Talk:V8 engine

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v8 vs inline-6

Recently Rolling Phantom changed the following:

Medium-weight trucks tend to use the straight-6 configuration since it is simpler and easier to maintain, and because the straight-6 is an inherently balanced layout which can be scaled up to any size necessary. Large V8s are found in the larger truck and industrial equipment lines.

to:

Trucks tend to use the straight-6 configuration since it is more economical, and have the potential for more torque for a given displacement. The straight-6 is an inherently balanced layout which can be scaled up to any size necessary, but despite of this V8s are found in large truck and industrial equipment lines, as well as in small to medium duty trucks. Having the potential for more hp than the 6 cylinder engine, the V8 may outrun it until the weight of load and steepness of hill combined exceeds a certain limit that may not exist in real life, while still maintaining good economy due to that its working cycle has no negative torque.

I reverted it with the comment "Revert good faith edit. Your reasoning doesn't always follow. Why does an inline-6 have more torque? Why does a V8 have a limit that doesn't exist in real life?" RP left the following comment on my talk page:

Because a 6 cylinder engine will have bigger cylinders and/or longer stroke than a V8 with the same displacement. 1 cylinder engines have the biggest possible torque potential for any given displacement. The more cylinders an engine has, the bigger the potential for much hp, simply because it can turn faster. The limit may not exist in real life simply because trucks dont normally have that heavy loads and when they dont the engine with more hp at that rpm range gets on top of the hill first. Why do you think this is a product of "own reason" ?

I have shifted his comment here so that others can point out any flaws in either of our arguments. Simple one first. I said "your reasoning" because the changes were not self evident and had no supporting references. A 6 will indeed have bigger cylinders for the same total capacity, which is balanced by the V8 having more cylinders. Torque should be the same. Why would one big cylinder have more torque than several smaller cylinders totalling to the same capacity? Assuming the same total capacity, why would more cylinders help an engine turn faster? An 8 cylinder would have a shorter stroke and smaller pistons (assuming bore/stroke ratio is kept the same), which would allow higher revs, but the better balance of the inline-6 also allows higher revs. The smaller V8 piston also puts a restriction on valve size, which would limit it compared to a 6 cylinder. So the upper limit is not a straight forward comparison to make and would rely on specifics on each engine (journal size, bore, stroke, valve size, valve lift, cam timing, induction, fuel and many other details). By negative torque I assume you mean small periods of time in the engine cycle when pumping losses and frictional losses are higher than the instantaneous torque produced by any currently firing cylinder. This depends very much on the burn time of a particular engine and depends on far more variables than just the number of cylinders. I don't necessarily think that you are wrong. But neither do I automatically assume you are correct. It must be either self evident or having supporting references so that laymen can follow without just taking your word (or WP's word) for it. Comments? Stepho talk 06:04, 13 October 2018 (UTC)[reply]

Well, I removed what I found to be wrong or just partially correct on the sequence, and replaced it with stuff I "know"(or feel I know from remembrance) from articles ive read (that may also well be wrong, since its written by humans.). I cant always find the reference when I do such edits but they should exist somewhere on the net if I remembered correctly, which I often do fiy. Heinrich Lanz said that: "A tractor can never be one cylindered enough" or something like that, due to the fact that a one cylinder engine has the (potential for) highest possible torque. (I believe the Wiki article on the one banger also featured that before.) Multi cylinder engines have potential for more hp simply because a small cylinder most often will have a higher output per displacement, as it must rev higher to achieve useful power at all. Thats why there are many cylinders in sports cars and the like, these engines have different properties. Would BRM be able to achieve 450+ bhp from a 4 cylinder naturally aspired engine in the 50s? 60s Honda racers, why 6 and not 2? The same tendency is found in 6 vs 8 same displacement engines, albeit not so pronounced. They have different properties, "behave" different so to speak.

Anyway, what I found to be somewhat sloppy is that MEDIUM trucks tend to use 6 cylinder engines "because they are easier to maintain", which is not necessarily the case at all. While BIGGER trucks with V8 engines are common. As the one thing I agree with, it says that "6 cylinder engines can be scaled up to very big sizes" which is why big trucks and even bigger heavy machinery tend to use inline 6 engines. Most truck manufacturers that previously used V8 engines therefore now use 6 cylinder engines, since they are more efficient and economical. A notable exception is Scania, that keeps their V8 for enthusiasts, claiming that its just as or more economical than a 6, as long as you dont drive like a grizzly bear on speed. The lack of negative torque may be a contributing cause for this.(yes its a term, look it up.) V8s on the other hand is more common in relatively small, mostly American (pickup)trucks, but can be found in medium sized trucks(often heavier versions of the afore mentioned pickup trucks) as well. Medium sized european trucks with V8 engines also existed(eg Ford Cargo) Thats what popped into my mind so I wrote it and didnt bother going through all the work with finding credible sources for all of it. Its kinda boring when you search for hours until you find it. But please do if you feel like doing so.

Rolling Phantom (talk) 22:56, 15 October 2018 (UTC)[reply]

While I neither agree or disagree with the above (some of it is above my head), it neither obvious, not referenced. Anything that is not obvious must be referenced, otherwise it can be deleted. Which does mean that many of the current statements that you find objectionable can be deleted if you think they are likely to be wrong, or tagged with {{cn}} if you think they are likely to be right. The onus to find a suitable reference is on the editor who wants something to stay. Note also that the reference can't just be somebody stating an opinion. WP lives or dies by being able to support what it asserts. I offer https://books.google.com.au/books?id=DoYaRsNFlEYC&pg=PA46&lpg=PA46 as a starting point. Stepho talk 22:49, 18 October 2018 (UTC)[reply]

Agree with Stepho, and in essence: TL:DR - source please. Chaheel Riens (talk) 11:46, 19 October 2018 (UTC)[reply]

AFAIK both MAN and Mercedes have dropped their V8 (and V6 in the latter case) truck diesels in favour of straight-6 engines, leaving Scania as the only big (European) player with a V8 option. Renault did offer the option of a Mack V8 in the Magnum but I don’t believe they sold many and they stuck to I6s when the T was introduced. Mr Larrington (talk) 17:51, 12 October 2021 (UTC)[reply]

Digby's latest edits

I've reverted your latest edits because I don't think they're necessary. The phrasing already takes into account the aeronautical application, and there's no source to support your change to specify race cars.

Please discuss, rather than claiming ignorance over who and why your edits are being reverted. Chaheel Riens (talk) 09:31, 12 December 2018 (UTC)[reply]

Agreed. How many RR are we up to now? I would agree with the claim that these (French V8s in the early years) are "popular for aircraft engines", particularly from Renault (and of course, Antoinette). I'm not wedded to any particular wording there, if someone has something clearer, but this repeated reversion in favour of (unspecified and unsourced) "race cars" is no way to proceed. Andy Dingley (talk) 15:20, 12 December 2018 (UTC)[reply]

Andy Dingley (talk) 15:23, 12 December 2018 (UTC)[reply]

WP:ANEW#User:DigbyDalton reported by User:Andy Dingley (Result: ) Andy Dingley (talk) 15:34, 12 December 2018 (UTC)[reply]

I've reverted again on the grounds of disruptive editing and WP:IDHT. The current text says "The V8 engine configuration became popular in France from 1908 onward, and was used in a number of aircraft engines introduced by Renault, and Buchet among others. Some of these engines found their way into automobiles in small quantities" - this corroborates the claim that the engines were popular in aeronautics, and that some then made their way to road-going vehicles. There is nothing to support the changes suggested by Digby.

Digby - it's very simple: If you want support for your version, come here and discuss it - preferably with sources to back up your claims. Chaheel Riens (talk) 15:37, 12 December 2018 (UTC)[reply]

How can a V-8 airplane engine be popular in France in 1908 when 1908 was the year Wilbur Wright went to France to demonstrate that his primitive airplane could actually fly? Until 1908, the French thought the Wright Brothers were a hoax. The first French-built airplane that actually flew was 1909, and it sure didn't have a V-8. But the French were building V-8 race cars at Le Mans and the Grand Prix, and that was 1904. I did not use 3 reverts, I used 3 edits, and they were all different. Chaheel Riens on the other hand made 4 actual reverts. Saying that V-8 engines were popular in France in 1908 is ridiculous, to anybody who knows what the word popular means. Race cars are not popular. They are specialty cars. Popular cars would be passenger cars, then as now.DigbyDalton (talk) 23:43, 12 December 2018 (UTC)[reply]

Santos-Dumont flew his 14-bis at the end of 1906, with a V8 Antoinette. This was an engine that was already established as one of the leading engines of the day, powering racing powerboats. So yes, the French knew about powered flight before 1908.

Which 1904 racing car are you thinking of? Andy Dingley (talk) 00:07, 13 December 2018 (UTC)[reply]

"Big block" vs. "Small block"

I am annoyed with the use of the terms "big block" as opposed to "small block". This categorisation is not defined anywhere I can see. There is nothing encyclopedical about it. Either these terms should be documented/referenced/explained, perhaps in their own articles or perhaps in a general article on piston engine terminology, including regional accents, or their use should be banned. Jan olieslagers (talk) 16:37, 12 April 2019 (UTC)[reply]

There are many "definitions" of big/small block - none of them are official. However, each V8 engine from the major American manufactures that have multiple V8 families is almost universally known as a big or small block. The simple answer used to be anything below 6 litres is a small block and anything above is a big block. But there are some small blocks greater than 6 litres (eg Ford 400M) and some early big blocks smaller than that. The next most common answer is deck height (from crank shaft centre to the cylinder head gasket) being less than 9.8 inches. But some recent small blocks for racing have exceeded that. Next is bore spacing - 4.4 inches or less is a small block, more is a big block. I don't know of any exceptions to bore spacing but there might be. Some people say it depends on how much a block can be overboard - which is also highly dependant on bore spacing. And the only real answer is that whenever a manufacturer has more than 1 V8 family (family defined as being able to share major parts like heads) then the physically smaller family is the small block and the physically larger family is the big block - although this could be argued as being a variant of bore spacing making the engine longer.

This is kind of vague but since the terminology is so prevalent in the industry, it should continue to be used. We just need to write down the various competing descriptions. Stepho talk 23:59, 12 April 2019 (UTC)[reply]

Thanks for this rapid and extensive answer. Please excuse me for questioning the "prevalency" bit: it would seem to me the terminology is only common in North American English. Of course the majority of V8's must be from North America these days, still it sounds like a regionalism to me. But I might well be wrong :) It would certainly help if the terminology were explained somewhere, however vague. Jan olieslagers (talk) 07:31, 13 April 2019 (UTC)[reply]

I'm Australian but most of our V8 engines are from America, so we copied their terminology. So I guess that might be regional. Any place that gets American V8 engines in any quantity is likely to be in the same position. We also get a lot of American car magazines (as well as European and our own) and thus read stuff in their own words - even with their funny spelling :) . European V8's don't seem to use this terminology. I guess all this can be added to the American section of this article. I'll wait a few days to see if anybody has something to say, then I'll give it a go. Stepho talk 09:55, 13 April 2019 (UTC)[reply]

Thanks again. I hadn't yet realised where you are - not that it matters much. I am looking forward to your "giving it a go" - be assured to have one critical but positivist observer :) Jan olieslagers (talk) 12:22, 13 April 2019 (UTC)[reply]

Cranking

The following was left at my talk page. I felt it would be better to discuss here, where other editors can join in. Stepho talk 00:56, 26 December 2021 (UTC)[reply]

Thank you for reverting my edit on V8 engine because you questioned whether hand-starting a V8 in 1912 would be harder than crank starting the typical 4 cylinder engines of the day. Your argument that a V8 might have the same displacement as a 4 is good, although there would be no point, the usual reason to use more cylinders is to make the engine bigger. Bigger engines are obviously harder to hand-start for reasons too obvious to mention, but even if the 8 cylinder engine had the same displacement as a 4, there are 2 reasons why it's harder to crank start an 8 than a 4. One is that the single firing piston has to compress the remaining pistons which are not yet firing. Imagine an engine with 50 cylinders. Would the 1 firing cylinder produce enough energy to compress the remaining 49 which are not firing? Of course not. That applies to 8 vs. 4 though not as much. The other reason is the number of degrees of crank for each piston with the person's arm. A 4 cylinder engine gives you 180 degrees of turn on the hand crank for each piston. (The 720 degrees in the Otto cycle divided by 4). The average person would be able to give a good amount of turn of an engine with only one compression on a 180 degree pull on the handle from bottom to top. On an 8 cylinder engine however, there would be a new compression to overcome every 90 degrees of pull on the crank. I don't think 90 degrees is enough time to get the engine turning fast enough to start before the arm has to overcome a second compression. I've seen early literature on the subject, not only Cadillac but Buick was holding off making a 6 cylinder car until they had an electric starter as well, the first Buick 6 was in the 1914 model 55 which had a whopping 331 cubic inches, and of course their first electric starter. Pierce Arrow made a massive model 66 with a 6 cylinder engine with over 800 cubic inches (not a typo) but only after they had an electric start. It is utterly impossible to hand start a Pierce Arrow 66, ask me how I know MorganDWright (talk) 21:10, 25 December 2021 (UTC)[reply]

Thank you for your polite query about my revert.

Bigger is better is obviously one reason for a V8. Another is that a 4-cylinder is buzzy (harmonics) and a 6-cylinder is long. The V8 is smoother than a 4 and shorter than a 6.

Comparing compressing 1 cylinder to 50 is assuming that each of those 50 cylinders is the same size as the 1 cylinder. For a 5.0-litre V8 vs a 5.0-litre 4-cylinder, the V8 cylinders have only half the capacity of the 4. It is not obvious whether double the number of half-sized cylinders will be easier, harder or about the same to crank.

The number of compressions per hand-stroke may be a possible reason. It might be possible that a single long push allows you to get some momentum into the engine, whereas many smaller compressions might not allow you to build up enough compression. But it is also possible that the smaller compressions don't need as much momentum to start - ie the first of the smaller cylinders to fire will start the rest. I would like to see a reference for this, as per WP:VERIFY.

The examples you gave of large engines requiring an electric starter is based on them being large - not on being a V8. Stepho talk 00:56, 26 December 2021 (UTC)[reply]

I stand self-corrected about the monster Pierce Arrow with an 825 cubic inch engine (with only 6 cylinders). It did NOT have an electric start until 1914, earlier models, 1913 had compressed air starters, but the 1910-1912 cars were over 700 cubic inches and had to be started by hand. So, I guess that makes the Cadillac argument moot. MorganDWright (talk) 17:10, 26 December 2021 (UTC)[reply]

I just dug out the old papers. Pierce Arrow made 203 cars in 1912 with 825 cid (5 x 7) engines without compressed air or electric start. 200 cars in 1913 with 825 engines with compressed air starter, and 1914, electric start.MorganDWright (talk) 21:27, 26 December 2021 (UTC)[reply]

2012 Chevy Silverado LT also takes flex fuel. I have a 8 cylinder vortec how do I find out out my liters size

Help 75.98.185.100 (talk) 17:12, 9 June 2022 (UTC)[reply]

Surely your license papers would list that?

Next place to look is Chevrolet_Silverado#Second-generation_Silverado_/_third-generation_Sierra_(GMT900;_2007). That lists several engines for 2007-2009 but only the 6.2 L V8 for 2009-2013. Following the link in the infobox to General_Motors_LS-based_small-block_engine#6.2_L, it lists the L9H with flex fuel for the Chevy Silverado 1500 . Stepho talk 01:57, 10 June 2022 (UTC)[reply]

metric vs imperial/US

@Michael F 1967: and I have a difference of opinion. MF says that a speed record was American, therefore according to WP:UNITS it should be listed as mph first. I read the same WP:UNITS and interpret it as 1) the entire article is to consistent, 2) the entire article is international, not US specific, 3) therefore all measurements in the article should be metric first, followed by imperial/US measurements. Stepho talk 01:48, 15 December 2022 (UTC)[reply]

Thank you, @Stepho-wrs:, for your very sensible and civilised approach to this business.

My thinking goes like this:

I'm not sure that it makes sense to view it as a whole-article black and white issue in this particular article which by its nature has, in its different parts, strong ties to lots of different countries, especially bearing in mind the fact that there's always been plenty of national rivalry when it comes to land speed records of all sorts.

It also seems to me that since Glenn Curtiss made his V8 bike in the US, set his top speed in the US, certainly measured his speed in mph, and also that the US still uses mph, it doesn't make sense to present that particular speed as anything but mph (km/hr).

Since both units are provided, thus informing everyone regardless of which unit they understand best - well, why not go with "close ties to the US in this particular bit of the article" to determine which goes first?

Personally, I'm not bothered one way or another: for irrelevant reasons, I can think just as easily in mph as km/hr.

(On a side issue: I've noticed that despite WP:UNITS requiring SI units unless there's an exception, the standard unit on Wikipedia for specific impulse seems to be "seconds" (an unscientific unit created by US engineers (no, I won't call them lunatics: that'd be rude) who - if I understand it - decided to mix up pounds-force with pounds-mass) rather than the SI version "metres per second". My point here is that Wikipedia is not internally consistent when it comes to the application of "SI unless...")

Michael F 1967 (talk) 16:49, 15 December 2022 (UTC)[reply]