Jan 2004 issue. Talks about what each is, how they are measured, what each does, and what to shoot for.

The old "short stroke/big bore small displacement faster than longer stroke/same bore" debate is put to bed. Some discussion on stroke vs. bore to obtain a certain displacement, and merits of each.

The article doesn't appear to be on line yet. If you don't subscribe, it's worth the newsstand price of the mag just for that article.

So, when this topic comes up in the future, all answers have to be consistent with the info in this article, or the person posting counter-claims will be cyberslapped...

(After you read the article, you might better understand the reasons GM went with the 305, even though they don't discuss that directly, and, even if you still don't agree with GM's decision...)

 

sounds interstin, i'll havta check it out.. maybe someone can scan it n post it up for everyone

 

Yep, my new issue just came in the mail yesterday. Let me scan the article real quick.

 

Hot Rod Horsepower article

You are going to have to save the pictures or copy them into adobe or something and zoom in on them because they are not quite big enough to read the writing. Sorry.

 

i cant read that. if i zoom in its all blury

 

I read the article. How does one determine the desired power range? How wide a power range can one make?

 

Sounds like I have to pick up a magzine tomorrow...

 

will some body email it to me?
i will then email it to two people who want to read it.
each of them two can do the same soon and one who wants it can have it
just a idea

 

I don't need to read the article, I already know that my motor makes 825 HP and 2,356 lb/ft!

 

I guess a discussion about the article is not possible.

 

A discussion sure why not?
The article seems mostly about big racing boat motors, i would rather talk about the small block chevy motor family and some of the big block chevys, but I'm not at all closed to the topic of big boat motors but hardly ever see one in a third gen.
here is my ideas, sure third gens came out with 305s but also in line 4s and v6s,hypothetical engine combos are nearly endless.
The idea that I'm suggesting is building a 305 side by side to a 350. the same amount of money spent on parts same amount of work done. the 350 seems vastly better to me. My idea on why GM has used the 305 so much. as it is a good mid size motor easy on gas. good for a light truck or van, family wagon. but it's not the one for a true sports car. As i often think of the Vets if they had pushed 305s back in 82 to 92 and not the 350s. maybe it would have killed off the Vets.
Torque and horsepower work together.and its easy to change the Torque out put of a motor just as it is easy to change the horse power out put. sure you can put a blower on a 302 and make it pull like a big block. but if you put a blower on a big block.then the sb can't match it or even come close. 350 is king. not just for its size but price and parts.305s are handicapped

 

No. 400 is KING!!!

Larger bore AND more stroke.

Actually, there is a similar article on Car Craft's website that's been there for probably 5 years.

Horsepower Vs Torque

 

For the most part i will agree with you're ideas on 400s it has more power and more size too, and i like 400s alot, my idea is 400s would be a better motor to build for third gens if the price of after market parts were the same, as for me i would always rather have the larger motor, i always want more more more.

Increased displacement is the easiest way to achieve increased torque. Very large cylinders and a long stroke offer the greatest cylinder volume and overall piston area for the fuel charge to push against the crankshaft or lever, if you will. a little clip from car craft. well its a better article i think than boat motors. wonder when will they do an article just about the small block family and keep it all motor only. that would be interesting reading.
what does car craft mean by this ''Engines don’t make horsepower''if engines don't then what does? i think when writers read too many books they say things like that. I'm sure he could point to a page in a book and say here this is what i mean. and he would have a valid point.but it just sounds kinda off beat to me. well it has some curve ***** in it.clip ''grunt work (torque) at lower engine speeds, which means reduced wear-and-tear and better fuel economy'' in my idea a grunt work motor is for fuel economy like in a grocery getter, family wagon and so on. just right for a 305. just my thoughts .

 

Do you feel better now?

 

If you think about it theyre right. Engines make torque, and they rotate. Torque x angular velocity = HP.

One thing that was interesting was their discussion on friction. Its interesting because I remember a problem from one of my college coarses that dealt with frictional losses in a sbc main bearing. With standard factory clearences and SAE 30 oil, a main bearing dissapates around 1 HP at 3600 rpm! Multiply that by 5, add in the eight rod bearings, wrist pins, friction on the piston skirts/rings, cam bearings, friction from the lifters, friction in the oil pump, friction in the rocker arm pivots, friction from misc. parts, and general drag from oil sloshing around, and well, thats alot of frictional losses! Guess the only way to combat all that is maintain the engine and run quality lubricants.

 

yes much,lol, and yes that is a lot of frictional losses.i will ad a-few additional drags to you're list if they are not already ''just for fun''seals the water pump, valve springs fuel pump centrifugal forces. the idea of torque VS horsepower never did sound just right. it makes it sound like torque and horsepower are fighting.who would you bet on if they could, torque could hit hard but horsepower would have more stamina lol.or maybe its the other way around.later he goes on to say torque and horsepower are closer to one thing. this sounds better.in my thoughts i still see horsepower and torque as two things but working closely together.normally motors are not very efficient about one third of the energy released during combustion actually drives the crank, Of the remaining two thirds, one third goes into the cooling system, and one third goes out the exhaust as heat. well you have my countenance on that idea.

 

speaking of quality lubricants... has anyone tried Royal Purple?

 

Here is an excellent article that everyone needs to read about torque and horsepower:

http://vettenet.org/torquehp.html

 

thanks for sharin that article,i was lookin for somthin like that

 

The thing I keep coming back to is where the performance is realized in the power band regardless to size.

Example:

600 HP below or above 5252rpm: Does it make a difference? Either way you have to gear it for the applicable speed range.

600 LB-FT torque above and below 5252rpm: What is significant?
All you are changing is clutch actuation.

Does higher rpm really mean better performance if the power band is really small? (What is an average size power band anyway?)

I think it would be cool to pull an average 350 FT-LB between 2500 and 6500 rpm. Granted the peak would probably be a good bit higher to accomplish that, but you could drive the darn thing in almost any gear at any time and walk if not fly away for most powered vehicles. Also what would the ramp up to the 350 look like?

 

These articles may still confuse a lot of people.

All you need to know is that torque is a force. POWER is force over time. Now, acceleration is a measure of how fast your car can go, in terms of seconds, minutes, right? So given a choice, I would rather have power than force because power allows me to do work in a specified amount of time, whereas "force"
does not give me any information about how quickly it can be applied.

You can go really deep into advanced mechanics (It's not simple at all, the output of IC engines is pretty darn complicated mathematically to model) but when it all boils down, we want horsepower because power is the ability to do work in an amount of time, and we want a wide widepowerband so we can do work for a longer period of time (since our engine speed will increase if we accelerate).

And that in a nutshell is why, for all the advantages of low-end torque in daily driving, why things like 0-60 and 1/4 mile times are based on hp-weight ratio, NOT tq-weight ratio.

 

So in reality life begins at 5252rpm...

Jason

 

My view of oil, horsepower and torque
Hear is one point to consider is the value of the motor, for example near to were i live you can find small block chevy s rather cheap or most American car motors for that matter, the dealers want about one dollar per c . i. so a 305 is around 300$ but i can buy 305s much cheaper than that. you could say from the same place the dealer gets them. As most people see cars not much differently then an refrigerator, or a toaster when they start to get old and the repair bill would be at or near to the value of the car they just junk it. As most cars do end up in the junk yard. I found a nice looking car for 3500 hundred dollars from a very nice lady, and she had always payed to have her oil changed every 3k . she kept ed telling me how it was do for its next oil change in a few days,She was nearly OCD,obsessive compulsive behavior disorder about it.The only reason Americans change their oil so frequently is marketing. A former ford development engineer said they would routinely run their development motors well over 25K, without changing the oil.And when the engines were pulled out for tear down they always showed a normal amount of wear. and from what i have seen first hand in motors that nearly never had their oil changed was maybe a-little more wear on the rod and main bearings, but thats after 150k to 200k.and most 305s had shown very little ring grove,as is often the case in small-displacement engines that I've had to pop the pistons out of. Marketing often is, Theft from people that don't know any better. Do a web search, And you'll find fleet testing that has gone well over 100K on a single oil change. Frequent oil changes enhances the resale value to some of the private buyers, as some people look down the oil filler hole for caked on oil with a light, in a nut shell,in some of my motors i change the oil very frequently for the main reason is that i often work them and don't like to work on a dirty motor.and feel that a few of the motors that i have are not going to end up in the junk yard any time soon so i will be working on the over and over again..rod bearings are worth less then the price of one oil change. I don't feel that frequent oil changes help the valve guides,as valve seals are to tight and exhaust valves run way to hot for oil to stay on them,same with the top piston ring and ring land.In a larger nut shell, i feel that i have spent way to much money on oil over the years in cars that i no longer own, was it worth it? And now the main topic.horsepower And torque. An engine's output is usually thought of in terms of horsepower. Actually, an engine produces torque, and the horsepower is calculated through a units conversion. The amount of torque an engine can produce is directly related to the amount of cylinder pressure it generates. And is affected by the characteristics of intake and exhaust capability, crank geometry, RPM s,and valve timing.With custom ground cam shafts and other engine builders 'secrets the possibilities are nearly endless. In my view the short block is basically just a ''pump'',so what you put on top of you're pump aka short block is the make or brake it deal, up to a point. I'll dumb this down a little more,at some point you're top is good enough and its time to look at improvements for the short block,to me 400HP is the starting point of when you have some thing called a hot rod.A 350 is a fine motor to build it can easily produce 400HP on a nearly stock short block.but some motors are built for fake out reasons,the owner might say its a 350,run my block numbers. but its really a 383.so even if you run block numbers you never really know what he has under the hood.maybe a 327 with a 383 crank. if i wanted over 500 HP i would get a bigger pump,aka as a big block, rather than spend a lot of time and money on a little pump like a 305.take 50ci away from a 305 and all you have is a v6 250 sized motor, take 50 a way from a bb 454 and you still have a 400. i rounded it off as many motors are not of stock bore. an engine's power output is about air exchange capability. The exhaust system is more reflective of the engine's ability to move air, as opposed to horsepower. Engine breathing and cylinder pressure has every thing to do with horsepower and torque.In a sports car you want every thing to kick in at higher RPM s.unlike the family car, as you already have tones of torque in you're first two gears. and if you have a low rear end 3 gears then. low and mid range torque motors is what you will find in 3/4 ton trucks, wagons vans, family cars.for me i like cars and motors built to do one particular thing with the intent to maximize performance within the parameters, what i call a one trick pony, try and do any more than one trick and you will have to compromise some thing. and we sure would not want that.The newer cars are in my opinion becoming overly electronicly sophisticated.An blind obsession with technical advancement, classics are so much more fun.can you imagine the likelihood of going to a 01 Corolla club meet or people telling tales of the fun they had in their 01 Mondeo not likely to happen to an toaster car. And now here are two Quotes from Albert Einstein,'' Anyone who has never made a mistake has never tried anything new. Common sense is the collection of prejudices acquired by age eighteen''.End of Quote. Any miss spelling are in the readers care.

 

So in essence get as much displacement as possible to get off the line and for part throttle driving, and make the thing strong so it can pull air up high.

The only thing I can see making is something that does two tricks minimum if you are going to drive it on the street. You have to drive to most events, and I can't imagine putzin along because it is only good at the track. And a car that's only good around town will leave you beggin for more on the open road, nevermind the track.

From a lot of what I've read so far, a lot of folks are recommending truck engines, only made more so by their part selection.

In either case it will still come down to how you gear it otherwise you will never be at the appropriate engine speed.

If it is a street driven car there should be a happy medium to changing parts. It is not the easiest goal to achieve, but it is definitely rewarding when accomplished.

Jason

 

This is how they should build car motors 4 valves 2 cams in each head and a carb for each cylinder .All of this is common enough in competition engines ,The current formula one engines, rev be-yond the 17 thousand RPM range. So the torque of the motor is one thing but not necessarily the single most important thing, Gears and RPM s are a differentiating factor, its the over all torque that matters what comes out at the wheel. a quick change rear end and a quick change intake manifold set up as just two ways to have a streatable car that can also run an 1/4 mile. in my view a car is best built to do one thing. but quick change is a way to skirt around that problem. just as you would change to wide slicks before going to the track. as long as you're happy with it thats all that counts, never let any one tell you what to build
Another point to consider is a longer crank throw makes more torque than a shorter one.As the longer throw has more time at the top, So lets say that you wanted more torque out of you're 327, so you decided to install a 283 crank and build a 302, but thats a shorter throw is that a contradiction, not really it's that the 302 can more easily be built to turn 12K and even a-lot more, so just back it up with supper low gears and there is the torque and HP, high RPM-s and very low gears,no one way is wright or wrong for every one
To get 12 thousand RPM s out of the 302, valve train parts have to be changed. factory stamped-steel rocker arms are not very good and that might be an understatement, stainless rockers are a world apart from the factory ones. And we would drill and grind most of the oil holes, with ultra light pistons and h beam rods. as far as the heads are concerned we would open the exhaust ports to what we felt was the max.that left just a very thin surface for the header pipe to seal at least 3/4 of the gasket had to be cut off, this is what we call flowing a motor ,just to name a few of the things we did. and thats part of the reason why i save my old blocks, in fact my 289 had such low gears that i could start off in third gear with only a 4 speed transmission. later went to a two speed automatic transmission..i don't have really strong feeling about one motor over another. have built more chevy-s, but like mopar and ford just the same. its just a chunk of cast iron.Two people a friend of mine and my self built our cars we each had the same make and year and the same size motor only thing was my motor was built to flat out scream 10 k + mine had very low gears, the differences were night and day. the low rear end greatly amplifies the torque.lets say you have 5.13 gears under you're car and take them out for some reason and put in more stock gears of 2.75 or some thing like that . at first it will feel like some one needs to give you a push just to get going, I have ran 7.50 gears on the street with no over drive and no problems. For example when you take off a lug nut that is very tight, slide a long pipe over the handle of you're strong arm, you will have so much torque at the nut but yet the handle could be moved with just one finger. so if you want a power amplifier, lower the rear end then you're motor needs to concede. Over the past 30 years I have built around 30 hot rod motors that I owned, but have worked on countless others, but no two have ever been built just a like. Very few people seem to have seen a fly cut engine. Put a 327 piston in with a 350 crank . Have it milled to a flat top. It puts the ring very close to the top of the deck. It worked great in stock cars for a class that needed a stock motor.with relief notches milled in it no one could easily tell the difference .with the broad interchangeability built in to the small block chevy motor family, people have been matching parts together in every way .The 305 with its 3.736" cylinders are not the easy or cheap way to go.you can put the same amount of work and money in to the 305 as the 350 and the 305 gives you less.Unless you want or need to run in that class, then why build a 305 and play the underdog? as it does not mix well with the rest of the small block family, for one thing,clearancing, valves that open wide tend to come very close the the block, but on a 4'' inch cylinder the valves can open in to the cylinder.Top of the line parts are not cheap. so it's nice to think you could reuse them on other motors. As for that one question on another thread no have never seen ford heads put on a chevy, seems it would be the other way around unsure. but have seen mopar on a chevy . The rotating assembly of a truck motor is not that different from most cars

A Quote from Albert Einstein

''He who joyfully marches to music rank and file, has already earned my contempt. He has been given a large brain by mistake, since for him the spinal cord would surely suffice. This disgrace to civilization should be done away with at once. Heroism at command, how violently I hate all this, how despicable and ignoble war is; I would rather be torn to shreds than be a part of so base an action. It is my conviction that killing under the cloak of war is nothing but an act of murder''

"Peace cannot be kept by force. It can only be achieved by understanding

 

alexander

You awareness of the possibilities outshines my small knowledge of the game. What is a quick change manifold? 7.X gears?!?!?!? Amazing. I did not know such a thing existed. And using a quick change rear in a street car didn't occur to me either.

My personal goal is drive 180 miles from my house to Grattan Raceway, run the course (including the 3200 ft. front straight) and drive home. The car will have to handle 65 mph and 150+ mph. My best guess is that having 350lb-ft. from 2500-6500 will make the whole trip fun based on the basic drivetrain packages available. If I can have 350 lb-ft. at 2500 and have the power increase as I accelerate up to 9000 rpm - whoa - I will definitely be in the magazines then!

Money solves almost everything you consider the perfect engine.

Heads-

http://www.araoengineering.com/Chevy/chevysmb.htm

Air/Fuel Intake

http://www.hilborninjection.com/prod...Id=52&CatId=37

That's over $11k on TOP of the cylinders. If I had that type of cash I'd have one very trick 3rd gen. Man, throw on a turbo, and a 400 block, and you would own the pros, shows, and hoes LOL!

How long do your 9000 rpm engines last in terms of miles? How often do you rebuild them? How DO you build one for that kind of use? All the books talk about are 6500 and down.

I guess when it comes down to it it doesn't matter how you make the power, as long as you have enough money to deal with the consequences.

But nobody has answered my questions yet. How wide an rpm range can you have and make a lot of power? Why does it matter if you make the same numbers above or below 5252 rpm? F1 cars rev that high because they are small displacement, light mass machines. They have to spin that fast to make the HP they do. You air pump has to move a whole lot of air with each stroke - 400 cid - or do a lot of strokes - 250 cid. The king of course is moving a lot of air And a lot of strokes, but that engine is rumored to have a very short lifespan.

For a street driven car can you get 20 mpg, blow low CO, run 12s in the 1/4 mile, and top 180mph? What does it take to do that?

Jason

 

I think you need to learn a little more. Torque is force times distance (pounds x feet is typical in English units), which is also the same units as WORK.

Power is work over time - (pounds x feet)/sec., for instance.

 

No I don't need to learn anymore, I already have my MS in ME

However thanks for pointing that mistake out, I am a dumbass! shame on me...


But lest anyone think otherwise, that correction in the definition of torque and power does not affect the validity of my statement,

which was that inherent in the definition of torque does not make any suggestion towards time.

 

I think your question about that is quite easy to answer by just looking at some current production cars and future models: the BMW M3, probably the new M5, the Honda s2000.

If you look at the dyno plots for the M3 and S2000, they both rev very high (>8k rpms) yet have an oddly flat torque curve from low ranges all the way to near redline, which does not fall off. You can see that as a testament to BMW and Honda, which arguably make the best engines in the world. Unfortunately the S2000 is still sluggish at low revs simply because it's only a 2 liter...

As for short lifespans due to revving high, It's a common statistical mistake to associate direct correlations like this. However, you are right in that the other factors related to a high revving engine (like being driven hard for starters...) will cause them to take more stress and fail prematurely

 

The BMW and the Honda also incoporate variable valve timing & lift, multiple valves, and an original intention to spin like crazy.

My truest heart's desire is to build a 5.7+L V-8 with at least 3 valves and 350 lb-ft of torque for as long as possible. Under 5252 it would be normal, but above, well shucks that would be fun.

The day that valve actuation can be detached from springs in a cost effective solution is the day that all of us speed junkies will overdose.

WTO push-rod two valve SBC (Gen-1) engines I would still like an answer.

Jason

 

I think I can explain...at least I'm going to try.

Lets take 2 example cars. Identical cars, identical weights. different

engines/transmissions. For example purposes, assume lossless powertrains. Also

assume cars have identical rear differentials/axle ratios.

Lets say car (car A) that is making 200 ft.lbs. of torque at 2000 rpm. Car A is

in a gear that is 1:1 ratio. That gives an output shaft speed of 2000rpm.

Now say car B is making 200 ft.lbs of torque at 4000rpm. It is in a gear that has

a 2:1 ratio. That gives an output shaft speed of 2000rpm.

transmission output shaft speeds are the same, and rear axles are the same ratio.

Both engines are currently producing 200 ft. lbs of torque. Which one is putting

out more force?


Car A is putting out 200 ft.lbs. of torque at the transmission output.
Car B, because of it's 2:1 gear ratio (which multiplies torque), is putting out

400 ft. lbs. of torque at the transmission output.

But how can that be, you say? Each engine is putting out "only" 200 ft.lbs. That

is where horsepower comes into play. Let's calculate the horsepower for each car,

at it's current rpm.

Car A's horsepower (@2000rpm) is 76.16HP (200tq X 2000rpm)/5252
Car B's horsepower (@4000rpm) is 152.32HP (200tq X 4000rpm)/5252

I hope I've put that into terms that make sense to you. I'd be more than happy to

clarify any points if you'd like, or correct any of my statments if they can be

found in error.

 

That part makes sense if we were only limited to one gear ratio. But since we are not, and we can optimize the gearratio to the power curve it really doesn't answer the question.

Thanks for your efforts though.

Jason