Ohv Engine Pushrod Length Calculation

Ohv Engine Pushrod Length Calculation Rating: 4,0/5 8119 votes

Components of a pushrod valve actuation systemAn overhead valve engine ( OHV engine), or pushrod engine, is a whose are situated in the. An OHV engine's operates its valves via a camshaft within the, cam followers (or '), and.The OHV engine was an advance over the older, whose valves were situated in the.

  1. Ohv Engine Pushrod Length Calculation Formula
  2. How To Find Pushrod Length

Some early 'OHV' engines known as ' used both side-valves and overhead valves. A variation over the OHV design is the, or 'OHC', engine, whose camshaft lies in the cylinder head itself, above the valves. To avoid confusion, OHC engines are not referred to as OHV despite also having their valves in the head. Valve-In-Head engine, illustration from 1904 patent, Buick Manufacturing CompanyIn early 1894, Rudolf Diesel's second Diesel engine prototype was built with a cylinder head featuring push rods, rocker arms, and poppet valves. Diesel had published this design in 1893.

In 1896, U.S. Patent 563,140, awarded to William F. Davis, illustrated a gasoline engine with the same head configuration, patenting his solution to the problem of how to cool the head, which problem had made the overhead valve engine difficult before then. Henry Ford's of 1896 had valves in the head, with push rods for exhaust valves only, the intake using suction valves. In 1898, bicycle manufacturer built a motor-trike with a one-cylinder OHV engine with push rods for both exhaust and intake.

In 1900, hired Marr as chief engineer at the Auto-Vim and Power Company in Detroit, where he worked until 1902. Marr's engine employed pushrod-actuated rocker arms, which in turn pushed valves to the.

Marr left Buick briefly to start his own automobile company in 1902, the, and made a handful of cars with overhead valve engines, before coming back to Buick in 1904. The OHV engine was patented in 1902 (awarded 1904) by Buick's second chief engineer Eugene Richard, at the Buick Manufacturing Company, precursor to the. The world's first production overhead valve internal combustion engine was put into the first production Buick automobile, the 1904 Model B, which used a 2-cylinder, with 2 valves in each head. The engine was designed by Marr and David Buick.Eugene Richard of the Buick Manufacturing Company was awarded US Patent #771,095 in 1904 for the valve in head engine. It included rocker arms and push rods, a water jacket for the head which communicated with the one in the cylinder block, and lifters pushed by a camshaft with a 2-to-1 gearing ratio to the crankshaft.

Was awarded US Patent #1,744,526 for an adapter that could be applied to an existing engine, thus transforming it into an Overhead Valve Engine. Picture of a (with removed), showing the, and rockers.The built their own airplane engines, and starting in 1906, they used overhead valves for both exhaust and intake, with push rods and rocker arms for the exhaust valves only, the intake valves being 'automatic suction' valves. They even built a V-8 engine with this valve configuration in 1910. In 1949, introduced the, the first V-8 engine with OHV's to be produced on a wide scale.is the world's largest pushrod engine producer, producing I4, V6 and V8 pushrod engines. Most other companies use overhead cams. Nowadays, automotive use of side-valves has virtually disappeared, and valves are almost all 'overhead'.

However, most are now driven more directly by the system. Few pushrod-type engines remain in production outside of the United States market. This is in part a result of some countries passing laws to tax engines based on displacement, because displacement is somewhat related to the emissions and fuel efficiency of an automobile. This has given OHC engines a regulatory advantage in those countries, which resulted in few manufacturers wanting to design both OHV and OHC engines.However, in 2002, Chrysler introduced a new pushrod engine: a 5.7-litre Hemi engine. The new presents advanced features such as technology and has been a popular option with buyers. The Hemi was on the list for 2003 through 2007. Chrysler also produced the world's first production variable-valve OHV engine with independent intake and exhaust phasing.

The system is called CamInCam, and was first used in the 600 horsepower (447 kW) SRT-10 engine for the 2008.Early air-cooled OHV BMW motorcycle engines had long pushrods and a single centrally-mounted camshaft; but the post-1992 BMW R259 'Oilhead' boxer engines had a camshaft in each cylinder head, located between the combustion chamber and the rocker arms. The pushrods were very short, allowing higher rpm and more power. For instance, the (which had a R259 engine) could achieve an output of 98 hp (73 kW) at 8,400 rpm, with no risk of valve bounce. Since, BMW engines have had OHC valve actuation.Advantages OHV engines have some advantages over OHC engines:.

Smaller overall packaging: because of the, OHV engines are more compact than an overhead cam engine of comparable displacement. For example, 's 4.6 L OHC V8 is larger than the 5.0 L I-head V8 it replaced. GM's 4.6 L OHC V8 is slightly taller and wider than GM's larger displacement 5.7 to 7.0 L I-head V8.

The uses the OHV engine to fit under its low bonnet line. Because of the generally more compact size of an engine of a given displacement, a pushrod engine of given external dimensions can have significantly greater displacement than an OHC engine of the same external size. As a result, the pushrod engine can sometimes produce just as much power as the OHC engine, but with greater torque (contrary to popular belief, this is simply due to the greater displacement of the pushrod engine versus the OHC engine rather than any inherent advantage of the pushrod design for torque production).

Only a single head casting is needed on vee and flat pushrod engines: Because of the need to drive both cams on one side of the engine, the camshaft orientation on OHC heads must be the same for both heads of a flat and vee engine. This means that the heads must be (more or less) mirror images of each other. And this requires that two different head castings be produced. Pushrod heads can simply be flipped around, which allows a single casting to be used on both cylinder banks. Simpler drive system: OHV engines have a less complex drive system for the camshaft when compared with engines.

Most OHC engines drive the or using a, a, or multiple chains. These systems require the use of tensioners which add complexity. In contrast, an OHV engine has the camshaft positioned close to the crankshaft which may be driven by a much shorter chain or even direct gear connection. However, this is somewhat negated by a more complex valvetrain requiring pushrods. Hydraulic lifters: Although RPM capability is limited by the use of hydraulic lifters, the valve lash is self-adjusting for the lifetime of the engine, reducing a significant maintenance requirement. Some OHC engines also use hydraulic lifters/lash adjusters, but the implementation is more complex in OHC designs.

Simpler lubrication system: Because OHV engines have no camshaft(s) in the head(s), the head(s) have much more modest lubrication requirements than the head(s) in OHC engines. Therefore, there is no need for oil galleys to supply the head(s) with oil or oil galleys in the head to provide lubrication for the cam bearings. OHV heads only need lubrication for the rocker arms at the pushrod end, trunnion, and rocker tip. This lubrication to is typically provided through the pushrods themselves rather than a dedicated lubrication system in the head. And lubrication for the camshaft is provided through the same block galleys that provide oil for the main bearings. The more modest lubrication needs of an OHV engine also mean that a smaller, lower capacity oil pump can be used.Limitations Some specific problems that remain with overhead valve (OHV) engines:.

Limited engine speeds or: OHV engines have more moving parts. OHV engines also typically use only a single intake and exhaust valve, which results in large (and heavy) valves, valve springs, and retainers. Thus, the valvetrain in an OHV engine has greater inertia and mass. As a result, they suffer more easily from valve 'float', and may exhibit a tendency for the pushrods, if improperly designed, to flex or snap at high engine speeds. Therefore, OHV engine designs cannot spin at engine speeds as high as OHC Modern OHV engines are usually limited to about 6,000 to 8,000 (rpm) in production cars, and 9,000 rpm to 10,500 rpm in racing applications.

In contrast, many modern DOHC engines may have rev limits from 6,000 rpm to 9,000 rpm in road car engines, and in excess of 20,000 rpm (though now limited to 15,000 rpm) in current using. High-revving pushrod engines are normally solid (mechanical) lifter designs, flat and roller. In 1969, offered a Corvette and a model with a solid lifter cam pushrod V8 (the ZL-1) that could rev to 8,000 rpm. The engines can rev to more than 7,000 rpm with their solid lifter camshaft. However, the LS7 of the C6 Corvette Z06 is the first production hydraulic roller cam pushrod engine to have a redline of 7,100 rpm.

The motorcycle engine has a 9650rpm redline, well above the usual limits for auto engines, due to the lighter weight of components. Limited cylinder head design flexibility: (OHC) engines benefit substantially from the ability to use, as well as much greater freedom of component placement, and intake and exhaust port geometry. Most modern OHV engines have two valves per cylinder, while many OHC engines can have three, four or even five valves per cylinder to achieve greater power. Though multi-valve OHV engines exist, their use is somewhat limited due to their complexity and is mostly restricted to low- and medium-speed diesel engines, with a few notable exceptions such as the four valve per cylinder motorcycle, and the engine. In OHV engines, the size and shape of the intake ports as well as the position of the valves are limited by the pushrods and the need to accommodate them in the head casting.

Spark plug placement is also less ideal in pushrod engines. This is important, since a centrally located spark plug improves combustion efficiency and reduces both emissions and tendency to detonate by reducing flame travel distance (which also reduces combustion time). DOHC engines with four valves per cylinder can have a truly centrally located spark plug because this space is free from both valves in the combustion chamber and valvetrain above this central area. Even SOHC engines with four valves per cylinder can usually accommodate a central spark plug.

But since pushrod engines almost always have only two valves per cylinder, it is impossible to have a central spark plug. Noise and refinement: OHV engines are generally noisier than their OHC counterparts owing to the increased complexity of the valvetrain and the adoption of chain or gear based camshaft drive. Maintenance: The location of the camshaft in the cylinder block often necessitates removal of the engine whenever camshaft work is required. This is particularly true for front wheel drive applications with a transversely mounted engine.

Longitudinally mounted OHV engines suffer less from this problem as the camshaft can be withdrawn from the front of the engine after removal of the. Additionally, replacement of lifters generally requires removal of the cylinder heads.

And cam bearing replacement generally requires the removal and complete teardown of the engine. Increased valvetrain friction and wear: Because OHV engines generally use only a single intake and exhaust valve, the valves are larger and heavier than those used in multivalve OHC engines. Furthermore, when the valve is closed, the spring must accelerate not only the valve and rocker arm, but also the pushrod and lifter. Therefore, OHV engines must use heavier valve springs than OHC engines (multivalve or otherwise). As a result, valvetrain friction and wear is increased. This is especially true with high performance OHV engines utilizing high lift/duration/ramp rate cams with heavier than stock valve springs. Limited ability to use variable valve timing: Because OHV engines use a single camshaft for all valves, the ability to independently vary intake and exhaust valve timing is limited, although it is possible to vary the phase of one set of valves while the other set's timing stays constant (as in the 'CamInCam' or 'DuoCam' system).

Also, because all cam lobes are on a single camshaft, there is little to no room for the extra high RPM lobes required for two stage systems like Hondas’s VTEC. Because of these factors, variable valve timing on OHV engines is limited to cam phasing systems that change intake and/or exhaust valve timing with no ability to vary lift or duration.1994 Mercedes/Ilmor Indianapolis 500 engine.

This section does not any. Unsourced material may be challenged. ( February 2015) Each year, the bears some vestige of its original purpose as a proving ground for automobile manufacturers, in that it once gave an advantage in engine displacement to engines based on stock production engines, as distinct from out-and-out racing engines designed from scratch. One factor in identifying production engines from racing engines was the use of pushrods, rather than the overhead camshafts used on most modern racing engines; Mercedes-Benz realized before the that they could very carefully tailor a purpose-built racing engine using pushrods to meet the requirements of the Indy rules and take advantage of the 'production based' loophole, but still design it to be a state of the art racing engine in all other ways, without any of the drawbacks of a real production-based engine.

They entered this engine in 1994, and because of the higher boost pressure and larger displacement that the 'loophole' allowed pushrod engines, dominated the race. After the race, the rules were changed in order to reduce the amount of supplied by the. This amount was still 13% higher than what was allowed for the OHC engines. The engine was also allowed to retain its considerable displacement advantage.

The inability of the engine to produce competitive power output after this change caused it to become obsolete after just the one race. Mercedes-Benz knew this beforehand, deciding that the cost of engine development was worth one win at Indianapolis.See also.References.

This page has a LOT of incorrect informationI think am image, say a CAD rendering could really improve this article. Does anyone have one that could be used? 18:08, 19 March 2007 (UTC)I just spent the day making an animation in Flash, now comes the tricky part: Converting to GIF. Flash 5 has crap support for any file format. 01:54, 27 March 2007 (UTC) Ok, fantastic.

I have the SWF done, but I can't get it converted to GIF without it either being huge, or losing a lot of quality (why the hell isn't that damn thing fading out?!), anybody have any suggestions? 02:02, 27 March 2007 (UTC)I don't know anything about Flash, but if you can make each of the animation frames into individual image files you could use Polyview to convert the frames into an animated GIF image. 22:23, 27 March 2007 (UTC)I have an AutoCAD drawing that I'm almost finished with but I don't have a way to make a nice rendering of it.

If anyone can make a nice render of a DWG file (or possibly other AutoCAD formats or exports) leave me a message on and I'll email it to you. 22:34, 27 March 2007 (UTC)Here's the drawing, this is the best I can get it with AutoCAD. I might try to improve it in Gmax but I'm not really sure how I can do that yet.

So again, if anyone can improve it let me know. Agreed on all points. The comparison of the LS7 pushrod motor is ridiculously unfair.

The author is pitting a motor sold in 2006 with motors designed many years prior. Comparing a 2003 M5 motor with the 2006 LS7 ludicrous. The M5 now has greater power to weight in its latest production year. This does not proove that the LS7 is 'exceptional'. It a flawed argument.This article is made by somebody that talks only of advantages of GM engines compared to another engine companies, and by this fact, it has a lot of mistakes and false information, please correct it!!! In addition, only car engine are mentioned, what happens with radial engine of early airplane? The article should be called 'Pushrod engines of GM' because any other pushrod engine is insignificant for this article.

Agreed on most points. I was going to make changes like what you are suggesting but I was waiting to see what happened with the merge between this and the cam-in-block article. I'm not really sure where any incorrect information is in this article though.

14:25, 26 January 2007 (UTC)Shouldn't this page really be at Pushrod engine instead of pushrod? What this page describes isn't actually a pushrod.Also, both limitation sections need NPOV, weasel word, and fact-check cleanup.- 18:18, 2005 Feb 20 (UTC)Why the plug for Radical Motorsports? I would change that to 'some engines.' The term used for years was OHV, and it was not chosen deliberately to get confused with OHC. A more encyclopedic article would give the history of such engines, and what advantages and disadvantages they had over those which came before them and competed with them. 02:55, 3 January 2006 (UTC)I don't think the comparison between the GM 3800 and the Honda J-Series is particularly valid. The J-Series has, makes noticeably more horsepower per liter than any other engine in the segment (for a direct example, it makes 50 more horsepower than Toyota's outgoing 3.0L ), and the 3800 is also being phased out, to be replaced by the newer LZ8/LZ9 3900 (which does have ).Removed:.

Torque and Fuel efficiency - Due to the inherent torque advantage of larger displacement, pushrods can often be tuned for fuel economy and performance at the same time. The V8 produces 303 horsepower, 323 ftlbf of torque, and returns 17 city/28 hwy mpg, currently without a multiple valve-per-cylinder arrangement or, although it does use.The production of torque has nothing to do with the type of valve actuation system used. Fuel mileage ratings are irrelevant as the fuel saving is largely due to a technology that is separate from the OHV configuration. 21:07, 30 July 2006 (UTC)Removed:. Torque - Generally pushrod engines create more torque at a given displacement. Reliability - Pushrod motors can be the most reliable engines. Chevy Smallblock, GM 3800 V6)The valve actuation system has nothing to do with torque production, torque is not an advantage.

The statement on the reliability of pushrod engines requires a reference. 15:53, 1 September 2006 (UTC)Removed:. Lighter less mass while producing higher output:.

7 L V8 I-head in 2007 Chevrolet Corvette Z06: 458 lb 208 kg, 505 HP SAE 377 kw @ 6300 rpm, 470 lbft 637 Nm @ 4800 rpm. 5 L V10 OHC in 2007 BMW M5 & BMW M6: 529 lb 240 kg, 500 HP SAE 373 kw @ 7750 rpm, 383 lbft 519 Nm @ 6100 rpmThis is a comparison of a V8 to a V10 so it doesn't make much sense. Also this isn't true very often. 23:46, 3 November 2006 (UTC)Removed:. Simplicity means less mass:.

7 L V8 I-head in LS7 from GM: 458 lb 208 kg, 505 HP SAE 377 kw @ 6300 rpm, 470 lbft 637 Nm @ 4800 rpm. 5 L V8 OHC in S62 from BMW: 527 lb 239 kg, 396 HP SAE 295 kw @ 6600 rpm, 370 lbft 502 Nm @ 3800 rpmPushrod engines only have simpler drive systems, they commonly have more (edit: reciprocating) parts overall compared with OHC engines, even when compared with OHC systems with twice the number of valves. The LS7 is an extreme example of power to weight ratio for production V8s in that price range. Most pushrod engines do not have superior power to weight ratios, OHC race engines have vastly superior power to weight ratios compared with pushrod race engines. In order to make anything stating that pushrod engines have superior power to weight ratios accurate you would have to list that there are many exceptions, which really makes the point moot. 05:10, 4 November 2006 (UTC).

Contents.RPM 'Custom manufactured or modified engines that utilize oversquare piston travel, and lightweight valvetrains similar to those used in NASCAR racing can rev in excess of 8000 rpm.' While this is technically correct, it's a bit of an understatement. NASCAR engines will routinely turn more than 9000 rpm, and at longer tracks such as Pocono they will occasionally see over 10,000. 21:57, 1 October 2006 (UTC)OHV? Overhead valve engines can also be OHC engines, it would seem this term could not be interchangeable with pushrod engine.

I have changed OHV to I-Head which is a term that cannot be confused with any other configuration. 17:56, 1 November 2006 (UTC)Comparing engines S: IJB TA, you removed the V8 vs V10, alright. You wanted a V8 to V8 comparison, I provided.Now you start talking about price range.The V8 BMW engine is heavier and MORE expensive.

Not even mentioning how much more expensive the V10 is.Then you talk about race engines and how much better OHC are. Alright, then explain how the Corvette C6.R has won the last 6 Le Mans championships with the pushrod LS7.R against the OHC from Aston Martin.My point here is that for large displacement the pushrod design can be better.The technology is evolving, don't get stuck in the past.This article is about the technology and it should at least mention the new developments.This is not a history article:-)You can make the point that you can use larger displacement with pushrod engines because they are more compact, but that really falls into the first advantage that is already listed.

Ohv Engine Pushrod Length Calculation Formula

Also larger displacement doesn't really mean much because pushrod engines commonly produce less power with that displacement. My only point is you can't just compare two engines and say that pushrod engines will always be lighter. F1 engines weigh little more than 200 lbs but make somewhere around 800 hp, I think the V10 F1 engines made 900+ hp and weighed around 260 lbs.

That power to weight will never be matched by a pushrod engine, I don't think it's even matched by gas turbines. Again, all you could really say is that pushrod engines are lighter sometimes, which doesn't really say much.

20:13, 4 November 2006 (UTC)S: Please name one OHC mass production performance engine that beats the LS7 in power to weight. Here is one that comes close but fails:Mercedes AMG V8 6.3 L OHC from the CLK63 AMG, 475 HP, 439 lb = 1.08 HP/lb vs 1.10 HP/lb LS7. Let us never forget the cost.

How To Find Pushrod Length

F1 engines that you mentioned are astronomically expensive. Any comparison should consider at least the same price range. Also the F1 engines were designed read pushed hard to last one race. Let's talk real life, reliable engines, comercial engines. To me anything over 10000 rpm is pushing it too far, regardless of the technology. Until new materials will come AND become affordable, the rev-it up trick won't work if the engine must last.2003 Porsche Carrera GT Porsche M80 5.7L DOHC V10 604hp 472lbs 18:00, 6 November 2006 (UTC)I'm looking for the weights of the Ferrari 360 Modena and F430 engines, I'm pretty sure both of those engines have better power to weight ratios but I can't remember where I saw them.

The point I wanted to make when I mentioned price range above was that there are plenty of high end OHC engines that have better power to weight ratios. If you want to include something about some pushrod engines generally offering higher peak power output for the cost I wouldn't have any objections. Also my main point still stands, only the LS7 has such a power to weight ratio, most pushrod engines have inferior power to weight ratios, so really it's still a rare trait that is specific to one engine.

21:31, 6 November 2006 (UTC)The Ferrari F50 V12 weighed 436.5 lbs and made 513 hp. Also, high-rev engines last just fine. F1 engines are required to last for two events, that includes qualifying. 22:23, 6 November 2006 (UTC)S: I hope there is at least one mass produced OHC engine to support this entire 'OHC is always better':-) The F50 V12 was VERY low production, only 349 were made. Also VERY outside of the price range of the LS7. Same for the Carrera GT engine. Funny that my V10 vs V8 comparison was not valid, but your V12 vs V8 is:-) I am not saying that all pushrods are better, it is just that LS7 is a notable exception and it should be added to the article, as the 1994 Mercedes Indianapolis engine was mentioned.Ok, I guess V12/V10/V8 comparisons will have to be valid, it's too difficult to find enough engine weights to make a direct comparison.

But your point that pushrod engines are always lighter is not valid. If you want the LS7 to be noted then make it so, I believe it deserves a mention as well.

But if you want to make a mention of the LS7 it should be made in the main part of the article and not in the advantages, it is only one pushrod engine out of many and this is not an article about the LS7. I never said OHC is always better, I'm only saying that pushrod engines aren't always lighter, if they were that would be an indisputable advantage of the configuration and I wouldn't have any objections here. 02:35, 7 November 2006 (UTC)This is such a bizarre discussion. Power/Weight of an engine is kind of an odd item to be looking at. What do we include?

Power steering and AC pumps? Exhaust manifold? If i cut the sump down from 6 quarts to 2 quarts, that improves the power to weight, does it make a better engine? Going from iron heads to aluminum heads of identical design, and/or iron block to aluminum block?

Good old ZL1 engine was aluminum 427, cranked out at least 550 hp, was a production engine although only two were actually produced. Less weight is certainly an advantage, but is it really a better engine than the iron block high performance 427s? Maybe the reason large displacement high power engines are pushrod is because a large displacement high power OHC engine would be ridiculously high power for a production car. As in the supercars, with their large displacement high power OHC engines with high power/weight which we aren't allowed to mention here. 17:40, 7 November 2006 (UTC)S: Power/Weight is a very important indicator for an automotive engine.

What is included or not leaves room for error indeed. But what we can do? We get whatever figure the manufacturer has published.

Some engines are sold as a 'crate engine' and the net weight is given. I really doubt any manufacturer would cut any important part of an engine just for improving the power/weight ratio. Because the engine must perform, for many years most of the time. There is no such thing as ridiculously high power for a production car.

Look at the Bugatti Veyron. What I suggest as a comparison index for engines is Power/(Weight.Price.Size). The price is obviously the most difficult to obtain if not impossible. Size may be approximated with Length.Width.Height of an imaginary box that would fit the engine.I'm not about to start arguing what engine design is better, that is purely a matter of opinion.

What I am concerned with is what is factually correct. The Ferrari F50 and Porsche Carrera GT both have engines with better power to weight ratios compared with any production pushrod engine, as far as I can tell anyway. But are they better?

To someone with enough money to buy them they absolutely would be. Does the fact that the LS7 is much less expensive make it better? I would say no. When you put a Z06 and a Carrera GT on a track together which performs better? Should the Z06 be allowed a handicap just because it is less expensive?

If it was shouldn't a '06 Honda Civic Si be on the same level as the Z06? It costs much less and it performs very well for its cost. What about powerband, the LS7, like all 2 valve engines without any kind of VVT has a pretty narrow one. There are just too many variables that could be brought into this comparison. What we can say here without any doubt is that pushrod engines do not always have better power to weight ratios, but that there are also many OHC engines that don't have great power to weight ratios either, so to be factually correct we can't say that either has an advantage in that respect.


20:45, 7 November 2006 (UTC)S: I say that 'being better' is a matter of the desired application/car/target price, so the only fair comparison would be to put the competing engines in the same type of chassis and then test the cars; obviously impossible. As for the powerband of the LS7, please look at the. Based of what I have seen so far it is better than all the engines in our table. But then again, we have to define what 'better' means?The F50 maintains 91% of its peak torque output over a 2,000 rpm range. The Carrera GT maintains 91% of its peak torque output over a 2,250 rpm range.

The Z06 maintains 89% of its peak torque output over only a 1,500 rpm range. All rpm ranges are from peak torque output to hp peak which are the only numbers I have.

22:37, 7 November 2006 (UTC)S: You must be joking:-) LS7 makes more torque than all those engines plus it makes it very early and on the entire rpm range. LS7 has more torque than the maximum torque of the Ferrari F50 engine almost on the entire rpm range!

The two very expensive OHC engines we have here win the power/weight comparison because they rev very high. But when talking torque they cannot match the LS7.Well, rpm is how you make power from torque and the higher the rpm you can make torque the more power you will have. Making more torque at lower rpm isn't an advantage unless you make enough torque to make more power. F50: 347 lb-ft @ 6500 rpm = 429 hp, Carrera GT: 437 lb-ft @ 5750 rpm = 478 hp, Z06 475 lb-ft @ 4800 rpm = 434 hp. You can see the Z06 makes about as much power as the F50 at peak torque rpm, but because the Z06 would have to shift sooner (only 1500 rpm after that peak) it would reduce it's torque output to the wheels before the F50 which could continue to accelerate in that gear for another 600 rpm which would make the car accelerate at a faster rate. 00:14, 8 November 2006 (UTC)S: High rpm are desirable, it's a known fact. But the definition of the is not the best.

I would use something like Power band = the rpm range where an engine makes at least 75% of its maximum power. I edited that article, hope people will agree.

Then it would be easy to see that both the Ferrari V12 and the Porsche V10 are peaky engines, with a narrow power band. Which is alright; peaky engines were used all the time for racing and high performance cars. LS7 has most probably a wider power band than the two exotic engines above. It does 352 lb.ft (75% of the max 470) from 1310 to 7000 rpm! Just look at the.

Changed^ the definition of the power band. It is called POWER band, not torque band:-) The LS7 does more than 379 HP 75% of the max power from 4350 to 7000 rpm, so the powerband is 2650 rpm wide. We cannot talk without having the diagram for the engines we compare.Yes. (meaning that's a good point which bears discussion in the article) 17:06, 8 November 2006 (UTC)More flywheel torque does not mean wide powerband. Although I can't say with total certainty that the F50 and Carrera GT make 75% of their peak torque over more of their rpm range compared to the Z06, the fact that they maintain more of their peak torque over a wider rpm range would suggest that they have a wider powerband.

Also I don't think that definition is particularly valid, the Civic Si I mentioned before maintains about 88% of its peak torque output over at least a 6,000 rpm range (75% of its rpm range) which is a very wide, very flat torque curve for a NA engine, yet it is considered peaky. I don't even think there is a proper definition of a 'peaky' engine here. I managed to locate the gear ratios for the Carrera GT and the Z06.

Www.fueleconomy.gov comparison.The Toyota is not only a good deal more powerful, but also quite a bit cleaner and more efficient. 00:36, 6 January 2007 (UTC)There is a recent trend that some automatic transmissions improve fuel economy more than manual transmissions. A case in point would be the new, which isn't even a 6-speed comparison, it's two 5-speeds. The fact that you don't believe that development cost is irrelevant when the 3900 is still using a cast-iron block, obviously for cost considerations, only underscores the fact that you should cite.

I note there was a similar issue with you on the OHC page.As far as the OHC page, all I said was that OHC engines can spin faster (can you name any 19,000 rpm pushrod engines?) and that they have fewer parts compared with pushrod systems of the same number of valves. Here's the only online reference I can give for the number of parts:. The 5 speed manual and the 5 speed automatic Civics get the same mileage in the city, the automatic only does better on the highway. Also both of those Civics have the same engine. How do you explain the fact that the Honda, Toyota and GM OHC engines get better mileage than the G6 3.9 liter and manage to have more power? I still don't see how developmental cost is relevant, that's not something consumers look at and it doesn't have a direct impact on the performance of the engine. 00:19, 9 January 2007 (UTC) Comparison Table (Removed) I took out the table at the end of the article: it's obvious someone put a lot of effort into including the table, but it was presented out of context and seemed to me to be nothing more than an attempt to bastion further the positive qualities of the LS7 engine.

If some compelling reason can be provided for including the table and the seemingly random cars that used those engines, then the table can be re-included, but as it appeared to me it was a violation of the policy, as it was obvious astroturfing for the title engine. 01:34, 5 January 2007 (UTC) KeplerNikoThe table was not out of context, it was showing a reality: the pushrod engine technology is far from being as bad as described.Yes, the LS7 is an exceptional engine, with a power/weight ratio better than many highly regarded DOHC engines. You cannot do anything about it. Just read car magazines and the exceptional reviews of the car with this engine, C6 Corvette Z06.Pick your choice of DOHC engines and let's compare them in this context. But no, it is easier to remove.This is why Wikipedia remains a flawed concept.I will not waste my time here anymore.The LS7 performs very well in its specific use, but this is not an article about the LS7.

It is about all pushrod engines and the LS7 does not represent all pushrod engines very accurately, just like the Porsche Carrera GT engine does not represent all OHC engines very accurately. Really the information in that chart shows that some pushrod engines can be competitive with some OHC engines in only one way. Also since there is no sure way to tell in what configuration the engines were in when they were weighed (accessories, wet or dry, etc. As mentioned by Gzuckier above) there is no way to determine the validity of the chart. 02:32, 9 February 2007 (UTC) I think the chart would be more useful if it contained more than the two closely related GM pushrod engines. It would also help to compare engines with similar displacement and aspiration (the BMW turbo 3.0l V8 being too extreme an example for comparison).

I would keep the LS7 and compare it to DOHC 500hp engines like ones in the BMW M5. I'll see what info I can dig up. 21:22, 13 April 2007 (UTC)I edited the chart to remove the three forced induction racing engines, leaving only naturally aspirated production car engines. I also added the Viper engine and sorted the whole thing by displacement.

21:55, 13 April 2007 (UTC)None of the engines listed in the chart used forced induction. Both the Motopower RST-V8 and the Powertec RPA V8 are available in road legal vehicles.15:49, 14 April 2007 (UTC)I think the chart looks great as of the revision by 00:23, 15 April 2007 (UTC) Agreed. 16:19, 15 April 2007 (UTC).

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