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Re: compression: point of deminishing returns
[Re: Streetwize]
#1545767
12/10/13 10:21 PM
12/10/13 10:21 PM
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Joined: Jan 2003
Posts: 12,076
Benton, IL.
DaveRS23
Special needs idiot
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Special needs idiot
Joined: Jan 2003
Posts: 12,076
Benton, IL.
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How would meth injection play in this? Would spending the $500 or so on a Snow or Devil's kit pay off in the long run?
Master, again and still
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Re: compression: point of deminishing returns
[Re: mopar dave]
#1545773
12/11/13 12:43 PM
12/11/13 12:43 PM
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Joined: Oct 2005
Posts: 46
Macomb Michigan
65 Belv A990
member
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member
Joined: Oct 2005
Posts: 46
Macomb Michigan
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Quote:
I don't know much about it other than its about 105 octane. some like it and some don't.
It is been said by many that E85 has an octane rating in the neighborhood of 103-105 octane. However in an excellent, often updated publication put out by the Renewable Fuels Foundation “Changes in Gasoline IV the Auto Technician’s Guide to Spark Ignition Engine Fuel Quality” they have this to say.
“The often cited 105 octane for E85 is incorrect. This number was derived by using ethanol’s blending octane value in gasoline. This is not the proper way to calculate the octane of E85. Ethanol’s true octane value should be used to calculate E85’s octane value. This results in an octane range of 94-96 (R+M)/2. These calculations have been confirmed by actual-octane engine tests."
That may seem like a low (R+M)/2 octane rating in relation to racing gas, but is a bit misleading due to the cooling properties of ethanol. E85 does have an octane rating higher than that of regular gasoline's typical rating of 87, or premium gasoline's 91-93 to be sure, but not by much. It’s this cooling effect of ethanol’s rapid evaporation rate that allows it to be used in much higher compression engines than one would think when you compare its detonation resistance qualities to that of gasoline. It’s these very high static compression ratios and the allowance of optimum cam timing events to produce the higher running dynamic compression ratios that produce more power per unit of displacement than their 100% pure gasoline counterparts with similar or even higher octane ratings. This is despite the fact that there is 30% less BTUs per gallon with ethanol, as long as the subsequent fuel and air delivery increase requirements are met.
I have watched closely at some of Darren Teddar’s mega inch E85 Hemi builds over the years. IIRC, I think he ended up with around 15.7-16.0 static compression on the 656” Hemi. That was with a 4.560 bore and piston with a wide,flat quench area. The small chambers of the Stage V Millennium heads allowed for a good squeeze without a mountain size dome that would tend to shroud the flame front. North of 1250 HP with a fuel that costs 20-30% of what an exotic racing gasoline would cost to support that kind of compression is impressive. I would think that a wedge engine that has a similarly large quench area that provides an aggressive squish and turbulent burn, would be even more successful at these high compression ratios than a Hemi that traditionally has fairly lazy burn characteristics
Whether you want to deal with the corrosive qualities of the fuel or not is a personal decision, but E85 is a viable alternative.
Ed.
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Re: compression: point of deminishing returns
[Re: mopar dave]
#1545774
12/11/13 12:44 PM
12/11/13 12:44 PM
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Joined: Jan 2003
Posts: 12,076
Benton, IL.
DaveRS23
Special needs idiot
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Special needs idiot
Joined: Jan 2003
Posts: 12,076
Benton, IL.
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Snow's site says their kits are fine for n/a engines. And claim that magazine tests point to performance better than C16 (116 Octane). So, should a guy consider building a street/strip motor with higher compression using 93 pump gas and water injection? Windshield washer fluid is much more convenient and cheaper than race gas. And the engine is kept cleaner to boot. What would be the the down side? I can see the possibility of several advantages with it. IF water injection works as advertised. What do you think? 
Master, again and still
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Re: compression: point of deminishing returns
[Re: B G Racing]
#1545778
12/11/13 02:17 PM
12/11/13 02:17 PM
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Joined: Apr 2005
Posts: 2,128
Salt Lake City
camastomcat
top fuel
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top fuel
Joined: Apr 2005
Posts: 2,128
Salt Lake City
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Quote:
The point of deminished returns on a gas fired engine is aprox.16 to 1 after that you won't need spark plugs and can run diesal or veggie oil or weassel piss depending on what performance level you desire.  
I have a 572 B1/MC 16.4-1, in Salt Lake at 6000 corrected runs 7.54@174 in a 1870# dragster. I run Sonoco Maximal. I'm guessing 7.20'2-7.30's in Las Vegas with good air at MATS.
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Re: compression: point of deminishing returns
[Re: AndyF]
#1545783
12/11/13 03:39 PM
12/11/13 03:39 PM
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Joined: Mar 2006
Posts: 9,910
Eighty Four, PA
B G Racing
master
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master
Joined: Mar 2006
Posts: 9,910
Eighty Four, PA
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Quote:
I increased the compression ratio in my 514 dyno motor to 15.5 from 13:1 and saw a significant increase in power. The higher compression ratio allowed me make use of the Q16 as well as compensate for the smallish intake ports.
Andy,do you have any stats on any engine that exceeded 16:1? 
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