KW's <---> What size Injectors ?
 

Hi anyone got a calculation method for injector sizing for a certain number of KW ?

IE. Aiming for 230-240KW ATW on an EJ207.
Will 560 CC injectors be sufficient. No upgraded FPR but Walbro pump installed.

Got a feeling I need 650cc's to be safe.

Comments / formula's ?

J

560cc should do it with a bit of head room to spare. A few people are getting 200kw ATW in 440c at around 95% IDC. So an extra 120cc should be able to handle it okay.

Personally, though, I'd still go the 650cc for extra headroom and for future mods and greater power outputs.

[url]http://www.rceng.com/technical.htm[/url]

What Dyno are we talking here DD ot Hub?

J

Sorry to go off topic, but are you aiming to do this the the VF36? I'm running a VF37 and would like similar power, but not sure if it's possible with this size turbo. In saying that though, the turbo seems like it could happily produce 1.8-2 bar so.....

Also, at those kinds of power outputs or more you should consider getting parallel fuel rails and a good quality FPR.

You dont need to touch the fuel rails or FPR. you can just mod the existing factory set up.
Having an aftermarket FPR just adds another potential problem when it fails

[url]http://www.perth-wrx.com/vb/showthread.php?t=1248&highlight=fuel[/url]

[QUOTE=Mister Two]Also, at those kinds of power outputs or more you should consider getting parallel fuel rails and a good quality FPR.[/QUOTE]

*sigh*

[QUOTE=Mister Two]Also, at those kinds of power outputs or more you should consider getting parallel fuel rails and a good quality FPR.[/QUOTE]

only if you subscribe to hot4's and are gullible.

jamie,
with stock fpr, walbro pump and standard injectors (cut-top's) you have about 816cc of fuel injector at your disposal. the standard fuel lines @ 40psi are also capable of delievering over 18litres per minute, so your current fuel system is fine (no need to modify it and you will have no problems with what youve got)

Assuming a target of 260kW with a bosch 910 pump on a 2.5. Stockies will do the job? Seems like its pushing the stock injectors a touch too far.

According to his profile... Hes got a 99 WRX right? Which means. You cannot de-cap the injectors. 99 WRX has side feed injectors. And while they can be high flowed, they cannot be decapped.

As for parallel fuel rails. stock GC8 rails can sometimes have fueling problems on cylinder 2 at high IDCs IIRC . Its easy to modify them to parallel setup.

Cheers All

Joe: Thats the formula I was looking for Guiseppe thanks. :)

Stace: FPR...Parallels....Sigh... Hot 4's :rolleyes: alright. I thought this was discussed ad infinitum in your FPR thread!!!

Foxey: Yes VF36, Built EJ207 + JDM worked heads with Spec C cams. :)


Just to clarify at moment I have MY99 Manifold +560cc STi side feeds, but can get 02 STi manifold with 816cc decaps.
If current 560cc system is enough then I will stick with that.

Is there any improvement with the MY02 STi manifold over the MY99 one ?

Not chasing big big KW but want to talk the Torque. ;)

J

[QUOTE=Mister Two]As for parallel fuel rails. stock GC8 rails can sometimes have fueling problems on cylinder 2 at high IDCs IIRC . Its easy to modify them to parallel setup.[/QUOTE]

MOTEC M800 = Individual cylinder trim on #2

[QUOTE=Mister Two]According to his profile... Hes got a 99 WRX right? Which means. You cannot de-cap the injectors. 99 WRX has side feed injectors. And while they can be high flowed, they cannot be decapped..[/QUOTE]

true, although i though he had a modern manifold.

[QUOTE=Mister Two]As for parallel fuel rails. stock GC8 rails can sometimes have fueling problems on cylinder 2 at high IDCs IIRC . Its easy to modify them to parallel setup.[/QUOTE]

not the case, this is due to the vacuum line on the fuel pressure regulator. move the vacuum line to the centre of the manifold and the FPR will have a correct pressure feed.

[QUOTE=WRXTASY]MOTEC M800 = Individual cylinder trim on #2[/QUOTE]
unless your logging cylinder EGT, i would suggest not doing this :)

[QUOTE=WRXTASY]Just to clarify at moment I have MY99 Manifold +560cc STi side feeds, but can get 02 STi manifold with 816cc decaps.
If current 560cc system is enough then I will stick with that.

Is there any improvement with the MY02 STi manifold over the MY99 one ?

Not chasing big big KW but want to talk the Torque.[/QUOTE]

i found 550's maxed out around 220kw with safety margins, (wideband lambda closed loop)

you'll want 816's for the boost, big torque needs it. at around 350hp i still only acheived around 65% duty.

the GD style manifold is better flowing then the GC manifold, i'll have definitative figures for it soon (if your really interested)

I have 700 cc side feeds with standard rails just bigger custom fuel lines with parallel setup to the Sard FPR. The sard lets u squeeze a bit more pressure out of the system if your injectors get marginal at higher hp levels.

Thanks Stace.....

Just plugged some figures into Guiseppe's calculator...

320bhp (240 KW) at 90% IDC = 560 cc/min, and that would only be at the crank.....

400bhp (300 KW) at the crank is about 240 KW at the wheels so yes its a GD manifold with the 816cc decaps.

Good discussion....

i tend to run IDC's up to 95%, beyond that i let wideband make the corrections for lean/rich to smooth it out.

im unsure what plans you have for your setup, but i assume you dont want to be doing it twice, pm me if need be.

cheers!

IDC's on my 440's were at 99% for ages without an explosion.

18 litres per minute.... you cant tip it down the drain that fasT!

Mr Two, read this

[url]http://www.perth-wrx.com/vb/showthread.php?t=1248&highlight=tuna+tech[/url]

How is the factory FPR going to be better than the super well constructed SARD FPR at holding just a 1:1 ratio eg not using the sards ability to increase pressure.

I think that the SARD has got to be better at running just a 1:1 due to superior construction out of billet and higher quality fittings.

When rexes have spontaneously had lean outs who's to say it wasn't the factory FPR shitting itself.

thats ok simon, you dont have to feel guilty for buying a sard fuel regulator. we all make mistakes.

[QUOTE=tuna]thats ok simon, you dont have to feel guilty for buying a sard fuel regulator. we all make mistakes.[/QUOTE]

I don't feel bad at all. I would feel bad using a stock FPR at your power levels when its a 5c part made in china probably.

I see enough Sard FPR's on 700+hp cars to make sure that I sleep soundly at night. Also yet to see a 10 second wrx with a standard FPR.

Here is the 800hp roger clark car with its non standard FPR's as usual.
[img]http://www.rogerclarkmotorsport.co.uk/gobstopper/images/094.jpg[/img]

comes down to an understanding of the equipment- if your not sure, by all means change it, but change it for the right reasons, not because a magazine thinks its a good idea.

the standard fpr is more capable then its given credit for, out of the 100,000's of EFI subaru's around the world, the failure rate would be minisquel, much less then failed fuel pumps, fuel blockages or aftermarket rails/accessories.

[quote]Here is the 800hp roger clark car with its non standard FPR's as usual.[/quote]
i would suggest this has a good reason, mainly the aftermarket inlet manifold, different injectors, and aftermarket fuel rails.
when the factory FPR is fitted to the factory rails, its understandable they were replaced, hardly rocket science.

[QUOTE=POLARBEAR666]I don't feel bad at all. I would feel bad using a stock FPR at your power levels when its a 5c part made in china probably.

I see enough Sard FPR's on 700+hp cars to make sure that I sleep soundly at night. Also yet to see a 10 second wrx with a standard FPR.

Here is the 800hp roger clark car with its non standard FPR's as usual.
[/QUOTE]

The RCMS car is also a technical showcase of what they can sell to customers who see shiney things and reach for their wallet.

I like being able to see the fuel pressure on the gauge attached to my Sard. Which is something I could not do on the stock one. That alone is worth the small price of $200.

If you had a MoTeC, you could run a $200 fuel pressure sender and log it on a laptop, or output it to a gauge.

[QUOTE=POLARBEAR666]I like being able to see the fuel pressure on the gauge attached to my Sard. Which is something I could not do on the stock one. That alone is worth the small price of $200.[/QUOTE]

the fuel pressure you are seeing is not the true fuel pressure, you also are unable to monitor this guage from within the car (somewhat pointless)

anyhow, what you really want to monitor is differential fuel pressure.
this fuel pressure value is the value of positive rail pressure against manifold pressure minus the return rail pressure.

the purpose of this is to see when you reach the ceiling of the fuel pump and to determine if your fuel pressure maintains its static pressure against manifold pressure. ie the rising rate. 43.5psi (299kpa) + 1bar positive mainfold pressure (14psi+), resulting in a true rail pressure reading of 57.5psi. (your guage will not display this value)

again, its an understanding of the equipment, not what looks fancy in a show car/magazine.

[QUOTE=POLARBEAR666]I like being able to see the fuel pressure on the gauge attached to my Sard. Which is something I could not do on the stock one. That alone is worth the small price of $200.[/QUOTE]

Is the guage in the cabin or under the bonnet ?

It's next to the paper punch, stapler & shredder.

Jamie,

I am getting between 220kw and 240kw at the hubs (ASG dyno) with 550cc injectors, and a Bosch 044.

built JDM 02 Sti Spec C motor, M800, TD05-16G @ 1.7bar....dont know what the duty is but It's pretty rich...backfires etc, can smell fuel often.

+1 for...
[URL=http://imageshack.us][IMG]http://img183.imageshack.us/img183/2852/tunaqk3.jpg[/IMG][/URL]
Shot at 2007-07-19

[QUOTE=atz 242]Jamie,

I am getting between 220kw and 240kw at the hubs (ASG dyno) with 550cc injectors, and a Bosch 044.

built JDM 02 Sti Spec C motor, M800, TD05-16G @ 1.7bar....dont know what the duty is but It's pretty rich...backfires etc, can smell fuel often.[/QUOTE]

Good stuff !!
Sounds pretty much like what I'm aiming for Pete, have you got a dyno map ya can post up. Specifically want to look at the boost RPM spread.

1.7bar, good stuff. ARP head bolts I'm sure. I want to wring the shit out of this VF36 I have too....

J

on the road, rolling on in 5th I get 1.5bar by 3100rpm.

Dyno says max torque @4400 max power 6500rpm...this was before the 1.7+bar retune and fitting of a different dump pipe...

torque was only about 380nm? probably closer to 400 now...dunno...feels fast anyway.

Edit, havent got a dyno print out since the 6 speed + new dump + retune for more boost but I have an old one, I'll scan it sometime, I'm up at work : (

yeah ARP studs, metal head gasket all forged stuff etc etc...

ATZ whats teh torque at 3100 when u hit 1.5 bar surely its higher than 400?

don't know, wasn't over 400nm...will have another look @ the print out when I get back to Perth.

[url]http://www.autronic/software/injsize.zip[/url]

useful tool :grommit:

[url]http://www.autronic.com/software/injsize.zip[/url]

Cheers