Can I change my 450cc injectors with 750cc ones??

[doornenbal]

I am posting this question for a buddy.

He has an early impulse Turbo Kit that does not have the stand alone fuel management system, but does have a pro logger. It has a 2860 turbo with a head shim ( i belive 30 thou).

Question is he does not think that the 450cc injectors are giving him enough fuel at around 18-19 lbs and was wondering if he could replace them with 750cc ones and go.....

I have seen the sled go at 17lbs and does good, he says he could go to 20 lbs I belive (on the right fuel) but as of right now he figures his injectors are not big enough.


Any help or advice would be great.

 

[NM]

You would never be able to do it without a fuel management system that would take fuel away pre boost. The 450 cc injectors are very limited as to what they will make for horsepower. More people should refer to a fuel injection calculator like this.http://www.injector.com/injectorselection.php

According to this calculator, three 450cc injectors would barely be capable of 200 hp with proper fuel pressure and duty cycle. You can only manipulate fuel pressures and duty cycle so much to get proper power...even then it is a real juggling act.

 

[doornenbal]

Neil

What I am hearing is that we could change out the fuel pump to a bigger one, intall the 750 cc injectors, buy a "boost it" fuel management system... and we are in the running with the horsepower and boost we need as well as controlling the fuel side of it.

Please correct me if I am way out to lunch on that one.....

 

[doornenbal]

As well based on the calculator to get up to 290 hp on that calculator I would need 1000 cc injectors ish at an 80% duty cycle.....

 

[NM]

Neil

What I am hearing is that we could change out the fuel pump to a bigger one, intall the 750 cc injectors, buy a "boost it" fuel management system... and we are in the running with the horsepower and boost we need as well as controlling the fuel side of it.

Please correct me if I am way out to lunch on that one.....

The Boost-It system does not control the injectors in the stock fuel rail. It is a standalone extra injector system that provide fuel for when boost comes on.
For example, if you run stock injectors and the stock motor is capable of 130 hp, then all of the extra power you need has to be provided for by the extra injectors. So if want 270 hp, then the extra injectors need to be able to handle fuel for 140 hp.

 

[doornenbal]

Ahhh

Excelent Idea!!!

For this system is there a restiriction on the fuel pump?? or does the kit come with one?? If not can I PM you for Pricing details ETC because it sound like it will solve his issues.

 

[NM]

Ahhh

Excelent Idea!!!

For this system is there a restiriction on the fuel pump?? or does the kit come with one?? If not can I PM you for Pricing details ETC because it sound like it will solve his issues.

He would need a fuel regulator and a pump. I can and have provided both if people need them.

 

[martin_e_wilson]

I have a nytro with a 2871 race kit and the 450cc injectors and mine will fuel is so rich that I will go into the 10's on my af gauge at 18lbs. You must have something else wrong.

 

[zebiraross]

As well based on the calculator to get up to 290 hp on that calculator I would need 1000 cc injectors ish at an 80% duty cycle.....

Ya, that calculator isn't very accurate IMO. On my old Apex I gaurantee I was making more then 300 hp on Stock injectors that are 380cc's. Ya, I was probably at or over 100% IDC but I never had a issue with the right fuel pump and fuel pump wiring. That calculator says I need 689 cc injectors to make 300 hp on a 4 injector system. That's not true. Maybe for a 70% IDC which I don't think is necessary.

Dornenball, to answer your question I wouldn't put in 750 cc injectors with the old fuel system. With out the stand alone it would be VERY difficult to maintain any control over idle/start-up/midrange/and even top end fuel control with the old fuel design and those large of injectors. It would be a nightmare. I agree, trying to manipulate fp with large injectors isn't the right way to control efi.