M- Body Quarter Mile times

[cruzerjd]

I was just wondering if anyone had an idea about what an m-body, i.e. Diplomat, LeBaron, etc. might run in a quarter mile. I'm not talking a built to the gills big block swap car, just yer run of the mill car. Mine has a 318 with a MP ignition, and a Holley 600 cfm 4 barrel on a stocker iron manifold. It has 2.76 gears and weighs about 4400 with your's truly aboard. No frills or special equipment, just back yard hop up. I was thinking maybe a 17.5 or 18.0 if I was lucky. Any ideas. cruzerjd

[PRO]

I dont think your car weighs that much, if its fully loaded with 5 passengers and luggage maybe(GVW). It should weigh more like 3600 or so and it sounds like your making 220 hp that should put you in the high 16.s to low 17.s at sea level,subtract if the motors well worn. The easiest improvement would be deeper gears like 3.21s,just swap in a different differential.That would knock off .4-.5...........PRO...

[This message has been edited by PRO (edited December 23, 1999).]

[cruzerjd]

That's what I was thinking. Right now I am looking for a 3.21 two legger rear end. This isn't a real out and out performance car, just a grocery getter with a minor attitude adjustment, lol. I had thought of taking it to the local strip in Woodburn just to see what kind of times I could coax out of it. Thanks for the info, cruzerjd

[Tim_K]

Sounds like mid-17's at 77-79 mph the way you have it right now. A 3.21 gear should get you into the low 17's at about 78-80 mph. Depends on how good the engine is. I don't think you have 220 hp, more like 160 to 170 NET.
Since it's against Tim_K policy to leave a short message, I'll tell how the times and mph improved with various additions to a '72 Satellite Sebring I used to own.
With me in the car, tools and tire and jack in the trunk, and standard (for drag racing) 1/4 to 5/16 of a tank of gas, with a 318, 904, 8-3/4" drivetrain, it weighed 3830 going down the track. 3500 with empty trunk, same fuel load, and me not in it.
When I first got it, with a 74,000 mile 318 2 bbl., single 2" exhaust, and 2.71 geared 8-1/4" rear, it would run 17.4 at 78 mph.
When I improved it with a 3.23 geared 8-3/4" and a 2-1/2" dual Flowmaster exhaust off the stock manifolds, 79,000 mile 318 2 bbl., it ran 16.7 at 81 mph.
When I added a '71 340 iron intake manifold (yes, ports were mismatched to the stock 318 heads) and a #6322S 850 Thermoquad that I rebuilt, the 85,000 mile car would run 16.3 at 84 mph.
All this time, the 318 remained stock, heads, cam, exhaust manifolds, all stock. The 904 upshifted at 4400 rpm. Running it to 4700 and 5000 rpm shifts lost time in the 1/4 mile.
The horsepower numbers for these 3 levels of performance were 150, 170, and 190. They were calculated based on weight and 1/4 mile trap speed using the system in the Mopar Engines book. This gives you NET horsepower. HP at the flywheel / torque converter. Rear wheel hp would obviously be less. Hope this helps to give you an idea of what you can realistically expect.

[cruzerjd]

I seem to remember a post on another forum about a guy who was running an ex police dippy as a bracket car. He had a 360 with a 4 barrel, MP ignition and a 2 1/2" single exhaust with a Flowmaster muffler. He was running mid 16's at about 80 mph. I figured he was running about 175 hp, according to a program I found on the net ( which i lost when the computer crashed a while back). Anyway, I figure I am probably running maybe 150 hp right now due to the single exhaust and the smaller valve heads. I know chrysler rated these engines at a measly 120 net, so there has to be more rom for improvement. The next thing is a Walker Turbo II muffler and maybe do the heads in the spring. Thanks for the info, cruzerjd

[rb77413]

I have an 86 Dodge Dip ex-cop car, and I ran an 18.4 at about low 80 high 70 mph. You can stop laughing now. I know its slow, but it turns real fast in reverse at about 20 mph. The infamous J-turn. Its my "stunt" car. Just to go out and pratice evasive manuevers on a dead road at about 2 a.m. It has the 318 4bbl with the computer still in it, not positive of the gears but I think they're 2.94's. The muffler rusted off, so now it has a 1 3/4 outlet on the end of the single exhaust. It has 3 cats on it. One on each end of the exhaust manifold, and one after the two pipes come into one. The only mod is that I disconnected the air pump off it. Plus it still passed emissions as is with no air pump! Now its a daily driver, so not much is getting done to it. Big Daddy Don Garlits drag racing museum, has a 440 5th ave, in the showroom. As the "Worlds fastest 5the Ave." runs somthin like a mid to high 10's.

[cruzerjd]

Right on, now all you need is an older exhaust off an early lebaron, dippy, etc. Mine has the 2 1/4" single exhaust and a blown muffler, so it sounds pretty rough, people tend to look strangely at me as i rumble by, so the wife sez I have to eplace the muffler. Too bad

[PRO]

cruzerjd I think we have a miscommunication as I assumed your 318 to be a factory 4 bbl mtr,as you state "stock intake",is it? Let me explain my previous thoughts, a 318 4bbl is rated at 195hp but thats the cop car only,is this what you have? a 318 2bbl is rated at 160hp, if you have a California equipped car(w/3 catalytic conv.s)its rated at 140hp. So add 20hp for the MP ign.and 5hp for the holley onto your 195(cop car) and 220 should be close and would run high 16s to low 17s.If you have a 318-2bbl add the 20 total hp(smaller cam)to the 160hp and you have 180hp,you should run 17.2-17.5,if you have the 3 cat version add 15hp for 155 total and you should run 18.0 or worse,if you can remove the cats and add true duals add 15hp,you know the one thing I hate about chat sites is nobody gives enough info and you have to make educated guesses......PRO....

[cruzerjd]

Yeah, miscommunication it is. What I have was a 2 barrel 318 originally, so it has the smaller port heads and the milder cam spec's. I bought an '81 Police Package 4 barrel manifold for it and ran the Holley carb on it. I also swapped the original Lean Burn computer for the MP ignition. Right now it has the single exhaust with a Walker Turbo II muffler and the original tail pipe. I was guessing about 150-160 hp figuring in the extra power from the 4 barrel and the ignition, but understanding that it will not flow at it's best till I replace the heads with some freer flowing units. I know I will have to at least mill the 360 4 barrel heads to attain useful compression. cruzerjd