SB, handling, & ballance, facts? oppinions?

[olddog]

Originally Posted by Streetwize

to get that massive "no effort" acceleration combined with the better-balanced handling and braking of a smallblock is really tough to beat IMO.

Not to hijack this thread, but I asked this very question a while back. No one really stepped up and claimed the lighter weight of a SB impoved handling enough that you could tell a differance. Most stated that the biggest factor is the driver, yea I get that, but what about the capability of the car? Would you care to elaborate? I am interested. I'll Start a new thread, so not to mess this one up any further.

Here is the new thread.

I'm not trying to start a war, rather trying to decide what engine I want to use, when I build my dream car. I would like to hear the oppinions of the owners of SB engines in Cobra cars. The pros and the cons.

[Rick Parker]

I think the reason for the lack of or hesitency of response is that there aren't a lot of individuals who have actually had enough experience with BOTH a Small Block & a Big Block to warrant expressing an opinion worthy of consideration. Speaking for myself, I have a 289 and am quite happy with it. That is really the only one I have any lengthy experience with.
There will always be a battle of words regarding the merits of which is better, I suppose we defend & justify what we have, right?

[Tommy]

My small block motor has 410 cubuic inches, 9.8:1 compression ratio, hydraulic roller lifters/cam and a single Holley four barrel carb. The components were optimized for maximum torque from 2500-6000 RPM. On the track it accelerates rapidly to 140 MPH and probably would have another 15 MPH in it if the straights were longer. On street tires, the rear end will break loose if I give it full throttle at 50 MPH in third gear. For me, it is more than enough torque for street and track use. A larger, heavier, more powerful engine might modestly improve top end speed (that I have yet to reach) and acceleration above 120 MPH. It would also increase the demands on my drive line, suspension and brakes. I think a well thought out small block is the optimum engine for a well balanced track car the size of a Cobra.

Now, if you want to nod knowingly when some stranger drving a Nissan asks, "Does that thing have a 427 in it?", get a big block. Or lie.

[Streetwize]

In my own case, I've been building and tuning high performance cars of all makes for roughly 25 years....So in general, comparing 2 motors of the same displacement and powerband, the only difference being 100 pounds or more mass due the BB/SB configuration, the one with the lighter internals will accelerate quicker due to the lighter rotational mass, not only in the crank/pistons/rods/ but also in the much lighter valvetrain. As far as cornering and braking, one could argue that 100 pounds of heavier motor would be similar to comparing for instance, the difference between a 235 pound driver to a 135 pound driver in the same car. In the end a car's handling is determined in large part by how well the static weight is distributed in the chassis and it's effect on the cars roll center during cornering and its instant (dynamic) center during acceleration. Bear in mind that every component comes into play, the driver, the battery placement, the transmission and also 50/50 is not always ideal sometimes a slight front or rear bias is preferable to a particular powerband, race course or driver preference. So there is no "right" answer...but, if then you consider the TOTAL weight, the overall lighter car (again all else being equal) is going to be faster and brake/handle better.

But with Cobra's and corvettes, a big inch small block can really make for an easy to set up chassis.....a 475-500 hp 400+ inch windsor can weigh the same or less than an all iron 289....another thing that comes into play is whether or not a scattershield is employed (highly recommended in a Cobra due to driver's proximity to the flywheel), a steel scattershield adds/concentrates about 45 pounds right near the center of the car and in a smallblock that centers the weight of the motor/transmission assembly (dynamically) back another couple inches, it can have a positive effect on the cars handling as well as add a tremendous safety factor. A big block can be very well set up, but to really get the weight down comparable to a small block is very expensive, especially when building an FE. Ironically FE Iron heads aren't that heavy (compared to many other big blocks) to begin with, but the block and rotating assembly is pretty heavy for 427" as is most big inch 60's motors. a 393-427" Smallblock Windsor can have a bobweight lighter than a factory 327 chevy...nice power in a lightweight package.

The "problem" when comparing Cobra combinations is that they are all set up differently...A well set up big block can run rings around a poorly set small block, no doubt...but that's not really appls to apples and I would say that the smallbock Cobra would likely be "inherently" better balanced "out of the box". The beauty of Cobras is that they can be and are all "seasoned to taste"; I personally tend to prefer the big block like torque over the high winding revs...but I prefer the light on it's feet (scales?) and predictable balanced feel of a lightweight smallblock powertrain in a 90" wheelbase car that puts a lot of rubber contact on the road. Again, it's about power to weight....apples to apples for the same power, lighter weight is generably preferable for handling, braking and acceleration.

Wize
www.fastraces.org (technical director)
www.streetwizeperformance.com

[Excaliber]

Much of it has to do with how the car is setup in the first place, regardless of SB or BB. I was astounded when I first put my BB ERA on a road track. From all the 'doom' I had heard about BB's on a road course I figured it would understeer around the corners or have other issues concerning handling. NOT SO! The front sticks like glue in even the hardest corners. Throttle oversteer can be induced. I found the car very well balanced indeed.

Compare that to my small block Excalibur with longer wheel base and solid axle. The Excal was MUCH more likely to spin out when pushed hard in the corners. Could be the longer wheel base, tires not as good, gears to low, shocks to soft. Whatever! Clearly showed me it's about the CAR not the engine when it comes to handling!

[olddog]

Thanks for the dialog. I was thinking along the line that if you figure 5 lb per hp for an average Cobra then an extra 200 lb engine would only require an extra 40 hp to to offset the weight. However I never considered the braking with a lighter car. That was a good point. Yes with more expensive brakes, you could offset that too, but in both accelleration and decelleration wouldn't tire traction limit the heavier car?

Another thing that has bugged me is the transmition, bellhousing, flywheel, and clutch. It isn't engine weight alone. What is the differance between the SB engine trany combination and the BB engine trany combination? I do feel that a blow proof bellhousing is an absolute must in a Cobra. Bigger radiator and more liquid have to make the total weight of the car more as well, but I cannot seem to lay my hands on any hard data on this subject. I understand that there are light weight flywheels out there, so maybe the correct way to ask this is dollar for dollar on the parts, what is the weight differance.

Is it true that with a BB the tail of the tranny is so close to the rear end that you almost have to have IRS or very poor ride and reduced handling with a straight axle? Or is the SB and BB very similar? I would think this would be a consideration, if they are different.

[Burgs]

Have you considered a new aluminum side oiler block, like the Pond, or Genesis?

[olddog]

Originally Posted by Burgs

Have you considered a new aluminum side oiler block, like the Pond, or Genesis?

Honestly money is a big thing for me. It's not so much that I do not have it as it is that the more I spend the more years I have to work before I can retire (at least in my mind). Putting huge amounts of money into an engine would kill the fun for me, as putting it to the floor and taking it up to 6000 rpm would have me thinking about all the things that could take $20K+ and turn it to junk. That would still bother me even if I hit the lottery big time. Just always was frugal. I cannot see a good reason to spend $20K when $5K would do the job just as well.

I am also looking at the FE, but frankly I was never impressed with Ford's pushrod engines, even back in the 60's and 70's I was not impressed. I have always loved the 427 Cobra, both from looks and performance point of view. I always liked the big block torque and sound. I hate a car that leaks oil on my garage floor. I would never consider anything other than a Ford engine in a Cobra. I'm definately torn and cannot make up my mind. Fact is I think the 4.6 DOHC modular is the best engine Ford ever designed, but I have reasons not to use it as well.

What ever I decide, I will build the engine myself. I have built SB & BB Chevies, as well as BB Mopar. I do not look down on anyone else who chooses differently, but for me building a engine is part of the bragging rights, for lack of a better phrase. Although it really isn't about bragging it is more about pride.

[WarrenG]

ERA has obviously built, set up, and driven both of their own and I believe that on their website they state that their 289FIA should do better on the skid pad than their 427. Don't know if that is strictly due to engine weight and distribution or if there are differences in the suspension set up also. I haven't seen any claims from them about which should do better over an entire road course.

[JCoop]

I have been fortunate to have owned and enjoyed both a 351 and a 460, both crate motors, both on a Superformance, and both built by Billy Andrews of HRE with very similar suspension components. I must say the SB felt a lot more nimble when driven hard in the twisties but the BB is just as capable; one just needs to build up one's biceps a bit more before driving the BB. I did not track either car but streetwise, the driveability of the BB won me over. By driveability, I mean being able to cruise and chug along below 2000 RPM around town in 4th or 5th without bucking and rear end clunking. Also, with the BB, when I'm cruising at highway speeds at 65, there is no need to downshift to quickly accelerate to 80. The SB just did not have that grunt to do it gracefully. At anything below 2000, the 351 Windsor would buck and complain; although above 3000, that motor would scream scarily. the 460 BB will chug along all day at 1500 RPM in any gear and just blipping the throttle will get you up there in a hurry. I miss flailing the SB around the nicely repaved streets surrounding the old Bridgehampton track. Doing the same thing in the BB makes it seem more sedate, even civilized, at the same scary speeds. It must be the "throatier" exhaust note of the BB...

[scott coyle]

The only pro of a bog block is just that, "it is a big block or a 427". Bragging rights is the only advantage. A small block based motor can be bored and stroked to get the same cubes and equal or more hp, is cheaper to build, offers more combinations, will stay together longer in general if you beat on it, and it is less weight so it aids in handleing.

Now, there are plenty of powerful big blocks that are in well set up chassis that handle well, and have stayed together over time.

It depends on what is important to you.

Scott

[01yelrt]

The basic principle of racecar handling is "lighter will corner better". The sole job Ol Shel had on the Viper project was to go to Lee and tell him to "KEEP IT LIGHT". The beauty of a Cobra is that it is a 2400Lb car with an enormous amount of HP and Torque. The car was selected by Shelby because it was first and foremost light. To use a BB is to add weight. All said and done, strictly from a physics perspective a large cube very light motor will be a bettter handling combination than a car with a heavier motor when it comes to braking and changing direction. If you are drag racing from corner to corner the BB will win. If you are trying to carry speed though the corner the lighter car will always win. I wanted bigger cubes and light weight and decided to use an aluminum block bored and stroked to 427 CI. Thinking that torque and HP will not suffer and weight will be an advantage. I recommend considering this approach. Ultimately Pick what you like!

[427SnakeSC]

I have a punched up SB 302 Ford in my Classic Roadster. My mechanic conseratively rated it about 350 - 370 hp. It is extremely quick and handles beautifully! Last year I took a 427 SO, cast heads, CSX out for a ride. I could feel no difference in handling or acceleration. As my mechanic asked me when I told him about my concerns of the extra weight of the BB over the SB. He asked me, do I ever plan to race the car? I am not planning to do this. I am, opting for a 427 SO in the new car I have ordered. I have done this, in an attempt to have the car as close to "correct" as I can possibly can. IMHO, both cars are deathly quick, with the BB probably having a greater top end. A top end, I might add, that it is extremely unlikely I will ever see! The advantage of the BB, as stated by the members before me, is that ability to lug it around town, and with just a blip of the throttle, slip it sideways and be gone in a heart beat. With the SB, it is a matter of the right gear and right RPM. Another major consideration is the cost, dollar wise. The cost of a "correct" BB can be 2 to 3 times the cost of a nice SB.

[Excaliber]

"Bragging Rights" with a BB. OK, some may see it that way, some may want it that way, but there is another more fundamental reason.

It's what the 427 competition cars came with (hey, just keeping it real).

I wanted to experience as close as I could personally get to what it felt like 'back in the day'. When I built my motor I spec'd it with that thought in mind! You can't SEE the flat tappet cam, I reckon my former ROLLER cam would offer more in the way of 'bragging rights'. I didn't use a flat tappet or original iron heads to 'impress' anybody. I wanted to capture a moment in time. It was important to ME to know whats inside the motor, if others are interested, well thats cool too.

Capturing the 'moment' aint gonna happen with a SB, unless your running an FIA with buggy springs.

[Morris]

If the BB is not up to par with the SB.......

Why did all of the Cam Am cars use Big Blocks????

Morris

[scott coyle]

The big block is more original or authentic in the 427 cobra, no doubt about that.

Back in the can am days, the small blocks were not well developed and the big blocks were. The situation is reversed today.

Scott

[427SnakeSC]

"Back in the day" of the Can Am cars, it was easier to get the horsepower out of the BB, than trying to get it out of the SB. Remember in Can Am it was all about top end and handling, hence the all aluminum ZL1, which dominated the series until Porshe showed up with the turbo charged 917. I saw one of the races with the Chevy powered Mclarens and the Porshe. The Porshe had some mechanical problems and the Mclarens had lapped it 3 times while it was in the pits. The Porshe came back out and reclaimed 2 of those laps before the end of the race. It was amazing to watch. I remember seeing the Porshe come down the back straight. It looked like you were watching a movie that had been sped up!

[dlampe]

Morris, I am building a small block with KMP 359 in the cross hairs!!!

I'll call you soon, we need to catch up.

[Excaliber]

Very true Scott, back in the day the answer to every horse power need was 'more cubes'.