Battle: small block vs big block

[elacruze]

                                         
As for the T-bar and swaybar thing, it's all about where the T-bars are pushing up on the chassis.  In this case it's the inner pivot point of the LCA.

Think of it this way.  Imagine if we're trying to hold up the front end of the car with coil springs.  Putting a huge 2000-lb spring under the center of the K-frame is not as stable as using a pair of 1000-lb springs with one under each LCA.  Same total spring force under the front end, different effects on body roll.  
                   

Not exactly-your example assumes basically a weight balanced on a single spring or between two. You have to consider the torsional rigidity of the car, and the effect of the rear wheels too; if the car was perfectly stiff, there would be no difference between coils outboard and torsion bars inboard. The biggest difference as driven is that in Chrysler cars, the shock towers/inner fenders don't have to bear the burden of spring load. Remember how Camaros and Mustangs had to have fenderwell braces so they didn't fold up? They put all the front suspension forces through those points, and suffered for it. Chryslers transferred those forces to the middle of the assembly and spread it out over a much larger area. The shock towers bore only the burden of shock absorbers, and the inner fenders only serve as stiffeners for the front frame stubs.

[Mike DC]

Yeah I realize that about the forces being held low in the chassis.  The T-bar setup really reduced the need for shock tower structure on these cars 

We also see the issue come up with the coilover conversions for these cars.  They don't go over too well unless the unibody's shock towers are reinforced.    (Although the RMS AlterKtion setup avoided the issue nicely with those upper spring mounts on the K-frame itself.)

IMHO the thing about the T-bars having less leverage against body roll was a wise thing overall.  A car with less leverage in front and more in the rear has a built-in tendency to understeer as the body rolls.  Maybe it's not as relevant to us now with all the aftermarket options we have today.  But in the 1960s they were tuning the suspension for safe understeer even on cars with no swaybars at either end.  We have to remember the engineers were designing this same basic setup for every car Mopar was making in that era.  The compacts, the sedans, station wagons, luxo-barges, etc.

   

[Ghoste]

As I think back on it, another not too small factor in that old car that I mentioned was that I likely had bias ply tires on it.

[68corazonetR/T]

Old Timers....Yuz had all the fun!   What's a biass tire anyway.....Jk
Anybody know why my icons don't work...... guess I'm no spring chicken ether  Looks like the battle is over and the Thread is dead

[68corazonetR/T]

Ohh WOW They do work 

[suntech]

These car bodies aren't really that heavy for their size.  They just end up feeling heavy because we put a huge chunk of cast iron in the front end.

How about replacing ALL cast iron with aluminum  That is well over 200 pounds shaved off the nose right there
Lots of cubes and torque, and low weight.......at least compared to a cast iron motor!

[Mike DC]

                            
Yeah, I wonder how low the engine weight could go with all aluminum motors.  Under 500 lbs seems do-able even for the 1960s based motors.

It would be nicer if we had a (streetable) aluminum version of the 340/360 block.  We don't have it and I doubt it's coming any time soon.  

But if you built a B-based wedge motor as opposed to the higher deck RB variant, and made that all aluminum . . . possibly in the 450 pound range?  That's down near aluminum Chevy SB weight and you could punch the displacement well over 500 inches.      

   

[Ghoste]

Aren't there examples out there of B-bodies with lightweight everything in the front end?

[suntech]

Yeah, I wonder how low the engine weight could go with all aluminum motors.  Under 500 lbs seems do-able even for the 1960s based motors.

I read somwhere here, and i think it was you Mike that posted it, that a standard BB was in the ballpark of 670 lbs, so i think 450 is possible then.

Aluminium block is 142 versus 309 for cast iron, so there is a 167 lbs saved just there. another 55 or so on heads, inlet manifold and waterpump?
That´s in the ballpark of 220 lbs saved just on motor!
Then an aftermarket front suspention can save 65 lbs, and a carbon hood another 40, and aluminum rad 10 more.
That is over 330 lbs lost, and ALL  of it just over the front wheels.
Then move the battery ( 40 lbs?) in the trunk, to help balance, an you would have a car 33o lbs lighter ( 370 lbs lighter on the nose, and 40 heavier on rear).

If i use the # from when i was on the scale with my car at the DOT, with me sitting in the car, and 3 gallons of fuel: 2155 front
                                                                                                                                                                      1650 rear

Just with these mods it would be: 1785 front
                                              1690 rear     
This would give us a weight distrebution of approx. 51,5% front/ 48,5% rear!!! Not bad for a 40 + year old ride..... and there is more to do to get it even closer to 50/50, without adding weight!

[Mike DC]

Okay now I'm curious.  Gonna start thinking . . .

Aluminum block is 142 versus 309 for cast iron

The aluminum numbers I've heard for RB blocks are either 133 or 142.  Maybe it's the different brands.  

309 is too high for the iron block numbers though.  The stock B and RB blocks are more like 215 and 230 pounds.  (But I would believe 300+ pounds for the beefed-up reproductions of the stock iron blocks.)  


The (wedge) cylinder heads alone can lose 50-60 pounds when they are switched to alloy.  The weight loss figure for the alloy intake/water pump/housing & tube headers & mini-starter  . . . that would probably add up more like 100 pounds total.  So figure 80 pounds off the block and 100 pounds off everything else.

If you did a low-deck stroker wedge motor (they do make low-deck versions of the aluminum wedge blocks now, don't they?) then you might be as low as 460-480 pounds.  Pretty amazing when you consider how much power comes from a decent 500+ inch Mopar wedge.

[suntech]

The weights i mentioned is the weights that was listed on the World Product website, for the Mopar Wedge/ Hemi block.
Vent to the website now, and the cast iron block was not listed, but i am positive it was listed with weight 309 lbs when it was there!!

[suntech]

The weights i mentioned is the weights that was listed on the World Product website, for the Mopar Wedge/ Hemi block.
Vent to the website now, and the cast iron block was not listed, but i am positive it was listed with weight 309 lbs when it was there!!

One thing is for sure......i WILL weigh the old 383, and i WILL weigh the new 611  ......like i am going to do with everything else i pull off and put on the car

[Ghoste]

One source I have lists the low deck block as being around 225 lbs.
Needless to say I think we all look forward to your real world measurements.

[firefighter3931]

The weights i mentioned is the weights that was listed on the World Product website, for the Mopar Wedge/ Hemi block.
Vent to the website now, and the cast iron block was not listed, but i am positive it was listed with weight 309 lbs when it was there!!

I have a world iron block and it weighs 300lbs bare. Stock RB blocks are 230lbs so there's a 70lb weight increase. Thats the price you pay for increased strength and larger cubic inches 

An all aluminum Hemi is still going to be fairly heavy....those big heads and all that additional rocker gear add up on the scale. It might be slightly lighter than a cast iron 383 but not by much. A buddy has an all aluminum 547 hemi and he told me it's no lightweight 


Ron

[Ghoste]

So an elephant on a diet is still an elephant?

[suntech]

So an elephant on a diet is still an elephant?

Hehe, i guess so!

So Ron, what you are saying is that the standard cast iron block i have(383) is app 230 lbs bare ?

[Bob T]

I grabbed the weights off another site.

Slant Six = 475lbs (215kg)
273-340ci V8 = 525lbs (238kg)
360ci = 550lbs (249kg)
361-383-400ci = 620lbs (281kg)
413-426W-440ci = 670lbs (303kg)
426 Street Hemi = 765lbs (346kg)
Alloy Hemi 528ci (assembled) = 470 lbs (213kg)


Back to the Rover ali 4.2, not bad, they were using them out here as race boat motors in the day, good power to weight, but orphans really , not much available for them .

[Ghoste]

Those are dressed weights though not bare blocks.  Which one were we trying to establish?  (or does it even matter?)

[firefighter3931]

Those are dressed weights though not bare blocks.  Which one were we trying to establish?  (or does it even matter?)

Exactly  

I was reading an older PHR magazine with an all aluminum ICH 572 Hemi build and the long block assembly was listed at 535 lbs. No waterpump/housing, no carb, no distributor, no headers/manifolds.


Ron

[suntech]

I guess since we are talking about total weight of car, drivability and weight distribution, the interresting thing must be the weight of the complete engine 

[Ghoste]

Ultimately yes but I thought we were just trying to break down the weight of some of the individual components and the bare block was the one we were having trouble with.

[suntech]

True Ghoste

There is also a lot of different weights on intakes etc that can play a factor. I think mine will be light, with aluminum runners, and carbon fibre plenum. Going fuel injected.

[Hissing Cobra]

To me, it's more a question of total weight vs. horsepower. Yes, torque does play a role but in order to move the car, you need proper gearing and a suspension/tire package that are worthy of taking advantage of that extra torque. All too often, I see people at the track with big blocks on skinny tires that run high 13's where they should be in the high 11's or low 12's. Most people forget that it's the ENTIRE package that makes a car what it is and not the fact that it's a big block that makes huge horsepower numbers.

I have a friend who own's a big block 455/Turbo 400 powered '72 Buick GS. His engine is built about as well as it can possibly be built and still be streetable. By streetable, I mean, the ability to drive it anywhere at anytime. Cruise nights, car shows, track rentals, Ice Cream outings, etc... He's making 368 naturally aspirated rear wheel horsepower, which equates to well over 400 at the flywheel and is well in excess of what his car was rated at when it was brand new (360 at the crank). His best time at the track has been a 12.90 @ 105 with crappy gears. For some reason, he can't understand how my naturally aspirated 306 powered '79 Mustang Cobra can outrun his "big block", especially since mine "only" makes 307 rear wheel horsepower. The answer is very simple. My car weighs 2,950 pounds vs. the 4,000+ pounds that his car weighs and my power to weight ratio is much more efficient.

The argument about "Big Blocks vs. Small Blocks" shouldn't really be compared at all as it'll be a never ending argument with nothing really proved. Sure, there are a lot of big blocks that will kill a small block equipped car, but there's plenty of small blocks that'll kill a big block powered car as well. It's all about power to weight ratio, maximizing the combination, and driver skill more than the size of the engine or the horsepower numbers.