Small difference Al vs Cast
 

Ron,
I have been a little surprised at how little the weight difference is between the blocks. This probably says more about my lack of knowledge at this point than anything. My car had the Aluminum 460 in it when I bought it. No way could I have built/bought the engine otherwise.

I'd really like to see some pics of your engine/installation sometime. Enjoy.

What about cost
 

I realize my response addresses something outside the original thread question. Please forgive.

Consider the costs of each: SB v. BB

If you are going to race, the SB will be a more cost efficient than a BB. THere are a lot of inexpensive ways to beef up a SB. BB start out costing more in iron or aluminum variety.

Engine Stuff
 

Jim-I would love to post some pictures of my car and engine work. But you see I am a total computer idiot and really don't care that much to learn it either. I really need to flash some pictures here on this board though. As for block weights I have heard that a aluminum FE block by Dove Mgf. weighs in at 120 lbs. Don't know if that's true though. If so I bet it costs a bunch.

JWeaton-I recomended a smallblock above. I have a serious love affair with big blocks though. I tend to ignore the pros and cons stuff on small vs big blocks and write them off as personal choice. I don't claim to know much either, but this much I do know. When it comes to building Detroit iron, the costs of building both small and big block stuff is really the same when you compare identical horsepower numbers. Big blocks will allways give you the edge in bottom end torque. Small blocks are lighter and you have to buzz the motor more. But again, the costs of both builds are always close to being the same unless you get into rare or exotic parts. The costs will climb quickly for both styles in that case.

Is one style better than the other? In a word , YES ! :LOL: :LOL:
:cool: :cool: cobrashock :cool: :cool:

Don Terrill is a former Winston Cup engine builder and R&D resource for Comp Cams. In his book "Secrets of a 740 HP Winston Cup Engine" in the Intro he writes;
"15 of the Biggest Engine Mistakes"
" Mistake #4 TOO MUCH LOW END TORQUE- Everybody says the same thing to me; I can hook up as much torque as you can build. They never can, but you can't tell them that. You've got to go ahead, build the engine and let them learn by themselves. I think the truly smart people in racing are those that have figured out how to build the right amount of torque."

I have to admit I was one of the people you couldn't tell anything, but I know now.

Torque anyone?
 

ScottJ- The question posed is one of semantics. I.E. , A question asked when building a cobra. To that it is hard to look past a smallblock, I concur.
But as for Rule #4-That's as wrong a statment I have heard in quite a while, to the point of being almost gross. Torque management is as much a part of building race cars as is handling,gas mileage,brakes.etc. One only has to look to All forms of racing when large cube motors were allowed. The end of big blocks was usially dictated by politics(I.E.- rule changes) , not about the pros and cons of what I read and see on these boards.
These folks that think so highly of small block engines only need to look at NHRA or IHRA racing to come back to reality. Those guys still race them "obsolete" big block motors.
As for me, as I have repeated this many times, my stated goal is to go 8.5's in the quarter mile and do it in street trim. I really don't think I can do that with a smallblock and stay streetable. All that in a cobra to! I have been NHRA racing for quite some time so I know this goal is reachable.
As for Winston Cup racing. Ever wonder how fast those cars would go if they still ran hemi's and boss engines? Remember, they went 200 mph in the early 70's. Guess I am showing my age!
cobrashoch ;) ;) :) :cool:

Easy Ron:) , I wasn't directing my comment toward drag racers, merely agreeing with what you said a few post back about the inability of these cars to get much more than 600 HP to the ground.

The one thing I've noticed being overlooked or at least not commented on when comparing engine weights is rotating inertia. Even if an aluminiun big block engine weighed the same as an iron small block it would still have more rotating inertia than the sm blk. A typical BB crank weighs about 80lbs and an ultra-light about 60lbs. A typical SB crank weighs about 55lbs and about 38lbs for an ultra-light or Cup crank. While the the additional rotating inertia might help to launch a car in drag racing, it hurts times in road racing and circle track. The weight loss, for components that rotate at engine RPM, is 15 times more effective than an equal weight loss for other components of the car.

My reality check came when I began racing (not the Cobra) in a division with the only engine rules being: any 4bbl carb, 2 valves per cyl., and gas or alcohol fuel. We have no restrictions on displacement, aluminium blocks, roller cams, carb size, heads, or anything else. In a class where virtually anything you want to build is legal, short stroke 360ci engines dominate. Why? Because they have the right amount of torque for the tires and chassis to get off corners and their 38lb ultra-light cranks allow them to be driven in deeper and rev quicker. At the national level 430 inch engines like mine are almost non-existent unless its a larger, momentum track.

Good luck in your effort to run 8.5 with your Cobra.

Scott

P.S. go easy on Don, before building Cup engines, where his had 2 poles, 5 front rows, 2 event records, and 1 track record in his first year, he built drag engines where his set 8 NHRA national records. ;) :)

It really depends on the "setup" of the car. When I was eighteen years old I had a friend teach me about "proper chasis steup". He showed me that a proper setup car was the difference in racing. He use to have a Pontiac Version of a Vega (called ASTRE) and he had put a 406 (400 stroker) small block Chevrolet in the car. He showed me that with 13" tires he could smoke a 427 Corvette from streetlight to streetlight from a stop. His car jumped one full car lenghth off of anyone he ever raced! As long as the race was only to about 120 MPH, it was never beaten (if the 427 Corvette had raced him from a 35 mph roll it would have been a different story).

I know that it is easier to setup a small block car compared to the nastier big blocks, but it can be done.

If I was going to race my Superformance car on a road track, I could find other things on the car to lighten besides the engine.

As far as the engine goes, some of you have seen to many 427/428 guys that like dual 4 bbl carbs. and Weber injector setups and don't realize that most 460/460 stroker engines are running with just one 4 bbl carb.. That alone is a decent savings of weight.

I guarantee that I can lighten the front half of any comparable Cobra and equal the weight between a small block car and a big block car. For example: if the front of a Superformance Cobra weighs 1,200 lbs with a small block 351 engine and the front of a Superformance Cobra with a big block 460 weighs 175 pounds more , I gaurantee I can find a way to get rid of the extra weight and then some.

It is so funny that people make a big deal about 175 more pounds and act like there is no way to lighten the front of the car.

More engine stuff
 

Scottj-Interesting thread we got going here , ya think? Don't know Don Terrill is but I will pickup his book. Don't think I will agree with much he has to say though or in the very least it may recap what I " think " I know. I'll see.
The weight of the rotatating assembly on the bottom end is but a one factor that determines how a engine accelerates a car. I've seen it repeated over and over again and this is the #1 oversimplification I see when guys want engines built. The overwhelming limiting factor to how a engine revs is the valvetrain or the topside of the engine. Other factors play limited roles like rod angles, friction reducing coatings, non skirted pistons, dykes rings, head port design and so on.
The top end problem is what has doomed the Chrysler hemi (old style) to a non competitive status in the last few years with gas engines. Valvetrain was just to complcated. Carried to the other extreme, why do formula engines rev to 17,000 rpms almost instantly? Because they don't have a valvetrain resisting rotation that's why.
Now , back to the bottom end. I've seen dirt cars (true mad dogs) engines with bottom ends so light that they actually slow down a car going into a corner. This is because a engines internal friction slows the car with no resip. weight to keep revs up when they let off the gas. There is a balance point here for performance on bottom end rotating weight. Another thing most guys don't know, Cup engine builders build engines to the lenth of the track and turn lenths. The same thing happens for drag guys to. To light and the car will not launch, to heavy and it slows down the big end R's. Back to the big block heavier crank weights- it's really a small cog in a very big wheel.
As for the cup guys engines, I haven't seen the rules they go by for a couple of years now. But back then they mandated types of rods,pistons and crank weights. All this stuff added rotating mass. We really had (or have?) much better aftermarket parts availible we can use on our "street" hot rods.

Bandit1- I am a big block guy. But when it comes to lightening up a car anything a big block guy can do, a small block guy can do to.
As for how big blocks run, I like the way you can get on them in any gear from any kick point. Small engine guys have to shift.
:LOL: :LOL: cobrashock :LOL: :LOL: :JEKYLHYDE

My comment wasn't about a big block car being lighter than a small block car. The comment was that there is a myth that a big block car can not be light enough to be non "front heavy".

When I test drove the small block stroker engined Superformance cars, I could tell that the front end would pretty much go wherever I told it to. I felt that I would have had to "over drive" the car to make it wipe out in a corner. There big block 460 crate engined car however felt that if I wasn't paying attention and planning my turns, I could end up in a ditch from just the extra weight of the front of the car.

My point is this:

1. Both of these cars were setup the same. There is no universal setup for a small block and big block car I know of.

2. The 460 was a basic "crate" engine and could of had alot of weight taken off of it.

3. If I was racing alot, I would have many things I would do to my car to lighten the front of the car. Because there are no weight restrictions that I know of in the racing events the Cobra's are in, I wouldn't think a small block Cobra owner would be to concerned with trying to get there car lighter.

4. Everyone is saying that the big block Cobra's are 175 + pounds to heavy in the front to road race, I am saying I could trim 175 + pounds from the front of the car and handle the added torque with no problem!

There was a recent thread on here stating that a big block Cobra was at Run and Gun and that the guy tried to road race but the car would just spin the tires the length of the track. My thought as any big block owner knows is to be on the edge of the power were you aren't spinning the wheels. When I give someone a ride there are two different styles I ride.

1. "Burnout". People think it is neat when the car spins the tires through the 4 gears and can spin them at 90 + mph. However, this is not the way to move the car fast.

2. "speed". This is me driving the car with just a small "chirp" out of first gear throught fourth and then into fifth just under the loosing traction throttle position.

It can be done, as soon as Superformance sponsers my next race car I will be happy to demonstrate... Big blocks rule!
:)

Big block madness
 

Bandit1- Love the way ya think.:3DSMILE: One of these days someone, but not me, will screw together a 600 cube monster car that will give All the small engine guys heartburn. Just a matter of time!:p :p
cobrashock:MECOOL: :MECOOL:

Paul,

aluminum engines are suitable for racing.

SB vs. BB:
The tires dictate the torque that can be delivered to the tarmac.

A reason why small blocks came pretty close to the big block performance numbers may be the lack of high-end development for the big-blocks in the last 20+ years.

Who is racing them these days? Offshore boats, vintage Can-Am cars. Who else?

A big-block Cobra is not 175 lbs too heavy in the front. That's overall. Weight distribution is still 50/50. Should be.

As mentioned: weight could be taken off the front (car).
Otherwise you loose during braking and in the corners.
My car weighs 1950 lbs. - with big-block.

The tires couldn't handle it - even on the straights.

Thanks for letting me join your discussion.

Dominik

Racing BB's
 

Guys- Forget all the tech stuff for a minute. Forget about the pros and cons of both styles. Forget weights and setups for a moment........ It costs much more to race bigblocks the right way. MUCH MORE. True the costs of building both styles engines is similar but that is only a small part of the picture. In the end if you do build a big block car "right" what happens? The small engine guys will say, "well he should have won, look at all that bad boy stuff he has". The big block guys will say it's about time. The real racers will recognize the true effort it took. ( both of them) In the end you will have much less money in your pocket. For a trophy? Maybe a time listed in some kit car rag? Maybe you will impress your girlfreind or wife? I don't think so, at least not for me anyhow. Now I got to ask you. To race a big block, do you really want to go there?????? Stiil a neat thread though.
:) :)
cobrashoch

Ron,

correct.
The cost of building the engine may be equal, but for the car it isn't. Good point.

Dominik

Come on, can you put a price on asking the small block owner how the rear of the car looks? I never said a big block was the same price to build as a small block, just faster!

If speed kills, I just don't want to live any longer...

P.S. Just kidding... :LOL:

mad dogs?
 

Ron, Yes it is interesting, lotta fun too. By the way, I have to oversimplify, I can't type.
I agree valvetrain has been the limiting factor, but... F1 engines have taken rotating/reciprocating inertia to the same extreme.
Now when getting back to bottom ends, you hit the nail right on the head. Those dirt car engines (mad dogs? I think thats a compliment:D ) aren't limited to just ultra-light bottom ends. The Latemodels eliminate the flywheel, the clutch, and the transmission gears, run aluminum or carbon fiber driveshafts and magnesium hubs. Every effort possible is made to reduce rotating inertia for exactly the reason you stated - we don't what the revs to stay up when letting off the gas. The quicker the engine shuts down, the deeper you can drive it into the corner. Likewise, the quicker the revs come up, the quicker it is off the corner. The problem with the big engines is you can't go too light on the crank or the extra torque shocks the tires, breaking traction and reducing forward bite.
Regarding matching engine cofiguration to track length: thats what I meant by my 430 ci engine being better suited to larger, momentum tracks.
Cup cranks are the lightest SB cranks at about 38lbs. They're the same ones used in our 360s.
BANDIT1 - The set-up used to hook up 750 HP & 690 ft/lbs of torque is the same one that has to turn at the end of the straight. Its about balance and momentum.
I think Dominik oversimplified it the best, tires dictate the torque.
Whether circle track or road racing as long as there are turns, acceleration, and deceleration these principles will apply.

Great, all this foaming at the mouth has messed up the key board. Scott a.k.a. Mad Dog

Scottj-I too have oversimplified stuff for the sake of making things short. I quit racing long ago and have never looked back. So with that in mind some responses.
I didn't talk about stuff "out back" of the engine though I hear ya loud and clear and understand. I also knew that stuff is going on w/dirters.
I understand the logic you use on your 430 and big tracks vs lite and small cranks.
All that stuff applys to those willing to go to the enth degree to gain some edge in formal racing. No problem.
What these guys are talking about though is street hot rods. To that I say the big vs small question is really moot. What counts is the WHO that does the work. Costs can indeed be ignored.

As for tire shock- thats the area I would work on if I was circle racing today. I can think of much that could be done with slipper clutches, suspension preloads and unloads, active suspensions, electronic traction controls and so on and so on. Can any of this this stuff be used by rule? most likely not. If I was to race a big block that is. BTW- that's exactly what those "hick" drag racers have been doing for quite some time.

Finally to repeat some stuff from posts above I've stated.
Racing is dominated by politics. Politics determines rules. Rules dictate a technical orthodoxy. Technical orthodoxy limits choices. Technical orthodoxys limited uses must be augmented by personalitys for racing to exist. Personalitys dictate politics. Politics dictates rules.

That's why I stated there is most likely not much I am interested in the book listed above. Sounds like it's cought up in the technical orthodoxy piece. When someone says you can't do that because,,,,,,,,,,,,,well I just run and hide. That's why I quit racing, I got tired of fighting the constantly changing rules and it just wasn't fun anymore.
cobrashock

My 2 cents: Take the BIGGEST, Baddest block you can find, bore it out until you can SEE the water flowing thru the jackets in between. Than find the BIGGEST crank you can and offset grind it until each cylinder will hold a weeks worth of laundry. Put it all together, say a prayer, and go out and show all those small block weenies why they built a FOUR HUNDRED TWENTY SEVEN CUBIC INCH COBRA in the first place! Let 'em feel good about themselves in the turns--WE know that there has to be a STRAIGHTAWAY SOMEWHERE on this damn course! You ever wonder why the roads have ripples---BIG BLOCK TORQUE! Anyway, you know ya want a big block to haul around your big, hairy brass bal-----**This message interupted while Mr Sharpe's sedative takes control. Please continue with your normal activities. That is all.****)

Lets end this
 

Big block lovers will never change their minds.
Small block lovers don't have to.
Cranky:LOL: :LOL:

I had a call today from an aquaintance who's reach exceeded his grasp (ran outta $$$) . Just happens to have a John Kaase built 835 CID -- yes EIGHT HUNDRED THIRTY FIVE CUBIC INCH DISPLACEMENT -- mountain motor he is selling. It was built to drag race, has very few passes, and is based on the FoMoCo 460 motorsport block w/ alum CJ heads. Hmmmmm...change a cam, different intake...What a pounder that would be!!!!! :3DSMILE: **) :3DSMILE:

here are a few "big block" crate engines for the bowtie lovers

http://www.sonnysracing.com/engines_may_2001.html

how about a
555" CHEVY 700 HP $14,900
555" CHEVY 870 HP $15,900
565” CHEVY 940 HP $16,500
615” CHEVY 1000 HP $20,500
632” BIG DUKE 1120 HP $34,900
712" PONTIAC 1400 HP $42,500

now those are some BIG BLOCKS :3DSMILE: :3DSMILE: :3DSMILE:

http://www.sonnysracing.com/images/sonnys_engines.jpg