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  #1  
Old 09-15-2004, 04:08 PM
400Magnum 400Magnum is offline
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Default Need opinions on my project

Hi All,

I've been absent from the board for a LONG time, but hopefully I can get some input from you guys.

I have a project that I'm trying to pursue, and I'm just wondering if I'm kidding myself or not. A few years ago, Hot Rod magazine did an article about cars that broke into the 12's and also got 20+ mpg. At the end of the article, they basically noted that all of the vehicles they tested were fuel injected, and typically had some form of forced induction. They then asked the question if there was anyone that could do this using a carburetor instead of fuel injection. So, I decided that I was going to make the attempt.

Here's the basics:

1978 Magnum - fully streetable
Weight reduced to 3700-3800 lbs
400, bored 0.030" over,
MP template ported 452 heads with Manley Race-flo 2.08/1.74 valves,
Holley Street Dominator intake, heat crossover blocked,
Federal Mogul 440 pistons, ceramic coated on top to reflect heat and on sides to reduce friction, bringing compression up to 9.6:1,
Worked over Thermoquad to maximize economy on primaries and power on secondaries,
Crane double row roller timing set,
Lightweight roller-tipped rocker arms, 1.5 ratio,
Lightweight pushrods,
Factory cast crank, checked and polished to remove stress risers,
Factory connecting rods, checked and polished to remove stress risers,
Total Seal Gapless ring set, to maximize cylinder sealing,
Hooker headers, 1-3/4" diameter primary tube, with Flowmaster 4-2-1 Scavenger collectors and an "X" style crossover to maximize the scavenging effects of the exhaust,
I am planning to replace the current 727 with a 518 someday. Right now the 727 has the factory hi stall (2200-2400 rpm) converter and a B&M shift kit,
The rear is a 9-1/4", it currently has 3.23 gears, but I also have a set of 3.55 gears for it. I will be installing a Sure-Grip someday.

There's a lot of little details that I'm leaving out just for the sake of keeping this short, but that should give you an idea of what I'm working with.

I've done several build up simulations using Performance Trends programs for the engine analysis, drag strip analysis, and the fuel economy. In theory, it seems like it can be done, but I also realize that there is a lot of difference between computer simulations done at home and the reality of a project like this. In the end, even if all of this should not meet the 12-20 goals, then I would still like to get as close as possible.

So, if anyone would like to share their thoughts, opinions, facts, etc., it would really be appreciated. Basically, I'm looking for information on cam choices, torque converters options, etc. Oh yeah, and I have to keep this really, really cheap too, otherwise it'll never get the funds to get finished.
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  #2  
Old 09-15-2004, 08:22 PM
rellik eeb rellik eeb is offline
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Man
Thats a difficult task, that car is a big one for sure, It will take around 350-375 horses to propell your car o 13's flat or 12.90's, in a optimal well geared, nice converter....a 3.23 and factory converter isnt going to get it. say a 4.56 and 4000+ stall will help very much, but say god bye to gas milage. If I were going to build this combo I would ditch the stock heads for some eddy's probably worth more than 50 horses over your heads, bring the compression up another point 10.5:1 or zero deck and 84 cc eddy's would be close. Add 3.91 or 4.10 gears witha Keisler 5 speed, which I dont think the make for your body. And a New Edelbrock Pro Flow EFI setup, which just been released not too long ago.

Probably not the answer your looking for, but just thought Id give you my .02$ worth. I honestly dont think it can be done with your combo. You need lots of torque for that car. And the 3.23 gears arent what Id call idea 1/4 mile gears, The only weigh to gain ET and gasmilage at the same time is put the c ar on a huge diet, maybe like Jerrid did at stubway If you could save 1500 lbs more off the car it sure would help.
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  #3  
Old 09-16-2004, 10:51 AM
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rumblefish360 rumblefish360 is offline
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I think an overdrive here is the main key with an engine making hi torque at cruise rpm being the second part as the targeted areas for this.
The cars weight is to much IMO. A duster would be better. Fiberglass abound.
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  #4  
Old 09-16-2004, 01:51 PM
400Magnum 400Magnum is offline
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Yea, I know the old girl is a little overweight, and I do have plans to get the weight down to maybe 3400, but that's going to be with a lot of effort. I know I can get to about 3800 without too much trouble. I know an A-body or an E-body would be a better candidate, but I have to work with what I have at hand.

Rellik, I would love to be able to add fuel injection, but then that would instantly negate my purpose of this project, and that's to do 12 and 20 with a carb. I figured I'd have the edge by having a T-Q to work with. I'm going to probably send it to DemonSizzler (if he's still around) to get him to work his magic on. I know the 3.23 gears are on the tall side, that's why I got the 3.55's. I was originally thinking 3.91, but I haven't been able to find a set of those dirt cheap. The 3.55's were almost given away, so I snagged them.

Torque was the one thing that the 400 will make a lot of, given a decent compression ratio. That's the only thing that's giving me a glimmer of hope, is that I find the gearing, cam, and weight combo that'll let the 400 do it's thing. The beauty of that 400 is that I won't have to rev the crap out of it, I'm hoping to be able to keep the revs down to the mid-4000 rpm range and let the gearing do the work at moving the car.

Well, this is what I'm looking for though, opinions on whether this is just completely out in left field or if there is a chance of succeeding. The computer says it can be done, but I work with computers enough to know that I can't believe everything they tell me.

So, I'm all ears to hear any other comments or suggestions. Depending on what sort of information I get, I can decide whether I want to draw out the time that it's going to take to make this project work, or if I can just go ahead and put it back together and start enjoying the car again.
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  #5  
Old 09-16-2004, 08:19 PM
rellik eeb rellik eeb is offline
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Wish you luck, i think it can be done, just dont know about the 20 miles per gallon hu? I always wanted to try Demon sizzlers carbs, let use know how it goes.
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  #6  
Old 09-16-2004, 10:14 PM
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fastmopars .inc fastmopars .inc is offline
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why not try and get a valiant? an a-body cuda, a dart, duster, they are all cheap cars if not in perfect condition or if they aren't a rarely optioned unit. it would take less work to scour every highway of your country side and find a dart in a barn than try and shave over a 1000 lbs from an automobile. you would have more money in the magnum than you could ever get back out of it
the only way to do this is with a curb weight of around 3000 lbs, that is why the cars hot rod pulled 20 mpg, they didn't weigh anything and had small motors, but they in turn needed forced induction to make up for the lack of engine size.
you would be better off attempting this in a 66 valiant with a 225 /6 and two turbos
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  #7  
Old 09-16-2004, 11:20 PM
400Magnum 400Magnum is offline
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I fully realize that this is not going to be easy, if it was, then everyone would be doing it, right? I used to have a 77 Aspen that would have been perfect for this, it was a 318/4spd OD car. In stock trim it did 25 mpg on the highway at 55 mph. It had no options, so was relatively light. It would have been an easy job to get the 318 pumped up to get into the twelves and still retain the mileage. But, that car is long gone, so I'm stuck with what I have.

The problem is that I don't have any place to put another car, plus to get one in half decent condition would cost more than I have to spend. If I were to get a basket case, then it'd never get off the ground because I do not have a lot of free time to put into this. To give you an idea, the Magnum that I have has been in pieces in the garage for over seven years now. I've SLOWLY been gathering parts here and there whenever I can get something dirt cheap. Unfortunately I have a job that takes a lot of my time, and pays very little, but it's the only ball game in town, so I don't have the luxury of quitting and going somewhere else.

So far the general consensus seems to be that this will probably never happen, and I am inclined to agree, but I thought I'd get some opinions and maybe some ideas from everyone here to make this thing at least come close to working.

Well, I guess I'll just keep collecting parts and see what I end up with.

Thanks for the input! Keep it coming! I'm still wide open for more information and opinions.
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  #8  
Old 09-16-2004, 11:31 PM
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MoparMarcIdaho MoparMarcIdaho is offline
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All you can do is try and I commend you for your efforts.The 400 is an oddball to make work like it should,the 383 on the other hand while sharing a lot of similarities seems to do better because of higher compression ratios.Ive never had a cast crank motor that I can really say I liked but Im old school too.Its guys like you that will come up with a way to make it happen-go for it.
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  #9  
Old 09-17-2004, 12:51 AM
powerwagon powerwagon is offline
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Default i commend you

go for it 'git r dun' like Larry the Cable Guy says. i would say this though, with as much flow as the listed valves are gonna give you, i would say that you aint gonna hit the 20 mpg mark, but that depends on your cam too (I didnt see numbers for that). An OD unit would help, cuz then you could run your 3.91 gears for the strip, but still putt a long down the highway in 4th gear to try and get your 20 mpg. Good luck, let us know how it goes, i think its cool that you are attempting something like that, i wish i had the money to do that kinda crap....
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  #10  
Old 09-21-2004, 01:56 PM
400Magnum 400Magnum is offline
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LOL!! I like Larry the Cable Guy too, makes me laugh every time I see him... He sort of reminds me of one of my cousins, and that's all I'm going to say about that...

Thanks for the encouragement guys, I appreciate the support. I did have plans for a few "secret weapons" that I was working on to help along the effort, but I don't know that they'll ever see the light of day.

At this point, the cam was going to either be the OEM cam (.434"/.430") or maybe a Hughes 0515, or maybe the smallest lift Crane roller cam ( I have my reasons for picking Crane if I go to the expense and trouble of going to a roller setup). My thought was that I would work the engine to develop a lot of torque, and let the gears do the work of getting 'er up to speed or do the cruising. Granted, not very exciting, but it seems to be my only hope of reaching this goal.

I'm not going to be opening up the ports on the heads or intake much, mostly just going to be gasket matching and a little blending. My thought being that if I keep the port sizes smaller, then the flow velocity will stay high and keep the fuel atomized better, resulting in a clean burn, rather than hogging it all out and just having the fuel dump into the cylinder. The valves are the stock size, they are just necked down and polished up to reduce any flow restrictions. The stock compression on the 400 is pathetic, mine worked out to something like 7.6-1, which is almost useless. But I'm hoping the pistons I have will make a significant boost while still being pump gas friendly. I may install a thicker head gasket just to knock it down from 9.6-1 to about 9-1 or 9.2-1. I'll try it at 9.6-1 to start with though, just to see how the engine handles it. Between the low cam lift and the (I'm hoping) turbulent mixture, the engine won't knock like a diesel.

Well, I don't have a lot of money to throw at this either Powerwagon, that's why the car has been sitting in the garage for over seven years now. Takes a lot of time to save up my pennies to get the parts I'm looking for, and even then I have to buy most of my stuff off of Ebay or other classifieds. I don't think I've bought anything new except for the gasket set!
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  #11  
Old 09-22-2004, 12:26 AM
powerwagon powerwagon is offline
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Default you aint the only one man

i just bought a thermoquad off ebay last week thats comin in the mail for my ramcharger Gotta love this new technology age i guess, although a lot of it is confusing for a simple country lad like myself.....
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  #12  
Old 09-22-2004, 09:44 PM
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benwest benwest is offline
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good luck. i am going to make my aspen a 10 secend street legal pump gas car someday.
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  #13  
Old 09-24-2004, 07:50 AM
400Magnum 400Magnum is offline
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Wow, that'll be a screamer!!! Do you mind sharing how you are planning on doing that?
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  #14  
Old 09-24-2004, 08:53 AM
DartGT66 DartGT66 is offline
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That's not so difficult. Little weight, make reasonable amount of power, good drivetrain and a working chassis. We have four of them in our neighbourhood, although one runs 9's. One is even equipped with a pretty low buck 400 (10.65 weighing 2930 lbs).
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Old 09-25-2004, 01:31 AM
Brian Mills Brian Mills is offline
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Default Hello 400 Magnum

Thought I'd throw in my .02. Since you have a 91/4, why don't you try and lay your hands on a set of 4.10's. They are very plentiful in pickup trucks, likely find one with a sure grip. The rational here is that will give you a final drive in the 2.82-1 area with an A-518. 3.54's will give you a final of 2.44-1. Both of these final ratios have the 20 MPG potential. 4.56's equate to 3.14-1 final, and 5.13's will give 3.54-1 final. You know those 4.56's even look good.

One word of advice is that the tourque converter seems to be fairly critical in these O/D transmissions. My 1991 318 4x4 has 3.54 and drops 700-900 RPM's at highway speeds. I put an A-518 in my 1985 Ramcharger with a 360, the trans is 1990 from a 318 truck, so I used the tourque from the 1985 360, and the revs typically drop only 300-350 RPM at highway speeds. To be fair the Ramcharger has a 3.23 rear gear and 33x12.5x15 tires however I think the 1990 318 tourque would have been a better choice to use had I just installed a set of external balance weights.

The truck market seems to like the 4.10's for economy these days, I know your car is 1500 lbs lighter than a 4 wheel drive pickup and the theory is that an engine that lugs loses efficiency. A few more revs shouldn't hurt cruising milage as long as you stay away from the secondaries.

Brian Mills
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Old 09-27-2004, 10:47 PM
400Magnum 400Magnum is offline
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Thanks for the confirmation Brian. I was thinking along those lines. I have a friend that installed 3.73 gears in his 5.0 Mustang at the same time that he did a lot of typical hot rod mods (headers, Flowmaster exhaust, high performance chip, intake, K&N, etc.) and he ended up making the car perform better and got better mileage too boot. He researched his choices for well over a year or two, to make sure that he got components that worked well together. In the end, he improved efficiency and power. Apparently, the car is able to get into overdrive sooner and not lug the engine, plus the engine has more power to move the car at lower speed in a higher gear, so it all works better. Sort of makes me wonder why the Detroit engineers can't do all of this from the factory.

Anyway, that was what I was thinking. If I can boost low-end torque to the point where I can run the car in higher gears than what is typically done and not lug the engine, then I should be able to meet the 20 mpg aspect of the project. Even though it's a 400, if I can keep the rpm relatively low and move the car using the right gearing, then I should be able to do pretty decent.

However, it's all becoming a futile effort. My job security is not looking real good right now, and there just isn't any extra money for the Magnum. So, unless I find the winning lottery ticket, not much is going to be happening for the foreseeable future. Oh well, I can still day dream about it happening...

Thanks for all your replies. If I ever get to pursue this any further, I'll be sure to let you know how it turns out.
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Old 09-30-2004, 12:59 PM
Brian Mills Brian Mills is offline
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Default 400

Sorry to hear about the job situation, hope it all works out.
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Old 10-02-2004, 04:51 AM
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rumblefish360 rumblefish360 is offline
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Never surrender the dream.
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