midiwall

Aren't you supposed to be heading to work now? (and yes... they're yours!)

rimpainter.com

I am at work now. I surf YT while I run Access queries.

My PC loves it

MTL_4runner

Mark, if you are heading towards 375 HP then I would definately go for the 440s because the ideal is to keep the injectors in the 80% duty cycle range in order to have some safety factor built in there (and you can push it higher at a later date if you so desire......and you know you will after spending all that money on tranny mods!!!). There are quite a few unknown variables in there such as rail fuel pressure, brake specific fuel consumption and injector duty cycle, but I would aim toward the conservative side of injector sizing rather than having to change them out again later when I found out they were unable to keep up with fuel demand. I just because your 305 injectors have been ok up to this point doesn't mean they aren't undersized (keep in mind the duty cycle....you don't want to be running in the 90-100% range!) for the HP numbers you are making.

There are a bunch of calculators out there, but here are 2 quick and dirty ones for you:
http://www.iroczone.com/calcs/injectorsize.htm
http://www.injector.com/injectorselection.php (assumes a low fuel pressure)

Here's the math behind the numbers:
http://www.rceng.com/technical.htm

I did find one source that said a good rule of thumb for the max power an injector can possibly make is to take the injector cc rating and divide by 5 to get the max HP per injector (then you obviously need to multiply by the number of injectors you're running on that engine....normally one per cylinder). This also assumes you are running them at 100% duty cycle (not a good idea). For 80% duty cycle you divide the cc's by 6.3 to get the HP made per injector.

Weasy2k

I got 370's in the tacoma and 550's going into the mr2...with the new fuel rail system thats coming out

Greedy

Yeah the price of fuel suks all right. the nice thing with the turbo port fueler is you only use it while in boost. All other times your working with the stock fuel injectors and ecu. Sooooo, if you stay out of boost you will get the same mileage as a N/A! However, whats the use of having forced induction if you don't use it right!! The 440's i'm putiing in will no doubt make my mileage go in the toilet, but with the port fueler probably a month or so off, I am willing to deal with it for awhile. When it comes out though, I will have a great deal on 1-2 month old injectors!!

midiwall

Thanks Jamie... it's kinda' tripping me out that you can compute projected HP based on injector size/fuel usage. I guess the figures that you can actually get the mixture into the cylinder, compress it and fire it. (i.e., there's nothing in the math to figure bore, stroke, etc.)

Okay, so the 318's won't help.... GREGG! HURRY UP WITH THE 440's!

OutdoorLiving

Next time I'm in Bothell, I'll have to look you up for a ride.

midiwall

How often do you get to this area? Drop me a PM or email with a couple of days notice and we can figure it out!

MTL_4runner

Actually all the bore, stroke, etc are all taken into account with the brake specific fuel consumption. That basically tells you how efficient the engine is at turning a certain volume of gas burned into work (ie HP). That shouldn't be too trippy for you, right?

http://en.wikipedia.org/wiki/BSFC

Here are some common values used in engineering for various engines:
http://www.prime-mover.org/Engines/GArticles/bsfc.html

"The brake specific fuel consumption of an engine depends on many factors including thermal efficiency, mechanical efficiency and air to fuel ratios. Most piston engines have a BSFC of between 0.5 and 0.55 lbs. of fuel per hp per hour at maximum power, set fairly rich with AFRs between 12 and 13 to 1."

It is a big unknown (unless you actually measure it on a dyno), but you'd be pretty safe putting it at between 0.5 and 0.55 on the 3.4L motor (true BSFC might be as good as 0.45 at WOT in the peak torque RPM of the motor), but all other conditions will be higher. In general the larger the engine cyclinder bore the higher the specific fuel consumption will be (you also need to take into account the number of cylinders).

Here's another good article where they go through all the math to size the injectors:
http://engine.firebirdv6.com/formulas.html

midiwall

hmmm.... {dig dig dig} {sponge sponge sponge}

Greedy

Alright NEW UPDATE AGAIN. Just spoke with Brian and URD and they are out of stock on the Bosch 440's. Looks like I am going to be waiting on the Port Fueler after all. Gadget said that they are being made at the machine shop and will be released within the next two weeks or so.

OutdoorLiving

3 times last year, 1 already this year. I'm sure there will be at least one more before the year's out...

midiwall

Cool. Seems like if you wait at least a month then you could talk Gregg (Greedy) into showing his hard earned $$$ as well.

Greedy

midiwall

I was infering that if Aaron didn't come up for a month, then you may have your truck all together and running with Gadget's new toy.

Greedy

Hell Yeah!! I'm hopin for 2 weeks to the dyno, can't come soon enuf....

midiwall

Hey Jamie... With my 440s on the way, I'm revisiting the math, and I think we may have gotten out of synch.

Working from the calcluator here:
http://www.rceng.com/technical.htm

What's the possibility that when you said "if you are heading towards 375 HP...", you were thinking RWHP? I'm looking at about 390 at the CRANK or 310ish at the wheels.

If I figure that you were thinking 375 at the wheels, then figure 20% loss through the auto, so that's 470 at the crank. Working from there, then the RC Engineering calculator starts pushing 400cc injectors (for a 80% duty cycle)

But, if I use 390HP, then it's drifting into the 330cc range.

oops?

midiwall

crap... okay... so, what IS the PSI rating of the Walbro 190?

I've now seen numbers of 60 and 90psi. If it's 90psi, then Jamie and I were both talking about crank (the pressure is great enough to drive 330cc injectors). 60psi says that he was talking about RHWP (so, 470 crank) (the reduced pressure would require 440cc injectors).

bluestreak701

Bump for info/ dyno charts!

midiwall

Gregg (Greedy) is waiting on the port fueler from URD.

There was a quick discussion on another forum about status, and it _appears_ that it should be shipped VERY soon. But, Gregg's going to need to source injectors for it, and that could take an extra couple of days.


Closer... Closer... CLOSER!

...but not quite yet.