I keep reading of the different ways of keeping detonation away and see that some turbochargers and superchargers use water/air intercoolers or air/air coolers and some turbo kits like that STS use water/mynthaol injection to keep it away. Just wondering which one works best. I am thinking the water/menthaol is better since it is injected straight in, but thats all I can think off. Can someone explain some pros and cons of both-thanks

 

TTT...

Lets hear it you Alky guys....
What kinda temp to you see?
What are the pros, cons and specfics?

Thx,
Claude

 

Tractor pull contestants can give you some insight into this matter, providing they are willing to share info. BTW, boost pressures seen, could make USAC blush.

WI requires less time to cool the air to any degree. Or actually, less time required to cool it even more effectively/efficiently. No need to put the emphasis on methanol, or use it at all. I consider that 'trendy'.

 

Methanol kicks waters butt

Nothing trendy bout running 29 PSI of boost on 93 pump with my stock internal motor.

If the discharge temps are 500 degrees..then no amount of any injection is going to work. If your trying to bring down air temps, and have a medium that burns while doing so, then your talking making power and at the same time reducing KR big time since methanol flashes at a lower temp, is of higher octane, burns clean, and twice is required to yield the same power as gasoline..

Water works, but blows the flame out at higher volumes. If you read to much aquamist literature, you'll miss the boat, I wont even get into the trendy stuff like hydrogen peroxide, nitromethane, acetone, etc..

Dont believe me..look at the Turbo Buick community.. they have been on alky since the mid 90's.. thats pretty trendy. Do the faster cars run water..hell no.

Air space in my motor is too small to cram non combustible stuff in there.

This debate whats better is always split down the middle. And typically by those that have never run 100% methanol/denatured alcohol. Those that have tried it, will never try anything else. It works that good. I have yet to see a post anywhere on the internet(pretty big place) where someone has made more power with water vs alcohol.

Hows that to stir things up.

 

As far as my buick is concerned..... with 93 octane i can run a max of 17 psi before getting knock. With the SMC alcohol injection pumping in pure 100% denatured alcohol and running at 3/4 max pump speed i can get 25psi before it starts knocking again (i have a larger than stock turbo, so compressor effeciency isn't an issue at these boost levels). I still have the stock intercooler, unmodified. A friend of mine with the EXACT same setup as me (same turbo, injectors, etc....different chip) installed a front mount intercooler and was able to run 19psi on 93 octane instead of 16-17 on the stock one. Not sure of the exact power differences, but i'm sure that at the same boost levels at or below 19psi he's making more power than me. But since i can run 6 or so more lbs of boost i easily beat him when we run. Also note that if i run the pump at more than 3/4 of max it drowns the spark and causes it to sputter and die.

Another friend of mine with an 86 GN put an EGT gauge on his car and found that the alky injection dropped his EGTs by about 300* at every level of boost.... so lower combustion chamber temps are an obvious benefit of alky injection.

IMO it's better to get a "decent" intercooler (or aftercooler for you SC'd peeps), not too extreme or expensive, and invest in a good chemical intercooling method such as alky injection or nitrous. Much better results for your dollar. My $.02

 

On that same note... alky vs water. My car runs best with pure alcohol. I tried a 50/50 mix of alky/water and kept running lean around 22psi. Went back to 100% alcohol and i was running 25psi again with little more than 0.5* of retard.

Propane injection is proving to be even more effective than alky. There are a few board members over on TB.com thats hitting upwards of 27-28psi boost on pump gas. It just quirks me that i'd be a bomb on wheels if i went that route.... having a big propane tank in the back seat isn't the most settleing feeling in the world.

 

The main draw of an air/air intercooler is its low cost and simplicity. The outside air offers a virtually limitless supply of cooling medium, and offers excellent efficiency at high speeds. Unfortunately, an air/air intercooler can never lower charge temperatures below ambient air temperature, and in some applications (such as the top mount unit found in WRX’s) at lower speeds can function more as an interheating then an intercooler (although this isn’t a huge problem, as at low speeds lower charge temperatures generally aren’t as important, if important at all).

The Air/water intercooler’s biggest performance draw is its ability to lower air charge temperature below ambient air below ambient air temperature. To do this, as pre-cooled cooling medium boost be employed, such as an ice water tank. However, such as setup can only be used for a short time, as after the medium absorbs all the heat of the air charge, no further heat exchange can occur.

To construct an air/water intercooler capable of cooling the air charge in a street application, a separate heat exchanger (along with a pump to power it) must be employed to cool the water itself. The benefit of such as setup is the ease of piping in applications where such is a consideration, and the desirable heat properties of water (water can transfer heat 14 times more easily then air). The obvious drawback is the need for a much more complex, usually much more expensive setup.

From http://davidenglish.com/swift/Tech/I...oling_101.html

 

Stock ic, stock TB, stock cam, stock heads, stock headers, stock motor cept valve springs, bigger turbo, and injectors..

I've blown past 30 PSI on methanol with ZERO KR. No sputter, no hesitations, no black smoke plumming from the exhuast..perfect.

Its all how you apply the alky to the motor. Gotta dial it in..guys with simple pressure switches for turnon at X psi boost..your missing the boat. Been there..got the shirt.. thats why i'm here.

See if at lets say 20 PSI boost you need 25 oz per minute to keep the motor from knocking. And at 25 PSI you need 30 oz per minute.. what happens when you shoot 30 oz per minute at 12 PSI when you activate the system.

Propane has the same problem as alky does at lower boost levels, it cuases surging due to the AFR dropping like a hammer to 8-9:1 when the turnon point is reached. I'm working on a progressive system for propane.. soon soon.. until then.. cant touch alky.

Unless you can keep AFR in the 11:1 range throughout your run..your losing out on HP and messing your drivability up..

IC even a little less than optimum, and some external injection cheap and easy. Very effective.

 

I consider a well planned/designed system to be progressive with the liquid implementation. Have you done an 'apples to apples' comparo, with water exclusively, to determine the actual advantage(s) of the alcohol injection? IOW, not just ETs, but mileage, reduced octane and fuel requirements for street use, and temp differences.

 

Julio,
What parts would I need from you for a progressive system for my supercharged Formula? Also, this may be a stupid question... but do I need/want the 3 bar MAP?

 

The phenomenon behind water, alcohol, and air/water intercooling are actually completely different. I'll explain:

- Air/air and water/air exchanger intercoolers: Reduces the temperature of the boosted air, which increases the density and lowers the pressure. Any compressor will flow more air with a lower discharge pressure. This can be seen by porting your heads on your supercharged car - the boost will drop, but cfm and power will increase. Essentially, instead of having to pump air against 12 psi, the compressor is only pumping against 10 psi, so it flows more air. The side advantage is that you can run more timing. I, for one, have seen 20 rwhp from an intercooler, but another 40 rwhp from increasing timing.

- Water injection: Cools the intake air using evaporative cooling. However, the boost level stays the same and the cfm flow through the supercharger does not change. This is because the water vapor displaces the condensed air. The air is more dense, but it has been replaced with non-combustible H2O. The only reason to use water injection is so you can run more timing.

- Alcohol injection: Cools the intake air using evaporative cooling. The boost level stays the same and the cfm flow through the supercharger does not change just like water injection. The difference is that you displace the condensed air with an oxygenated vapor. So, even though there is no more flow through the compressor, there is more oxygen entering the cylinder and more power can be had. Once again, you can also run more timing.


Based on this, water injection is inferior to both alcohol and exchanger intercooling. The power potential of alcohol versus exchanger intercooling is probably close, but the alcohol doesn't have the added restriction of an inter/aftercooler. An intercooler, however, doesn't have to be refilled regularly.

I have to ask, though, if you are going to inject an oxygenated compound into the intake tract for the purpose of cooling the intake charge and adding power, why not inject nitrous oxide? It will cool much better than alcohol, plus has more oxygen.

Mike

 

In addition to the high heat of vaporization water will also have a dampening effect on the chemicaly pathways for detonation (formation/rxn of radical's).

But as pointed out, it reduces flame temp also. Anything that reduces temp is reducing energy output - you may gain it back in other areas, but if you can gain in those areas without reducing flame temp appreciably then you have the potential to make more power.

Chris

 

There appears to be misconceptions, as to what WI is actually capable of. The following is not new to the engineering community, and has be verified with actual testing.

A- WI has the capabiity to raise the anti knock cpability of the fuel.
B- The water in WI can in deed participate in the combustion process.
C- In the correct amounts, the water in WI can actually replace fuel, without a loss of torque observed.
D-In the correct amounts, WI can, and has been proven to be more effctive than intercooling, in cooling of the combustible intake charge mixture.

As a sampling, and simplistic overview of documented info available, the following link offers some 'tip of the iceberg' insight. The DIY-EFI forum list, from/in the past, along with government and independant engineering studies/testing, can be, and have been helpful in understanding the full potential of WI.

http://not2fast.wryday.com/thermo/w...r_chemistry.txt

As for real life examples, one need not look further than tractor pull competition, as noted above, for the effectiveness of WI in cooling of the intake charge.

Oh, and no, probably will not find this info on Buick forums.
Also, and for those not that familiar with WI, I believe the original intent of alcohol in the water mixture, was to prevent freezing, not for changing the fuel composition, as Buick racers have successfully accomplished.

 

http://www.kennedysdynotune.com/

Click on "Custom Water Injection" on the left menu bar.

There is a dyno graph with the water injection on and off. It lowers intake temps from 187 to 140 deg. F, but only gains 10 peak hp, probably due to detonation suppresion.

Mike

 

Well see when i've used water, I was able to run a couple extra lbs of boost and a little extra timing. See the TTA will run from the factory knock free about 16-17 PSI. On water I can get it up to 20 PSI..but the motor feels a little seat of the pants faster..but lazy. If I add alcohol to the water I can then run a couple extra PSI boost before seeing KR. On straight alcohol, I buried my AM 30 PSI guage with zero KR. I dont like running it there, but find myself running 27-29 all the time now. its a bad addiction, but the car is no fun at 20 PSI.. I wont drive it.

Now I do understand the benefits water has, and I have customers that run 5% water for that benefit.. So the advantage of running higher concentrations of alcohol are a radical improvement in detonation control.. beyond any measure, using the big pump and pumping some volume through the motor, I have yet to see KR in high gear. I personally in my own car havent tapped the limit..yet.. I'm trying tho. 2 years of 25+ PSI flogging and never have popped a HG, or opened the motor. I hope I dont curse myself..but what can I say. Today I saw 28 PSI at least 6-8 times driving around..briskly