30lb injecotors and E85?

98COBRA281 · Nov 1, 2009

im planing running e85, and i just bought a brand new set of 30 lb injectors, but i know that e85 needs 30% more fuel that gas, and im not sure that the 30lb'ers will be enought with the e85, im hoping to make at least 335rwhp....

i do have an adjustable fuel regulator, so i could tune the fuel pressure up to compensate if the injecotors are a little small.....

oxfordgt · Nov 1, 2009

30lbs injectors in an E85 set up will support 250rwhp.

injector size x BSFC x number of cylinders = fwhp

fwhp - 30% = E85 fwhp capability

That math is for 100% duty cycle on the injectors so if you want to run them at 80% then multiply the E85 fwhp by .85

Then subtract about 15% to get your rwhp.

98COBRA281 · Nov 1, 2009

hmmm...... that sucks

bhuff30 · Nov 2, 2009

A small error in Oxfords formula... divide by BSFC instead of multiply. Otherwise, your (8) 30lb injectors are only good for 120hp on gas and 100% DC.

I always think these injector calculators are a bit silly. It will give you a rough idea, with a wide margin of safety. But in the real world, you can push the injectors a lot harder. If you don't add any more power, you could probably get by with a 30lb injector. Worst case, change the base fuel pressure to 50 lb and tell the computer you have 33.5 lb injectors. Of course, you won't have room to grow, and you should be careful not to push too deep into the 90% DC range.

For example, based on my hp, the injector calculators say my 2.3 needs 90lb injectors after accounting for E85. I currently, I'm running 52lb injectors from the junk yard, pushed to the max.

98COBRA281 · Nov 2, 2009

bhuff30 said:
A small error in Oxfords formula... divide by BSFC instead of multiply. Otherwise, your (8) 30lb injectors are only good for 120hp on gas and 100% DC.

I always think these injector calculators are a bit silly. It will give you a rough idea, with a wide margin of safety. But in the real world, you can push the injectors a lot harder. If you don't add any more power, you could probably get by with a 30lb injector. Worst case, change the base fuel pressure to 50 lb and tell the computer you have 33.5 lb injectors. Of course, you won't have room to grow, and you should be careful not to push too deep into the 90% DC range.

For example, based on my hp, the injector calculators say my 2.3 needs 90lb injectors after accounting for E85. I currently, I'm running 52lb injectors from the junk yard, pushed to the max.

so what the MAX power i could make with E85 and 30's

oxfordgt · Nov 2, 2009

Still the same as what I said. I use a little different math then what he is talking about.

30 x 1.666 x 8 = 399.84
30 / .6 x 8 = 400

98COBRA281 · Nov 2, 2009

oxfordgt said:
Still the same as what I said. I use a little different math then what he is talking about.

30 x 1.666 x 8 = 399.84
30 / .6 x 8 = 400

is that 400 on gas or E85?

bhuff30 · Nov 2, 2009

Yeah, he's probably talking about 400hp on gasoline. I did a few calculations and you 'might' be able to get 380 hp at the flywheel on E85, but it would require 55psi base fuel pressure and a 90% DC. That could easily be considered unsafe, especially on high impedance injectors. Basically, you need to buy bigger injectors, but you could probably make it work safely on E85 if you are making 350fwhp or less and ran 50psi base fuel pressure. Of course, that is a bandaid for proper injectors. You have the good parts, keep up with the right parts.

oxfordgt · Nov 3, 2009

98COBRA281 said:
is that 400 on gas or E85?

That gas at 100% duty cycle

E85 will only be 280fwhp at 100% duty cycle.

Both at 43.5 psi. You can raise the fuel pressure to 60psi max to be safe and get them to support 336fwhp but that is still at 100% duty cycle. At 80% duty cycle they will support 285fwhp. Which is only 242 rwhp.

Just get bigger injectors.

oxfordgt · Nov 3, 2009

If your making 310 to the wheels right now and adding an intake and retune for e85 I will guess that you will be making 330rwhp (I'm being really nice) you will need 42 lbs injectors at a minimum.

Sell the 30s, they are worthless in just about any application.

98COBRA281 · Nov 3, 2009

oxfordgt said:
If your making 310 to the wheels right now and adding an intake and retune for e85 I will guess that you will be making 330rwhp (I'm being really nice) you will need 42 lbs injectors at a minimum.

Sell the 30s, they are worthless in just about any application.

i made 310 eith the stock plastic intake, i will be retuning with the edelbrock manifold, JLT rai, 90mm maf, and i wanted to do e85, to get the max HP out of the setup.......

so how much can the 42's handle with e85? and it sucks because the 30's are brand new with less then 200 miles.........

30lb injecotors and E85?

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