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Which Engine 318 or 400?
#913629
01/25/11 02:02 PM
01/25/11 02:02 PM
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Joined: Aug 2007
Posts: 1,819
Middle of A Field
OrangeProwler
OP
top fuel
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OP
top fuel
Joined: Aug 2007
Posts: 1,819
Middle of A Field
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Just wondering if you had the choices between these two setups for power and possible fuel mileage.
#1 Numbers 68 318 with Enginequest heads, KB167 pistons, Performer Intake; 800 Thermoquad, headers, Lunati Voodoo 60401 and .039 head gaskets matched to a low gear 904, 2k stall and 2.76 gears.
#2 74 400 block with stock heads KB240s, headers, performer intake, 800 TQ, and Lunati 60300 or 60301 cam; and not sure on the head gaskets. Stock 727 wity 2k stall and 2.76 gears.
On the street which engine would be better and get better fuel economy? I know that sounds like an oxymoron but, with gas going to 5 bucks a gallon potentially in the future. I have to ask.
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Re: Which Engine 318 or 400?
[Re: OrangeProwler]
#913631
01/25/11 03:20 PM
01/25/11 03:20 PM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
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Quote:
Just wondering if you had the choices between these two setups for power and possible fuel mileage.
#1 Numbers 68 318 with Enginequest heads, KB167 pistons, Performer Intake; 800 Thermoquad, headers, Lunati Voodoo 60401 and .039 head gaskets matched to a low gear 904, 2k stall and 2.76 gears.
#2 74 400 block with stock heads KB240s, headers, performer intake, 800 TQ, and Lunati 60300 or 60301 cam; and not sure on the head gaskets. Stock 727 wity 2k stall and 2.76 gears.
On the street which engine would be better and get better fuel economy? I know that sounds like an oxymoron but, with gas going to 5 bucks a gallon potentially in the future. I have to ask.
#1 I'd wager at ~320-330 hp, 350-370tq
#2 I'd wager at ~340-370 hp, 425-460tq
highway cruising I could see the 'teen getting significantly better mileage, probably upper teens vs. lower 20's...in town, probably little difference
for the price difference in the pistons, you could probably pick up a rebuildable 360 shortblock and KB107's, I'd expect probably 330-350hp and 400-430tq out of that, mileage probably in between the other two....
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: Which Engine 318 or 400?
[Re: Mr.Yuck]
#913633
01/25/11 04:13 PM
01/25/11 04:13 PM
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Joined: Sep 2003
Posts: 1,168
Vancouver, WA
MoparMarq
super stock
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super stock
Joined: Sep 2003
Posts: 1,168
Vancouver, WA
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Quote:
why bother...get a honda if you are concerned about gas prices.
I'd say if you have a B or E body use the 400 if you have an A body use the 318. I would however not use 2.76 gears on either. lower gear doesn't always mean better mpg. Plus you'd have to drive it a TON on the highway to get any benefit. $5 a gallon is nothing compaired to the cost of building and maintaining a muscle car.
Agreed. As an aside, back in the day, my '72 RR had the factory 400/727 with 3.55s in the rear. Needless to say, fuel economy not too good. Swapped in 3.23s to improve it a bit. It did improve it some. Went to 2.76s later on, zero difference. Same as the 3.23s. Of course, the top end was a lot better, but it was a pig off the line. Much depends on power, weight, torque, how it's driven, etc.
If fuel economy is the goal, I'd go with the 318. The weight difference between the two will help with economy numbers, as will engine power.
The goals aren't mutually exclusive; but how much do you want to spend anyway?
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Re: Which Engine 318 or 400?
[Re: Mr.Yuck]
#913634
01/25/11 06:57 PM
01/25/11 06:57 PM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
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Quote:
why bother...get a honda if you are concerned about gas prices.
I'd say if you have a B or E body use the 400 if you have an A body use the 318. I would however not use 2.76 gears on either. lower gear doesn't always mean better mpg. Plus you'd have to drive it a TON on the highway to get any benefit. $5 a gallon is nothing compaired to the cost of building and maintaining a muscle car.
some of us enjoy driving our cars on a regular basis...I built a 318 along the same recipie as him, except I'm using a small hydraulic roller, eddie RPM air gap, and OEM magnum castings. it's enough motor to push my 3900 lb pig to mid 14's using 27" tires, 3.55's and an A500, and is very entertaining to drive, while yielding a solid 17+ mpg in daily (mixed) driving....
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: Which Engine 318 or 400?
[Re: OrangeProwler]
#913635
01/25/11 09:31 PM
01/25/11 09:31 PM
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Joined: Nov 2006
Posts: 1,456
oklahoma
forphorty
pro stock
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pro stock
Joined: Nov 2006
Posts: 1,456
oklahoma
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I have a 318 in my duster but all my B bodies have had big blocks. I would never consider a small block in a B body myself unless it was already in there. If you run a small block , all the cheap headers hang low on the drivers side and have the center link pass through them. The big block headers do not. With a big block, intake swaps are much easier and you dont have to drain any water. Distributor is up front where it should be. Windage trays are cheaper and don't require extra hardware. If you have to change a broken water pump on the side of the road, you will appreciate that it only requires removing four bolts for the fan and pulley and four bolts for the pump and its off, whereas with the sb you will be fooling with the lower hose and PS brackets. Yep, i prefer big blocks. Having said that, my Duster will probably end up with a 360 magnum. As far as mileage goes i don't know what's good or bad. My 73 gets about 15- 17 mpg on the highway. Has a .030 400 with a 268 XE comp, 750 DP, MP 175k converter and 2.76s. My 440 powered Satellite gets much worse but has more cam, more converter, etc.
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Re: Which Engine 318 or 400?
[Re: patrick]
#913636
01/25/11 11:03 PM
01/25/11 11:03 PM
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Joined: Jan 2003
Posts: 24,562
Brookeville, Md
Mr.Yuck
Not enough dumb comments...yet
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Not enough dumb comments...yet
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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Quote:
Quote:
why bother...get a honda if you are concerned about gas prices.
I'd say if you have a B or E body use the 400 if you have an A body use the 318. I would however not use 2.76 gears on either. lower gear doesn't always mean better mpg. Plus you'd have to drive it a TON on the highway to get any benefit. $5 a gallon is nothing compaired to the cost of building and maintaining a muscle car.
some of us enjoy driving our cars on a regular basis...I built a 318 along the same recipie as him, except I'm using a small hydraulic roller, eddie RPM air gap, and OEM magnum castings. it's enough motor to push my 3900 lb pig to mid 14's using 27" tires, 3.55's and an A500, and is very entertaining to drive, while yielding a solid 17+ mpg in daily (mixed) driving....
what's that got to do with it? I enjoy driving mine too I wouldn't have built it if not. I was running 12.0's in a 67 coronet w/ a 440 and getting 12-13 with 3.91's. My 72 340 swinger ran 13.86's with a mild 340 and 3.55's and netted 17+mpg's. Car is not going to be very impressive at all w/ 2.76 gears and they might hurt his milage. If he was building a Bonneville car the 2.76's would be fine. I'd wager a cold 12 pack the difference in mpg's between 2.76's and 3.55's would be less than 2mpg (compined driving) Put the performance would be way up.
I guess my main point is people dump all kinds of dumb $$$ into a ride and worry about mpgs and how much it costs to fill the tank. Gas won't be $5/gallon for a long while. I doubt 93 will go over $4 for too long. Build it to run it's best. If you build a performace engine, back it up. If you want a pretty car you can drive everyday build a stockish roller 360 and get a set of 3.23's.
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Re: Which Engine 318 or 400?
[Re: Mr.Yuck]
#913637
01/26/11 12:44 PM
01/26/11 12:44 PM
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Joined: Jan 2003
Posts: 5,788
Hamilton, Ontario Canada
Magnum
master
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master
Joined: Jan 2003
Posts: 5,788
Hamilton, Ontario Canada
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This thread seems to be losing a bit of focus. It also fails to mention the goals and what car it's intended for.
All else equal, 318 will surpass a 400 in mileage.
Also, I'm not buying the deeper gear might get better mileage. May for the 5 to 10 seconds it takes to accelerate from a light but once you are at a constant speed. Lower rpm equals better mileage.
69 Super Bee, 93 Mustang LX, 04 Allure Super
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Re: Which Engine 318 or 400?
[Re: Magnum]
#913638
01/26/11 12:53 PM
01/26/11 12:53 PM
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Joined: Jan 2003
Posts: 8,936
Holly/MI
Dean_Kuzluzski
master
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master
Joined: Jan 2003
Posts: 8,936
Holly/MI
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Quote:
All else equal, 318 will surpass a 400 in mileage.
Also, I'm not buying the deeper gear might get better mileage. May for the 5 to 10 seconds it takes to accelerate from a light but once you are at a constant speed. Lower rpm equals better mileage.
Agreed. Any time you can run down the road with the engine at highest vacuum, closest to idle, you'll get best mileage.
Driving like there's an egg, not hardboiled, between your foot and the gas pedal will gain best mpg. The trouble is, with mild gearing that means letting the vehicle attain cruising speed in a longer manner at it's own rate. In more populated areas it isn't practical. Rural it works. My 318, 904 lock-up, 2.20:1 geared 80 Cordoba got a VERY honest 20 mpg with every tankful for 2 full summers. I drive 24 miles each way to work with only 2 traffic lights on the way there.
R.I.P.- Gary "Coop" Davis 02/09/68-05/13/04
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Re: Which Engine 318 or 400?
[Re: Mr.Yuck]
#913639
01/26/11 01:46 PM
01/26/11 01:46 PM
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Joined: Apr 2005
Posts: 15,134
Kelowna, B.C. Canada
DPelletier
I Live Here
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I Live Here
Joined: Apr 2005
Posts: 15,134
Kelowna, B.C. Canada
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Quote:
Quote:
Quote:
why bother...get a honda if you are concerned about gas prices.
I'd say if you have a B or E body use the 400 if you have an A body use the 318. I would however not use 2.76 gears on either. lower gear doesn't always mean better mpg. Plus you'd have to drive it a TON on the highway to get any benefit. $5 a gallon is nothing compaired to the cost of building and maintaining a muscle car.
some of us enjoy driving our cars on a regular basis...I built a 318 along the same recipie as him, except I'm using a small hydraulic roller, eddie RPM air gap, and OEM magnum castings. it's enough motor to push my 3900 lb pig to mid 14's using 27" tires, 3.55's and an A500, and is very entertaining to drive, while yielding a solid 17+ mpg in daily (mixed) driving....
what's that got to do with it? I enjoy driving mine too I wouldn't have built it if not. I was running 12.0's in a 67 coronet w/ a 440 and getting 12-13 with 3.91's. My 72 340 swinger ran 13.86's with a mild 340 and 3.55's and netted 17+mpg's. Car is not going to be very impressive at all w/ 2.76 gears and they might hurt his milage. If he was building a Bonneville car the 2.76's would be fine. I'd wager a cold 12 pack the difference in mpg's between 2.76's and 3.55's would be less than 2mpg (compined driving) Put the performance would be way up.
I guess my main point is people dump all kinds of dumb $$$ into a ride and worry about mpgs and how much it costs to fill the tank. Gas won't be $5/gallon for a long while. I doubt 93 will go over $4 for too long. Build it to run it's best. If you build a performace engine, back it up. If you want a pretty car you can drive everyday build a stockish roller 360 and get a set of 3.23's.
I tend to agree. It may not really answer the OP's question (which is impossible without knowing how much weight HE assigns to power vs. economy)but after buying my car, restoring it, building a garage to put it in, etc. etc. Fuel economy is my last concern (obvious with my 440-6 and 4.10's, I suppose).
I'm not knocking anyone trying to maximize thier economy in order to spend more time driving my car, but (for me) If it ever gets too expensive to drive my car, I'll drive it less before I'll sacrifice most of the performance.
Dave
1970 Super Bee 440 Six Pack
1974 'Cuda
2008 Ram 3500 Diesel
2006 Ram 3500 Diesel
2004.5 Ram 2500 Diesel
2003 Ram 3500 Diesel
2006 Durango Limited
[url] http://1970superbee.piczo.com [/url]
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Re: Which Engine 318 or 400?
[Re: Magnum]
#913640
01/26/11 01:49 PM
01/26/11 01:49 PM
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Joined: Apr 2005
Posts: 15,134
Kelowna, B.C. Canada
DPelletier
I Live Here
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I Live Here
Joined: Apr 2005
Posts: 15,134
Kelowna, B.C. Canada
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Quote:
This thread seems to be losing a bit of focus. It also fails to mention the goals and what car it's intended for.
All else equal, 318 will surpass a 400 in mileage.
Also, I'm not buying the deeper gear might get better mileage. May for the 5 to 10 seconds it takes to accelerate from a light but once you are at a constant speed. Lower rpm equals better mileage.
You have a point, but the truth is that it certainly IS possible to get as good or better mileage AROUND TOWN with a lower gearset. The increased torque multiplication for acceleration from a stop can overshadow the steady-state rpm based fuel consumption. A lower rpm equals better mileage on the highway.....but around town that doesn't necessarily hold true.
Dave
1970 Super Bee 440 Six Pack
1974 'Cuda
2008 Ram 3500 Diesel
2006 Ram 3500 Diesel
2004.5 Ram 2500 Diesel
2003 Ram 3500 Diesel
2006 Durango Limited
[url] http://1970superbee.piczo.com [/url]
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Re: Which Engine 318 or 400?
[Re: DPelletier]
#913641
01/26/11 01:58 PM
01/26/11 01:58 PM
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Joined: Apr 2007
Posts: 2,826
NY usa
540challenger
master
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master
Joined: Apr 2007
Posts: 2,826
NY usa
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Quote:
Quote:
This thread seems to be losing a bit of focus. It also fails to mention the goals and what car it's intended for.
All else equal, 318 will surpass a 400 in mileage.
Also, I'm not buying the deeper gear might get better mileage. May for the 5 to 10 seconds it takes to accelerate from a light but once you are at a constant speed. Lower rpm equals better mileage.
You have a point, but the truth is that it certainly IS possible to get as good or better mileage AROUND TOWN with a lower gearset. The increased torque multiplication for acceleration from a stop can overshadow the steady-state rpm based fuel consumption. A lower rpm equals better mileage on the highway.....but around town that doesn't necessarily hold true.
Dave
True but i think the OP stated he had a 904 with a low gear set in first gear that should help out and IMO it would be a better way to go for what the OP wants to do.
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Re: Which Engine 318 or 400?
[Re: 540challenger]
#913642
01/26/11 02:49 PM
01/26/11 02:49 PM
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Joined: Apr 2005
Posts: 15,134
Kelowna, B.C. Canada
DPelletier
I Live Here
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I Live Here
Joined: Apr 2005
Posts: 15,134
Kelowna, B.C. Canada
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Quote:
Quote:
Quote:
This thread seems to be losing a bit of focus. It also fails to mention the goals and what car it's intended for.
All else equal, 318 will surpass a 400 in mileage.
Also, I'm not buying the deeper gear might get better mileage. May for the 5 to 10 seconds it takes to accelerate from a light but once you are at a constant speed. Lower rpm equals better mileage.
You have a point, but the truth is that it certainly IS possible to get as good or better mileage AROUND TOWN with a lower gearset. The increased torque multiplication for acceleration from a stop can overshadow the steady-state rpm based fuel consumption. A lower rpm equals better mileage on the highway.....but around town that doesn't necessarily hold true.
Dave
True but i think the OP stated he had a 904 with a low gear set in first gear that should help out and IMO it would be a better way to go for what the OP wants to do.
Yep, I don't necessarily disagree (I have a 318/904/2.76 setup in the 'Cuda) but I just wanted to point out what I believe to be an error in fact to do with the contention that a higher gear set ALWAYS means better mileage. I don't think that is true in every circumstance.
Dave
1970 Super Bee 440 Six Pack
1974 'Cuda
2008 Ram 3500 Diesel
2006 Ram 3500 Diesel
2004.5 Ram 2500 Diesel
2003 Ram 3500 Diesel
2006 Durango Limited
[url] http://1970superbee.piczo.com [/url]
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Re: Which Engine 318 or 400?
[Re: DPelletier]
#913643
01/26/11 02:59 PM
01/26/11 02:59 PM
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Joined: Apr 2007
Posts: 2,826
NY usa
540challenger
master
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master
Joined: Apr 2007
Posts: 2,826
NY usa
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Quote:
Quote:
Quote:
Quote:
This thread seems to be losing a bit of focus. It also fails to mention the goals and what car it's intended for.
All else equal, 318 will surpass a 400 in mileage.
Also, I'm not buying the deeper gear might get better mileage. May for the 5 to 10 seconds it takes to accelerate from a light but once you are at a constant speed. Lower rpm equals better mileage.
You have a point, but the truth is that it certainly IS possible to get as good or better mileage AROUND TOWN with a lower gearset. The increased torque multiplication for acceleration from a stop can overshadow the steady-state rpm based fuel consumption. A lower rpm equals better mileage on the highway.....but around town that doesn't necessarily hold true.
Dave
True but i think the OP stated he had a 904 with a low gear set in first gear that should help out and IMO it would be a better way to go for what the OP wants to do.
Yep, I don't necessarily disagree (I have a 318/904/2.76 setup in the 'Cuda) but I just wanted to point out what I believe to be an error in fact to do with the contention that a higher gear set ALWAYS means better mileage. I don't think that is true in every circumstance.
Dave
 Very true
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Re: Which Engine 318 or 400?
[Re: DPelletier]
#913644
01/26/11 06:52 PM
01/26/11 06:52 PM
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Joined: Jan 2003
Posts: 24,562
Brookeville, Md
Mr.Yuck
Not enough dumb comments...yet
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Not enough dumb comments...yet
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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Quote:
Quote:
This thread seems to be losing a bit of focus. It also fails to mention the goals and what car it's intended for.
All else equal, 318 will surpass a 400 in mileage.
Also, I'm not buying the deeper gear might get better mileage. May for the 5 to 10 seconds it takes to accelerate from a light but once you are at a constant speed. Lower rpm equals better mileage.
You have a point, but the truth is that it certainly IS possible to get as good or better mileage AROUND TOWN with a lower gearset. The increased torque multiplication for acceleration from a stop can overshadow the steady-state rpm based fuel consumption. A lower rpm equals better mileage on the highway.....but around town that doesn't necessarily hold true.
Dave
true. a tale of two trucks one a 94 dakota V6 3.55's one a 95 sport dak w/ 5.2 and 3.92's. Both 5 speeds bought 2 weeks apart. My 5.2 got better gas milage than my buddies V6 and CRUSHED it an every catagory. Why the small engine has to work harder at low rpm to move the vehicle. A 318 w/ 2.76's in a heavy b-body would require the engine to work harder than the 400. Depending on cam, converter selection 2.76's might not even work as well as a stock cam. If you ahve any performance upgrades you need to look at converter and gear selection. For your 2.76's to pay off you will have to be doing a ton of highway driving at a maintained speed.
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Re: Which Engine 318 or 400?
[Re: OrangeProwler]
#913646
01/26/11 08:58 PM
01/26/11 08:58 PM
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Joined: Aug 2007
Posts: 1,819
Middle of A Field
OrangeProwler
OP
top fuel
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OP
top fuel
Joined: Aug 2007
Posts: 1,819
Middle of A Field
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To answer some other questions the reason why I am thinking of doing the 318 is because it is different and the org engine to the car. #2 is because it is about 100 lbs lighter than the 400 not to mention a 904 is 35 lbs lighter than a 727 and with less loss. I figure it might be close in performance because of those factors.
I am considering the 400 because of its bore size, transmission, and because it could make the car worth a little more potentially but, value is not at the top of my list. Just wasn't sure how close it would be because I have heard of 383s and 400s getting 20 mph out on the open road which is where my LA-headed 318 is now.
Last edited by magnumminded; 01/26/11 09:02 PM.
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Re: Which Engine 318 or 400?
[Re: Mr.Yuck]
#913648
01/27/11 12:43 AM
01/27/11 12:43 AM
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Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
HotRodDave
I Live Here
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I Live Here
Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
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Quote:
Quote:
Quote:
This thread seems to be losing a bit of focus. It also fails to mention the goals and what car it's intended for.
All else equal, 318 will surpass a 400 in mileage.
Also, I'm not buying the deeper gear might get better mileage. May for the 5 to 10 seconds it takes to accelerate from a light but once you are at a constant speed. Lower rpm equals better mileage.
You have a point, but the truth is that it certainly IS possible to get as good or better mileage AROUND TOWN with a lower gearset. The increased torque multiplication for acceleration from a stop can overshadow the steady-state rpm based fuel consumption. A lower rpm equals better mileage on the highway.....but around town that doesn't necessarily hold true.
Dave
true. a tale of two trucks one a 94 dakota V6 3.55's one a 95 sport dak w/ 5.2 and 3.92's. Both 5 speeds bought 2 weeks apart. My 5.2 got better gas milage than my buddies V6 and CRUSHED it an every catagory. Why the small engine has to work harder at low rpm to move the vehicle. A 318 w/ 2.76's in a heavy b-body would require the engine to work harder than the 400. Depending on cam, converter selection 2.76's might not even work as well as a stock cam. If you ahve any performance upgrades you need to look at converter and gear selection. For your 2.76's to pay off you will have to be doing a ton of highway driving at a maintained speed.
I dare someone to explain what it means from a physics point of view what happens in a engine that is "working harder" and getting worse MPG. The fact is the smaller engine is going to have less friction, less pumping losses due to smaller displacement and since you have to run a higher throttle angle to achieve the same HP output you will have less vacuum fighting the pistons downward movement. It will also have the air and fuel molecules packed more closely together so they burn better, just because mopar failed with the execution of the 3.9 does no mean it should get worse MPG than a 5.2 my current 3.9 dakota v6 is the first V6 truck I have owned after owning many 318 and 360 trucks and with the same driving habits it kills ( or CRUSHES) the other dodge trucks I have owned in the MPG department. I built a 318 just to get better MPG in my cuda and got 29 mpg, I got significantly worse MPG with a 2.94 gear than I did with the 2.76 INCLUDEING in town. It is all about execution of the entire package. And if you tune it to get proper air fuel mix and ign timing at low RPM than it will get better MPG when geared higher. Low speed/high load tuning is very hard with a carb and distributor. I also dare someone to explain how they built a 512 cube big block with 4.88 gears that got 29 MPG because it hardly had to work at all to move a cuda. How come a neon with only a 122 cube engine and even heavier than my cuda can get 33 mpg? That little engine is working its butt off to move those things, especially the newer ones that are bigger and have an OD gearset.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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