big-n-italian
Enthusiast
just got home from the dyno - i need more fuel! what are my options?
my engine is starving for fuel!
- Thread starter big-n-italian
- Start date
Fast Freddy
Enthusiast
i assume you have a supercharger?
OP
OP
big-n-italian
Enthusiast
sorry, yes freddy - you are correct.
10 lbs of boost, supercharger, stock injectors, etc for the time being.
10 lbs of boost, supercharger, stock injectors, etc for the time being.
OP
OP
big-n-italian
Enthusiast
here is one of my sheets. i am being told that i am running lean and we arent able to do a full pull.
Russ M
Enthusiast
Alot more info would be needed, whats on your car, fuel/ignition management, etc...
But to begin with the stock injectors are only good for about 480rwhp.
But to begin with the stock injectors are only good for about 480rwhp.
OP
OP
big-n-italian
Enthusiast
sure. sorry, but i am new to this.
vec2. vortech supercharger. according to the gage -10 lbs of boost. 93 octane fuel. stock injectors. no headers. no head work. 1997 car. only borlas mufflers in the side sills, straight pipes all the way out.
what other info can i provide?
vec2. vortech supercharger. according to the gage -10 lbs of boost. 93 octane fuel. stock injectors. no headers. no head work. 1997 car. only borlas mufflers in the side sills, straight pipes all the way out.
what other info can i provide?
TOOOFST
Enthusiast
Should be OK up to 650RW.
On the dyno up to 700RW.
been there with many cars.
On the dyno up to 700RW.
been there with many cars.
VIPER D
Viper Owner
Something doesn't seem right. Blown cobras put out more hp. Do you have a kenny bell boosta pump?
Doesn't the roe blower come with injectors? and fuel rails?
whats your afr?
vd..
Doesn't the roe blower come with injectors? and fuel rails?
whats your afr?
vd..
OP
OP
big-n-italian
Enthusiast
<< Do you have a kenny bell boosta pump? >>
no. again, everything is stock, which we believe is why we are running out of fuel.
<< Doesn't the roe blower come with injectors? and fuel rails? >>
again, vortech supercharger.
no. again, everything is stock, which we believe is why we are running out of fuel.
<< Doesn't the roe blower come with injectors? and fuel rails? >>
again, vortech supercharger.
Marc Lublin
Enthusiast
You need a fuel system in order to run that kind of boost. You should talk to the guys that do centrifugal SC systems like Jason and Doug. They can get you on the correct path. If I were you I wouldn't drive under boost until you do this. You will run lean, have detonation and blow your motor.
Joseph Dell
Enthusiast
stock fuel PUMP is good for ~650... stock injectors, well, not so much. that graph looks normal. with 53lb injectors he'd have slight improvement, but to run that kinda boost, one really needs a full fuel system of some sort.
JD
JD
Russ M
Enthusiast
Like some already said you need a fuel system.
Fuel pump(s), bigger injectors or much more fuel pressure to make your injectors work. But I am not sure if you can get that much more flow out of stock injectors even with alot more pressure.
Make sure you dont go hitting the gas pedal on that car, or you will be replacing your motor very very soon. If it was my car I would not even drive it untill you install a fuel system and tune it.
Fuel pump(s), bigger injectors or much more fuel pressure to make your injectors work. But I am not sure if you can get that much more flow out of stock injectors even with alot more pressure.
Make sure you dont go hitting the gas pedal on that car, or you will be replacing your motor very very soon. If it was my car I would not even drive it untill you install a fuel system and tune it.
Fast Freddy
Enthusiast
fuel supply is reallly basic. bigger fuel pump, bigger fuel pressure regulator, bigger fuel injectors and bigger fuel lines and fuel rail. that's all there is too it. none of these items should be needed until you make in excess of at least 600 rwhp and maybe even as high as 700 rwhp. i think the problem you are having is either mechanical in nature or your tune with that POS vec 2. put a new fuel filter in and make sure your fuel lines and fuel injectors are clean and working properly. also put in new spark plugs with the correct heat range and gap. get some MSD 8.5 mm plug wires while you at it.
what was you A/F ratio? on a supercharged car you should be at 12.5:1 max. and some would prefer 11.5:1. personally i would tune for 12.0:1. you won't start loosing power until you go leaner than 13.2:1 so you must be runnin pretty damn lean to be down on so much power. i assume you have an intercooler? with 10 psi of boost on a stock gen 2 viper engine you should be makin at least 650 rwhp. i assume you were tested on a dynojet and not a mustang dyno.
personally if this was my car i would spend the $$$ to get a bigger fuel pump and bigger fuel injectors. you should be able to get this for about $1,000. but no matter how you slice it i would dump that vec 2 crap and get a real tune. centrifugal superchargers have a tendency to run rich at low rpm's and lean at high rpm's just like turbos so the tune is critical.
what was you A/F ratio? on a supercharged car you should be at 12.5:1 max. and some would prefer 11.5:1. personally i would tune for 12.0:1. you won't start loosing power until you go leaner than 13.2:1 so you must be runnin pretty damn lean to be down on so much power. i assume you have an intercooler? with 10 psi of boost on a stock gen 2 viper engine you should be makin at least 650 rwhp. i assume you were tested on a dynojet and not a mustang dyno.
personally if this was my car i would spend the $$$ to get a bigger fuel pump and bigger fuel injectors. you should be able to get this for about $1,000. but no matter how you slice it i would dump that vec 2 crap and get a real tune. centrifugal superchargers have a tendency to run rich at low rpm's and lean at high rpm's just like turbos so the tune is critical.
OP
OP
big-n-italian
Enthusiast
thanks for the info guys. the car is definately sitting till the fuel system is figured out.
freddy, yes it has an intercooler. dynojet yes. i will check the filter and lines. good idea. i am going to show another graph - A/F? maybe this is the one you guys are asking about.
freddy, yes it has an intercooler. dynojet yes. i will check the filter and lines. good idea. i am going to show another graph - A/F? maybe this is the one you guys are asking about.
OP
OP
big-n-italian
Enthusiast
Fast Freddy
Enthusiast
17.5:1 
and thats at only 4,400 rpm's 
how long have you been running the engine in this condition? if its been more than 100 miles the tops of your pistons are probably paper thin by now. as you can see as your boost goes up your fuel flow is basically doing absolutely nothing. i think you have multiple problems here
and thats at only 4,400 rpm's how long have you been running the engine in this condition? if its been more than 100 miles the tops of your pistons are probably paper thin by now. as you can see as your boost goes up your fuel flow is basically doing absolutely nothing. i think you have multiple problems here
99 R/T 10
Enthusiast
To get a "quick fix", get a Boost-a-pump and larger injectors. That should keep you relatively safe for the moment and allow you to drive it in a sane manner. Next, design and install a complete fuel system. I don't know (maybe someone else does) if you can get a larger side feed injector, but call either DLM, Heffner or Macedo Motorsports for advise and help. Macedos number I just happen to know off the top of my head, 407-246-6511. I'm sure others know the number for DLM and Heffenr.
Marc Lublin
Enthusiast
Wow, crazy AF. Surprised you still have pistons left. Bolting a SC onto a car is the easy part. If you haven't already done motor damage, your car is 1/3 from completion. Now you need a fuel system and proper tune. Freddy, what's the beef with the Vec2? I run one and my car is probably putting about a grand to the tires with no issues. What are your issues?
Russ M
Enthusiast
Fast Freddy,
I may be missing something here but the factory 29lb injectors at stock fuel pressure are not good for 650rwhp.
My car with an AEM unit exhaust/pulley/no cats basicly maxes them out. Somewhere along the lines of 97% duty cycle.
And dump the vec 2 crap? What do you suggest he gets thats better for the price? An AEM unit will cost him much more, and a motec will cost him much much more.
Thanks
I may be missing something here but the factory 29lb injectors at stock fuel pressure are not good for 650rwhp.
My car with an AEM unit exhaust/pulley/no cats basicly maxes them out. Somewhere along the lines of 97% duty cycle.
And dump the vec 2 crap? What do you suggest he gets thats better for the price? An AEM unit will cost him much more, and a motec will cost him much much more.
Thanks
OP
OP
big-n-italian
Enthusiast
<< 17.5:1 and thats at only 4,400 rpm's how long have you been running the engine in this condition? if its been more than 100 miles the tops of your pistons are probably paper thin by now. as you can see as your boost goes up your fuel flow is basically doing absolutely nothing. i think you have multiple problems here >>
i dont remember what the original AF reading was, but we were actually quite rich on the first few pulls out of 6 or 8 i believe. we had played with things awhile before this last pull trying to solve the fuel problem. we finally realized that we had a "lack-of-fuel" problem and not a tuning problem. this was the last reading before we called it a night.
i guess it all comes down to a fuel system now, and then back to the dyno. it is the exact details of that fuel system i am still trying to figure out.
i dont remember what the original AF reading was, but we were actually quite rich on the first few pulls out of 6 or 8 i believe. we had played with things awhile before this last pull trying to solve the fuel problem. we finally realized that we had a "lack-of-fuel" problem and not a tuning problem. this was the last reading before we called it a night.
i guess it all comes down to a fuel system now, and then back to the dyno. it is the exact details of that fuel system i am still trying to figure out.
GTSnake
Enthusiast
Where did you get your SC system? Didn't it come with a fuel booster or bigger injectors. It's almost a prereq to have bigger injectors and fuel boost for a SC. Especially with 10lbs.
When you go with a larger fuel system you might want to go to bigger lines while you're at it. Here are some pics to give you ideas. My lines are -10 but they're a little overkill. I use a Weldon pump with an Aeromotive filter before it, a BG heat sink then an Aeromotive regulator then a Y-block to each of the fuel rails.
When you go with a larger fuel system you might want to go to bigger lines while you're at it. Here are some pics to give you ideas. My lines are -10 but they're a little overkill. I use a Weldon pump with an Aeromotive filter before it, a BG heat sink then an Aeromotive regulator then a Y-block to each of the fuel rails.
Big-an-Italian:
1. With the information you supplied no one can answer your question, everyone is guessing.
2. At 500 hp (dyno graph) the oem injectors and pump have no problem, your issue is elsewhere.
3. Have the shop plot a normal "multiple" graph that shows hp and torque on the top and the a/f on the bottom.
4. What is marked over at the top of the graph.
1. With the information you supplied no one can answer your question, everyone is guessing.
2. At 500 hp (dyno graph) the oem injectors and pump have no problem, your issue is elsewhere.
3. Have the shop plot a normal "multiple" graph that shows hp and torque on the top and the a/f on the bottom.
4. What is marked over at the top of the graph.
OP
OP
big-n-italian
Enthusiast
<< ..the oem injectors and pump have no problem, your issue is elsewhere. >>
thanks jack. what is "elsewhere" though? the plugs are reading fine. dirty fuel filter? spark plug wires? ???
what else should i look at?
thanks jack. what is "elsewhere" though? the plugs are reading fine. dirty fuel filter? spark plug wires? ???
what else should i look at?
Fast Freddy
Enthusiast
any one of these problems that everyone is stating here could be an issue. that bein the case since you don't have any of these mods for your fuel system i would get them all. and as far as the vec goes i have heard of people having problems with those. i have never heard anybody having a problem with the AEM or motec, so.........
Fast Freddy
Enthusiast
in marine applications and towing applications where centrifugal superchargers are used i have always seen a boost-a-pump used. thats because centrifugal superchargers build boost like turbos. you need a rising rate fuel pressure curve as your rpm's increase 
GTS Dean
Enthusiast
You're an idiot. It's best that you quit now, while you're behind.
(edit: directed to freddy, in case there was any doubt.)
(edit: directed to freddy, in case there was any doubt.)
Big-an-Italian:
you are getting flack because you don't understand the basics or how to relay them. You need more than a guy who runs a dyno, you need someone who can diagnos. Just the way the operator printed the curve makes me wonder. Find a good tuner, a/f is very basic.
you are getting flack because you don't understand the basics or how to relay them. You need more than a guy who runs a dyno, you need someone who can diagnos. Just the way the operator printed the curve makes me wonder. Find a good tuner, a/f is very basic.
OP
OP
big-n-italian
Enthusiast
<< you are getting flack because you don't understand the basics or how to relay them. >>
no problem, i agree.
i am definately not at the knowledge level you others guys are at. (yet ). i think my local tuners know what they are doing. i just wanted second opinions.
besides they were the only ones who returned my calls.
no problem, i agree.
i am definately not at the knowledge level you others guys are at. (yet
). i think my local tuners know what they are doing. i just wanted second opinions.besides they were the only ones who returned my calls.
Russ M
Enthusiast
big-n-italian,
I dont know how to say this the politicaly correct way so for your sake I am going to say it the best way I know how.
1)STOP listening to almost everyone in this thread, it appears that they are clueless and trying to pull you down with them.
2)Call ROE/DLM/etc... tell them your dillema and have them sell you the right equipment.
3)If you like you can listen to me but you have no reason to believe me over the others so I suggest going to step 2 again.
Bottom line is this:
a)The stock fuel pump at stock pressure is good for about 650rwhp.
a1)If you raise the fuel pressure that number goes down significantly.
b)Stock injectors are good for about 480rwhp, at stock fuel pressure. You can raise the pressure to get more out of the injector but then you run into a1.
c)Vec 2 is fine for what you are doing, but it must be tunned by the right person. Any fuel/ignition management system should.
If I were you the first thing would be to get bigger injectors, and see how much you could get out of the stock pump at factory pressure.
I dont know how to say this the politicaly correct way so for your sake I am going to say it the best way I know how.
1)STOP listening to almost everyone in this thread, it appears that they are clueless and trying to pull you down with them.
2)Call ROE/DLM/etc... tell them your dillema and have them sell you the right equipment.
3)If you like you can listen to me but you have no reason to believe me over the others so I suggest going to step 2 again.
Bottom line is this:
a)The stock fuel pump at stock pressure is good for about 650rwhp.
a1)If you raise the fuel pressure that number goes down significantly.
b)Stock injectors are good for about 480rwhp, at stock fuel pressure. You can raise the pressure to get more out of the injector but then you run into a1.
c)Vec 2 is fine for what you are doing, but it must be tunned by the right person. Any fuel/ignition management system should.
If I were you the first thing would be to get bigger injectors, and see how much you could get out of the stock pump at factory pressure.
