What fuel pump to use with my nitrous system
 

I am in the process of installing my Zex kit in my car. I currently have the mods listed below in my sig. I will start out with the 75 hp jetting but will eventually tune my way up the the 125 level. I have a 155 lph in tank now with the 24 lbs injectors and I was planning to step up to the 190 lph. Should I just skip that and go with the 255??? Will the return lines be able to handle that much fuel? Any advice would be greatly appreciated!

Thanks!

With a 51cc chamber head, ANY nitrous use should be carefully thought out, I recommend you go with a 190 intank and a T-rex in-line, 30-36lb injectors, cold range plugs and timing at 8 degrees, an AFPR too. The return lines will not be an issue.

I agree with the above post. Anytime you use a 51CC head with Nitrous, you HAVE to be careful. Good luck with it and be safe!! I run two holley blue's on mine and one mallory 190 pump!

Eric

With my pistons, my compression ratio is just over 10.5:1 and I was always told the higher compression motors with aluminum heads and nitrous go well together??? Do I really need 30 or 36 pound injectors for just a 75 shot?? I do have the adjustable FPR and I also installed a window switch to turn on and turn off the flow of nitrous at specified rpms.

Thanks guy's.

No sir, high compression is a proven NO NO with spray, even with aluminum heads that do add a bit of a cooling advantage over iron heads, when nitrous is introduced into the motor it effectively increases compression drastically. For example, purpose built nitrous motors are based on a low compression motor, like 8.5:1 or so. With 51cc chambers, you will need lots of fuel, and it will limit any high horsepower shots to a minimum. Good luck.

Well not to mess you guys all Up but Many Racers Have LOTS of Compression and Run No2 and lots of it as well But...... they reabuild them all the time And Are Not EVERY Run on the street. Just saying you can But there is a risk yes with the Higher Compression. Better Fuel and More of it as well.

No.

Nitrous and your compression is fine. Your just going to need to adjust the timing accordingly.

I would go with a 255lph Forced Induction Holley Fuel pump. It flows a lot more than the regular 255 and that will be fine.

Skyler

It is my understanding that nitrous does not increase the compression ratio but rather add a "dense" concentration of oxygen to allow you to burn more fuel thus making more combustion pressure. I know that blowers and turbo's do increase compression by forcing a larger volume of air into the cylinder and then compressing that mixture to achieve the same goal - more oxygen to burn more fuel to make more power.

we run a 255 intake pump with 19# injectors on a 150 dry shot...only mods to motor are ederbrock heads and a e303..this gets us mid 11 second time slips on slicks spraying out the hole..i have 10deg timing on pump gas and 12-13 on race gas..also i run 2 step colder autolites

Get the 255
 

Mike - Sounds like the 255lph is the one to go with.

Sky - what's the difference b/t the F/I Holley Pump and a 'regular' 255 pump. I've heard that the F/I Holley is better, just always wondered why. Thanks.

E

Re: Get the 255
 

it keeps the pressure higher under high fuel demands of forced indutcion

Higher pressure and more flow. It really does more than 255, they just call it that.


Skyler