Does anyone know the correct fuel pressure to run with a 70 shot, and with a 100 shot? I read that Thomas (SX7R) is using the stock fuel pressure regulator, and Matt is using an adjustable one, is anyone else doing this or using an aftermarket one? Does anyone know the cheapest place to get the Walbarro fuel pumps? Thanks in advance. More power coming soon...

 

http://members.home.com/syclone/APE/

Thank 1MAX2NV ... you want the 2nd Gen DSM Pump

FPD006 - $113

 

Thanks Sprint... and 1MAX2NV. I was expecting to pay a LOT more.

 

on a 75 shot, i'd say the pressure should be around 70-75psi. on a 100 shot, my fuel pressure is between 80 and 85psi, depending on bottle pressure. what you should do is do some test runs, pull over, check the plugs, and then adjust fuel pressure accordingly. i always run my setup a little bit on the lean side. to increase fuel pressure, decrease the size of the jet in the bypass tee. i'm assuming they gave you a .042 jet for that. so you would go to a .040 to run richer(increase FP) or go to .044 to run leaner(decrease FP).

 

Thanks Man. Looks like I'll be ordering some more jet's tomorrow to go with my new fuel pump. What size jet are you running in your's right now, just so I have some idea how high I need to go. Thanks in advance

 

you're ordering jets for the bypass tee right? or are you ordering nitrous jets? for what shot, 75 or 100? and you're on a stock fuel pressure regulator right?

i'm running open line for the bypass tee right now - no jet. i'm only doing this cuz my bottle pressure is high enough that there is enough pressure going to the stock fuel pressure regulator that i don't need a jet in there. the last jet i tried putting in there was a .090 and my fuel pressure was over 100psi, so i took that out. but i don't recommend you running open line because you have to have a very predicitable setup. if your bottle pressure were to drop, then your fuel pressure would drop significantly also.

 

I'm going with the 75 shot first, but I'm going to order the 100 shot also, for later... I was wondering about the bypass jet tee though. I am on the stock fuel pressure regulator, but I'm thinking of upgrading that so I don't have to worry as much. I don't have a bottle heater yet, so I'm running around 950psi depending on the temp outside. Any recomendations or opinions you have are greatly appreciated. Thanks in advance.

 

which bypass jets to get depend on if you are running rich or lean. so, just stick with your .042 jet in the bypass for now. put in the 75 shot, check what the fuel pressure is, and pull the plugs and see if you are rich or lean. then go from there.

 

My .042 is only boosting my fuel pressure up to about 60-62 psi. Will increase more with the new fuel pump?

 

definitely.

 

Thanks Thomas. I guess I'll work from that then.

 

no problem

 

oh yeah?? you think your so smart?? then what pressure do you run on a 500 shot??

 

43psi because you tap the fuel line instead of bumping up fuel pressure via the bypass tee.

 

You'll should thank Matt because he was the one that pointed me to that site

 

Actually, shouldn't be somewhere in the 53psi? Isn't that the fuel pressure at WOT?

 

Normal WOT FP is 43psi

 

 

Well...looks like all your questions have answers.
Would the FP be any different between auto and stick?

I know @ WOT (no NOS) im at 42-43psi
@ WOT (w/ 50 shot of NOS) im at 60-62psi

What should i expect from a 60 shot and 70 shot?

 

Well thats the F'd up thing about the NOS dry kit. The amount of fuel pressure won't change with the 60 or 70hp shot. It will probably work, but I didnt dig it. The difference from 50 to 70hp is not that big, but come on NOS if you add more nitrous you need more fuel, RIGHT! Well that's why I went for the fuel pressure and EGT gauges. I think 70hp is pushing it with only 60-62 psi, my plugs looked like crap with the 70hp nitrous jet and ~60psi. I'd recomend ~70psi of fuel pressure for the 70hp shot. Seeing as I run ~83psi of fuel pressure with a 100hp jet and my EGT's dont go above 810degC on a full 1-4th gear 1/4 mile pass and my A/F ratio was a safe ~12.5:1 ratio, 70psi should be just about right for a 70hp shot. BUT I dont think the factory fuel pump will hang in their at 70psi. Follow the method thomas outlined above for raising the fuel pressure while using the nitrous, you will get to a point where the pressure will rise up and fall back down back to the max pressure the pump can handle wich is IMHO is ~60psi or just where your at. I'd recomend you try the 60hp shot and check your plugs. Then try and raise the fuel presure, see what your stock pump can handle. But ultimatly you will need to upgrade the fuel pump. Its a ~$130 investment but then you can run a 75-100hp shot with no problems. After seeing Thomas's dyno and a/f ratio chart where he ran 1200psi of nitrous pressure on a .047 100hp nitrous jet and he didnt crack a piston ring land, I bet a 125hp shot is reachable at 1000psi of bottle presure and a .052 nitrous jet with ~87-93 psi of fuel pressure. I'd try it but I got this motor swap thing with a S/C to do

 

 

gettin some free posts matt?

 

dooouuuggghhhhh!!!!

So whats the smiley for I'm a dumass? :dumass: