engine at full throttle you have 0 vacuum, the effective fuel pressure is 58psi. now at idle under around 18" of vacuum (-10psi roughly) your effective fuel pressure is now 68psi. this effectively makes the injector have a higher flow rate at idle because of the higher effective fuel pressure. now the ecm takes this into account and just trims the pulse width of the injector down. now installing a larger injector as needed for a modified engine or for a boosted engine, and the tune needs to trim that pulse width down further, and it can get to the point where you can hit the minimum pulse width of the injector, and the end result can be a rich idle, or a rough idle.

now under boost, the opposite is true. as you put pressure in the intake manifold the effective fuel pressure drops, so that same 58psi rail pressure under 10psi boost is now 48psi effective. now this has a snowball effect, the more boost you run the less effective pressure you have, so you need to go with an even larger injector to get the same fuel flow. this compounds the idle problem.

here is a good example of this, my 2005 cobalt ss 2.0l supercharged. from factory it runs a returnless system with 58psi rail pressure, 33lb/hr injectors around 10lb boost. now those 33lb injectors are maxed from factory, 42lb/hr injectors and a tune net you another 15-20hp without a boost increase. a pulley swap and 2-3psi more boost results in around 240hp, but the 42lb injectors are maxed, where in a return system with 58psi rail pressure you can see 300hp. my car makes 270hp, to do that im running 60lb injectors, and it runs around 17-18psi boost. the effective fuel pressure is down to 40psi, and the result is near maxed out injectors. as it is, its hard to get a clean idle, the best tuners can do it, but it takes a lot of time. to make more power you need to go with 80lb injectors as more boost ends up with lower effective pressure. the real fix is a return system with an adjustable regulator that manifold refferenced. this will allow those 60lb injectors to run all the way to 440hp.

what im getting at is having a return system with a manifold refferenced regulator is the way to go for a boosted engine. it keeps your fuel injector sizes lower and allows for better tunability. for your targets of 500-550hp you can run a 42lb injector and still have some safety margin.

sharkey

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Re: Fuel pump options

Post  yamamtx on Thu Jan 12, 2017 6:12 am

Wowza Sharkey at 5:45 in the morning you made my head spin, but it all made good since. On most articles and tv shows it seems they always throw 80lbs injectors in and call it good or at lease they don't get into detail like you did. I will start searching fuel system upgrades and probably be back with more questions for you if you don't mind? Thanks

yamamtx

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Re: Fuel pump options

Post  sharkey on Thu Jan 12, 2017 12:02 pm

im happy to answer anything i can.

a lot of people do just jam a big injector in and hope for the best, thats what most blower kits for ls vehicles do. but then people wonder why their idle quality isnt quite as good, why it has the odd misfire code, and why startup on a cold day is crappy. it goes right along with the rest of the fuel system in these kits. ive seen many times where you get up over 500hp and at the top of the rpm range its going lean, installing a bigger fuel pump gives a little more head room, but a 3/8 fuel line will only flow so much fuel. many tuners will just crank the injector pulse with up in the top end as a band aid fix, but that creates inconsistent lean/rich conditions.

boost is a very unforgiving thing, having a proper fuel system is very important to keep an engine alive and happy.

sharkey

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