Supercharged w/ CJM Return Fuel Issues
02-15-2007, 10:37 AM
#1
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Supercharged w/ CJM Return Fuel Issues
I was just curious if any one else was running into problems running the CJM return fuel system with their supercharger. Seems like im losing fuel pressure starting at around 5800 rpm and it gets dangerously low after 6500. I'm using rc550 injectors with my setup. Issues or not please post your setup (Vortech/ATI) and the size of your injectors. Also what size pulley your running. Thanks
02-15-2007, 10:53 AM
#2
Being that a system of fuel line plumbing is rather simple in function, there are only a few potential things that could be causing your system to loss pressure on the top.
a) the fuel pump is maxed out
a supercharger causes extreme parasitic drag on the engine and reduces RWHP potential of a given mass of air/fuel. i do not know how much drag your particular setup has, as vortech could not tell me when i called and asked them. however, it is definatly no question that a supercharger car will max out a given fuel pump at significantly lower rwhp compared to a turbocharged car.
b) pump is not up to par
bad or damaged pump could be operating at less efficiency.
c) there is an internal or external pressure leak
this will easily cap the potential of the system. for internal leaks you can check the pump output nipple seal and the fuel pressure regulator plug o-rings. external leaks are obvious.
d) pump wiring not up to par
so far i have not seen any issues of this in the 350z, it appears the factory fuel pump wiring is sufficient to max out a single walbro pump without issue. but its something to be checked in diagnostic stages.
e) restriction in the line somewhere
pressure after a restriction will be less then pressure before a restriction. this is why our stage 2 kit is able to get more out of a single walbro pump by eliminating more OEM restrictions. its possible that you may have a kink in a line, or a piece of debris (not as likely). You may want to check the hardpipe adapter to make sure the compression fitting did not compress in some wierd way and cause a restriction in the line (no known cases of this yet, but its a factor I would consider since it would only take a brief moment to check on while under the car.)
My best guess would be its either just A, or a little of C on top of A. Unfortunatly I do not have a lot of data as to how much rwhp to expect from the Stage 1 kit on a supercharged car, however as you know, there is another member with a setup close to yours that is experiencing the same issue.
a) the fuel pump is maxed out
a supercharger causes extreme parasitic drag on the engine and reduces RWHP potential of a given mass of air/fuel. i do not know how much drag your particular setup has, as vortech could not tell me when i called and asked them. however, it is definatly no question that a supercharger car will max out a given fuel pump at significantly lower rwhp compared to a turbocharged car.
b) pump is not up to par
bad or damaged pump could be operating at less efficiency.
c) there is an internal or external pressure leak
this will easily cap the potential of the system. for internal leaks you can check the pump output nipple seal and the fuel pressure regulator plug o-rings. external leaks are obvious.
d) pump wiring not up to par
so far i have not seen any issues of this in the 350z, it appears the factory fuel pump wiring is sufficient to max out a single walbro pump without issue. but its something to be checked in diagnostic stages.
e) restriction in the line somewhere
pressure after a restriction will be less then pressure before a restriction. this is why our stage 2 kit is able to get more out of a single walbro pump by eliminating more OEM restrictions. its possible that you may have a kink in a line, or a piece of debris (not as likely). You may want to check the hardpipe adapter to make sure the compression fitting did not compress in some wierd way and cause a restriction in the line (no known cases of this yet, but its a factor I would consider since it would only take a brief moment to check on while under the car.)
My best guess would be its either just A, or a little of C on top of A. Unfortunatly I do not have a lot of data as to how much rwhp to expect from the Stage 1 kit on a supercharged car, however as you know, there is another member with a setup close to yours that is experiencing the same issue.
Last edited by phunk; 02-15-2007 at 02:25 PM.
02-15-2007, 10:59 AM
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Yeah I'm in no way trying to give your CJM fuel system a bad name and I do know its working great for turbo'd cars. I found a member today with your fuel system and a 3.12 pulley on a Vortech with no issue. He was running 440 inj though. I'm just wanting to find a solution so I can get my car up and ready for summer. And i don't mind buying something else to back up the fuel system if you think I need it or your can manufacture for me to get it working right.
02-15-2007, 11:17 AM
#4
Just currious why you guys are running bigger injectors. I know you need them when you go big in horsepower numbers like over 450. I am running the complete Vortech system with my stock fuel injectors with no issues or problems. I have the upgraded 3.12 pulley and other mods.
02-15-2007, 11:21 AM
#6
Originally Posted by Barzten1
Yeah I'm in no way trying to give your CJM fuel system a bad name and I do know its working great for turbo'd cars. I found a member today with your fuel system and a 3.12 pulley on a Vortech with no issue. He was running 440 inj though. I'm just wanting to find a solution so I can get my car up and ready for summer. And i don't mind buying something else to back up the fuel system if you think I need it or your can manufacture for me to get it working right.
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02-15-2007, 11:25 AM
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I am running ati procharger with 750 cc injectors, about to upgrade the 9psi pulley. No issues with fuel pressure as of now, but then again I do not have the vacuum line connected yet. I have it set to stay at just under 30 until i get the retune.
02-15-2007, 11:26 AM
#10
Originally Posted by Barzten1
Thats some of my frustration. I knew your safer running a return fuel system on a boosted car. I didn't have fuel pressure problems before.
The return system aids in tuning and driveability, however the Vortech setup had more top end potential due to its additional fuel pump. I can help you come up with a plumbing solution to add that pump back in with your return system if you wish.
If there are no leaks in your system, this or a voltage booster to your existing pump may unfortunately be the only solution aside from a full twin pump upgrade which feels so overkill to me.
02-15-2007, 11:27 AM
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Originally Posted by 350Z_LEE
I am running ati procharger with 750 cc injectors, about to upgrade the 9psi pulley. No issues with fuel pressure as of now, but then again I do not have the vacuum line connected yet. I have it set to stay at just under 30 until i get the retune.
02-15-2007, 11:39 AM
#12
I'll post my results as I get them, but right now the only thing I've found as a temporary (I hope) solution is to use the MSD booster pump to gradually raise my fuel pump voltage while under boost and it does work. So because it works that makes me think there isn't a restriction, but probably a leak or something not sealed quite right.
My shop tried replacing the fuel pressure regulator after adjusting it a million times but no luck. They tried giving it a dedicated boost line from the blower itself (which helped a little). I went from 550cc to 750cc injectors to eliminate the injectors as the issue and that didn't solve it either. We replaced the walbro pump with another brand new one with the same results.
I tried using a AAM ECU flash for 750cc injectors instead of the TS flash which was flashed for 440cc injectors and eliminated the emanage ultimate. That didn't solve the issue either (but runs soooo much nicer having the ECU running the 750cc injectors vs the emanage attempting to clumsily scale them, and no start up or blown coil issues anymore) I have the stage 2 CJM fuel line, but think I'll just wait for the twin pump assembly and do them at the same time since it really doesn't seem be a restriction of the main fuel line's size
I'll buy the CJM twin fuel pump assembly as soon as it becomes available. It's going to be overkill for my setup, but if it works then I don't care. If anything I'll have a plenty big fuel system ready to go if/when I go to a 4.24 stroked engine
If the twin pump assembly doesn't work, I'll have no choice but to build an auxilary feed tank with a seperate racing fuel pump like the AAM stage 2 system. That should work. This whole thing is rediculous though. It shouldn't be this hard unless I was doing like 800+whp
My shop tried replacing the fuel pressure regulator after adjusting it a million times but no luck. They tried giving it a dedicated boost line from the blower itself (which helped a little). I went from 550cc to 750cc injectors to eliminate the injectors as the issue and that didn't solve it either. We replaced the walbro pump with another brand new one with the same results.
I tried using a AAM ECU flash for 750cc injectors instead of the TS flash which was flashed for 440cc injectors and eliminated the emanage ultimate. That didn't solve the issue either (but runs soooo much nicer having the ECU running the 750cc injectors vs the emanage attempting to clumsily scale them, and no start up or blown coil issues anymore) I have the stage 2 CJM fuel line, but think I'll just wait for the twin pump assembly and do them at the same time since it really doesn't seem be a restriction of the main fuel line's size
I'll buy the CJM twin fuel pump assembly as soon as it becomes available. It's going to be overkill for my setup, but if it works then I don't care. If anything I'll have a plenty big fuel system ready to go if/when I go to a 4.24 stroked engine
If the twin pump assembly doesn't work, I'll have no choice but to build an auxilary feed tank with a seperate racing fuel pump like the AAM stage 2 system. That should work. This whole thing is rediculous though. It shouldn't be this hard unless I was doing like 800+whp
Last edited by sentry65; 02-15-2007 at 11:58 AM.
02-15-2007, 11:48 AM
#13
Originally Posted by drifter23
Just currious why you guys are running bigger injectors. I know you need them when you go big in horsepower numbers like over 450. I am running the complete Vortech system with my stock fuel injectors with no issues or problems. I have the upgraded 3.12 pulley and other mods.
the stock vortech fuel system and SS box are fine for power levels up to 400 or so whp. Running the injectors at near max injector duty cycle is never a great solution though. It's risky
02-15-2007, 11:53 AM
#15
Originally Posted by sentry65
If the twin pump assembly doesn't work, I'll have no choice but to build an auxilary feed tank with a seperate racing fuel pump like the AAM stage 2 system. That should work. This whole thing is rediculous though. It shouldn't be this hard unless I was doing like 800+whp
02-15-2007, 12:41 PM
#17
Originally Posted by sentry65
I agree
the stock vortech fuel system and SS box are fine for power levels up to 400 or so whp. Running the injectors at near max injector duty cycle is never a great solution though. It's risky
the stock vortech fuel system and SS box are fine for power levels up to 400 or so whp. Running the injectors at near max injector duty cycle is never a great solution though. It's risky
Brazen and Sentry are the only ones Ive seen that has a problem with going to a return fuel system and bigger injectors . The power level isnt there to think that you've maxed it out . Ive said it before , Im at 430whp and have plenty of injector duty cycle left . The lose in whp turning the blower shouldnt be enough to cause a 550 injector to be maxed . Im guessing on a MT6 car running 12psi , its getting close to 100whp . If you look at a TT car running 12psi , the whp is around 500 to 550whp and Sentry's car is running 12psi and making 430whp
That being said , Phunk's list of problems that are possible . One or more of them has to be the problem and I sure hope you find it .
Last edited by booger; 02-15-2007 at 12:56 PM.
02-15-2007, 01:32 PM
#18
Originally Posted by sentry65
I agree
the stock vortech fuel system and SS box are fine for power levels up to 400 or so whp. Running the injectors at near max injector duty cycle is never a great solution though. It's risky
the stock vortech fuel system and SS box are fine for power levels up to 400 or so whp. Running the injectors at near max injector duty cycle is never a great solution though. It's risky
Do you think I should upgrade my injectors? I am at 380 whp right now and will be hitting 400whp by next month. You think my stock injectors are running at it's peak cycle? My tuner says I will be fine but, wanted to get some input from you guys just in case. Thanks in advance.
02-15-2007, 01:50 PM
#20
booger, my car isn't making 430whp at 12 psi
it was making around 420whp on a dynodynamics dyno with the engine hot at 10 psi because the belt was slipping and wouldn't go beyond 10, maybe 10.1 psi. I can scan in the boost curve from the dyno if you want to see it...boost was stopping right at 10psi at 5200 rpm to redline last time I was dynoing. Even still, that was probably around 450whp if I took the car over to a dynojet. Some people have done that here locally and the dynojets are reading 6-11% higher than the dynodynamics depending on which dynojet it is. JoeDirtPharmD did and his car was a full 11% higher at a portable dynojet than what Dynocomp's dyno read.
My car made 12 psi after tightening the belt, but I didn't redyno it because I want my tuning $ to actually go towards tuning new mods. My car's in the shop adding water injection and a dual 2.5 exhaust replacing my nismo single 3 inch exhaust. My best honest guess is it'll end up somewhere around 450 on the dyno dynamics dyno and around 480whp on a moderate calibrated dynojet.
besides, a 12 psi TT with test pipes and a really open exhaust is in a completely different ballpark than a "12" psi SC with smaller exhaust and cats
If I ran test pipes and a dual 3 inch exhaust, I'd be at 10 psi and also have to suffer the greater amount of parasitic loss from the SC so of course it'd be less than a TT
I've only seen a 13 psi TT make 550whp on a dynojet, not sure I've ever seen a 12 psi TT make that much though
you're probably fine for now at that power level
it was making around 420whp on a dynodynamics dyno with the engine hot at 10 psi because the belt was slipping and wouldn't go beyond 10, maybe 10.1 psi. I can scan in the boost curve from the dyno if you want to see it...boost was stopping right at 10psi at 5200 rpm to redline last time I was dynoing. Even still, that was probably around 450whp if I took the car over to a dynojet. Some people have done that here locally and the dynojets are reading 6-11% higher than the dynodynamics depending on which dynojet it is. JoeDirtPharmD did and his car was a full 11% higher at a portable dynojet than what Dynocomp's dyno read.
My car made 12 psi after tightening the belt, but I didn't redyno it because I want my tuning $ to actually go towards tuning new mods. My car's in the shop adding water injection and a dual 2.5 exhaust replacing my nismo single 3 inch exhaust. My best honest guess is it'll end up somewhere around 450 on the dyno dynamics dyno and around 480whp on a moderate calibrated dynojet.
besides, a 12 psi TT with test pipes and a really open exhaust is in a completely different ballpark than a "12" psi SC with smaller exhaust and cats
If I ran test pipes and a dual 3 inch exhaust, I'd be at 10 psi and also have to suffer the greater amount of parasitic loss from the SC so of course it'd be less than a TT
I've only seen a 13 psi TT make 550whp on a dynojet, not sure I've ever seen a 12 psi TT make that much though
Originally Posted by drifter23
Do you think I should upgrade my injectors? I am at 380 whp right now and will be hitting 400whp by next month. You think my stock injectors are running at it's peak cycle? My tuner says I will be fine but, wanted to get some input from you guys just in case. Thanks in advance.
Last edited by sentry65; 02-15-2007 at 02:35 PM.