Injector Sizing - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

luke91 · 11-25-2002, 08:45 PM

I'll need to buy inectors soon.  

Are there any good reasons not to run bigger injectors (720cc) unless you need them?  

for my set-up, I'll only need to run 550cc's.  In the future, I will either upgrade again, add nitrous, or both.  At that time, I will need 720's.  I really don't want to have to buy new injectors all over again, so I'm thinkin' I'll just buy the 720's now.  Any comments?

thanks

--luke

gschroeder78 · 11-26-2002, 12:30 AM

From what I understand about Z32 TT injectors, unless you are running big turbos with alot of boost, 555's are fine. In your case I would think the 550's would be fine and there would actualy be no need to upgrade in the future.  Of course I'm not hardly an expert on the subject so don't take my word for it. It's just what I've gathered about the 300ZX over the years.

*Jeff240sx* · 11-26-2002, 01:17 AM

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (gschroeder78 @ Nov. 26 2002,02:30)</td></tr><tr><td id="QUOTE">From what I understand about Z32 TT injectors, unless you are running big turbos with alot of boost, 555's are fine. In your case I would think the 550's would be fine and there would actualy be no need to upgrade in the future. Of course I'm not hardly an expert on the subject so don't take my word for it. It's just what I've gathered about the 300ZX over the years.</td></tr></table><span id='postcolor'>
370cc injectors come on Z32 TTs.  They are only capable of 260hp or so.
555cc are good for up near 400hp.  If you want more, or nitrous, get the larger injectors.
The only cons to large fuel injectors are that you will idle horribly, as well as get poor fuel economy.
You will also need a reprogram, or some other form of tuning to not flood out at idle.
-Jeff

gschroeder78 · 11-26-2002, 01:20 AM

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (Jeff240sx @ Nov. 26 2002,01:17)</td></tr><tr><td id="QUOTE">370cc injectors come on Z32 TTs. They are only capable of 260hp or so.
555cc are good for up near 400hp. If you want more, or nitrous, get the larger injectors.
The only cons to large fuel injectors are that you will idle horribly, as well as get poor fuel economy.
You will also need a reprogram, or some other form of tuning to not flood out at idle.
-Jeff</td></tr></table><span id='postcolor'>
So on an SR odds are you would never use or need 720cc injectors correct?

*Jeff240sx* · 11-26-2002, 01:26 AM

Boosted is running 740cc (72lb) injectors on his KA-T.  He is also fiddling around the 400hp mark.  Better to run rich than lean.
-Jeff

gschroeder78 · 11-26-2002, 01:28 AM

Good to know. Thanks

luke91 · 11-26-2002, 09:28 PM

I'd really like to know how the 720's idle.  Anyone have them?

Also, how is thee gas mileage?  

Thanks Jeff

--luke

*Jeff240sx* · 11-26-2002, 09:35 PM

Boosted is running 740cc.  I don't generally like to post for other people, but he said that while boosting, he got 14mpg.  Dunno anything else.  Mabey he'll pop in here and post up.
-Jeff

Foxcolt · 11-27-2002, 07:32 AM

I'm also interested. I plan on upgrading to 550's but don't want to reupgrade when I decide to turn up the boost. Should I just go with 720's right off the bat?

Please more info!

Jed

11-25-2002, 08:45 PM	#1
luke91 Zilvia Member Join Date: Sep 2002 Location: Pittsburgh, PA Age: 43 Posts: 218 Trader Rating: (0) Feedback Score: 0 reviews	I'll need to buy inectors soon.   Are there any good reasons not to run bigger injectors (720cc) unless you need them?   for my set-up, I'll only need to run 550cc's.  In the future, I will either upgrade again, add nitrous, or both.  At that time, I will need 720's.  I really don't want to have to buy new injectors all over again, so I'm thinkin' I'll just buy the 720's now.  Any comments? thanks --luke __________________ '91 fastback.  '97 S13 blktop SR20DET.  Cstm Frnt Mnt IC w/ cstm 2 1/2" piping.  stnls stl fltr.  3" cstm DP & exhst w/N1 muff.  Walbro FP.  ACT 6 pck cltch.  Go Fast Bits crnk plly.  Ground Control coils.  KYB AGX shks.  12.98@106 w/g-tech pro.  17psi.  All work and fabrication done by ME

11-26-2002, 12:30 AM	#2
gschroeder78 Zilvia Junkie Join Date: Nov 2001 Location: Westminster, CO Age: 46 Posts: 507 Trader Rating: (0) Feedback Score: 0 reviews	From what I understand about Z32 TT injectors, unless you are running big turbos with alot of boost, 555's are fine. In your case I would think the 550's would be fine and there would actualy be no need to upgrade in the future.  Of course I'm not hardly an expert on the subject so don't take my word for it. It's just what I've gathered about the 300ZX over the years. __________________ 1989 240SX Coupe -Eibach Prokit Springs -KYB AGX Struts -Apex-i N1 Dual Exhaust Westminster, CO

11-26-2002, 01:17 AM	#3
Jeff240sx I hate you too... Join Date: Jul 2001 Location: Tampa, FL Age: 42 Posts: 5,828 Trader Rating: (0) Rides Gallery: Jeff240sx Feedback Score: 0 reviews	</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (gschroeder78 @ Nov. 26 2002,02:30)</td></tr><tr><td id="QUOTE">From what I understand about Z32 TT injectors, unless you are running big turbos with alot of boost, 555's are fine. In your case I would think the 550's would be fine and there would actualy be no need to upgrade in the future. Of course I'm not hardly an expert on the subject so don't take my word for it. It's just what I've gathered about the 300ZX over the years.</td></tr></table><span id='postcolor'> 370cc injectors come on Z32 TTs.  They are only capable of 260hp or so. 555cc are good for up near 400hp.  If you want more, or nitrous, get the larger injectors. The only cons to large fuel injectors are that you will idle horribly, as well as get poor fuel economy. You will also need a reprogram, or some other form of tuning to not flood out at idle. -Jeff __________________ Whatup?

11-26-2002, 01:20 AM	#4
gschroeder78 Zilvia Junkie Join Date: Nov 2001 Location: Westminster, CO Age: 46 Posts: 507 Trader Rating: (0) Feedback Score: 0 reviews	</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (Jeff240sx @ Nov. 26 2002,01:17)</td></tr><tr><td id="QUOTE">370cc injectors come on Z32 TTs. They are only capable of 260hp or so. 555cc are good for up near 400hp. If you want more, or nitrous, get the larger injectors. The only cons to large fuel injectors are that you will idle horribly, as well as get poor fuel economy. You will also need a reprogram, or some other form of tuning to not flood out at idle. -Jeff</td></tr></table><span id='postcolor'> So on an SR odds are you would never use or need 720cc injectors correct? __________________ 1989 240SX Coupe -Eibach Prokit Springs -KYB AGX Struts -Apex-i N1 Dual Exhaust Westminster, CO

11-26-2002, 01:26 AM	#5
Jeff240sx I hate you too... Join Date: Jul 2001 Location: Tampa, FL Age: 42 Posts: 5,828 Trader Rating: (0) Rides Gallery: Jeff240sx Feedback Score: 0 reviews	Boosted is running 740cc (72lb) injectors on his KA-T.  He is also fiddling around the 400hp mark.  Better to run rich than lean. -Jeff __________________ Whatup?

11-26-2002, 01:28 AM	#6
gschroeder78 Zilvia Junkie Join Date: Nov 2001 Location: Westminster, CO Age: 46 Posts: 507 Trader Rating: (0) Feedback Score: 0 reviews	Good to know. Thanks __________________ 1989 240SX Coupe -Eibach Prokit Springs -KYB AGX Struts -Apex-i N1 Dual Exhaust Westminster, CO

11-26-2002, 09:28 PM	#7
luke91 Zilvia Member Join Date: Sep 2002 Location: Pittsburgh, PA Age: 43 Posts: 218 Trader Rating: (0) Feedback Score: 0 reviews	I'd really like to know how the 720's idle.  Anyone have them? Also, how is thee gas mileage?   Thanks Jeff --luke __________________ '91 fastback.  '97 S13 blktop SR20DET.  Cstm Frnt Mnt IC w/ cstm 2 1/2" piping.  stnls stl fltr.  3" cstm DP & exhst w/N1 muff.  Walbro FP.  ACT 6 pck cltch.  Go Fast Bits crnk plly.  Ground Control coils.  KYB AGX shks.  12.98@106 w/g-tech pro.  17psi.  All work and fabrication done by ME

11-26-2002, 09:35 PM	#8
Jeff240sx I hate you too... Join Date: Jul 2001 Location: Tampa, FL Age: 42 Posts: 5,828 Trader Rating: (0) Rides Gallery: Jeff240sx Feedback Score: 0 reviews	Boosted is running 740cc.  I don't generally like to post for other people, but he said that while boosting, he got 14mpg.  Dunno anything else.  Mabey he'll pop in here and post up. -Jeff __________________ Whatup?

11-27-2002, 07:32 AM	#9
Foxcolt Zilvia FREAK! Join Date: Apr 2002 Location: Northern VA Posts: 1,264 Trader Rating: (0) Feedback Score: 0 reviews	I'm also interested. I plan on upgrading to 550's but don't want to reupgrade when I decide to turn up the boost. Should I just go with 720's right off the bat? Please more info! Jed __________________ Driftec www.midatlantic240sx.com