Alright, been reading a lot here this week or so, using the search feature, and still find myself wondering what benefits I would yield from a Super Six setup on my 1966 Dodge Dart. I know what my goals are, and will quickly convey them for the experts. The Dart is a family heirloom so not going to go all out on it, but would like to have some gains for towing up to 1000 pounds of trailer/garden tractor behind it to local car/tractor shows. So mainly looking for improvement of torque, but know hp will help me maintain speed up my WV hills. The plan is to rebuild the 225 engine next winter, .020 over, shave the head a little to true it up, and a basic stock rebuild. Then the upgrade would be carburetion and exhaust, but is it really a gain to me? Regardless I do want to go with Dutra Duals into a larger single exhaust since I know I already have a cracked exhaust manifold on my one barrel setup. Second, I know for factory spec rebuild of a slant six, a four barrel carb is out, and Super Six setup would be the most I could do. But, how much more would it gain me over just adding the Dutras to my stock one barrel setup? I am somewhat confused, and probably over reading into everything, but I still don't think I am crazy... Yet lol. Thanks

The super six is a great upgrade. It may only add 10 HP but when you only have 100 to start with, it is easily felt in the driving of the car. With your Dutras and a little more compression, you will be impressed with the improvement.

Rick

PS Where are you located in WV?

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

Near Pennsboro, WV

If you are going to have the engine apart, significant gains can be had by upgrading the camshaft and increasing your dynamic compression ratio to around 8:1. This doesn't add very much cost to the rebuild, but it will require you to select your camshaft ahead of time and do some measuring. You will be machining the head anyway, so why not take the opportunity to really improve the power and efficiency of the engine? The stock cam in your 66 Dart is one of the weakest cams Chrysler put in the slant six. Even stepping up to the stock 72-up cam would be an improvement.

Honestly, I would upgrade the cam and compression before upgrading the carb. A larger exhaust is definitely a good idea.

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Casually looking for a Clifford hyperpak intake for cheap.

Ok, so say I upgrade to a 72-up cam, how much off the head would it be to bring the dynamic compression up to 8:1?
Then, what if I don't want to shave that much off, and just took off even half of that, how much dynamic compression could I expect?

If you are going upgrade cam and compression that will only help your super six to run even better. But upgrading to a stock 72 cam ?? It costs no more to do a real upgrade in the cam and many people on here have done so. Do a search or get a recommendation from someone like Doc. He is a real expert!

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

Ok, I know I could do a real cam upgrade, but I really don't want to get too far from stock since I do want it to still start and idle well, and if I ever decided to go back to the factory 1 barrel setup it wont hurt me later. With it being a car with family history, I have zero reason to make the engine capable of ripping out the rear axle lol. But being I would be in the engine anyhow, small gains would be great for overall performance since I would like to tow a small trailer.

This question cannot be answered until you do all the necessary measurements and calculations. Do a search on the forum for "calculate dynamic compression ratio" and start reading. It takes a while to wrap your head around it, but it is a very important number to understand.

Really, if all you are after is a mostly stock rebuild for a family cruiser, then just leave it stock. Maybe upgrade the exhaust to a larger diameter, but don't worry about things like cam and carb upgrades.

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Casually looking for a Clifford hyperpak intake for cheap.

This isn't the type of upgrade they are asking, if you are going to tow a ligth trailer, and want to keep the mileage then this build is what you will be shooting for (and what they are recommending):

9-9.2:1 compression ratio (right now your car could be 7.5-8.4 at best guess considering the factory was not into tolerances for the 'grocery getter budget engine'...
Add a super six to improve breathing and add the 2 1/4" exhaust pipe...do a search for Aggressive Ted's "254" cam or a Comp Cam 252....these will keep the low end torque for mileage/towing and when cruising it will keep up with a 273/318 car....a little distributor spring work and it all good.
Since the machinist has to work on the head to get that compression ratio, have him clean the casting icicles and ridges out of the ports and bowl and install new exhaust seats so you can use unleaded without worry. Also the machinist will need to "degree" the camshaft and not "line up the dots, or it will not work out so well (get local recommendations and go talk to the guy and see if he can do this...if he doesn't it will really show).



This is easily do able and fun to drive but won't compromise the look of the car (and it really is almost all "stock" parts), and it's only a hair above the stock build (and with gas adding ethanol, this will help keep a little mileage, the stock engine will show a 5-10% decrease in mileage with the new formulation).

-D.Idiot

DI,

I appreciate our input, and went reading about both the 252 and 254 cams for a few minutes. Are these the the most mild cams out there, aside from factory? Or I guess what I am asking is what is the factory cam number so I have a way to understand the relationship between them.

I guess I get lost on one detail still, compression ratio. I think you are talking in the static when you say 9-9.5:1, and the others are talking dynamic when they say 8:1. Am I reading right when I say these are the same acheived goal and are directly related to each other, or am I confused now...

I still plan either way to add Dutra Duals into a single 2.5" exhaust all the way back, want to eliminate the cracking exhaust issues and help it breathe better. Oh, and I am kinda looking to achieve a little visual "wow" factor under the hood of the four door family car. Shiny parts help lol.

By the way, when I said I had no reason to tear the rear axle out, I was only saying, I want to keep it a mild build, and started to feel scope creep lol.

The stock 1972 cam is in the 240-244 range with about and 1/8" or so less lift (.414-.424)...compared to say the 252/254 at .435...

A quick run down on SCR vs. DCR...I figured since you are newer to the board and it would be easier to work with the 'bread and butter' numbers the typical end user is used to vs. the engine buildinging hobbyist that is now looking to get the most out of the build...

The SCR or static is just swept volume ratio, volume of piston BDC vs. piston at TDC, this tells a little about the engine's setup 'vaguely' but really isn't as useful as the DCR or dynamic ratio which takes into the account that the cylinder does not really start making useful compression until the intake lobe ends and the intake valve is closed...it also is a useful scale to see what your engine build may do (i.e. stock static compression and a big cam? DCR says even a turbo won't help (5:1) and the the model T will beat it at the light...lots of compression and a short RV cam to build lots of cylinder pressure, or lots of advance when setting the cam sometimes...yep, the DCR will tell you that Diesel or the highest grade gasoline may not get you out of that (11:1)...)

For best street manners and to get best power out of our little engine, and still run it on lower octane pump gas, shooting for 8-8.1:1 DCR is a very good target.

By the time you get your duck in a row and do the build and the upgrades, you'll be more of an officianado than most V-8 builders...
and can say that you did it and why...


-D.Idiot

Ok, I am on board with the idea of the 252 cam over the stock 1972 cam.
Been doing more reading and leaning toward the Erson 254 cam now.
And the target of 8:1 dynamic compression sounds to be a reasonably simple goal to achieve on this engine. And given my plan of the super six upgrade with Dutras it sounds to be one of the most well matched up parts to use for a light towing, fun driving, gas sipper. Now I just have to figure out how to use that calculator to determine how much off the head that could be...

I did like your analogy of "even a turbo can't help you and the model T will beat you" LOL

Ok, adding a question here. Crank, rods, pushrods, etc, are there any tricks or are these going to still be the stock pieces. I know that sometimes a truck crank can be used to get more durable, but are all the stock parts going to live up to a mild build or will I have to get better ones?

You may need custom pushrods after taking a generous cut out of the block and head to get your SCR where you want it...all the other components are more than fine for this build(My last motor was in the 12:1 range and it's still a stock car, mid-70's crank with stock reconditioned rods....I think I'd worry if I were planning the 300hp slant, but a 250 hp slant is fine at this point...just make sure to take care of the little details like the pocket porting and casting flash in the runners in the head and it will be a whole different beast.

-D.Idiot

How generous of a cut are we talking?

I almost lost my Midnight snack over here when I read that generous cut out of block. I know shaving the head is nothing and true up the block is minor, but a generous cut... How generous???