stock injectors capacity

[Jist_95]

Hey i searched for awhile and couldnt come up with anything. But i have a 95 GST and just got all my supporting mods to put on my MBC. I was wondering how much boost the stock injectors can support. I am not planning on jacking the boost up very high mabey 2-3 psi or something near there. Thanks

 

[DSM90AWD]

(4) 450cc injectors @ 43psi base => 257.14 HP @ 90% DC ; 285.71 HP @ 100% DC

Remember the stock T-25 doesn't like to boost very high so don't go crazy

 

[Tomeek]

16psi is max, or your turbo WILL DIE

 

[CanadianTSi]

The stock Injectors can handle anything the t-25 can throw at them...

 

[v8s_are_slow]

The stock Injectors can handle anything the t-25 can throw at them...

what he said. but keep in mind, that's on a T-25. when you upgrade turbos, that changes things. could possibly go with a 14b on there or even a 16g and be okay with them though. only datalogging and a wideband would tell ya for sure. but the fuel pump and fpr would be the 1st fuel upgrades ya need to worry about. and a rewire.

 

[94awdcoupe]

i used the 450cc injectors as far as they would push me a few years back on a Big T28. i had every single supporting mod, fuel wise except injectors. I uped the fuel pressure to 54psi and was running 19psi of boost on pump with no knock and also ran it in the 1/4 and pulled a 12.8 @ 109 on this setup. it just takes alot of tuning.

 

[Batty200]

(4) 450cc injectors @ 43psi base => 257.14 HP @ 90% DC ; 285.71 HP @ 100% DC

Remember the stock T-25 doesn't like to boost very high so don't go crazy

What A/F ratio are you suing to come up with these numbers? I have personally seen a much higher hp per cc on these cars. If all else is functioning properly and you are tuned properly the injectors are good for tons of power. On a DSM with just VPC, FPR, fuel pump, SAFC and full exhaust I have seen 248whp at 16psi and with plenty of headroom on the injectors. I feel 300whp is poss on them at 12:1 A/F and 43psi. Some here disagree with me but this is my opinion.

Later

 

[dsm_illicious]

I ran 20 to 25 lbs. on my stock T25 for a year with no problems (with religious Royal Purple oil changes). Now I'm using a 16G @ 15LBS and it's awesome...no need for fuel injectors.

With the setup you have, consider purchasing a A'Pexi SAFC-2, you can easily get a bunch of horses with basic bolt ons plus this little miracle of a electronic device...Easy tap-in install but needs professional tuning.

Good Luck!

 

[Tomeek]

well... i don't see the 20-25psi but whatever, anyway's save up some money and do it RIGHT, rather than breaking your turbo-engine-or whatnot, so get all the mods, starting with a

$90 WALBRO 190/255/255HP --- try ebay or some other vendors --- if you wanna run the 255hp you need a AFPR thats another $140 + lines and fittings

$150+ 6xxcc fuel injectors (if used) --- classified is a good place to get them --- you can get 550lbs for cheap but they won't do too much

$100-$200 S-AFC --- one of the best investments there is till you get aem ems or dsm link

thats it so for from about $400 to $500 you'll have a nice lil setup
and for about $550-$650 you'll have a better setup, if you buy these used

let me just tell you it is better to do it right once, than to fukc it up because of someones opinion, YOU ARE GONNA REPAIR IT, or at least you gonna pay if it breaks, and that is more than $500 if you mess up either your engine and your turbo

. i hope that helped

 

[2DSMs]

At a base pressure of 43 psi, stock 450cc injectors will support 342 hp at 100% duty cycle.
At 90% duty they will support 307 HP. The injectors should support a small 16G turbo provided you upgrade the fuel pump. The formula for is: injector cc X .1902 X # of cylinders = max horsepower (X inj duty %).

 

[DSM90AWD]

At a base pressure of 43 psi, stock 450cc injectors will support 342 hp at 100% duty cycle.
At 90% duty they will support 307 HP. The injectors should support a small 16G turbo provided you upgrade the fuel pump. The formula for is: injector cc X .1902 X # of cylinders = max horsepower (X inj duty %).

On a naturally aspirated engine you are correct. On a turbocharged engine the BSFC (Brake Specific Fuel Consumption) is .60-.65 not .50 (which is what your formula is using).
FYI.. I used .60 in my calculations in post #2 above.

Check RC Engineering's website for more information

 

[2DSMs]

That formula I posted was from RC engineering many years back and YES it applied to turbocharged cars only. What you calculated at 100% duty cycles=285 hp is to the WHEELS. If you add 21% drivetrain loss (which is typical for a 5spd car) with AWD car then you get roughly the 342 hp I posted at the CRANK using my formula. So technically speaking we're both right, we just got there using differing formulas.

 

[DSM90AWD]

That formula I posted was from RC engineering many years back and YES it applied to turbocharged cars only. What you calculated at 100% duty cycles=285 hp is to the WHEELS. If you add 21% drivetrain loss (which is typical for a 5spd car) with AWD car then you get roughly the 342 hp I posted at the CRANK using my formula. So technically speaking we're both right, we just got there using differing formulas.

Actually your wrong. RC Engineering's calculator is Crankshaft HP.
I entered the numbers from my #2 post and came back to 453cc

You'd actually need to subtract 20% from my values to find your WHP rating (~205WHP).

So are you still recommending 450s for a 16G?

 

[2DSMs]

I think that figure is low. I think you're WRONG. Call up the Buschur or Extreme and tell them what you calculated. Get ready for some . RC is in the business of SELLING injectors. That's why they insist on 80% IDC to help you justify a purchase. Ask yourself why some JDM 4G63 motors come with small 16G turbo's fueled by, now get ready for this drum roll please.........450cc injectors. The JDM 4G63 with Big 16G with mere 510's FCOL!
Call Mitsubishi and give them a piece of your mind for being such uninformed idiots and not
using RC's little money grabbin' formula. Small wonder why most wise DSMers
never care to post at all on these boards with all the misinformation floating around.

I think I'll stick to my formula which in fact came TURBO and HIGH TECH performance magazine and not RC. I think most others will agree that it's far more accurate than yours.
At least there is no conflict of interest there, is there?

 

[DSM90AWD]

That formula I posted was from RC engineering many years back and YES it applied to turbocharged cars only. What you calculated at 100% duty cycles=285 hp is to the WHEELS. If you add 21% drivetrain loss (which is typical for a 5spd car) with AWD car then you get roughly the 342 hp I posted at the CRANK using my formula.

I think I'll stick to my formula which in fact came TURBO and HIGH TECH performance magazine and not RC. I think most others will agree that it's far more accurate than yours. At least there is no conflict of interest there, is there?

Je-sus... you waffle more than Kerry
So which is it? RCs formula or Turbo Magazines formula? BTW, RC has been a huge advertiser of Turbo Magazine since before you could drive so the likelyhood of them using RCs formula is very high.

Call up the Buschur or Extreme and tell them what you calculated. Get ready for some . RC is in the business of SELLING injectors. That's why they insist on 80% IDC to help you justify a purchase.

RC gets the same money outta you for most size injectors so implying they would lie about flow is a desparate act by someone whom knows he's wrong. Look on Buschurs /Tuners staged upgrades sites. Both recommend a minimum of 550 injectors with a 16G turbo. Coincidence? If I sold you an injector that had to flow 100% DC to supply enough fuel would you buy again

Ask yourself why some JDM 4G63 motors come with small 16G turbo's fueled by, now get ready for this drum roll please.........450cc injectors. The JDM 4G63 with Big 16G with mere 510's FCOL!

(4) 510s can support ~300HP @90% DC which is 50more than 450s. I think if you do the math (for once) you'll see that that would be in line with the Stock HP rating of said JDM car.

Small wonder why most wise DSMers never care to post at all on these boards with all the misinformation floating around

Unfortunately it is often "unwise" people such as yourself whom spouts misinformation on such basic concepts as this

 

[Batty200]

I personally have seen a stock injector car make 248whp at 16psi with stock SMIC. This was without hitting fuel cut either. The ECU will fuel cut well before the injectors are maxxed out. When we upped the boost to 21psi the car had fuel cut issues so we swapped in 550's only to get around the fuel cut issues. If the fuel cut is safely remove without leaning out the car completely then 300whp on stock injectors would be possible.

I have also seen a Supra TT with COMPLETELY stock fuel system and ECU do 497whp with less than 80% duty cycle on 6 550's running very rich (sub 11.0:1 A/F). I use a pretty good basic fuel equation for injectors which I derived from an arlticle in SCC a while back that has proven very reliable for me in the past. Just take total cc of injectors and divide by 6 and you will get close. Example: 450x4=1800 1800/6=300. I have seen this method work well on many cars at the dyno. Using the Supra above it works out to 550x6=3300 3300/6=550.

ON a 6 cylinder car the injector size is basically the amount of power it can support.


Later

 

[LessIsMore]

small 16g@15psi boost
3000gt fuel pump
450cc@37psi fuel pressure

Logging a third gear pull shows IDC average ~95% after 5.5K rpm and peaking at 100% around 6.3K rpm. Log shows no knock and peak timing advance of 23 degrees, O2's in the .91-.93 volt range.

The car does have a boost leak at the throttle body seals, which may be causing a slightly rich condition, driving up duty cycle.

By raising base fuel pressure and using an afc to lean things out I hope to push my stock injectors a little further. Hoping to see ~18psi on the small 16g and stock injectors.

Could people with stock injectors and 16g turbos please post logs or any relevant info. It would be nice to compile some information about stock injectors their limitations.

 

[unior]

the 347 crank hp number is way closer to accurate

300whp IS attainable on a 4 cylinder on 450cc injectors

of course most of the moderators around here then to think differently

 

[wortdog]

450cc injectors don't last all that long at high duty cycles, I burned out three injectors from running them around 100% (EVO III 16g, 20psi) all the time. My 850s might see 65% duty cycle at high RPM

 

[unior]

450cc injectors don't last all that long at high duty cycles, I burned out three injectors from running them around 100% (EVO III 16g, 20psi) all the time. My 850s might see 65% duty cycle at high RPM

well running your injectors at 95% is fine - 100% they are held WIDE OPEN and never close - that is when they burn out.....

Better to just run 90% and bump up your fuel pressure

 

[DSM90AWD]

the 347 crank hp number is way closer to accurate
300whp IS attainable on a 4 cylinder on 450cc injectors

From your own profile

i need fuel!

You're running 13.6@100 which is ~250WHP. Why would you need more fuel if your stockers can supply 300WHP as you say

I will concede that 300WHP may be possible on 450s if you're running race gas as your engine can run a much leaner mixture (i.e. less fuel). Though Phil Beers (the quickest 14B guy on stock engine/inj..etc) was 34HP shy of that number on Race Gas.

 

[unior]

From your own profile


You're running 13.6@100 which is ~250WHP. Why would you need more fuel if your stockers can supply 300WHP as you say

I will concede that 300WHP may be possible on 450s if you're running race gas as your engine can run a much leaner mixture (i.e. less fuel). Though Phil Beers (the quickest 14B guy on stock engine/inj..etc) was 34HP shy of that number on Race Gas.

Why do I need fuel? Because I'm not bolting on my tnetics manifold, full garrett 50 trim, tial ex wg, etc till i have bigger injectors and my megasquirt EMS.

Hardly anyone believes you can make 300whp since everyone is hitting fuel cut way before that hp - and 90% of the people out there just buy 550s/2g mas or chip or AFC to fool the stock ecu and/or eliminate fuel cut. Who wants to buy a chip for 450s ya know?

 

[DSM90AWD]

Why do I need fuel? Because I'm not bolting on my tnetics manifold, full garrett 50 trim, tial ex wg, etc till i have bigger injectors and my megasquirt EMS.

Awww.. come on. Don't you want to be known as "That Guy that proved everyone wrong that 450s can support 300WHP"

FYI.. on the Dyno Graph I have posted in my profile I was running 78% DCs (and knocking like hell) trying to get a 11.5:1 AFR on Denso 660s (Flows 710cc/min). This equates to ~100% DC on 550s and ~123% DC on 450s (if there is such a thing). This was on a 50-trim on 93 octane and still not 300WHP.

 

[Steve93Talon]

I ran 12.7 on a small 16g and SMIC waay back in the day on stock injectors. This was on a stock MAF and 5 knob AFC, no logger, no EGT, no wideband, just old skool throwing on parts and driving. As for the injector calculations, everyone's wrong. You're forgetting to add 1psi of fuel pressure per psi of boost, for example a base FP of 43 at 20psi gives ya 63psi, and 450s will flow alot more at 63psi than they will at 43

 

[unior]

Awww.. come on. Don't you want to be known as "That Guy that proved everyone wrong that 450s can support 300WHP"

i don't wanna waste money on a chip for 450s when my goal is 400whp

FYI.. on the Dyno Graph I have posted in my profile I was running 78% DCs (and knocking like hell) trying to get a 11.5:1 AFR on Denso 660s (Flows 710cc/min). This equates to ~100% DC on 550s and ~123% DC on 450s (if there is such a thing). This was on a 50-trim on 93 octane and still not 300WHP.

what were you using to log DC - pocketlogger always seems way off to me

because 550s will support 450+whp at less than 90% DC without insane fuel pressure