Inj Size And WHP Output - Page 5

STRATTON · 03-03-2007, 04:19 PM

370 cc = 250 WHP * Purple SR20DET
---------------------------------------------370 cc @ 4 bar = 290

dre, got a question, 370cc @ 4 bar @ 90-92% injector duty cycle would = out to about what kind of whp ??

stratton.

Hanzzzzz · 03-05-2007, 05:49 PM

This is what i got based on information from this thread, someone please correct me if i am wrong.

assuming it is a 4 cylinder at 4BAR fuel pressure:

For a turbo car at 12:1 fuel to air mix:
(injector size in CC's) x 0.783 = max whp the injector can support (roughly)

For a N/A car at 13.5:1 fuel to air mix:
(injector size in CC's) x 0.881 = max whp the injector can support (roughly)

Since duty cycles were not given, I dont know how they would factor in.

I am not a tuner, just a guy who passed grade 9 math.

Sigfod · 03-05-2007, 06:05 PM

Oh do 3 bar next!

BoostThis · 05-13-2007, 10:11 PM

what are the HP numbers for the top feed 00-02 RR sr20motor injectors?? its not listed in the first post.

DeNismo · 05-17-2007, 11:39 PM

what type of injectors are in the VZ-r?

XxToKeSxX · 05-18-2007, 01:13 PM

Quote:

Originally Posted by Hanzzzzz

This is what i got based on information from this thread, someone please correct me if i am wrong.

assuming it is a 4 cylinder at 4BAR fuel pressure:

For a turbo car at 12:1 fuel to air mix:
(injector size in CC's) x 0.783 = max whp the injector can support (roughly)

For a N/A car at 13.5:1 fuel to air mix:
(injector size in CC's) x 0.881 = max whp the injector can support (roughly)

Since duty cycles were not given, I dont know how they would factor in.

I am not a tuner, just a guy who passed grade 9 math.

That's pretty good

In reality though, I don't think the relationship is linear... Since its volumetric flow. The formula probably has a couple polynomials, like to the second or third order or something... if your testing maximum flow there is probably only one variable still. If the duty cycle is taken into account you would be dealing with less than maximum flow, and another variable might be thrown in there... but this is just taking it from not much higher than a 9th grade math basis.

In other words, your rule of thumb calc is fine for rough numbers.

The reason max flow is calculated is because that gives you what your potential whp output is... if you want a rough calculation for whp just take what your duty cycle is and multiply it times the maximum whp numbers that are given (if the numbers given are at 100% duty cycle...

Are the number's shown on the first page maximum whp numbers for injectors at 100% duty cycle?

If yes... for a rough number... given the numbers provided are maximum potential whp numbers

370cc's at 4 bar = 290whp from first post (assumin MAF supports)...

92% duty cycle = 0.92 x 290whp = 266.8whp (roughly)

93% duty cycle = 0.93 x 290whp = 269.7whp (roughly)

and so on...

I'm probably wrong... but its all rough estimation, there are a few more factors, the best way to get true numbers is dyno test data, and injector flow test data.

RedDragun · 05-22-2007, 02:01 PM

How much whp are the Subaru injectors good for at 4 bar?

chriscar · 05-22-2007, 02:22 PM

Quote:

Originally Posted by RedDragun

How much whp are the Subaru injectors good for at 4 bar?

Well if you look at the original chart, and divide the whp by the injector size, you'll come up with .67 for 3bar setups and .77 for 4bar.

I had my STi injectors flow tested at 520cc so at 4bar, that calculates out to (520*.77) = 400whp

C

RedDragun · 05-22-2007, 04:33 PM

I thought they were 525cc at 3 bar?

chriscar · 05-22-2007, 06:31 PM

Quote:

Originally Posted by RedDragun

I thought they were 525cc at 3 bar?

Mine were tested and came out to 520 @ 3 bar. You're going to sweat 5cc?

C

RedDragun · 05-22-2007, 11:37 PM

Lol no I thought you had said that they were 520cc at 4bar but then I re-read it and I get it now.

ruthlessef-9 · 06-05-2007, 07:08 AM

whats with this changing of chip/map?? is this with FWD SRDET's?

or does this go for RWD too

cause If i can' get more WHP with just increasing my fuel pressure Im going to 4bar ASAP!

gomba · 06-05-2007, 02:42 PM

Quote:

Originally Posted by chriscar

Well if you look at the original chart, and divide the whp by the injector size, you'll come up with .67 for 3bar setups and .77 for 4bar.

I had my STi injectors flow tested at 520cc so at 4bar, that calculates out to (520*.77) = 400whp

C

The STI injectors should be added to the original post.

STRATTON · 07-05-2007, 11:40 PM

what to be sure here so ill ask the guru's. what injector will run at 4 bar fit in a stock rail and fit in a aft market rail that will fit a 02 intake manifold ?

stratton.

P11-144 · 07-07-2007, 10:54 AM

Is there any sense in raising the fuel pressure on a, apart from intake and header, otherwise stock motor ? I heard it could get rid of a ' flat' spot in the power curve ?

fullahwickednez · 07-16-2007, 01:54 PM

Quote:

Originally Posted by Andreas Miko

3 bar or 44 PSI with vacum hose off is stock fuel presure.

so on the list its stated 259 cc = 175 WHP * Red SR20DE those are the factory injectors correct?

so at 3 bar they can support up to 175 WHP but at 4 bar, those injectors could be capable of flowing 300cc? how much WHP is that good for?

SENTRASER · 07-16-2007, 01:58 PM

Quote:

Originally Posted by fullahwickednez

so on the list its stated 259 cc = 175 WHP * Red SR20DE those are the factory injectors correct?

so at 3 bar they can support up to 175 WHP but at 4 bar, those injectors could be capable of flowing 300cc? how much WHP is that good for?

175 / 259 = .67 *300 = 202 whp

fullahwickednez · 07-16-2007, 02:02 PM

Quote:

Originally Posted by SENTRASER

175 / 259 = .67 *300 = 202 whp

hehe I just scrolled up and saw the rough formula and got that number also. thanks for the help though, I appreciate it.

Well if theyre capable of handing 200WHP, why do people flame the noobies who want to use their stock injectors on a bluebird t25 at stock boost? I thought a DE on a t25 makes 200 to the crank?

[of course this is with upgraded fuel pump]

SENTRASER · 07-16-2007, 04:51 PM

Because why pay for the program and MAX out your stock fuel injectors when for around $100 you can atleast get 370's? I didn't use the formula, I just figured it out actually.