Greedy

I was in the same boat deciding between the 370's and 440's for my turbo set-up. Brian at URD said that the 440's would be a better match for me but that they can be hard to control at idle and low throttle with a piggy back fuel controller. He said that they lose some of their "resoultion" and do not provide as smooth throttle response as a 370 would. I was only going to use them as a temporary solution untill they released their port fueler. If marks secret weapon is a standalone fuel managment then it's a different story URD could explain it better than I can but the impression I got is that we should only run the 440's with the piggy back controller if there is no other option.

MTL_4runner

That port fueler is actually a very clever idea on their part (not sure if others have designed something similar) because when you begin moving to larger and larger injectors not only are you getting more fuel, but you are also lowering the duty cycle at idle (since they flow alot more). Generally you want to be around 20% duty cycle for idle (normal injector duty cycle range is between 20-80% under normal driving conditions) or again you have issues with controlling the injector similar to what happens when you run it above 90% duty, essentially it may or may not do as it is told by the ECU. The other issue is that on the larger injectors, the stepping becomes more coarse (ie each step of duration sprays alot more fuel) so the control of the injector is not as smooth. The cleverness of the port fueler design is that it flows like a large injector (since you have 2 sets of smaller injectors and the flows are additive), but you can drop out the port fueler set when you need to, leaving only the stock injectors to control lower RPM fuel demands and idle (which a smaller stock injector does very well). Thus the entire system of injectors are always within the 20-80% duty cycle range we aim for.

midiwall

argh... I forgot about the 440's being a bear at idle. The FTC and SMT piggybacks are only 8 bit controllers so they can only have so much granularity when it comes to spliting microsecond hairs.ugh.

Now I'm wondering if I should stretch a set of 370's.. They'd be a lot less stretched than my 305's are now.

Hmmm... the MegaSquirt is a 16 (18?) bit controller. I know it's got 1us resolution. Man, maybe I should open THAT can of worms again. That'd be a nice weekend project - replace the ECU!

TRDOLMAN

Mark---If I might make a suggestion.
From what I understand, trying to control 440cc injectors with a piggyback at anything other than WOT can be a real pain in the ass. 370cc injectors may not be much better. Have you ever thought about making up a 7th injector setup? All you would have to do is mount a large injector, tap a fuel line to it from the fuel rail, then control it with the URD additional injector controller.

On my setup I run the 6 stock injectors. Gadget said he flow tested the stockers at 238cc. I also run the 7th injector from TRD that is supposed to flow 630cc. If you do the math it comes out to 238cc X 6 = 1428 + 630cc = 2058cc total. If you divide by 6, that equals to me running 6 injectors at 343cc each. I don't know what my injector duty cycles are but the system holds a 12.0 AFR running 304 rwhp at 11 psi just fine with the stock FPR and a Walbro 190 fuel pump.

TRD uses the EGR port on the blower housing to mount the injector. The good thing about a setup like that is that you can use the stock main injectors without the need of a piggyback to control them. No sensor (MAF) signal is altered. The engine runs as stock unless you are in boost and the extra injector kicks in.

My extra injector setup works flawlessly with no closed loop or tuning issues. You might want to give some thought to a setup like that.

Sorry about the thread jack Ivanr

midiwall

Always!

...but not that one.

ARGH!

Okay... back to the think tank. argh.

argh. argh. argh.



Yes... sorry man.

ivanr

It's ok guys. I got my questions answered. Now I'm just getting eduacted

MTL_4runner

Is anyone running the 370s successfully right now?

mt_goat

Hey TRDOLMAN, was that with a 2.0 drive pulley? Your mods list a 2.2 and a 2.0? Thanks

TRDOLMAN

Yes, that dyno run was with a 2.0

midiwall

Okay, against everyone's (and my) better judgement, I'm going to try 440s.

I just got a SCREAMING deal on a set of 6 - SCREAMING I tell ya'. I figure that the worst that can happen is that I resell them for more than I paid for them. I _expect_ problems in controlling them down low, but I'm willing to give it a shot.

I should have them "soon", though I'll have to wait on an order from URD to get the connectors.

Greedy

Good luck Man! I hope that they run good for you. Are you going to be running the 2.0 pulley as well then??

midiwall

Nah, not right away. I'll have enough on my plate getting the 440s tuned and the mister in. Once all that happens, then I'll see about spending more money with Gadget and getting the 2.0 pulley.