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Old 06-18-2006, 07:50 PM   #1
sticrazy
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Default Power/performance difference between 50/50 and 100% methanol for water injection?

I'm about ready to get my tune at topspeed, check out this thread for my project:

http://forums.nasioc.com/forums/show...1#post13837791

Anyway, what are the main differences of running 50/50 versus 100 percent meth? From a power standpoint, reliability stanpoint, "engine cleaning," risk, etc, etc.

From what I hear 100 % meth does NOT give you twice the gains of 50/50. Any thoughts or experiences?

thanks guys
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Old 06-18-2006, 10:24 PM   #2
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There is very little difference between power potential of the different injection mixes. Pure water will actually allow slightly higher power output if tuned to the limit than a 50/50 mix. Pure alcohol should have slightly lower potential than 50/50 due to its lower cooling potential.

This is assuming you are running your setup for its detonation suppression effects as a WI system. If you are running so much alcohol that you are in effect running a dual fuel setup, then provided you don't get into detonation the alcohol will have a slight advantage over 50/50 mix.

It is nearly impossible to give a hard and fast comparison because there are so many unknowable variables that could effect the total package.

I would recommend you get a tune for 50/50 as it is the most well documented mixture and only after you explore its limits should you play with others combinations so you have a good reference point.

Larry
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Old 06-19-2006, 12:11 PM   #3
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bumpers before my tune anyone?????
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Old 06-19-2006, 01:14 PM   #4
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Quote:
Originally Posted by hotrod
There is very little difference between power potential of the different injection mixes. Pure water will actually allow slightly higher power output if tuned to the limit than a 50/50 mix. Pure alcohol should have slightly lower potential than 50/50 due to its lower cooling potential.

This is assuming you are running your setup for its detonation suppression effects as a WI system. If you are running so much alcohol that you are in effect running a dual fuel setup, then provided you don't get into detonation the alcohol will have a slight advantage over 50/50 mix.

It is nearly impossible to give a hard and fast comparison because there are so many unknowable variables that could effect the total package.

I would recommend you get a tune for 50/50 as it is the most well documented mixture and only after you explore its limits should you play with others combinations so you have a good reference point.

Larry
I dont understand how you can say that pure water has more power potential that 50/50?

XX Tuning in CT suggested 50/50 mix over 100% since there are minimal gains for 100% vs 50/50 and they do not overshadow the safety concerns.

50/50 mix is the equivalent of 108 octane. I run 21 psi on a safe tine with no hint of knock. 372 ft/lbs at the wheels at 3700 rpm peak, 360 ft/lbs by 3100 300 ft/lbs by 2700!!!! COme on early and comes on hard
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Old 06-19-2006, 03:04 PM   #5
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^^^^

I'm pretty sure what Hotrod means is that water is the best for cooling the intake charge - better than 50/50 or pure meth. As you increase the percentage of meth to water you get less cooling of the intake charge than water. But the positive side of adding more meth is that you can pull more fuel and add more meth, increasing your octane. So it becomes a balance of cooling and octane.

You would most likely get best results with 100 meth (especially with your FMIC and intake), but the total difference is not that much from 50/50 and it's a lot more expensive.
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Old 06-19-2006, 04:37 PM   #6
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Put Octane booster in the gas tank. Add cooling and Oxygen in the water injection. Simple.
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Old 06-19-2006, 08:35 PM   #7
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Quote:
Originally Posted by xrocket21
I dont understand how you can say that pure water has more power potential that 50/50?
{correction}
Actually I just re-checked some of the old WW-II reports and I miss-remembered them, (they use funky graphs with each graph line identified by different patterns that are hard to read - I did a "one off" error and was reading the water alcohol trace as the water only trace ---oops) water and water alcohol mixes are only equal in power potential at lean mixtures or at richer mixtures under moderate boost pressures. The alcohol/water mixes did produce more power at typical fuel air mixtures, but you need to be able to increase boost enough to take advantage of this characteristic. If you have a limited max boost pressure that is below waters maximum allowable boost curve, you will see no significant benefit to adding alcohol to the mix.

At lean mixtures they got 1.52x rated gasoline power, using 100% water injection and 1.59x rated power on 70/30 mix of alcohol water. At typical fuel air mixtures (near 12.5:1) they got 1.41x rated power on water and 1.8x rated power on 70/30 water alcohol mix.At richer mixtures (near 11.1:1) they got 1.28x rated power on water and 1.75x rated power on 70/30 water alcohol.


These numbers are also highly dependent on other variables like ignition timing and boost pressures as well so some tuners will have better luck on one mixture than on the other due to their choices of how to manipulate things like boost, timing, and fuel curves to compliment the W/I setup.

You might find this an interesting read -- it is the story of the man who developed high performance water injection as we know it today.

For example at lean mixtures 100% water will allow higher boost pressures than 70/30 alcohol water. At an AFR of 18:1 water would allow a boost pressure of 42.5 psi but 70/30 mix of water alcohol would only allow 35 psi.

At near stoich mixtures the two mixtures are identical in allowable boost, but waters allowable boost is flat from there up to 9:1 mixtures where the 70/30 mix increases in allowable boost as the mixture gets richer to about 10:1.

As a result 100% water injection has a nearly flat max power potential at mixtures from 12.5 - 9:1.


http://enginehistory.org/Frank%20WalkerWeb1.pdf

At the beginning of the war the R2800 aircraft engine was producing 2000 hp on 130 PN av gas, on the first night of WI development they raised power to 2150 hp with water injection. Ultimately they got to 2800 hp on the B series engine and on the C engine hit 3800 hp running 150 in hg boost (75 psi) compared to the stock 49 in hg boost (24.5 psi).

Larry

Last edited by hotrod; 06-20-2006 at 01:33 AM.
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Old 06-20-2006, 01:16 AM   #8
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Quote:
Originally Posted by hotrod
...Ultimately they got to 2800 hp on the B series engine and on the C engine hit 3800 hp running 150 in hg boost (75 psi) compared to the stock 49 in hg boost (24.5 psi).
Boy, I'm a pilot and even consider myself to be somewhat of an airplane aficianado, but I had no idea they ran those things that hard. All the more reason to doff the cap to the boys that flew 'em. 75 psi...whowee.

Anyway, as to the thread I think I already mentioned to the poster over in another forum that my tuner saw about a 3% (12 whp on a GT30R) difference between 50-50 and 100% meth. How far into the respective bleeding edge he pushed both mixtures, I dunno, but that certainly isn't enough to warrant the extra risk in my opinion.
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Old 06-20-2006, 10:25 AM   #9
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good info Hotrod, I had previously planned on toying with 100% meth but reading a prior thread by you I decided to stick with the 50/50 mix since I was happy with gains.
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Old 06-20-2006, 01:47 PM   #10
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Also have to take into consideration that 100% meth boils at 150 degrees Fahrenheit. 50/50 significantly raises the boiling point. A hot tank under the engine isn't good.
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Old 06-20-2006, 06:16 PM   #11
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Quote:
I had no idea they ran those things that hard. All the more reason to doff the cap to the boys that flew 'em. 75 psi...whowee.
Those were "proof runs" just to show what they could do. I doubt the operational aircraft went much above the standard boost level. I know they did some high performance setups on a handful of aircraft to get them fast enough to catch and shoot down the V1 buzz bombs.

The unlimited air race folks play around at those boost levels today as do the unlimited hydroplanes. The folks that really push water injection are the tractor pull builders, some of them are running over 100 psig boost levels.

Larry
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Old 06-20-2006, 06:35 PM   #12
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Diesel Turbos have jaw dropping numbers. There was a great article in one of the Race magazines about a year ago. My Mechanics father [retired not] worked for Garrett. He was telling us stories about using turbos in the WWII planes, as he was part of it. Interesting.

Said he was building water injection turbo set ups for cars back in the 50's.
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Old 06-25-2006, 08:20 PM   #13
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Quote:
Originally Posted by hotrod
The unlimited air race folks play around at those boost levels today as do the unlimited hydroplanes...
I've been to the Reno air races 3 times and I can certainly believe that. The last time I was there 2 planes had their engines grenade and they had to dead stick them to the ground. At the time, however, airspeed wasn't a problem...
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Old 06-25-2006, 09:27 PM   #14
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Good info... thanks guys. Looks like I will probably be running a 50/50 mix of meth and water when my Coolingmist kit comes in!
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Old 06-26-2006, 03:59 AM   #15
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I can confirm and withness those setting, Lanair ran WI and won three consecutive years - no engine failure. Below power chart is ruuning 100% water.



More read:
http://www.aquamist.co.uk/rescr/gall...r/lancair.html


Richard



Quote:
Originally Posted by flycaster
I've been to the Reno air races 3 times and I can certainly believe that. The last time I was there 2 planes had their engines grenade and they had to dead stick them to the ground. At the time, however, airspeed wasn't a problem...
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Old 06-26-2006, 10:56 PM   #16
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Cool info Richard I didn't know you had any equipment in service with the air racers.

I understand the "Rare Bear" runs about 75 inhg manifold pressure (37.5 psi) and one of the other unlimited air racers is supposed to run about 85 in hg manifold pressure (42.5 psi), Dago Red is supposed to hit 120 in hg (60 psi).

Larry

Last edited by hotrod; 06-26-2006 at 11:04 PM.
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Old 06-28-2006, 03:17 AM   #17
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those big ole v12s are built more like diesels than gas motors hence the pressures they hold... i mean some of them redline below 3500 rpm

a friend of mine is building a classic unlimited hydro with an Ellison v12 in it.. and damn... its neat but i can't help but think with some precision they could wind them soo much higher.
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Old 06-28-2006, 04:45 AM   #18
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Its Allison V12

http://staff.jccc.net/droberts/p40/p40power.html

They have serious piston speed even at those lower RPM's due to the large bore and stroke, so significant RPM increase is limited.

Larry
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Old 06-28-2006, 05:49 AM   #19
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Hi Hotrod,

We get roped into many weird and wondeful applications, we supplied a sytem for a gas turbine powered speed boat!

It is a pity that they have stopped participating a few years ago so my connection to the reno air race has ended.

Our latest project is a twin-turboed, twin diesel engined car (totalling 1500BHP) that runs in excess of 60 psi, it will be at bonneville this August attempting to break the 300mph record. It is called the dieselmax by JCB.
http://www.jcbdieselmax.com/html/home.php

I hope to be there as an observer.

Richard

Quote:
Originally Posted by hotrod
Cool info Richard I didn't know you had any equipment in service with the air racers.

I understand the "Rare Bear" runs about 75 inhg manifold pressure (37.5 psi) and one of the other unlimited air racers is supposed to run about 85 in hg manifold pressure (42.5 psi), Dago Red is supposed to hit 120 in hg (60 psi).

Larry

Last edited by Richard L; 06-28-2006 at 07:21 AM.
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Old 06-28-2006, 06:19 AM   #20
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Quote:
Originally Posted by xrocket21
I dont understand how you can say that pure water has more power potential that 50/50?

XX Tuning in CT suggested 50/50 mix over 100% since there are minimal gains for 100% vs 50/50 and they do not overshadow the safety concerns.

50/50 mix is the equivalent of 108 octane. I run 21 psi on a safe tine with no hint of knock. 372 ft/lbs at the wheels at 3700 rpm peak, 360 ft/lbs by 3100 300 ft/lbs by 2700!!!! COme on early and comes on hard

Impressive, even rather scary power levels...

I have about 290wtq at 3100 , 316 peak and it is darn quick, I can't even imagine 360 it must be a shift-o-rama ...

<end threadjack>
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Old 06-28-2006, 09:13 PM   #21
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Personally with my evo which I self tune, the difference between 50% and 75% is about 1 degree more timing, leaner afrs and slightly faster track ets and traps...
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Old 07-06-2006, 11:54 PM   #22
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I can confirm the statements made from the unlimited race airplanes. I worked on a team (very successful team) where it was common to run 130 in manifold pressure and ADI (anti-detonation injection). We also added manganese to the fuel. The airplane made over 3500 hp. 500+ mph level flight 75 feet above the ground...yeah, I can handle that.

Late
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Old 07-07-2006, 12:54 AM   #23
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can we use purified water instead of distilled?
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Old 07-09-2006, 01:50 PM   #24
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Somethings to consider.
Aircraft engines dont need to spin fast and shouldnt if they are a direct drive. 4000 rpm is the most you can spin a normal prop before it cavitates.

One other thing to think about 100% meth is the corrosion factor. If you use it alot you will go through spark plugs left and right.
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Old 07-09-2006, 02:16 PM   #25
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100% meth doesn't mean 100% of the fuel. It's still probably gonna be less then 25% of the fuel even at 100% meth injection. I have no stats to put up, but from what they say water has better cooling propperties then ,meth. I'd think that with 50/50 you'd get the best of both worlds, but it might be a bit harder to tune for then 100% meth depending on what type of system you have and the size nozzle you use. Course this is just my opinion....

peace
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