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I supported Toymods
Location:
Australia
Registered:
November 2003
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What uses large Top feed injectors?
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Thu, 03 March 2005 01:49
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New question:
What uses large Top feed injectors?
Prefer hi-impedance.
400+
I hear gen1 3stge is 430cc top feed, but is that lo or hi?
I'm looking for new injectors for my 1uz.
Using those injector calculators I get these results.
Using the Brake Specific Fuel Consumption as 0.40, I need 278cc
Using the Brake Specific Fuel Consumption as 0.45, I need 313cc
Using the Brake Specific Fuel Consumption as 0.50, I need 348cc
And using the divide by 5 rule, I get 266cc
That is also using a duty cycle of 0.8
Now, what BSFC should I be using?
I plan to run the stock fuel rail pressure (2.9bar/42psi)
That is also using a duty cycle of 0.8
The stock injectors are 250cc
Can they handle it?
I may not reach the desired HP, so should I just go for it?
Suck it and see kind of thing?
If I should upgrade, what is available in high impedance top feed?
Ta
[Updated on: Thu, 03 March 2005 04:31]
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Brake Specific Fuel Consumption/Injector Sizing/Top feed injectors
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Thu, 03 March 2005 03:58
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i would initially just go for it... (unless you are planning higher rpm than normal).
once you get up past about 6000rpm, you also need to choose injector size based on the available time to inject.
if you do plan to go to higher rpm than stock, i would choose injectors based on that.
for example, for my 1.3L, a 145cc/min is ok for 6000rpm, but for 8000 i need 180cc/min
from Megatune (MS tuning prog). 350cc/min with 12:1 AFR and 100% VE gives 11.6ms pulse.
thats close to 8300rpm.
for 250cc/min, it's 16.3ms, which is about 5900rpm...
so even for the same efficiency, the rpm (above 6000) will dramatically affect the injector sizing...
if it was me, and i was gonna take to motor to 8000rpm, i would go straight for 350cc/min.
(unless my calcs are wrong  )
Cya, Stewart
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Brake Specific Fuel Consumption/Injector Sizing/Top feed injectors
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Thu, 03 March 2005 04:02
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and if you need high inpedance, you can always use some "ohmite" 25W, 7.5ohm resistors (one per injector) (or a stock injector resistor pack). the difference, when using plain signal to hold it open are not very great. if you were to compare peak n hold to normal.. peak and hold is better, but the opening time difference between a high Z, and a low Z with resistor is not great enough to worry about.
Cya, Stewart
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I supported Toymods
Location:
Australia
Registered:
November 2003
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Re: Brake Specific Fuel Consumption/Injector Sizing/Top feed injectors
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Thu, 03 March 2005 04:06
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I plan for an 8000-8500rpm redline.
Sounds like biggies are needed.
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Brake Specific Fuel Consumption/Injector Sizing/Top feed injectors
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Thu, 03 March 2005 04:26
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well, put it this way.. if you tune it on dyno, and then find you only reach 75% duty, you are not losing a huge amount of idle resolution (maybe 5%). but if you get to 90%, then maybe you will have erratic injector operation....(i have seen this on the stim, firing my injectors, between 85 and 95% commanded duty)
better to have headroom than a sudden lean condition at high rpm 
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I supported Toymods
Location:
Australia
Registered:
November 2003
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Re: Brake Specific Fuel Consumption/Injector Sizing/Top feed injectors
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Thu, 03 March 2005 04:29
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| oldcorollas wrote on Thu, 03 March 2005 12:26 |
better to have headroom than a sudden lean condition at high rpm
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Oh, I realise this, hence the point of this thread.
Sounds like larger injectors are the way to go.
Now to find to 400+ top feeds...
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I supported Toymods
Location:
Australia
Registered:
November 2003
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Re: Brake Specific Fuel Consumption/Injector Sizing/Top feed injectors
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Thu, 03 March 2005 04:29
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Oh, and if a 2jzgte can idle with 550's, I think a 1uz can with 440's.
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Location:
Perth
Registered:
October 2003
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Re: What uses large Top feed injectors?
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Thu, 03 March 2005 04:38
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Are you getting some cams made Cruzida?
Whats the problem with low impedence? Is your Microtech fuel only? Cause you could go for the 7mgte.
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I supported Toymods
Location:
Australia
Registered:
November 2003
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Re: What uses large Top feed injectors?
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Thu, 03 March 2005 04:42
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| Skip wrote on Thu, 03 March 2005 12:38 |
Are you getting some cams made Cruzida?
Whats the problem with low impedence? Is your Microtech fuel only? Cause you could go for the 7mgte.
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Cams are the plan.
Microtech is not fuel only, but high impedance would be plug and play. Just trim the fuel by 50% and I can drive it to the dyno.
I'd rather pay a bit more and have no worries, than get cheaper low impedance ones and frig around with extras.
I should call microtech and find out if it can handle lo-impedance without a resistor.
Maybe I just have to change a value somehwere.
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Location:
Syndey
Registered:
December 2002
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Re: What uses large Top feed injectors?
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Thu, 03 March 2005 05:11
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yes it can handle 2 2ohm injectors per channel,
you dont have to change anything just wire them up and go
Dale
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I supported Toymods
Location:
Australia
Registered:
November 2003
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Re: What uses large Top feed injectors?
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Thu, 03 March 2005 05:13
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| 10sec_rx7 wrote on Thu, 03 March 2005 13:11 |
yes it can handle 2 2ohm injectors per channel,
you dont have to change anything just wire them up and go
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Serious?
It doesnt care about running 7 times the current?
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Location:
Syndey
Registered:
December 2002
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Re: What uses large Top feed injectors?
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Thu, 03 March 2005 05:16
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im serious, i do it all the time you wont have a problem
read the manual that came with it, it states on the wiring digram that you can use 1x1ohm, 2x2ohm, 4x12ohm per channel
i run 2x7mgte injectors off 1 channel no problems at all
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I supported Toymods
Location:
Australia
Registered:
November 2003
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Re: What uses large Top feed injectors?
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Thu, 03 March 2005 05:18
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w00t!
That makes it 10times easier to get injectors.
Now, to find 8 cheap 7mgte ones!
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Location:
Syndey
Registered:
December 2002
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Re: What uses large Top feed injectors?
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Thu, 03 March 2005 05:20
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easy stuff!
i might be able to get you some recoed ones for about $60 each if you cant find any cheaper ones
Dale
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I supported Toymods
Location:
Australia
Registered:
November 2003
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Re: What uses large Top feed injectors?
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Thu, 03 March 2005 05:22
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60 each is a bit much.
Cleaning them only costs me $12-$15 an injector.
But if I gets desparate, I know who to call!
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Location:
Syndey
Registered:
December 2002
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Re: What uses large Top feed injectors?
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Thu, 03 March 2005 05:24
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it adds up when you have to buy 8 of them!!
usually they got for $200 not cleaned on here for 4
Dale
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