injector question

[Balaska347]

Does anyone know how much RWHP 30 lb injectors can handle on a NA combo?

[speedracer]

Does anyone know how much RWHP 30 lb injectors can handle on a NA combo?

I used a injector calculator and it came up with 400hp but it dosn't say rwhp so I'm going to assume thats at the crank and if you subtract 17% drive train loss you get 332rwhp

[phillysrt4]

stang N/A noobs like me shouldnt post numbers.

[349Stroker]

WAY OFF!!!!!


I had 435 rwhp in my old coupe with 30's and they were just fine.The car was actually rich on the a/f

[Pure Stock]

Does anyone know how much RWHP 30 lb injectors can handle on a NA combo?

Here are two real-world, proven, record setting, EFI combos:

Ex.1 N/A 310.7 c.i.d, GT-40 heads, Cobra intake, tuned with EPEC. 363 RWHP Utilizes 24 lb. injectors.

Ex.2 N/A 302 c.i.d., TFS heads, Holley SMII, untuned. 374 RWHP
Utilizes 30 lb. injectors.

There is definitely some room to grow in the 2nd combo. Volumetric efficiency, BSFC, and other considerations need to be examined when selecting injector ratings.

[phillysrt4]

WAY OFF!!!!!


I had 435 rwhp in my old coupe with 30's and they were just fine.The car was actually rich on the a/f

curious, what was the setup?

darn na throwing off calculations! (even though you said NA I used a forced a typical forced induction BSFC for my calc) :P

[fastfox91]

30s can support way more than 325 on a n/a engine i seen the car whlstnder is talking about and 30s were more than enough

[349Stroker]

349

Track Heat Stage 2 heads

TFS R intake

Stage 3 cam

30's & 95mm Pro M

G Force 5 speed

4.30's

28" tire

I tuned it with a pms and lleft it rich.I sold the car and the guy took it to Englishtown and went 11.0's.He went to Big Daddy Performance and it made 403/407 @11.3 a/f.They leaned it out to 12.0 and made 435.They took it to the track and it went 10.78@128

[phillysrt4]

349

Track Heat Stage 2 heads

TFS R intake

Stage 3 cam

30's & 95mm Pro M

G Force 5 speed

4.30's

28" tire

I tuned it with a pms and lleft it rich.I sold the car and the guy took it to Englishtown and went 11.0's.He went to Big Daddy Performance and it made 403/407 @11.3 a/f.They leaned it out to 12.0 and made 435.They took it to the track and it went 10.78@128

ah ok thats cool. that helps sort out (in addition to a horrendously innacurate BSFC for an NA engine) why I was so low on the calcs.

Learn something every day :)

[Martin0660]

I know its not a straight answer to your question, but I like to work this stuff out for myself, and would rather show you the information than lead you astray. Here is great information on injector sizing....

http://www.rceng.com/technical.aspx

As Philly got mixed up, be carefull with the BFSC you apply, for forced induction its something you need to be real careful about ;) For your stuff, I would think .50 would be a good place to work. RC always says to stay under 80% duty cycle, I would stay with that unless someone can confirm for you that the 5.0 EEC's can command higher. For the 2.3 stuff, I'm not affraid of 95%, we have low impedance injectors and I've personally run at 100% using fuel pressure only, but its scarry.

Also be aware of the fuel pressure differences and how they are rated. Most injectors are rated at the industry 43.5 psi. Well, Ford decided to use 39 for a lot of their stuff, and I'm not sure what you actually run (static, no vacuum). As you start to look at this, here is another calculator that converts flow rate based on fuel pressure. This is a case where you need the real data on the injectors, not what they are rated based on the application and MAF supplied.

http://www.csgnetwork.com/fiflowcalc.html

This is also on the RC site, but easier to use on the other link.

This is a start, let me know if you want to work through the formulas.

Bob Myers

[Balaska347]

Thanks for your help guys. I'm debating on sending my TW heads out to Fox lake and the intake. I talked to a guy out there and he said I should be able to pick up 50 RWHP if they do my heads and intake with the rest of the setup i have. The car made right around 350/350 at the wheels, so that should put me around 400. I run a 255lph intank and a T-REX booster pump and a aeromotive reg. with 30lb injectors. I think I should be ok with the same fuel system.

[Viper_ed]

I'd say you'd be fine and you're sending that stuff to the right place for sure!

[fastfox91]

the current fuel system u have will be fine u have plenty of room to grow with what u have as long as there is no poweradder being added nitrous, blower, turbo