450cc Injectors -- What size RRFPR

[m90daytona]

Quote:

Originally Posted by Ondonti Point of increase is important when transitioning into boost.......now where it starts increasing 1:1 in vacuum.

1:1 as in 1lb fuel pressure to 1in vacuum?

[mwinkle353]

actually, it averages out to about 2inHg to 1 psi of fuel pressure decrease from base.

[m90daytona]

the vortech unit you can adjust via the vacuum screw.

[Ondonti]

I dont know why you would want to change point of base rate increase.

Changing point of of increase when getting into boost is the issue and what BEGI takes care of.
.....unless someone explained the vortech incorrectly

[m90daytona]

Quote:

Originally Posted by Ondonti I dont know why you would want to change point of base rate increase. Changing point of of increase when getting into boost is the issue and what BEGI takes care of. .....unless someone explained the vortech incorrectly

you can change it if you want but you dont have to. its just another adjustment you can use to fine tune your fuel curve.

for example, if you have a fuel rail that doesnt flow well (like ours), and you cant get base pressure down far enough to idle well w/ big injectors you can then use the sfmu along w/ megasquirt. what you will do next is turn the base down as far as you can, use ms to adjust the pulse width of the injectors and then adjust the vacuum screw on the vortech unit to maybe start rising at 5in vacuum instead of 18 or 15. because you have too much fuel pressure at idle, you might not want it to rise right away and so you can fix the problem by doing that. but, if you want, the sfmu WILL start raising fuel pressure from idle up to 0in vacuum (atmospheric pressure). i dont know what the rate is (might be 1:1) but i can find out.

[Ondonti]

The point is being missed.

The BEGI can adjust where the "rising rate" ratio for boost is applied, which is not the same thing as adjusting where the base rate increase is applied.

We are talking about using a RRR to add fuel for a turbo setup not to use it as a suppliment.

The only time i would use one as a suppliment would be if I was trying to cheat and get more HP out of the same injectors (but then you would need a better fuel pump for the same HP level). Probably better to buy the correct injectors.

[m90daytona]

Quote:

Originally Posted by Ondonti The point is being missed. The BEGI can adjust where the "rising rate" ratio for boost is applied, which is not the same thing as adjusting where the base rate increase is applied. We are talking about using a RRR to add fuel for a turbo setup not to use it as a suppliment. The only time i would use one as a suppliment would be if I was trying to cheat and get more HP out of the same injectors (but then you would need a better fuel pump for the same HP level). Probably better to buy the correct injectors.

so the begi unit will start to increase boost at 3 or 4psi if you want?

i still dont know what your talking about. the begi unit is a supplement. it doesnt come from the factory and it is added to the fuel system to increase fuel pressure. the begi and sfmu both increase fuel pressure so how is one a supplement and the other not.

give me like a "for instance" scenario because i am having a hard time understanding what the diffrences are.

[Ondonti]

Quote:

Originally Posted by m90daytona so the begi unit will start to increase boost at 3 or 4psi if you want? i still dont know what your talking about. the begi unit is a supplement. it doesnt come from the factory and it is added to the fuel system to increase fuel pressure. the begi and sfmu both increase fuel pressure so how is one a supplement and the other not. give me like a "for instance" scenario because i am having a hard time understanding what the diffrences are.

BEGI can start increasing fuel pressure (whatever ratio you have it set at) above or below atmospheric pressure.


When i say supplimental, I mean in addition to a megasquirt. That practice makes no sense to me unless you have a giant fuel pump and tiny injectors. It would be best to just get injectors that are the correct size.

[m90daytona]

Quote:

Originally Posted by Ondonti BEGI can start increasing fuel pressure (whatever ratio you have it set at) above or below atmospheric pressure. When i say supplimental, I mean in addition to a megasquirt. That practice makes no sense to me unless you have a giant fuel pump and tiny injectors. It would be best to just get injectors that are the correct size.

if you make alot of power you need big injectors. its hard to make big injectors work at idle even if you lower the fuel pressure. thats why using small injectors and an fmu is beneficial. even w/ megasquirt you cant make a 36lb injector make 450hp...but w/ an sfmu you can make tons of power and have good driveability. combine megasquirt w/ an adjustable fmu and the skies the limit as far as tuning goes.

[Ondonti]

Quote:

Originally Posted by m90daytona if you make alot of power you need big injectors. its hard to make big injectors work at idle even if you lower the fuel pressure. thats why using small injectors and an fmu is beneficial. even w/ megasquirt you cant make a 36lb injector make 450hp...but w/ an sfmu you can make tons of power and have good driveability. combine megasquirt w/ an adjustable fmu and the skies the limit as far as tuning goes.

I really dont believe this as plenty of v6 guys use 680-880 or bigger injectors. Ive seen 1000cc's on a 6g74 idle wonderfully.

[m90daytona]

from personal experience my friend has a hard time getting his 550cc injectors to idle in his turbo maxima. i know one thing alot of people have been doing too is adding more injectors. this gets you around all the problems. you know in the long run there is amillion diffrent ways to accomplish the same end result. none are necessarily wrong though some may work better than others.

[Ondonti]

Quote:

Originally Posted by m90daytona from personal experience my friend has a hard time getting his 550cc injectors to idle in his turbo maxima. i know one thing alot of people have been doing too is adding more injectors. this gets you around all the problems. you know in the long run there is amillion diffrent ways to accomplish the same end result. none are necessarily wrong though some may work better than others.

If it wont idle then the FI setup he is using is not very good.

[m90daytona]

Quote:

Originally Posted by Ondonti If it wont idle then the FI setup he is using is not very good.

it idles okay now. when he first got it together he had a real hard time though. and if for some reason it doesnt start rite away and he has to crank it for a while...forget about the plugs. they'll be trash. if you think about it though, people w/ huge injectors still need to raise fuel pressure. huge injectors usually mean really low base pressure and low fuel pressure is not good for high hp. i would assume that most people would still need an fpr that does more than 1:1.

lets say 22psi base pressure, and someone pushing 20lbs boost on a 1:1 fpr only brings fuel pressure up to 42psi...which isnt bad but on 1000cc injectors you would max out at 690 crank hp if it where a v6. and i have seen 1000cc injectors support 900+ whp.

[87turbodance]

I really like idea of staged injection in MS. You use 6 tiny injectors for good idle and cruise fuel resolution and then you have 6 big injectors that only kick in when you start to get on it. I'm not quite sure how to implement this right now. I figure you'd need to have a second fuel rail setup maybe further up the plenum. It'd be relatively easy on an intake like you'd find a SOHC 24 2.5. HMM... just some thoughts

[Ondonti]

Quote:

Originally Posted by m90daytona it idles okay now. when he first got it together he had a real hard time though. and if for some reason it doesnt start rite away and he has to crank it for a while...forget about the plugs. they'll be trash. if you think about it though, people w/ huge injectors still need to raise fuel pressure. huge injectors usually mean really low base pressure and low fuel pressure is not good for high hp. i would assume that most people would still need an fpr that does more than 1:1. lets say 22psi base pressure, and someone pushing 20lbs boost on a 1:1 fpr only brings fuel pressure up to 42psi...which isnt bad but on 1000cc injectors you would max out at 690 crank hp if it where a v6. and i have seen 1000cc injectors support 900+ whp.

You are missing something


A good fuel injection setup can run 1000 cc injectors at NORMAL fuel pressures and not have a problem.

The things you keep mentioning are bandaids when something else is not up to par. Running low fuel pressure when you dont even have very big injectors just indicates that your fuel injection system is not adequately adjustable.

1600cc..now that might not be able to get the injector pulse width low enough but no one here is trying to make 1800hp.