Bigger injectors vs. Stock injectors..

[peepsalot]

How do you know what the duty cycle is on your injectors?

 

[TurfBurn]

Exothermic reaction?

???

exo means releasing.. endo means absorbing... any time something evaporates it is an endothermic reaction.. that's why we sweat... to keep us cooler... and gasoline vaporizing will pull energy/heat from its surroundings so it can vaporize due to the vapor pressure... it's a higher energy state... It'll get that energy from the air around it... it's a minor effect and I don't even know if it would account for 1 degree of change overall. I don't plan on trying to measure it either!

 

[TurfBurn]

How do you know what the duty cycle is on your injectors?

You have to figure out how many times they fire per second... which is rpm based.. so say at 3000 rpm's... it'll fire once in theory.. which means 50 times a second which is .02 seconds or twenty milliseconds. If you have an injector open time of 10 milliseconds you are at 50% duty cycle. Now go up to 6500 rpm's a cycle is now only 9.3 ms long... and thus if you are at 9.3 ms you are at 100% duty cycle.

 

[orangezoom]

You have to figure out how many times they fire per second... which is rpm based.. so say at 3000 rpm's... it'll fire once in theory.. which means 50 times a second which is .02 seconds or twenty milliseconds. If you have an injector open time of 10 milliseconds you are at 50% duty cycle. Now go up to 6500 rpm's a cycle is now only 9.3 ms long... and thus if you are at 9.3 ms you are at 100% duty cycle.

Wow you discribed it much better then I would have

 

[Spooled]

Anyone tried Lucas or Bosch disc injectors? They have very fast response times, but narrow spray patterns.

 

[peepsalot]

You have to figure out how many times they fire per second... which is rpm based.. so say at 3000 rpm's... it'll fire once in theory.. which means 50 times a second which is .02 seconds or twenty milliseconds. If you have an injector open time of 10 milliseconds you are at 50% duty cycle. Now go up to 6500 rpm's a cycle is now only 9.3 ms long... and thus if you are at 9.3 ms you are at 100% duty cycle.

Well, yeah but what do I use to tell me my injector is being opened for 10ms or whatever.

 

[LinuxRacr]

Just for reference..

Here is what the nozzles of my injectors look like:

 

[TurfBurn]

Well, yeah but what do I use to tell me my injector is being opened for 10ms or whatever.

Microtech EMS .

I think some scanners will tell you... otherwise it is typically the EMS/piggy that tells you what the cycle is at. You can measure it with an oscilliscope too... probably other methods but those are how I know to do it.

 

[TurfBurn]

Here is what the nozzles of my injectors look like:

That looks mucho different from mine.

 

[LinuxRacr]

That looks mucho different from mine.

How does your's look? Pics?

 

[LinuxRacr]

Anyone tried Lucas or Bosch disc injectors? They have very fast response times, but narrow spray patterns.

I think that HiBoost is using Bosch injectors now. Not sure what type they are.

 

[low_psi]

The WRX 440's have much smaller ports, but about 20 or so of them. It almost looks like a screen in the center.

Not a great picture but you can make out the spray ports somewhat. -Thanks YP5Toronto for the picture!

I think the idea fuel setup would be to have what Terry did on the MP3(Turfburns) & MPNick has done for Fastlane: 2nd fuel rail mounted to the intake manifold with an extra injector in each intake port. Granted Turfburn has 550primaries and Fastlane kept the OEM primaries(more ideal to me)... Cold start and idle issues would be kept to a minimum while you let the secondaries aid with boost related fuel needs.

I don't know the software of the EMSs everyone is using but I assume you can set the primaries to run at say 80%IDC max to prevent them from going static then start feeding fuel in through the secondaries with the primaries happy at 80%IDC.

 

[PaulMP3]

Turf,

you think if you went back and put stock injectors in your stock locations and use the 550 for when in boost would this make the tuning on the Microtech easier? or since it is a full standalone would there be idle and cold start issues regardless?

 

[TurfBurn]

How does your's look? Pics?

I'll post pics tonight... but it basically has a small pin that protrudes out the middle I believe... and one other injector type (I have 8 injectors 4 of each type and all are 550's) is just a single hole I believe. I'll double check and post tonight but I'm quite sure they are rather different.

 

[TurfBurn]

Turf,

you think if you went back and put stock injectors in your stock locations and use the 550 for when in boost would this make the tuning on the Microtech easier? or since it is a full standalone would there be idle and cold start issues regardless?

The tune difficulty is close to the same. Getting the car to start and idle "fine" between injector sizes is no more difficult. Getting the car to idle "great" versus "good" is a little easier with the smaller injectors... largely depends on resolution. Again I was 100% happy with my startup and idle on my 550's.

But regardless of injector tuning startup on a standalone is the single hardest part.. tuning the power band is cake compared to trying to get startup right.

 

[TurfBurn]

I think the idea fuel setup would be to have what Terry did on the MP3(Turfburns) & MPNick has done for Fastlane: 2nd fuel rail mounted to the intake manifold with an extra injector in each intake port. Granted Turfburn has 550primaries and Fastlane kept the OEM primaries(more ideal to me)... Cold start and idle issues would be kept to a minimum while you let the secondaries aid with boost related fuel needs.

I don't know the software of the EMSs everyone is using but I assume you can set the primaries to run at say 80%IDC max to prevent them from going static then start feeding fuel in through the secondaries with the primaries happy at 80%IDC.

Keep in mind that I've already maxed out my 550's before in the primary already... and I wouldn't be surprised if we could max out the 270 plus the 550's.

I don't remember how the MPI does the extra injectors... I tuned it one before but don't remember the exact specifics now... and I don't know how the haltech works... but the way the Microtech works is it sprays them as a percentage of the primaries. So you say that at 3,000 rpm's and 10 psi it sprays 10% of the cycle time... so if your primaries are at 7ms the secondaries will spray for .7ms. Otherwise, you can wire them together and then they'll fire equally regardless...

 

[TurfBurn]

did some rough calculations. An FI car making 500 horse and 80% duty cycle on the injectors would need roughly an average size in an 8 injector package of 340cc injectors. If you use 550's in the secondary rail you need 200 cc injectors in the primary. So a 270 strock injector plus 440's or better in the rails should get you over 400 horse safely.

 

[daedalus]

We have run upto 12psi with the stock injectors and the MPI Tuner.

Was that safe??? That is the exact amount of boost I am trying to run with the MPI tuner. I dont know if i should get the additional injector setup or just stay with my stockers.

 

[LinuxRacr]

Call Nick and find out before you do that much boost. Better safe than sorry.

 

[TurfBurn]

a wideband will tell you if it is safe.... well more or less... it'll tell you are hitting AFR, but if you lose an injector you should know it otherwise anyway... There is no single device more critical to tuning a car than a wideband and by no stretch of the imagination does a narrowband cut it!