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Old 11-03-10, 01:34PM   #31
TIN TIGR
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we are running full timing on e-85, at 100 hp..as far as jets go, forget this thought pattern..flow your system, as used on the car, and measure the weight of fuel/hour..this is the only way to correctly calibrate your toys..the beauty of e-85 is its tuning window..its wide, and still works..
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Old 11-03-10, 01:35PM   #32
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heath is a great source of info for those wanting to switch to e-85..good guy.
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Old 11-03-10, 08:31PM   #33
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Quote:
Originally Posted by Rick View Post
Here is my NOS problem. I started running E85 this past year. Love the fuel but can't get good info on what size fuel jets to use. Nitruos Works have no idea (or clue). I am running a simple plate system with changable jets. 200 hp max.
I have a "beginning jet chart" somewhere at home.
See if i can find it.
My prob is the air bleeds. Have to drill and and tap mine(850/925 carb)
NO ONE knows what ones to start with.
If they do, thier not tell'n.
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Old 11-03-10, 08:54PM   #34
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for e-85?..i can get you close
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Old 11-04-10, 06:09AM   #35
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Quote:
Originally Posted by 68 Silverbird
X2! I'm trying out my plate this weekend.I've read to go up 6-8 fuel jets,or 30% more diameter and pull 1/2 degree additional timing per 100hp on E85 vs gas.This info is from Heath on raceone85.com.
Ok,I can accept that one may need 30% more fuel mass/volume for E85,that's a fairly commonly percentage I've seen thrown around on that topic.

But the 30% more jet dia. comment is almost certainly wrong.

If it's using like 40 lbs/hr of fuel,and you then needed 30% more fuel mass than that,I can see that no problemo,if my math is right that would be like 52 lbs/hr of the "new" fuel.

Seeing as 12 is 30% of 40,then 40 + 12 = 52.

But the 30% more jet dia.,,,that has gotta be wrong...

First thing first,you cant really look at orifices in terms of diameter.

To quote the guys @ Kinsler fuel injection,the flow of an orifice can not be interploated by the ratio of the diameter.

IE: an .080" orifice does not flow twice that of an .040" orifice.

As I understand this,one has to go off of the orifice area.

To convert the orifice diameter to the orifice area use this formula:
(radius x radius) x 3.14159 = area

Or just use this online calculator:
onlineconversion.com/shape_area_circle

So the area of the .080" orifice is .00527" sq/in
And the area of the .040" orifice is .001257 sq/in

That's a ratio of 3.999.

So the area of the .080" dia jet is nearly four times that of the .040" jet.

Now I'd buy he meant 30% more jet area maybe,just not 30% more jet diameter.

If using a .040" orifice above as an example,that would mean adding .000371 sq/in of area to that .001257 sq/in of the .040" orifice.

And that would indeed end up @ an orifice of appx. .045" to .046" or so (yep that's the 6-8 jet sizes mentioned).

But adding 30% to the jet diameter,that would end up being a bit more than that.

30% of .040" is like .012" (see above ^^^^),so adding 30% more jet diameter would net something like a .052" orifice as SOP.

That would increase the area of said orifice a bit more than 30%.

That would increase the orifice area to like .002123".

If my math is correct,that would be more like 41% more orifice area.

So I'm fairly sure he meant 30% more jet area,not 30% more jet diameter.

As for the lbs/hr that change makes,you'd almost hafta flow the orifices to be 100% sure that's how much more fuel mass your actually getting for that sorta jet change,just as Ron (TINTIGR) said.

I've seen some reliable flow numbers given for some larger jets/orifices (holleys),and some smaller (MFI) ones too,but actual flow numbers for jets/orifices in the .040" to .055" neighborhood are kinda hard to find for some odd reason.

And this all assumes your working with a set fuel pressure too.

Change the systems fuel pressure,and you'll change the lbs/hr as well.

That's a whole other can of worms...

Though once you know the actual flow of an orifice for a given fuel pressure,then figuring out the lbs/hr changes from a given fuel pressure change is a pretty easy thing to do as well.

It's knowng the orifice's actual lbs/hr flow @ a given pressure that's the real trick there.

Then all that's left is to figure out the nitrous side lb/hr numbers.

HTH

Bret P.
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Old 11-04-10, 12:32PM   #36
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Your logic is correct for a 30% change

► z= 0.001257
► z + (.3 * z) = 0.0016341 sq. in.
which is 0.0456" diameter

► ((0.0456 / 2)^2 * pi) = 0.001633 sq. in.



I have a 0.040" gas jet need to be 0.0488" for E85 - 0.5169" for Ethanol and 0.06" for Methanol, but an still testing this.


Stan

Last edited by Stan Weiss : 11-04-10 at 12:53PM. Reason: To get my math correct
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Old 11-04-10, 10:52PM   #37
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wanna get crazy?..jet size, length, inlet radius, exit radius, wall finish, pressure differentials..it all counts..but how accurate do you have to be?..

the bottom line tho, is the better you get, the better the machine reacts..

life aint fair, or equal..WE make it so...enjoy..
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Old 11-05-10, 10:30AM   #38
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Yeah Bret you are right,I had already calculated the area for several different jets + 30%.I don't know why I typed diameter.oops
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Old 11-05-10, 01:01PM   #39
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Found a guy near me mess'n with E85 for 2 seasons. Says his required a 15% increase.
Asked if he may of been to rich on gas before switching? He said no...
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Old 11-05-10, 03:45PM   #40
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a 15% increase in fuel volume wont cut it..unless his carb is stooooopid fat..
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Old 11-05-10, 04:23PM   #41
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Quote:
Originally Posted by TIN TIGR View Post
a 15% increase in fuel volume wont cut it..unless his carb is stooooopid fat..
X2

Also based on the BTU output of GAS verses E85 a 15% increase would product a net decrease in HP.

Even taking in to account the difference in specific gravity where E85 has more weight per unit volume. Remember air fuel ratio is by weight.

Stan
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Old 11-05-10, 05:05PM   #42
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Quote:
Originally Posted by TIN TIGR View Post
a 15% increase in fuel volume wont cut it..unless his carb is stooooopid fat..
Could be his nitrous tuneups are STOOOOOPID fat and he is just using 15% less of what he is already putting too much in of.
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Old 11-05-10, 05:17PM   #43
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Originally Posted by turbo69BIRD View Post

robin I will tell Chris you said hello. I will be seeing him again soon to help him tune his ride. I drive and he tunes!

Hes freaking crazy I am running 120 MPH and he doesnt look up from the screen Just keeps saying Keep you god damn foot in it!!!!!!!!!!!!

Hes insane, but a great tuner and getting better everyday.


LOL... I can totally see you 2 knuckledraggers on the news with the back of your car stuck halfway in some old ladies house and your only defense being "At least we weren't texting!!" Meanwhile Chris is still smiling because you didn't lift......
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Old 11-05-10, 05:27PM   #44
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Quote:
Originally Posted by Stan Weiss View Post

► z= 0.001257
► z + (.3 * z) = 0.0016341 sq. in.
which is 0.0456" diameter

► ((0.0456 / 2)^2 * pi) = 0.001633 sq. in.


Stan
Stan, do you have a pocket protector? JK.... Seriously, are you a Math guy, Engineer or some kinda Mensa Challenge winner?? I have heard and experienced that as jets get larger the percentage differences change. Let me explain further. Take a fogger nozzle with a 28N and 24F using 950psi and 6psi accordingly and the air fuel ratios come out nicely. Take the same nozzle with a 42N and a 38F (same split, right?) and it is WAY fat. Can you mathematically explain this?
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Old 11-05-10, 06:21PM   #45
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Find area of each jet
► n1 = (.028 / 2)^2 * pi
► n2 = (.024 / 2)^2 * pi
► n3 = (.042 / 2)^2 * pi
► n4 = (.038 / 2)^2 * pi

Area of each jet in sq. in.
► vars
Variable Name Variable Value
n1 = 0.0006157521601035995
n2 = 0.0004523893421169302
n3 = 0.001385442360233099
n4 = 0.001134114947945915

ratio of the areas
► n2 / n1 = 0.7346938775510202
► n4 / n3 = 0.8185941043083899

in case two you can see about an increase 8% in the difference of the ratios

use the ratio of the first group to find the needed jet size
► n3 * n2 / n1 = 0.001017876019763093 sq. in. which is a 0.036" diameter jet

New Jet will have same ratio
► n6 = (.036 / 2)^2 * pi
► n6 / n3 = 0.7346938775510202




My web site - main page - has a number of calculators
http://users.erols.com/srweiss/index.html
My software
http://users.erols.com/srweiss/winscren.html
Cylinder Heads Flow Data at 28" H2O.
http://users.erols.com/srweiss/tablehdc.htm
Electronic Fuel Injector (EFI) Flow Data Table.
http://users.erols.com/srweiss/tableifc.htm

Stan

Last edited by Stan Weiss : 11-05-10 at 07:12PM. Reason: Double checking my math
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