Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!!
[Re: dmerc]
#47751
04/06/08 06:22 PM
04/06/08 06:22 PM
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Joined: Jan 2005
Posts: 12,423 Kalispell Mt.
HotRodDave
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OP
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Kalispell Mt.
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I think the main problem running lean is for high HP motors. The lower power motors will take longer to be affected by a lean condition, less overall heat. I also think by getting a really good homogenius mixture will allow you to run leaner with less problems because you eliminate hot spots during combustion, or at least reduce them. I left the exhaust valve rotators on this motor to help keep them more even tempertures. The area between the seats is where these heads like to crack so I polished that area to reduce stress risers and hot spots there. I have a list of stuff I would like to do to it still but I am broke and I think I have snatched up the simplest improvements, everything else is going to be like pulling hens teeth, cept mabey the OD trans. A friend is offering to pay my way to the Chrysler classic in BG for my 30th bday so I might get to run in the 1/4 and see how fast it is. I am torn bout them lettin the brand Xrs in though.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!!
[Re: QuickDodge]
#47754
04/09/08 11:27 AM
04/09/08 11:27 AM
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Joined: Dec 2005
Posts: 1,160 Cruising!
QuickDodge
super stock
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super stock
Joined: Dec 2005
Posts: 1,160
Cruising!
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Hotroddave40, do you mind telling us some more details about your ignition system. I know you posted earlier that it is an electronic ignition system. Can you give us some details on the advance curve? What do you have the base timing set at? (since changing to electronic ignition) Are you running a factory coil and spark plug gaps?
Last edited by QuickDodge; 04/09/08 11:41 AM.
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Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!!
[Re: QuickDodge]
#47755
04/09/08 04:03 PM
04/09/08 04:03 PM
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Joined: Jan 2005
Posts: 12,423 Kalispell Mt.
HotRodDave
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OP
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I have a chrome accel coil. Mopar electronic ign dist and harness with a autozone box. The distributer is the new adjustable mallory one. I set the idle for the most vacume then drove it with the vacume unhooked and adjusted the mechanica, it didn't need much taken out from factory, till it quit knocking at any throttle. Then I hooked up the vacume advance and did the same thing, drive adjust drive adjust till the knocking just went away. I would have to check again but I think the initial ended up about 16btdc and the total mechanical was around 32 btdc.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!!
[Re: HotRodDave]
#47756
04/19/08 07:14 PM
04/19/08 07:14 PM
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Joined: Jan 2005
Posts: 12,423 Kalispell Mt.
HotRodDave
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Just had it weighed at bowling green, #3077 and it had a full tank of gas. BTW the miledge seems to be pretty consistant 17 in town if I am real hard on it and 29 on the highway if I am real easy, like a steady 65mph. Most of my tanks are mixed driving and get about 25. If I am real easy on it in town it will still get around 20-21 I can't seem to get over 30 with it though
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!
[Re: dmerc]
#47758
04/20/08 02:26 PM
04/20/08 02:26 PM
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Joined: Jan 2003
Posts: 16,123 Grand Haven, MI
patrick
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I Live Here
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Grand Haven, MI
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no, for mileage you want efficiency, which means lots of cylinder pressure, so you want as high of compression as possible with as little overlap....if you wanted to really boost mileage, I'd use mag or 302 heads milled down to about 55cc w/flat tops, run a short duration cam like dave is, and water inject it (like a lot of turbo guys do) for detonation resistance.
1976 Spinnaker White Plymouth Duster, /6 A833OD 1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!*** 2011 Toxic Orange Dodge Charger R/T 2017 Grand Cherokee Overland 2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!
[Re: FuryUs]
#47760
04/21/08 12:43 AM
04/21/08 12:43 AM
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Anonymous
Unregistered
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Anonymous
Unregistered
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If I might chime in for a second.... There are a few factors you need to take a long hard look at. #1 is your ignition timing as it relates to burning efficiency. If you map out piston velocity relative to crankshaft position you'll see a sine wave pattern. In order to make the most power and waste the least fuel you want all of your fuel to burn as quickly as possible when the piston has the most mechanical advantage. But you can't let the chamber exceed a particular temperature or you'll have auto-ignition (knocking). If you're at 16 degrees BEFORE TOP DEAD CENTER that means you're starting the burn way way in advance of it's maximum mechanical advantage. This indicates either (A) Your fuel is not ideal for your goal -OR- (B) Your combustion process is slow and inefficient. There's not much you can do about A but B you can change. #2 EGT (Exhaust Gas Temperature) Again relating to efficiency of burn. Whereas previously we're seeking maximum use of our mechanical force, EGT dictates maximum use of your CHEMICAL "force". When the fuel burns and does what it does, heat is generated. Heat is energy. Wasted energy is wasted fuel. A VERY HOT EGT INDICATES ENERGY WASTED. A hot EGT is also caused by a lean mixture. Lean out the mixture and the EGT goes up. Makes no sense? That's because the burn cycle is taking longer than the duration of the power stroke. You're wasting power by dumping it out the exhaust. Again, shorten the burn time.
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Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!
[Re: 360view]
#47762
04/26/08 11:11 PM
04/26/08 11:11 PM
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Joined: Jan 2003
Posts: 9,887 USA
CrAlt
master
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master
Joined: Jan 2003
Posts: 9,887
USA
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Any new numbers from this 318? Im looking to start a project like this but with a 170cui slantsix or a 273
I was asked to contribute money to help solve the civil unrest in Egypt, but I suspect it's some sort of pyramid scheme.
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Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!
[Re: QuickDodge]
#47763
04/26/08 11:24 PM
04/26/08 11:24 PM
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Joined: Jan 2008
Posts: 3,886 Lost and Spaced
bboogieart
master
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master
Joined: Jan 2008
Posts: 3,886
Lost and Spaced
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Quote:
Would installing valves made from a more heat resistant material help to reduce the chance of burning the valves by running a lean mixture? Seems like a logical solution, but what kind of valve(s) would be more heat resistant?
aluminum pistons will melt before your valves will. burnt valves are usually due to an exhaust leak.That is why they look like they have been cut with a torch. Basically that is what happens. when oxygen is introduced to the exhaust charge.
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Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!
[Re: CrAlt]
#47764
04/27/08 03:06 PM
04/27/08 03:06 PM
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Joined: Jan 2005
Posts: 12,423 Kalispell Mt.
HotRodDave
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OP
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I have been driving it a lot and it always falls right in range with previous postings. Tennessee has started putting %10 ethenol in all the gas but it didn't seem to make any differance. As a matter of fact I topped it off with 5 gallons of E-85 the other day to fill the tank, didn't seem to affect the way it drives any I will post how it affects the MPG when I finish off that tank. It was about 50 cents cheaper than 93 octane and Tn does not subsidize it. I would not be afraid to run another point or 2 compression with it to bring back some of the suposed eficiency loss I would recomend the 273 over the slant because the only custom thing you need is pistons. With the slant you need a ton of milling to get closed chambers and zero deck. If you did all that milling I bet you would still need a custom piston to get valve clearance and low enough compression unless you want to make it run on e-85. If you could go this way though I bet a 170 would get better mpg on e-85 than a 273 on 93 octane. However if you threw an a-500 behind the 273 it might be close. I do beleive based on what I have learned: a 273 built with custom pistons and custom cam and a performer intake and OD that 35 mpg is reasonable. Also if I was running a motor that small that slow I would get some smaller headers like 1-5/8 and mabey add in an extra 12 inches to the primaries to boost low rpm tq. A narrower wheel would probably be good also, mine are 7.5 wide but have a very low profile tire to lower rolling resistance. If I built it for e-85 I would open the heat crosover to gain some bit of efficency that it suposedly loses. It burns cooler so it should still not ping. Mine is blocked and I think it would knock if I opened it. I mention all the e-85 stuff because I am thinking of switching it over with thinner head gaskets and some head milling.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!
[Re: HotRodDave]
#47766
04/27/08 11:49 PM
04/27/08 11:49 PM
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Joined: Jan 2003
Posts: 9,887 USA
CrAlt
master
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master
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USA
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Wow so much info out there... My goal is to SAVE money so $$custom$$ parts are out. Anything I do is going to be done with off the shelf parts. Also running on 87 is a must. The higher grades jump 10 or 15 cents between the grades here. Im leaning more to the 170. Mainly because I already have 1, 2, and 4bbl intakes to play with and 2 diff sets of headers. As well as a ported, milled head with the MP oversized valves. My plan so far is to put the better head on my original 225 thats in the car with a supersix (carter BBD) intake/exst manifold and run 2.25" exst. Drop the front of the car to match the sagging rear springs Clutch fan (already have) Multi-spark MSD box. (already have) And some type of belly pan to blend the front bumper to under the K-member. There is kinda a big gap there and it looks like the K-member is just hooking the air. I'll keep my goal low at 25highway. I already get 18-22 with the messed up 225 thats in there. Since i already have most of this crap kicking around i'll see how it works out. If it goes well ill spend the money on doing up a(still looking for one) 170short block.
I was asked to contribute money to help solve the civil unrest in Egypt, but I suspect it's some sort of pyramid scheme.
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