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Author Topic: Pure Methanol vs C-16 Race Gas Spooling Rate  (Read 8876 times)
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Paolo Castellano
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« on: June 18, 2015, 12:29:43 PM »

Has anybody run both of these fuels on the identical setup without changing compression or turbo sizing?

They guys on Yellowbullet swear alcohol spools the turbos faster but they never really keep track of changes like compression ratio and other possible changes to their setup before making that kind of statement.

There seems to be a much more analytical crowd here.........

Anybody?

Thanks!
« Last Edit: June 18, 2015, 10:05:39 PM by Paolo Castellano » Logged
tauruck
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« Reply #1 on: June 23, 2015, 10:40:17 PM »

A guy I know runs a 9sec. Mazda 3. Pretty good at our altitude (6000ft).
He went from race gas to Ethanol and then to Methanol without changing
what you mentioned.
Methanol was the best at the track and on the dyno but he had huge problems
starting the motor when it was cold. He said he had to remove the plugs and pre heat
them to get the car running. Not something you want to have to do in the staging lanes.

He went back to Ethanol. If you need his details PM me.
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Peter Jack
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« Reply #2 on: June 23, 2015, 11:42:33 PM »

We just sprayed a little gas down the injectors to start a methanol engine. Everything works fine once you build a fire. The injectors can get coated in ice if you leave them idling.

Pete
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tallguy
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« Reply #3 on: June 24, 2015, 02:15:00 AM »

I can confirm about ice formation due to the evaporation of alcohol.  Here's a story
(a little off-track, but what the heck). . .

I chose Mechanical Engineering as a college major, due to my interest in race vehicles. 
While I was a student at Cal Poly (San Luis Obispo, CA), in the early 1970s, I bought a
used minibike, and a friend and I would take it to a nearby junior college that had a paved
runway for small aircraft.  One of us would ride the minibike, Rollie-style, while the other
drove alongside in a car, reading its speedometer.

Best we ever did was 34 mph on straight alcohol, without changing jetting, gearing, or
anything else after using gasoline.  The alcohol did frost the exterior of the carburetor
with ice.

Ah, youth!
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Milwaukee Midget
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« Reply #4 on: June 24, 2015, 08:30:07 AM »

For those of the analytical mindset -

http://www.afdc.energy.gov/fuels/fuel_comparison_chart.pdf

Not a lot of energy in methanol, caustic to pump components and lines, washes down cylinder walls, but I can't imagine how it would "spool the turbo faster".

Looks like changing to methanol from ethanol without adjustments, and assuming the EFI wasn't compensating, would put you pretty lean pretty quick, but it's a slow burning fuel. 
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Stainless1
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« Reply #5 on: June 24, 2015, 09:00:16 AM »

What is missing from the chart is stoichiometric ratios for the fuels... it would show that while Methanol has low power, you have to use a lot more of it so the boom is bigger.
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Stainless
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MSA Bockscar Lakester #1000 my fastest mile 245 and change, 84 ci turbobusa motor... but Corey's 233 MPH H/BFL record is still 3MPH faster than mine.
jl222
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« Reply #6 on: June 24, 2015, 09:18:42 AM »

  Big difference on supercharged gas engines without intercoolers. The latent heat of evaporation cools and shrinks
the hot supercharged air as well or better than an intercooler.
 Might explain why spooling is faster as more denser mixture is being exploded.
  
          jl222
« Last Edit: June 24, 2015, 09:21:56 AM by jl222 » Logged
Milwaukee Midget
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« Reply #7 on: June 24, 2015, 09:37:56 AM »

Ahhh - C-16  VP fuel - my bad - I thought  ethanol v methanol.

RTEQ


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"Problems are almost always a sign of progress."  Harold Bettes
Well, I guess we're making a LOT of progress . . .  rolleyes

We are NOT rebuilding . . . We are reloading.

GOD SAVE MG - The Queen can take care of herself!
jl222
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« Reply #8 on: June 24, 2015, 12:40:20 PM »

Has anybody run both of these fuels on the identical setup without changing compression or turbo sizing?

They guys on Yellowbullet swear alcohol spools the turbos faster but they never really keep track of changes like compression ratio and other possible changes to their setup before making that kind of statement.

There seems to be a much more analytical crowd here.........

Anybody?

Thanks!


   They would have to richen a lot. Maybe a bigger fuel pump also.

               JL222
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NathanStewart
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« Reply #9 on: June 24, 2015, 02:53:34 PM »

The mass flow out the exhaust is probably significantly higher on methanol vs gas.  This is likely due to the fact that a boosted methanol engine will run at .50-.55 Lambda which would be stupid crazy rich on gas.  Gas would only run down to about .65-.70 Lambda which is going to be significantly less fuel mass than methanol running at .50 Lambda.  More mass flow through the turbine will equate to more turbo shaft speed and more airflow out the compressor. 

I saw this same behavior once on a very different application.  I once did some pretty copious testing of a water injection kit on a diesel application for emissions purposes.  I looked at temps at a few different places: exhaust gas temps, compressor outlet pre i/c temps, post i/c temps, and post water injection point temps.  I was also monitoring manifold pressure.  What I found was that with the water injection active, EGTs would drop as expected but compressor outlet temps went up along with a slight increase in manifold pressure.  Looking at a compressor map, the only way to get more heat (from less compressor efficiency) and more airflow/boost out the compressor is to increase the turbo shaft speed and the only conceivable reason why shaft speed would go up when water injection was active was that the net exhaust mass flow had gone up. 
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« Reply #10 on: June 24, 2015, 02:55:05 PM »

The answer should be yes. Alcohol fuels generate more exhaust gas volume for a given amount of intake air flow (which is usually a limiting factor).

I have run both gasoline and E85 on the same physical engine/turbo setup, and switching to E85 caused a very significant change in boost onset behavior.
I had to dial my boost controller way back to keep from having boost spikes on hard acceleration and over boosting the engine. (working from memory)

On high octane gasoline I had the boost controller set up to limit boost on the street to18-20 psi, as soon as I switched to E85 I immediately saw peak boosts of 24-26 psi, and a much harder boost hit when the turbo began to spool.

It is simply a matter of chemistry. With the very rich fuel air mixtures you can run on alcohol fuels you have all that burned fuel combustion and its combustion products. In the case of E85 the difference is about a 20%-30% increase in exhaust gas volume on max power rich mixtures if I recall correctly, because you have to burn about 30% more fuel to get the same effective combustion mixture. On Methanol you increase fuel about 50%, so I would expect you will need some changes.

You can spool a larger hot side on alcohol fuels and for a given hot side size it will spool faster. EGT temps will be a little lower all things being equal, but volume of gas will be greater.
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Paolo Castellano
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« Reply #11 on: July 13, 2015, 11:48:58 AM »

 Nathan Stewart, Hot Rod and everybody else, thanks for the input!

I got the email of Tauruk's(Mike) friend to get some more data as well Thank you Mike!

I am going to have an extra(Smaller) pump gas fuel tank that will flush out the alcohol at the end of the day and also to start the car and get it up to operating temperature. The EFI will have a separate map for cold start with pump gas and for post methanol use flushing idling.

Here is an interesting link to some viewpoints on methanol that I had never really considered:

http://www.killerrons.com/12.cfm
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« Reply #12 on: September 10, 2015, 01:23:39 PM »

Yes, This is good stuff.
Something I've never considered before because I always (for the most part) ran gasoline on my turbocharged engines. I did run some e100 and e85 and never really noticed a big change in spool rate but it was before I had ability to data log so that would just be opinion.
I fight with guys all the time about what spools a turbo. Heat and airflow or just airflow? EGT is much lower on methanol than gasoline but spools turbo faster. That tells be it's the more about the pressure differential between the inlet and outlet and total airflow that causes that turbine to spin faster. I often wondered if injecting a mist of water at high pressure into the exhaust header would increase exhaust volume and spool faster as steam is so much bigger than liquid water. There would be some cooling to the exhaust but would that matter for spooling at all or would it completely offset the volumes gained by steam expansion. This water in the exhaust is interesting to us as we are trying to keep engine compartment temps under control. We plan on pushing 1700f EGT's in the Carbiliner on gasoline of course.
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« Reply #13 on: September 10, 2015, 04:59:40 PM »

From Bill Jenkins 40 years ago!
Quick-disconnect lines run hot water from the push truck through the race engine, and back again. I would guess that the race engine's thermostat or water restrictor plate is bypassed for this operation.
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NathanStewart
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« Reply #14 on: September 11, 2015, 09:32:05 AM »

Rob see my post re water injection on a diesel.  The answer is yes but you'd take better advantage of injecting water into the intake and combustion chamber than just into the exhaust.
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El Mirage 200 MPH Club Member
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