E85Forum.com

RonM · Joined: 23 Jan 2011 Posts: 2 Location: SF Bay Area

I'm building a Datsun 510 project car and swapping in an SR20DET (turbo 2.0L 4 cylinder). I will be running this car on E85 and hope to produce 400whp @ 23psi boost. The fuel system will deliver 300lph @ 55psi. I'm hoping to run injector dynamics ID 1000cc injectors @ 80% duty cycle. I have been told that for E85 I will need 1,400cc injectors to make that much HP, but 1. this feels like way overkill, and 2. I'm concerned the bigger injectors will make it harder to tune at idle, because of poor atomization, and there would be greater dead time to compensate for.

My understanding is in order to calculate proper hp to injector size for E85 you simply multiply 1.33 to the equivalent injector size you would use in a gas application to produce X hp.

My calculations: Using gas 750cc injectors will produce up to 500hp, so 750 X 1.33 = 997.5. I'm assuming that with E85 using 1000cc injector, @ 400hp they will be working @ 80% duty cycle. Is this correct, or are there other factors that should be included in this calculation?
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There is no "try" there is only do, or do not. Master Yoda

89shortbox · Joined: 04 Nov 2007 Posts: 153 Location: Michigan

My calculations you would need at least 1176 cc injector to be at 80% DC.

500hp x .75 = 375 lbs/hr. on e85
375/4 = 93.7 lbs/hr injector x 20% =112lbs

20% is to cover the 80% DC

112lbs/hr converted to cc is 1176cc

or 750cc x 1.5 to get 1125cc would work to.

In some combos its a 50% increase in fuel at WOT .
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89 S10
406 SBC Twin Turbo BT
Going E85 this coming season
HAHA, the season is alreay gone to another season.

RonM · Joined: 23 Jan 2011 Posts: 2 Location: SF Bay Area

For anyone interested. here's another way to calculate the correct injector size for the amount of hp you'd like to produce

HP (1) X BFSC (2) Number of cylinders X duty Cycle (3)

* Brake Specific Fuel Consumption: This is the amount of fuel consumed (in lbs. per hour) for each horsepower made.  This should be .45 to .50 for naturally aspirated engines and for Turbocharged engines.60 to .65

To calculate the injector size for E85 use a multiplying factor of 1.47 . The 1.47 number represents the difference between the stoiciometric fuel ratio of gasoline and E85. Gasoline is 14.7 and E85 is 10.0

Keep in mind, all there numbers are averages and are dependent on things like tuning, boost levels, etc, but this will get you in the ball park.

Here's mine:

HP 400 X BSFC .6 = 240 X 4 = 960 X .8 = 768cc injectors for gas. X 1.47 = 1128.96 cc injectors for E85

Anyone know were to get 1128.96cc injectors?
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There is no "try" there is only do, or do not. Master Yoda

skiracer · Posted: Tue Jan 25, 2011 2:51 pm Post subject:

You might want to check the Nissan forums since i'm sure they got the injector size nailed down for E85 by now.

You can try:
http://www.deatschwerks.com/catalog/

http://www.rceng.com/

Note, on most Evo's running a Walbro 255lph pump, the pump gets max'd out at 450whp level. So, you might consider running a double pump if you'll be bumping the 400+ level.
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'06 Evo IX Stage 1 by RRE,Walbro 255lph fuel pump,RC Engineering1000cc Injectors, AVO exhaust,RRE flash, (325whp @ 22PSI 91 octane, 353whp @ 25psi on 100 octane, 383whp @30psi on E85),Zeitronix wideband/Ethanol Content Analyzer, Defi gauges

nelson8708 · Joined: 22 Aug 2008 Posts: 67

you could get the ID 2000's and not have to worry about injectors again for the most part Laughing

....You should be able to make 400whp on e85 with 1000's no problem. With the base fuel pressure @ 43psi and running 23lbs of boost that is 66psi of fuel pressure (with a 1:1 fpr). An injector that flows 1,000cc at 43psi will flow 1,242 @ 66psi. I'd say you will be under 85% duty cycle @ 400whp. Depending on how efficient your setup is i wouldn't be surprised if it was in the ball park of 70-75% DC...

Turbo?
Manifolds?
Cams?
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Boosted since 06-06-2006
Tuned on e85 as of 3-30-2009
KA24E-T sold 10-3-2009
KA24DE purchased 12-5-2009 (here we go again)
KA-T running on corn with water injection coming soon

hotrod · Joined: 19 Apr 2005 Posts: 872 Location: Colorado

Remember that the injector only sees the differential pressure across the injector.

43.5 psi base fuel pressure plus 23 psi boost and 66 psi fuel pressure in the injector still only has 43.5 psi across the injector.

base pressure + boost referenced fuel regulator pressure increase - manifold boost pressure = pressure across the injector.

On my Subaru WRX stock fuel pressure is 43.5, but I run 55 psi base fuel pressure and a 1:1 regulator with peak boost of 24 psi. Fuel pressure at peak boost in the fuel rail is 79 psi, but the injector only knows about the difference in pressure between the fuel rail pressure and the current manifold pressure and flows at the 55 psi rate.

Larry

jon6.0 · Joined: 17 Feb 2011 Posts: 3 Location: Tonopah, Az

What about running a big dog Magnafuel pump and running base pressure at 80psi with 20psi of boost? That's what I'm going to try with some 1000cc injectors for my 403.
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2005 GTO, TH400, transbrake, 4000 stall, 403 LS2, 9.3:1, twin TC76's, 250/254 .625/.600 on a 115.

TimZ · Joined: 02 Feb 2008 Posts: 48 Location: Dearborn, Michigan

jon6.0 · Joined: 17 Feb 2011 Posts: 3 Location: Tonopah, Az

I'm using a Magnafuel MP-4303 that's rated for 20-120psi. So it "should" work.
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2005 GTO, TH400, transbrake, 4000 stall, 403 LS2, 9.3:1, twin TC76's, 250/254 .625/.600 on a 115.