matty

iTrader: (54)

I have a basic S/C kit with a 3.125" pulley...Im going the JWT route with the raised rev limiter and Im trying to decide on injectors.

I know all the guys on here are running 370's with there s/c/JWT setup but im thinking maybe its better to go with the 550's so I dont go into 100% DC alot of the time with the 370's...what do you think..im new to all of this stuff still on the aspect of injectors and safe zones

enlighten me

-matt

IceY2K1

iTrader: (3)

Assuming stock fuel pressure and a SC relatively safe BSFC=0.55.....

370cc:
-------
80% DC ~261whp
100% DC ~327whp

550cc:
--------
80% DC ~389whp
100% DC ~486whp

I'd personally go with 450cc-550cc injectors to keep IDC <80% for 300-350whp on stock internals.

You sure about the JWT route? Why not eManage?

Nealoc187

iTrader: (23)

This is a good page for determining the correct fuel injector sizing:

http://www.rceng.com/technical.htm

matty

iTrader: (54)

I dont know much about emanage...very confusing to me on what to buy...and I wont have the raised rev limiter...

Emanage and J&S safeguard are all soo confusing to me

-matt

Stephen Max

iTrader: (59)

Those hp numbers seem a little low. What fuel pressure were you assuming? Don't forget to use whatever your fuel pressure is when you are boosting. For instance, I am at about 58 psi fuel pressure when I'm boosting, so that's the number I use in the calculations on the rcengineering site.

matty

iTrader: (54)

Still a toss up...I really dont plan on going to a 2.87 but I may and I know IANSW is running 370's with the 2.87 fine and i would be on the 3.125 with 370's...I just dont want TOO Much of an injector for what I need

any help

-matt

Mad-MAX_SE

iTrader: (2)

honestly if it were me, which it's not, i would rather have more injector than i need rather than just big enough to get by

IceY2K1

iTrader: (3)

Stock fuel pressure.

I don't count on the 1:1 FPR boost rise.

matty

iTrader: (54)

Well are the 550's that much bigger and will I see any "negative" effects of running the 550's rather than the 370's ?? I know alot of guys with s/c and the same pulley I have, and are running 370's fine...The price isnt all that much so I need to make a decision very fast before I call up JWT ??

-matt

IceY2K1

iTrader: (3)

It's all dependent on fuel pressure factor. If you don't worry about rasing fuel pressure to keep DC safe, then the FMU route and 370cc are a great choice.

550s just allow you to dump the Cartech(after all the crap you've recently gone through with it, I'm sure you'll understand) or at least reduce the amount it raises fuel pressure. One major drawback of larger injectors is the idle quality. Not all injectors/ECUs can compensate and it can be rough. Mardi is the only person I know of that had the 550cc JWT program and he said it was fixed for the cold startup issue. Others, SX7R I believe, have run 550s with the eManage without issue. I've not seen/drove their cars, so I'm just going from what they've said.

Honestly, if you can keep the FP below 80-psi for your WHP with the 370s and Cartech, I'd go that route, since it's proven. Personally, I don't want a FMU, so I'll need larger injectors.

JeffesonM

iTrader: (5)

Mardi said his 5xx cc injectors ran fine with no idling problems, so I recommend getting the 550s so you have some room to grow.

matty

iTrader: (54)

Well my plan was to pull the cartech after I put in the JWT...considering the JWT will take care of all my fuel delivery needs, and also keep things safe

If I do keep the Cartech, Ill dial it down to introduce alittle more gas in at highere RPM's to comenate for my MEVI, by haveing it tuned

So the risk you run with 550's is rough idle ??

-matt

IceY2K1

iTrader: (3)

Rough idle and flooding during cold starts.

With the first JWT 550cc program with his 515cc injectors, Mardi had to wire up an "S2000" start button, so the ECU wouldn't dump in tons of fuel and flood the engine. Recently, he got the new program from JWT for the 550s and it was fine. However, he pretty quickly moved up to 740cc with JWT+eManage, so I'm not sure how much time he got to test out the 550s.

JeffesonM

iTrader: (5)

I think this is the general fear behind big injectors, but as Icy said, Mardi runs the JWT+550cc with no problems.

turbomax97

iTrader: (6)

I just have the emanage for the injectors - no flooding - idle's fine.... I'm actually getting the same/ if not better gas mileage as the oem ones

IceY2K1

iTrader: (3)

Good.....NISMO 550s and eManage sounds like a GREAT combo then.

turbomax97

iTrader: (6)

The other good side is - it works with oem fuel press - I guees it really is more useful if you're running an auxillary pump with a hobbs switch as opposed to a pump like the walbro though. I think it's very possible though that u can compensate with the fuel map on the emanage for the slightly higher fuel press from adding the walbro w/an oem fpr vs an adjustable fpr.

matty

iTrader: (54)

Well I kinda wanna Dump my FMU and just run the JWT and AEM FRP

I have about 2 days to decide If im gonna go with 555's or 370's....I plan on keeping my S/C and never going Turbo maybe just upgrading to 2.87...alot of guys say that the 555's are overkill and the 370's will be fine ???

I Will have a Z32-MAF as well

-matt

furbiss112

iTrader: (9)

tt supras come with 550, so it isn't an overkill.you just never have to worry about maximg them.

slimer

iTrader: (13)

yeah, ferhan has the 555 jwt setup too.

Stephen Max

iTrader: (59)

Dang! You're right, Icey, and this is a point I myself have made in the past.

You need to enter in the fuel pressure less the boost pressure. So, in the case of a 1:1 fpr, you just use whatever your fuel pressure is at onset of boost.

matty

iTrader: (54)

Is that with Turbo or S/C ??

-matt

IceY2K1

iTrader: (3)

Haha....I was going WTF...StephenMax was the one who pointed that out before in my head.

IceY2K1

iTrader: (3)

Yes, 555s are more injector then the V1/V2 SC could ever use. A 450cc injector would probably be perfect, however you don't have that convienient choice of injector size. RC Engineering could probably do it, but then JWT would have to give you a custom program, since they're pretty much set on 370cc, but offer a "new" program for 550s.

Anyways, it will take JWT SEVERAL weeks as usual, so you probably have more then 2days to decide. You can always jump from 370cc to 550cc program for $100 chip change later.

If you can keep the FMU to add a little fuel, that would be my choice, since you'll be over 80% duty cycle on 370cc injectors with 260+whp but not too dangerous until you surpass 90% duty cycle at ~295+whp.

Again, you can easily upgrade for $100 JWT chip later to a bigger injector(those will cost though).

I30tMikeD

iTrader: (8)

I wouldn't be worried about JWT getting to work on you ECU as soon as they get it. I probably takes them a couple hours, if that to modify it. So mine sat there untouched for 2 months before they did the upgrade.