I am building a 422 with stage 3 heads, ls6 intake, ported tb and a .600 lift mid 230 to low 240 duration with a 113 lc. heads are not finished yet and cam won't be ordered till heads are done it will be 11.5 to 11.2 to 1 compression. I will be spraying this with a 150 shot wet kit. I have a walbro 340 in tank pump. 61 psi at idle 55 psi at wot with 2 stages flowing. I am wondering what size injectors I will need to support 475 to 500 rwhp NA. I had posted this earlier and now I know more of what I am looking for. Is there a injector calculater that will allow you to ajust for fuel pressure the one that was posted last time didn't even tell you what fuel pressure the injectors would have to at to get the flow #'s they were showing. Any info would help. Thanks Rich

 

I come up with 48lb injectors. Use this formula:
lbs/hr=(BHP X BSFC)/(No of inj X DC)
BHP=Peak Horse Power
BSFC=Brake Specific Fuel Cosumption
DC=Duty Cycle
So, (650 X .50)/(8 X .85)=47.79lbs/hr. I've been told to use .50 for the BSFC of engines with power adders such as blowers/turbos/dry nitrous systems. No power adders use .45 BSFC. If you used a .55 BSFC you'd come up with 52.57lbs/hr. The .85 is for 85% injector duty cycle. Hope this helps.

 

Thank you for the reply. I assume the 650 in the brake hp is the hp at the flywheel natrally aspirated. not the 500 rwhp + 150 wet shot. where in the equation do you account for fuel pressure?

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif"> Thank you for the reply. I assume the 650 in the brake hp is the hp at the flywheel natrally aspirated. not the 500 rwhp + 150 wet shot. where in the equation do you account for fuel pressure?
</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">No, the 650 is your estimated 500 + 150 wet shot. I don't understand what you mean by accounting for fuel pressure. I'm assuming you'd be running the LS1 58 psi. Rated injectors can/will flow more with more pressure but once you've set your fuel pressure via a regulator it should stay right on (with a good aftermarket unit anyway). Hence the SVO injectors pushing more fuel in LS1's as they are rated at 43.5lb/hr and the LS1 injectors being rated say 28.6 ('98?) at 58psi. Or is that is what you are asking? If you have a rated flow of 43.5 psi and a 30# inj you get 30lb/hr. Up the pressure to 50 psi and you get 32.16lb/hr. Up the pressure again to 60psi and you get 35.23lb/hr out of the same injector. A 55lb/hr at rated flow (of 43.5 psi) goes to 58.39 at 50psi and 64.39 at 60psi. As long as your buying injectors advertised for an LS1 they should be rated at 58psi. For most (but not everything) else they will be 43.5 psi rated flow. I went ahead and did the math-43lb/hr injectors would flow 50lb/hr at 58 psi. 50lb/hr injectors would flow 57lb/hr at 58 psi. So some injectors in the 43-45lb/hr range should be good.
It's late and I might not be comprehending what you are asking. If not I'll give it another shot. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

<small>[ February 20, 2003, 03:05 AM: Message edited by: 68LSS1 ]</small>

 

just get 42's they will be more than enough, but you will want to do something with the pump to support the extra wet shot.. maybe a dedicated inline for the nitrous would be the easiest solution?

for new 42's for $300, pm me

 

I thank you for the detailed info. I don't under stand why I would have to add the extra 150 hp for the n2o when the n2o supplies its own fuel (wet kit) and has nothing to do with the injectors like a dry kit. All the injectors see is N.A. hp. Please correct me if I am wrong. Thanks again Rich.

 

your fuel pump still has to supply enough for both.

 

I understand that the fuel pump is going to support both the engine fuel system and the extra fuel for the n2o. I will need to upgrade the fuel system to support 650 hp combined. I am refering to the equation you gave for the injectors with the engine being 500 hp na that is all the injectors should see with a wet kit the extra 150 hp of n2o will supply its own fuel through the separate system( fuel solenoid and jet).

 

hey rich, i don't think they are geting what you are saying. lets figure 15%driveline loss(guess), so your looking at no more than 600fwhp. now use that number in his formula. everything i have read says .50bsfc for a NA set up, sooo

(600 x .50)/(8 x .85)=44.11lb/hr

now lets look at those 42svo's, to figure the flow at 55psi you need to take the (square root of 55/43.5) x 42 = 47.22actual flow at 55psi.

being very conservative it looks like the 42's would be ideal

<small>[ February 23, 2003, 03:19 PM: Message edited by: parish8 ]</small>

 

Thanks1 What is your thought Mighty Mouse? sounds right to me.

 

Hi Mightymouse,

I'm in pretty much the same boat as rich is. I've got a MTI 422 that I'm looking to run a dual stage NX MAF kit on in the spring with a 100hp/75hp set. I've dropped in the WS-340 intank pump and the SVO 42s look like the right package. I shot you a PM to get the contact info for the shop.

Thanks,
Rick