Big Block vs Small Block

[Seymour Snerd]

.....This is a 'car nut' forum where such stuff is discussed openly freely and unconditionally.
..... you have totally failed to live up to the expectations and reputation of this fine forum.

I think we have a fundamental disagreement about the purpose and value of defined-topic forums in general, and GT40s.com in particular. Where is it written that discussions are "unconditional?" And why are the topics identified in the forum names if the responsibility for replies are unconditional?

We have here a person who has rejected multiple attempts to help him on the basis that they are "technical" while participating in a forum that is defined as technical. Are you and I required by your "unconditional" stipulation to persist in the face of that kind of resistance to try to help someone who will not help himself?

We have a person who has described my responsibility to him as being that of a vendor or a teacher, both of which are paid positions. Is that my responsibility? Do you really want to support the idea that as a member of this forum you and I owe a complete and total stranger anything at all, much less an unconstrained amount of time in an apparently futile effort?

In your use of the word "reputation" for this forum you have completely negelcted the quality of the writing, the organization of contributions by topics, and the deep knowledge behind those contributions. I think it's terribly sad that someone would look at GT40s.com and see its primary value as the fact that we will serve anyone, any time, on any topic. That attribute is free and easy and worthless; it exists like weeds elsewhere on the internet and in fast food outlets across the world. Is that GT40s.com?

What is rare and unusual about GT40s.com is the level of critical thought, domain knowledge and technical expertise represented by its members. This individual has shown a profound lack of perception and respect for those values by simply dismissing the advice provided by several of us (not just me, and yes, I know who I am) that he would be better off engaging in some self-education. He seems to think his time is far more valuable than ours.

If you really think your own questions and contributions are of the same level and value as those of the other individual then you have far less respect for yourself than I have for you. That too is sad.

And finally, I don't quite see what's wrong with expecting questioners to have made at least a nominal attempt to find answers to questions on their own before asking for the valuable time of for members. I always do, and I suspect you do to.

Anyway, just to reiterate the principles that I think this thread and some of his others violates:

1. It's off topic: it isn't really about GT40s, it's about car engines in general. We don't currently have a subforum for "general automotive" but I think we should. In the meantime the Paddock would be fine. If the discussion were started or moved there it would completely resolve my concerns.
2. It's author presumes that we owe him assistance no matter how lazy and impatient he may be. Forum participation is voluntary and when it occurs it is a gift.
3. And yes, people really should make a reasonable attempt to answer their question on their own. This principle is consistently evident in other threads where users are requested to use the search function first. Not to do so shows a profound lack of respect for the value of the time and knowledge of the other forum members.

If you have issue with any of the above principles I would really like to know how and why.

 

[Seymour Snerd]

BTW I should have said "lighter weight faster AND FURTHER" in post #31 (even though the "further" is implied by its moving faster in the same time).

But Tim, in your allegory you left out the part where the wind changed, turned the glider around and blew the folded paper into Colin's eye, so Hot Rod had to drive him to the hospital. Wadded up paper rules.

(By the way, when did Hot Rods become declasse?)

 

[Ian K]

Horsepower = how fast a car can go
Torque = how fast it can get to that speed

A very broad generalization, but OK.

Also, it seems to my understanding from whats been read is that, Horsepower dertermines the top speed of a vehicle (whether 200kmh, 300kmh, 400kmh etc), not the RPM range it functions in.

So whether big block, High CI discplacement at 6000-7000rpm or small block with Lower CI displacement at 8000-9000rpm, both will have the same top speed given they both have the same HP, given the Big Block was geared correctly, as both will be geared differently as they make power differently.

On the other hand, the more CI displacement an engine has, the larger the power band would be, thus the 'average' power it makes would be more overall. So though the BB and SB peak at 600hp, the BB would actualy be better in accelerating (other than the fact its 100 ft/lbs of torque more) due to having that power for a longer period of time.

You are making a large number of assumptions here - proper gearing, the BB having more torque, the BB having a larger power band. The latter two issues - the BB having more torque and a broader power band are not necessarily true, and with the SB's larger RPM range, it could actually have a much broader power band. I have seen interesting comparisons between a 454 ci Chevy, a 502 ci Chevy (bored and stroked 454), and a 383 ci Chevy (bored and stroked 350). The 383 actually had a broader power curve than the 502 (the 502 fell off sharply), and more peak torque than the 454.

But, you also need to take into consideration what your transaxle options are with the BB vs. the SB, and properly gearing the BB to make up for 1500 to 2000 RPMs less (or more) might be more difficult than you think. And, it could make for a car that will not behave well at all on the street.

Ian

 

[George]

THanks Ian.

Alan, you keep implying that I 'dont want to read' in every post you make whether directed to me or others... have you simply just not read the fact in quite a few posts I said "I researched, I read" ? Have you also missed the post where I said I did quite a bit of reading on Torque, RPM etc but needed an explanation of what I read to make a little more sense? Have you also missed the entire post that Ian did not miss... that, that is what I got out of the reading I did and asked for any corrections if I perhaps misunderstood something?

So as far as I see, I am reading, and your clearly not reading whats been said.

O and btw about this whole dribble about "tech" forum and yada yada yada

"
GT40 Tech - Engines/Induction/Exhaust (13 Viewing)
Motors and engine related - right here!
"

Do you see that bottom part? MOTORS AND ENGINE RELATED - RIGHT HERE

Is not my question MOTORS AND ENGINE RELATED?

Re-examin yourself. Seems more or less you are annoyed and are trying to make the forum bend to your ideals of a forum, thus your the dictate as to how it should/shouldnt be, get over yourself?. If everyone is meant to know the answers before posting on here... there wouldnt be a forum cause nobody would be posting anything. To my understanding, a person signs up to a forum because

A: They love the car the forum represents and
B: They know they will receive help/opinions/ideas from other enthusiasts as to how to build or how they did there own car and why.

Thus a forum is a place to learn and share ideas with other forum members. Learn/share about what? The car it represents, the GT40 in this case. My question is why BB or why SB in a GT40. Ive read, ive researched, Im stuck. So I asked here from other 'enthusiasts what they think or if they can clarrify few things for me' given they probbably have experience with BB/SB and many different kind of cars that I have not had.

If a person off the street came to me and asked me "Man I heard you like Mopar, which one should I get a Dodge CHarger or a Dodge Challnger, or a plymouth cuda or roadrunner? and which one would perform best n which engine should I use?"

I wouldnt say "Hi mate, thanks for the question but go read a book and after u done that come back to me and I might be more tolerant"

Thats just a bull... reply "Im better than you" attitude.

I would say "Well in my experience, ive had the challenger and the charger, If you want a lighter car to have slightly better performance, the Challenger is lighter and can be made lighter for alot less $ than it would cost the charger, I would run a BB in the car because the car is heavy, however I personaly think u can get the Charger to more than fast enough and it tends to look alot more mean with that black grill in the front, btw, if you like the look of 15" wheels, have a look at a set of billet alloy 12.19" nascar brakes and have a look at a good set of shocks, car should be fun, handle decent if you upgrade your T-bars to 1.12 and off you go"

You notice the difference?

Im an enthusiast who had experience with that car, so ofcourse I would tell the fellow man what I have experienced with it so he has some informed decision, rather than :"sorry mate, im too good for you, go read heaps of books because once u do,guess what? U wont have to ask me and i wont have to waste my time on u, cause, well, ur worthless u see so its just not worth my time answering ur question, have a nice day"

As far as I see I asked a very simple question which has turned into a whole complicated load of dribble.

The smple question was

600 HP BB with 650 ft/lbs torque

600 HP SB with 550 ft/lbs torque

Both geared to have the same top speed

Which would be generaly faster? If speed is based of torque and HP irrelivant of what RPM say, then the BB wins. And I dont need the whole "But u need stronger parts, u need this n u need that", if the car was built with a BB, it would automaticaly be assumed all parts are fitted to match, and if going a SB again assumed automaticaly all parts are fitted to match. This is why Im purely asking about engine not hte rest of the suspension that would make car go fast, cause all that stuff will automaticaly be made to match to be ideal, so the only thing left is the engine choice, the rest will be done accordingly.

IS that a hard question? If you had experience with both and understand how all that technical stuff works, then the end result you should also know otherwise... maybe YOU dont know the technical side and hence you dont know the END RESULT as to which is faster in that sense.

 

[Terry Oxandale]

I don't think it would be easy to say. In your question, the SB's smaller torque value for the same HP implies that perhaps the peak torque will be in the high 5000 RPM range, which means the BB's peak torque may be in the high 4000 RPM range. So, you're drag racing these two motors in identical cars (sans the motor), and while the BB is shifting into 2nd gear (because it is now past the peak torque RPM of the BB motor), the SB is still pulling in 1st gear for another 1000 RPM because it has a torque peak about 1000 RPM higher than the BB. Now, multiply this gearing advantage by 4 gear shifts, and the SB crosses the line in 3rd gear while the BB is crossing in 4th gear. The identical gearboxes will result in a lower average torque multiplication to the rear wheels for the BB (because of the greater amount of time in the higher gears), while the lower torque motor is getting the advantage of more average time in the lower gears (meaning higher torque multiplication through the gears), which could be hypothetically, make up for the larger torque of the BB.

End the end, the results may be identical. So ask yourself; is the practicality of the BB's pick-any-gear you want torque advantage something you desire over a lumpy, snarling, but choose your gears wisely SB? Driver style and preference becomes the primary driver of the choice, rather than the numbers. Personally, having a BB with a pasty, cod fish cam is not much of a choice for me. Give me the sound that matches the ride.

 

[Seymour Snerd]

....maybe YOU dont know the technical side...

Yeah, that's the whole problem with this thread, my ignorance.

Now that that's settled, let's go back to (or to, for the first time) GT40s and big blocks vs small blocks. It seems to me there have been some aspersions cast, albeit wittily, on Mk IIs because they won by "Hot Rod" methods. As a Mk II owner it's my solemn duty to respond lest my car fall off its jack onto my foot some night.

So lets go back to the glorious days of yesteryear, around 1965. You're FoMoCo and you just dropped about $10 million on two attempts to win at Le Mans. That's about $50 million in 21st century dollars. So far mostly what you've done is litter European tracks with Collotti gearbox pieces and wet them down with coolant.

At this point you have a few choices: you can further develop the small block and maybe get it to 400 hp at 7K RPM; you can put the other engine you've been using in stock car racing in the car and see what happens; or you can develop an entirely new engine.

So you try the second thing, detuning it by over 10% and rather easily installing it in the existing chassis., Right out of the box it laps the Romeo, MI track at 180 mph. You fiddle with the aerodynamics and lap at over 200, hitting 210 on the straights. Yeah it isn't quite as spritely in handiing as the predecessor, but as David Hodges says, the Mk I cars "could never have achieved lap speeds approaching 180 mph, let alone in excess of 200."

Getting to choice three, instead of this you could have put the program on hold for a couple years while you spend a few more million developing a brand new triple-over-head-cam 5-and-a-half valve engine with magnesium connecting rods so no one would accuse you of Hot Rodding (God Forbid!). But then nothing in your car would be common with the production vehicles. And the whole idea in the first place was to "win on Sunday, Sell on Monday." This is, after all, a business you are running and it has shareholders who expect appreciation in value.

Well, we all know what happened. So my question for the anti-hotrod crowd is this: if you were HF-II "the Deuce" what would you have done in April 1965 that would have better served the program objectives and the Ford shareholders than what he did?

What's your superior, non-Hot Rod, plan?

 

[Steve C]

Alan,

Well said in your last post.

Of course it is a matter of personal preference but, for me my MK11 with the FE BB IS far better than the high strung 351 Windsor 408 I had in the Cobra. It is docile and tractable on the street (70MPH @ 2K RPM) but with just a touch of the pedal WOW.

After 5,500 miles I am convinced that for me I made the right decision.

The 600HP BB engine should last a lot longer than a high revving SB also no buck and bronco on the street in traffic that I experienced with the high strung 408 SB (fun for a while going through the gears to get HP but if you use the car other than exclusively on the track can get tiring!).

IMHO if you are racing AND ONLY racing maybe a hi rev SB would be better/ quicker in the twisties but, for a dual use car I'll take the FE and it is more period correct in our MK11's

My 2 cents

Steve P2125

 

[George]

Thanks guys.

My car is gonna be street/cruise mainly with Race for fun days out in controlled environment. In this case, the BB is the better choice as it would last longer, be more maintenence friendly and more economical on the road (aka get more km's before fueling up) and ready to wheelstand (in a sense) when you just wanna press the pedal down the street or something rather (Reaching 100 from 0 faster than the SB would). However if it were purely a race car, then perhaps the weight advantage of the SB would be better where there are alot of turns because the SB could take those turns at higher speeds than the BB due to less inertia wanting to pull the car off the track. So given you did the same speed in a BB that weighed more, you would find yourself kissing the tires on the grass. So only chance for BB after losing some in the cornr would be to catch back up on the straight where it does have 'more torque' to do so with. Meaning same overall in circuit sense just 'different' style driving needed (given the BB weighing more).

Guess all thats left then is... can too much torque (650) in a GT40 cause the car to actualy be 'slower' than the SB cause u cant get all that down on the ground through 335 wide street tires?

Just 1 thought I had, no need a whole discussion on it, it just popped into my mind...Given the BB would be 600HP and 650ft/lbs torque, what if we did the SB build at 650hp (to match the 650 torque of the BB) with 600 torque (matching the BB HP)?

Still has all the RPMs.... less torque yes, but more HP thus more top end speed... how would it work out now between the 2? I assume in this scenario the SB would have the advantage unless the BB stuck 650HP in it, however its TQ would be near 700 then.

I thought of that cause if too much TQ can make it slower/worse due to not being able to put it to the ground causing the car to be like on ice, then perhaps increasing the HP and dropping back on the TQ and shifting it higher up in the RPM range would prove better and safer/more controlable. As a street car, you dont have to rev up to 4000rpm, thus keeping the torque etc 'backed off' for general driving. If the BB has 500ft/lbs at 2000rpm onwards... isnt that gonna be like flying where your just trying to drive normal as ur sitting on 500! ft/lbs where ur meant to be cruising, or that doesnt work like that?

 

[Doug S.]

Guess all thats left then is... can too much torque (650) in a GT40 cause the car to actualy be 'slower' than the SB cause u cant get all that down on the ground through 335 wide street tires?

Just 1 thought I had, no need a whole discussion on it, it just popped into my mind...

The answer isn't a simple "yes" or "no".

Keep in mind torque is just a measurement of how much "tendency to rotate around an axis" an engine can produce.

If both SB and BB have equivalent torque "numbers", they would most likely occur at different points in the power band.

So, at lower speeds, the BB would most likely light the tires before the SB.

A posi-trac in your differential will make things better....if all that torque goes through one tire, as seems to happen in an "open" differential, it becomes easy to understand why these things can get crazy on the street or track!

Lighter weight, one of the factors in the SB's favor, tends to help more than just acceleration, though....handling, ride comfort, and braking all seem to benefit from lower weight. If you're going to go with the BB, I'd suggest you start saving now for an engine with an all-aluminum block. That will save you considerable weight and would probably put the entire engine weight down in the range of an all-iron SB.

Cheers from Doug!!

 

[roaldin]

This is the third time I have tried to post this... Apologies if it confuses later posts by others etc.

George - Faster? could you define that in more technical terms? ...just kidding. ;p

But seriously, yes I think it is a hard question because that word will be defined differently by different people and because it really is more than just BB performance characteristics V SB performance characteristics.
It seems that you do indeed want just opinion and other peoples "recipes" and I think it unlikely that you will find a chorus of agreement in answer.
It is even difficult to answer if we keep it as simple as - GT40, in a straight line, over a mile, because differences in weight and a lot of other factors will affect the outcome.
For me faster means faster on average at the things I like to do, which is circuits, hill-climb etc - things that use the capabilities of the whole car and not just its engine.

However... I'll give it a go... - ALL ELSE BEING EQUAL, if the two engines (both 600 bhp) had the same shape torque curves (in practical terms) just at different revs (thus different peak figures - you REALLY need to understand this), and the gearing took that into account, then both cars would be the same.
Work is work.
Perhaps think of it this way, if a gearbox divides rev's downs then it multiples torque up, and vice versa...
Unfortunately all else will not be equal, this is where the trouble starts...


Alan -

I'd have listened and fixed the heads... maybe I wouldn't have but that's what I'd like to think.

I think you understand my Hot Rod comments.
I replaced a power supply in my computer the other day, I put in a much bigger one. obviously I am now responsible for the design and shape of the computer and you are no longer allowed to build a similar computer without purchasing a license from me.
Also my computer is now no longer an XYZ, it is a Tim. I am a genius comparable to Konrad Zuse (and obviously others, I'm not getting into that argument...)
Ok, maybe I'm stretching it a tad, but then again...

I will admit that I may have developed a slight prejudice against "Hot Rodders" because of the following - I was invited, by an organiser of a local hot rod event, to take my GT40 along to his event. On arrival I was treated with contempt by the other participants because my car did not conform to their ideal. I bigger bunch of snobs I have never met. The only people who would even talk to me (other than to be derisive about the car being fibreglass or not being a rod) were the organiser himself and two Canadian tourists from a visiting cruise-liner - I like Canadians.

As for paper aeroplanes... damn I hoped you wouldn't notice that.

I am also beginning to understand your frustration, but I still agree with Keith.


Tim.

 

[Ian K]

Alan,
The 600HP BB engine should last a lot longer than a high revving SB

Again, this is a generalization that may not prove true. Piston speed is a good indication of how much stress the rotating assembly is under. The higher the piston speed, the harsher the effect of stopping and starting at TDC/BDC is on the assembly, block main webs, and main caps.

For example, a 428FE has a 3.98 inch stroke. At 6000 RPM, the piston is traveling about 3980 feet per minute. At 4000 RPM, the piston speed is about 2650 feet per minute.

A 302 has a 3.00 inch stroke. At 8000 RPM, the piston is also traveling about 4000 feet per minute. At 4000 RPM, it is only traveling about 2000 feet per minute.

So, the higher revving 302 at 8000 RPM stresses the rotating assembly about as much as the 428 at 6000 RPM, but at the same RPMs, the 302 rotating assembly is significantly less stressed. At 7000 RPM, the 302 piston is traveling about 3500 feet per minute, at 5500 RPM the 428 piston is traveling about 3650 feet per minute.

Also bear in mind that the 428FE piston is also heavier, and since F(orce) = M(ass) * A(cceleration), the piston speed difference is magnified by the heavier mass of the FE's piston.

Ian

 

[roaldin]

Doug - or you could do what I did and use an alloy SB.

Tim.

 

[Steve C]

Ian,

If we are strictly talking racing I agree but, in my post I try to give my experience with a 351 W (408) in the Cobra vs my Shelby all aluminum 482 in the MK11.

I use the car as a road car and believe me it is much more user friendly with the 482 than the 408 and at the lower rev's of 2000 to 2500 for crusing much easier on the engine with a ton of fun with just a little throttle.

With the 482 was able to get more performance than the 408 with a less radical cam ect.

Again my experience in how I use the car.

I was talked out of a BB when I did the Cobra but, really happy with my decision to go with one in the Gt40.

If I was racing likely different.

Steve P2125

 

[Seymour Snerd]

I think you understand my Hot Rod comments.
I replaced a power supply in my computer the other day, I put in a much bigger one. obviously I am now responsible for the design and shape of the computer and you are no longer allowed to build a similar computer without purchasing a license from me.
Also my computer is now no longer an XYZ, it is a Tim. I am a genius comparable to Konrad Zuse (and obviously others, I'm not getting into that argument...)
Ok, maybe I'm stretching it a tad, but then again...

I will admit that I may have developed a slight prejudice against "Hot Rodders" because of the following - I was invited, by an organiser of a local hot rod event, to take my GT40 along to his event. On arrival I was treated with contempt by the other participants because my car did not conform to their ideal. I bigger bunch of snobs I have never met. The only people who would even talk to me (other than to be derisive about the car being fibreglass or not being a rod) were the organiser himself and two Canadian tourists from a visiting cruise-liner - I like Canadians.

As for paper aeroplanes... damn I hoped you wouldn't notice that.

I am also beginning to understand your frustration, but I still agree with Keith.

You'd have "fixed the heads?" You would have lost.

When does your Mk II computer come out? And what size uranium core will it use? You do like your parables and metaphors don't you....

My experience with Hot Rodders is nothing like that, and even if it were, we're talking about 80 years of west coast culture here... So it's a little like running into a snob at a Vivaldi concert and saying because of that you don't like Bach or any other Baroque music. If you do that you're going to miss out on a LOT.

BTW was the contempt for you or for your car?

I just thought of analogy closer to home: it's like reading one really stupid thread on GT40s and deciding you don't like the internet.

Anyway, as you can see I have two issues with the "Hot Rod" <-> Mk II thing:

1. That FoMoCo was "Hot Rodding" or for that matter that the Cobra is an example of a Hot Rod. It's a mis-use of the term. Cobras were successfull, important, and effective, as was the Mk II. Are they elegant in the same way that a 250 GTO is? Of course not. But since you like Chapman let me just say "Lotus 40." I think there's a little more grey here than you're allowing for.

2. That even if they were "Hot Rodding", that "Hot Rod" is a pejorative term. There's a lot more to Hot Rodding than blindly and stupidly dumping a large motor into an alien chassis (that's funny, that reminds me of the start of this thread). It's most of all a visual medium, and a lot of what they do makes GT40s look like planaria. Check it out some time.

I also think you're smearing Hot Rodding and the MK II program with some stuff that's just Shelby and his marketing genius. And like it or not, it was genius. Did anybody ever write a hit single about Ferrari? Was it good music? No, it's asinine.

I'm not frustrated, I'm disappointed. And not in the OP. Look at this thread; we're on post 52 and no closer to any useful conclusion than post 1. How many more times is someone going to say something like "you really need to understand this?"

As for "agreeing with Keith" what part of my three principles do you disagree with specifically?

 

[roaldin]

There is a lot to laugh along with in your post lol.
It's like this guy I knew... ;p

I think there is another principle that runs alongside those that you have stated.

Me or my car, don't know. All I got was harrumphing, derisive comments about fiberglass and statements like "what is that doing here, its not a rod". The organizer was very apologetic. That story was not meant to mean that I am firmly against rodders btw, I am not.

I'm starting to get very grumpy with this stupid device changing everything I write... I may have to come back to this later.

Oh and as for the lotus 40, Da Vinci had the front and rear wheels of his
"tank" turning in opposite directions... He was still a genius.



Tim.

 

[George]

Now this is a Hot Rod

GT40 = Hot Rod? If you say so :lipsrsealed:

 

[roaldin]

Deep Purple, Burn: obviously about the 458.

Tim.

 

[Jon Briggs]

Well, we all know what happened. So my question for the anti-hotrod crowd is this: if you were HF-II "the Deuce" what would you have done in April 1965 that would have better served the program objectives and the Ford shareholders than what he did?

What's your superior, non-Hot Rod, plan?

I'm not anti hot-rod in any way, but I couldn't let this question go by with out an answer.

What would I have done? I would have listened and taken on board what John Wyer was telling me. I would then have gone out and won in 1965. Probably with a 427.

 

[Jon Briggs]

As for the OPs question. There are far too many variables in a car to say that a BB or SB is the better engine.

My advice would be to think very hard about what you want the car to do, write a list of wants and don't wants. Then take this list to an engine builder you trust, and let him advise you.

 

[Darrell]

Your words
My car is gonna be street/cruise mainly with Race for fun days out in controlled environment.


George can you tell me how you are going to get a big block registered for road use in Australia,have you spoken to a certifying engineer?

Darrell
DRB LS1 G50