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BEGi S3 vs FM2
11-04-2012, 06:41 PM
#141
Holy ****, are you really that ******* dumb? If your MASS INPUTS AREN'T EQUAL THERE'S NO POINT IN COMPARING THE TWO. One apple has less caloric value than two bananas well who the **** cares?
I should show this thread to my old thermo professors, I always wondered what I could do to make them cry. Miataturbo: teaching high school chemistry one post at a time.
I should show this thread to my old thermo professors, I always wondered what I could do to make them cry. Miataturbo: teaching high school chemistry one post at a time.
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11-04-2012, 07:38 PM
#143
It's clear that whatever comparison you are trying to make with your science is not the same comparison that I made in my post. I show how the complete combustion of ethanol involves more fuel and results in more product than the complete combustion of octane with the same quantity of air. What did you read there that's debatable now?
It's like saying burning one graham cracker makes less H2O than burning two saltines, it might be true but it's not a good means of comparison.
I wonder who I'm going to trust, basic chemistry and thermodynamics, my background as a chemical engineer, or some ******* on a forum regurgitating things they read on another forum. The things I am writing are proven science, not speculation based on some story you read.
Last edited by albumleaf; 11-04-2012 at 07:57 PM.
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11-04-2012, 09:04 PM
#146
Boost Czar
iTrader: (62)
Join Date: May 2005
Location: Chantilly, VA
Posts: 79,504
Total Cats: 4,079
What does all that have to do a maxed turbo? No one is arguing that u wont make more power with e85. Yet u respond to his question directly of the turbo with common uncontested knowledge of e85 vs gas.
Jesus Christ.
For the sake of simplifying things, say you have 10kg/min input air and fuel. Assume max power gasoline @ 12.5afr, E85 7.0afr
E85: 8.73kg air, 1.26kg fuel
Gasoline: 9.25kg air, 0.75 kg fuel
1.26 kg E85 * 33.1 MJ/kg = 41.70 MJ
0.75 kg gasoline * 47.2 MJ/kg = 34.9 MJ
Here's the amazing part that you keep looking over. MASS IS CONSERVED. 10kg in, 10kg out.
If you move the numbers closer to stoich, the power output/kg advantage moves down to 3% or so for E85 which isn't quite as encouraging, but the fact of the matter is that E85 will make more power without changing the mass flow rate.
For the sake of simplifying things, say you have 10kg/min input air and fuel. Assume max power gasoline @ 12.5afr, E85 7.0afr
E85: 8.73kg air, 1.26kg fuel
Gasoline: 9.25kg air, 0.75 kg fuel
1.26 kg E85 * 33.1 MJ/kg = 41.70 MJ
0.75 kg gasoline * 47.2 MJ/kg = 34.9 MJ
Here's the amazing part that you keep looking over. MASS IS CONSERVED. 10kg in, 10kg out.
If you move the numbers closer to stoich, the power output/kg advantage moves down to 3% or so for E85 which isn't quite as encouraging, but the fact of the matter is that E85 will make more power without changing the mass flow rate.
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11-04-2012, 09:23 PM
#147
You're missing a step, that being specific volumes, specifying a temperature and pressure, picking an equivalent mass basis for the reaction, etc.
...
I wonder who I'm going to trust, basic chemistry and thermodynamics, my background as a chemical engineer, or some ******* on a forum regurgitating things they read on another forum. The things I am writing are proven science, not speculation based on some story you read.
...
I wonder who I'm going to trust, basic chemistry and thermodynamics, my background as a chemical engineer, or some ******* on a forum regurgitating things they read on another forum. The things I am writing are proven science, not speculation based on some story you read.
You can choose to make it more complicated. I don't have apples and oranges or spiders and centipedes or incandescents and LEDS. I do have H2O's and CO2's, and in an ethanol combustion cycle, I have more H2O's and more CO2's to push through the same turbine and wastegate than I do in an octane cycle.
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11-05-2012, 03:03 PM
#150
If you search the googles for plots with e85 and similar sized turbo housings on pretty much any car you will find a lot of the same as brain posted.
The power to be had from e85 is around a 3% difference. The real benefit of switching to it is so you can get a bigger turbo and push more boost without det right? not the 3% gain from the actual swap. Although nobody would complain about 3%. it's definitely not even close to the 30 or 50 hp we're talking about.
The power to be had from e85 is around a 3% difference. The real benefit of switching to it is so you can get a bigger turbo and push more boost without det right? not the 3% gain from the actual swap. Although nobody would complain about 3%. it's definitely not even close to the 30 or 50 hp we're talking about.
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12-10-2012, 11:10 PM
#157
Senior Member
Thread Starter
Join Date: Feb 2009
Location: Philadelphia
Posts: 916
Total Cats: 70
Just really going back and forth on the GT2860/3071 or the EFR6258. FM claims the 3071 has same spool as 2860 so there's no reason to run a 2860 because i can run a 3071 and have same power at lower boost and lower operating temps.
On the other hand, some builds make EFR seem like god. Since thread was derailed, just bumping to see if there's any other feedback on those turbos. If I did garrett turbo, I'd probably run FMs kit. Would there be any benefit to paying the extra to get an external wastegate with either of those Garrets?
On the other hand, some builds make EFR seem like god. Since thread was derailed, just bumping to see if there's any other feedback on those turbos. If I did garrett turbo, I'd probably run FMs kit. Would there be any benefit to paying the extra to get an external wastegate with either of those Garrets?
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12-11-2012, 12:31 AM
#159
Senior Member
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Join Date: Feb 2009
Location: Philadelphia
Posts: 916
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I was pretty much set on the EFR but I am looking at other things as options. I'd entertain to get something that will work with an FM manifold and bolt into my MSM that's also another good option. Seems like EFR is going to cost much more money, for a few hundred RPM spool difference? For a car that's recreationally driven on the street, I am not sure if that money is worth spending. GT2860 with .86AR seems popular also and would suit my needs fine. FM2 with gt2860 .86 is cheaper than EFR by a good bit isnt it?
On the EFR side I was going to go with ARTech manifold and downpipe so there's roughly $2500 already.
Not saying you're wrong, but I did a bunch of searching and it seems like a lot of the debates are just dick-swinging contests between people who own one turbo or the other. I'd like to make a decision and NOT choose to go another route 5000 miles later because my choice sucked.
On the EFR side I was going to go with ARTech manifold and downpipe so there's roughly $2500 already.
Not saying you're wrong, but I did a bunch of searching and it seems like a lot of the debates are just dick-swinging contests between people who own one turbo or the other. I'd like to make a decision and NOT choose to go another route 5000 miles later because my choice sucked.
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12-11-2012, 01:03 AM
#160
There is a reason why Indy cars use off-the-shelf EFR's and not another brand.
A few hundred rpm? It's more than that, and the EFR will make more power/torque everywhere.
As far as cost, do you have any parts yet? The 2860 will set you back over a grand, easy. Add in an external wastegate and you're up there with the EFR which will have a better wastegate and an internal BOV. FM hardware is great and reliable, but ARtech hardware is much more efficient.
Have you read these yet?
https://www.miataturbo.net/dynos-tim...-6758-a-68914/
https://www.miataturbo.net/build-thr...ild-you-61522/
Soviet's dyno comparing a 6258 (open-loop ebc) vs. a 6758.
A few hundred rpm? It's more than that, and the EFR will make more power/torque everywhere.
As far as cost, do you have any parts yet? The 2860 will set you back over a grand, easy. Add in an external wastegate and you're up there with the EFR which will have a better wastegate and an internal BOV. FM hardware is great and reliable, but ARtech hardware is much more efficient.
Have you read these yet?
https://www.miataturbo.net/dynos-tim...-6758-a-68914/
https://www.miataturbo.net/build-thr...ild-you-61522/
Soviet's dyno comparing a 6258 (open-loop ebc) vs. a 6758.
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