Talk:Pushrod engine
This page has a LOT of incorrect information
I think am image, say a CAD rendering could really improve this article. Does anyone have one that could be used? PhasmatisNox 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.Ahanix1989 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?!) Here is the SWF, anybody have any suggestions? Ahanix1989 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. IJB TA 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 my talk page and I'll email it to you. IJB TA 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. My talk page.
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. IJB TA 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. --Milkmandan 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. --Sobolewski 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 VTEC, 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 1MZ-FE), and the 3800 is also being phased out, to be replaced by the newer LZ8/LZ9 3900 (which does have VVT).
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 GM LS4 V8 produces 303 horsepower, 323 ft·lbf of torque, and returns 17 city/28 hwy mpg, currently without a multiple valve-per-cylinder arrangement or VVT, although it does use Displacement on Demand.
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. IJB TA 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. (i.e. 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. IJB TA 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 rpm
This is a comparison of a V8 to a V10 so it doesn't make much sense. Also this isn't true very often. IJB TA 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 rpm
Pushrod 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. IJB TA 05:10, 4 November 2006 (UTC)
RPM
edit"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. 24.113.18.109 21:57, 1 October 2006 (UTC)
OHV?
editOverhead 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. IJB TA 17:56, 1 November 2006 (UTC)
Comparing engines
editS: 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. 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. IJB TA 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. 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[1]Gzuckier 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. IJB TA 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. IJB TA 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. IJB TA 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? alternator? Air cleaner? 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. Gzuckier 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. IJB TA 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 torque-rpm diagram. 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. IJB TA 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. IJB TA 00:14, 8 November 2006 (UTC)
- S: High rpm are desirable, it's a known fact.
- But the definition of the Power band 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 torque-rpm diagram.
- 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)Gzuckier 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. Since I only have the numbers for torque peak and hp peak for the Carrera GT I'll have to use those for comparison.
- Peak tq to the wheels in 3rd gear.
- Z06: 2092 lb-ft @ 1079 rpm
- GT: 2627 lb-ft @ 951 rpm
- Peak hp to the wheels in 3rd gear.
- Z06: 1873 lb-ft @ 1416 rpm
- GT: 2398 lb-ft @ 1324 rpm
You can see the Carrera GT can accelerate longer in each gear while supplying more torque to the wheels, which obviously makes it a faster car.
Some interesting charts of "peaky" engines:
Civic Si output JDM Integra Type-R output JDM Integra Type-R wheel torque
Made some changes ^ IJB TA 21:59, 8 November 2006 (UTC)
- It looks like its actually closer to 90%+ of peak torque over a 6000 rpm range for the Civic. Isnt the definition of a wide powerband when an engine can produce more of it's peak power over a wider rpm range, not a wider percent of its rpm range? Engine rpm still translates to a certain amount of wheel rpm. Mister E 23
- S: We were talking engines and power band here. Where are you IJB going? Of course the Carrera GT is a faster car, it better be as it's 4 times more expensive :-) Plus what you are ilustrating is gearing. Total ratios [3rd gear and final drive] are: Z06 1.30*3.42=4.45, GT 1.36*4.44=6.03! Of course the GT has more torque at the wheels with such a difference in gearing. When talking engines we should stick to engines. But I will stop here, we are wasting our time continuing.
- I'm proving that I was correct in saying that the Z06 has a narrow powerband, what I have illustrated is a wide powerband. You need high torque over a wide rpm range at the flywheel to have high torque over a wide rpm range at the wheels. You could change gearing all you want but you can't simply make power that isn't there just by using gears. Anyway point made, and continuing is off the subject here. IJB TA 16:20, 9 November 2006 (UTC)
- A correction here (even if it is somewhat irrelevant). The Civic Si maintains about 90% of its peak torque output over about 86% of its rpm range since it does not idle at 0 rpm. IJB TA 23:55, 19 November 2006 (UTC)
Can we delete this section? It's not really relevant anymore. IJB TA 12:09, 7 December 2006 (UTC)
"Currently few pushrod type engines remain in production, a result of the fact that it has become difficult to achieve competitive engine performance with the configuration."
Difficult to achieve competitive engine performance???? The LSX and Hemi series of engines are two fantastic examples of competitive performance. Thats a horrible quote, and I am deleting it. There is a myriad of pushrod engines out there that prove that it is easy to achieve competitive engine performance without a doubt!!!!!!!!! Not only that, but the DOHC engine configurations have been playing catch up since day one and will continue to play catch up. Pushrod motors put out the most power bar none. Every time you give an example of a Carrera GT motor or an F50 motor, I can give you an example of a crate motor that will blow it out of the water. If you give an example of a F1 motor, I will give you an example of a bigger race motor. So enough with that horribly biased statement, its wrong and its gone.
There is no bias here only fact. I would love to see those examples. IJB TA 10:48, 10 December 2006 (UTC)
Your original statement was: "Currently few pushrod type engines remain in production, a result of the fact that it has become difficult to achieve competitive engine performance with the configuration."
You said that, I said it was bogus and biased. My evidence to back up my statements consist of big block race motors that you can purchase for an expensive amount of money, but nonetheless back up my statement with 100% accuracy. The links below have motors that range from moderate 500Hp levels all the way to 1500HP levels. Keep in mind this is all naturally aspirated V8 Big block motors. Granted it would not be fun to drive these engines on the street everyday, nor would a 900hp 20,000rpm F1 motor, but it nonetheless proves my point.
http://www.greenwoodchevy.com/engine5.htm 720HP http://www.cmengines.com/Engines/RaceEngines/tabid/98/Default.aspx Many listed, up to 950HP http://indyhe.fatcow.com/sitebuildercontent/sitebuilderfiles/page02.pdf Many listed, up to 1165HP http://www.indyheads.com/id1.html More pictures on the website above http://paceperformance.com/index.asp?PageAction=VIEWCATS&Category=10015 Many listed, up to 900HP http://www.steveschmidtracing.com/engines/585-super-pro.html 1200HP
http://www.steveschmidtracing.com/engines/dyno-charts/760-commander-dyno.html 1539.9 http://www.steveschmidtracing.com/engines/760-commander.html more info
Your next argument should consist of F1 motors reaching 1,400 HP, but those were the turbo models. The new V8 F1 race motors should hit 1000-1100 HP in this season and will continue to go up, as will the race crate motors that I have provided you with. In the 80's, the F1 turbo motors saw 1400HP. If you turbo the big block motors above, one might net 6000HP. The are all pushrod motors that I speak of.
Clearly I have provided the evidence, and clearly I am correct.
Also, please stop deleting my statement on torque. A pushrod designation creates more torque in the low RPM's as DOHC motors create more torque in the high RPMS. HP is a function of torque, therefore an advantage of a pushrod motor is more torque and horsepower in the lower rpm's in most scenarios. Get it?
I looked up an 800 hp crate engine from Summit racing Here Its shipping weight is 740 lbs, so its actual weight is probably right around 700 lbs. You're saying that somehow an engine that weighs 500 lbs more than an F1 engine with the same amount of power will somehow be better? Please explain the logic in that thought process. Also:
- Compare
Which makes more torque at a lower rpm?
Also take a look at the engine output for the Integra Type-R above and compare it to the LS7 in the links above. Which makes more torque over a wider rpm range? Also pushrod engines almost always make less power and torque from a given displacement, compare just about any engine you can find: BMW M3 - 81.875 ft-lb/l, LS7 - 67 ft-lb/l. Also compare the output of the OHC Ford engines to the GM pushrod engines, the Fords have higher torque output for a given displacement. IJB TA 02:57, 11 December 2006 (UTC)
I looked up an 800 hp crate engine from Summit racing Here Its shipping weight is 740 lbs, so its actual weight is probably right around 700 lbs. You're saying that somehow an engine that weighs 500 lbs more than an F1 engine with the same amount of power will somehow be better? Please explain the logic in that thought process.
Is this about horsepower or weight? Clearly I am correct, but you instead mentioned the weight of it. Again your statement said: "Currently few pushrod type engines remain in production, a result of the fact that it has become difficult to achieve competitive engine performance with the configuration." And I proved you wrong, and now you want to bring in weight? Nothing weighs as much as an F1 motor, and nothing puts out as much power as a Big Block V8 that makes 1500hp. Looks like we have hit the crossroads of engine design philosophy. Im not mechanical engineer, so I cannot tell you, but there are different philosophies on the subject. The point of the matter is you said it is difficult to make power with a pushrod, and I have shown you its not. If you want to jump into another argument about weight, then so be it. There is another wikipedia page for that, if you want to talk about it there with me, go for it, but its not relevant here.
'*Compare
Which makes more torque at a lower rpm? '
Clearly the Ford does, but take a look at earlier engine architecture from the sixties...
1965
Production: 23,652 Coupe: 8,186 Convertible: 15,376
Engines: 327 V8 250 bhp @ 4400 rpm, 350 lb-ft @ 2800 rpm. L75 327 V8 300 bhp @ 5000 rpm, 360 lb-ft @ 3200 rpm. L79 327 V8 350 bhp @ 5500 rpm, 360 lb-ft @ 3600 rpm. L76 327 V8 365 bhp @ 6200 rpm, 350 lb-ft @ 3400 rpm. L84 327 ("fuelie") V8 375 bhp @ 6200 rpm, 350 lb-ft @ 4600 rpm.
The peak torque ratings are 2800rpm, 3200rpm, 3600rpm respectively. Yeah they are off by 5hp or so, but that could be associated with a plethora of things like the tranny they used.
Also take a look at the engine output for the Integra Type-R above and compare it to the LS7 in the links above. Which makes more torque over a wider rpm range? Also pushrod engines almost always make less power and torque from a given displacement, compare just about any engine you can find: BMW M3 - 81.875 ft-lb/l, LS7 - 67 ft-lb/l. Also compare the output of the OHC Ford engines to the GM pushrod engines, the Fords have higher torque output for a given displacement.
I never said a pushrod makes more torque over a wider rpm ranged, I said its flatter, begins earlier, and there is usually more of it. Thats a good point, there useable torque over the RPM range. Thats why OHC motors make more power at higher rpm because theres more torque up there, which gives them more horsepower, whereas pushrods lose the torque, therefore losing the horsepower.
You can play the displacement to horsepower/torque argument all you want, especially with Honda fanboi's on street racing sites who make moot arguments consisting of how I cant beat your V8 but I have a better displacement to power ratio. Truth of the matter is, its a number on paper and has zero relevance, unless you are really into numbers on paper that have no effect on the real world. Granted the bore and stroke an engineer choose will affect the outcome of torque and horsepower, but the lower it is, doesnt make it better. You could make up silly ratio's all day long, and get nothing out of it, just like the displacement to power ratio. Its silly, unneeded, and has no effect on anything but biased MotorTrend Editors. Its all about how much power is actually put out. The M3 motor is gone, they are not using it anymore. Why? It's reached its capacity. BMW is going with a 4 liter V8 to try and surpass the LS2, because a 3 liter is too small. Big displacement is what makes more power. The natural evolution of engines is to increase bore and stroke to make more power. It sounds like you would like that number to be kept at a minimum to satisfy better "ratio's."
I am putting back in what I said before, because its fact. -Dezelon
You clearly don't understand anything about engine design. Pushrod engines make more torque when? When they have huge displacements? Fine, so why not compare a 333 liter Caterpillar engine to a 1 liter Honda engine, clearly it makes more torque because it's a pushrod engine. I really would like to know your basis for that statement. The only thing you are actually saying is that a bigger engine makes more torque, that's all, and I think just about anyone knows that. Fact is: muli-valve OHC engines of the same displacement as a comparable 2 valve pushrod engine will almost always make more torque, therefore are capable of making more power.
I never said a pushrod makes more torque over a wider rpm ranged, I said its flatter, begins earlier, and there is usually more of it.
I just proved you wrong on all of those points. Where the torque peak occurs has nothing to do with the system that opens the valves. It's all tuning and you have the same exact tuning options with an OHC engine as you do with a pushrod engine. Yes it is true that many DOHC engines are tuned to make power at high revs, that is the main reason for using a DOHC configuration. Because of that ability those engines can produce more power from a given displacement. You need to get your facts right. IJB TA 05:56, 11 December 2006 (UTC)
- Looks to me like the M3 engine is doing just fine: M3. In the past it did have a bearing problem, but that was only a mistake on the part of the bearing supplier. IJB TA 05:56, 11 December 2006 (UTC)
"Currently few pushrod type engines remain in production, a result of the fact that it has become difficult to achieve competitive engine performance with the configuration."
Clearly you have no concept of how engines work if you write a statement saying that pushrods cant make power these days. Duh. PROVED WRONG!
Beyond that I gave you examples of a 327 Corvette motor from the sixties to compare to your Ford truck motor. It torque peaking earlier in the RPM range. If you use the nifty formula that I keep on posting, then you will see that more torque down low means more horsepower down low too. Thats all I am trying to say. I am not saying pushrods make more power in the high rpm's cus they dont, I am saying they are making more power down low around 1000rpm-3000rpm. Its pretty damn simple. You need to get your facts right. Maybe click some numbers into that formula and you will see I am correct. Its common knowledge that pushrods make power down low, and overhead cam motors make power up top, thats all I am trying to say. It has everything to do with the system of valves and cams. Why would there be such a clear difference since 1960 to right now? I am very involved in the racing industry and can tell you that all builders know that the pushrod has more down low, and the DOHC has it up top. Go build an engine, dyno test it, and do it another thousand times and you will be at my level.
Why are you giving me a link to an M3 data website? I told you it cannot make much more than 300rwhp in N/A form, and they are switching to a V8 to make more power. Thats all. I only brought it up because you were talking about the displacement argument, so dont give me stupid links to some website thats completely irrelevant.
And back in goes my info...Whats tomorrow tuesday? Go into a racing shop tomorrow after work, or whatever you do, and check out the pushrod motors and talk to the guys that build those things all day long and dyno test them. See what they say about low end power. YOU COULD REALLY LEARN SOMETHING, in fact, it might change your life. -Dezelon
Ok, why is an engine from the '60s even relevant? It's not going to meet current emissions requirements, same with those crate engines, so there is no point in comparing them to current production engines. You can make all the power you want at low rpm it's not going to provide you with any benefits. On the road I don't see people flooring their cars from a stop to drive normally and racing engines spend very little time at low rpm if any, so unless you can present how more power at low rpm is a benefit I don't think it's a valid point. Also, again that's a trait specific to any large displacement engine, not pushrod engines. Why would there be such a huge difference between engines from the '60s and now? TONS of reasons, probably more reasons than any one person can explain. Obviously you haven't noticed but engine technology has made HUGE leaps in the past 40 years. I take back what I said about facts, they seem to be somewhat correct, it's the HUGE amount of information you are lacking that is the problem. Maybe if you take the time to inform yourself about how engines from the '60s differ from current production engines you will understand what I'm trying to say here.
Again, you can tune any engine to make power anywhere in the rpm range you want. Where are you getting this idea that somehow a DOHC engine can only make power at high rpm? What is the basis for that thought process?
You said the M3 engine was gone, I gave you a link to show that it isn't. IJB TA 01:55, 12 December 2006 (UTC)
- Also, BMW is not switching to a V8, most of their line up uses an I6 and will continue to do so. It's not like they're going to offer the one of the most powerful engines they make in every model of vehicle they have. IJB TA 02:06, 12 December 2006 (UTC)
I'll put this information right here so there's no mistake:
- Ford: 5.4-Liter Triton™, 90-Degree V8, 24-Valve, SOHC, SEFI Engine; Front Mounted With Horsepower Of 300@5000, Torque Of 365@3750, Iron Block and Alloy Cylinder Heads (Standard)
- GM: 6.0-Liter Vortec, V8, 16-Valve, OHV, SEFI Engine; Front/Longitudinal Mounted With Horsepower Of 300@4400, Torque Of 360@4000, Cast Iron Block and Alloy Cylinder Heads (Standard)
Engines available for the Pontiac G6:
- Pushrod engine: 3.9L V6 SFI (240 HP [179 kW] @ 6000 rpm, 240 lb-ft [325.1 N-m] @ 4600 rpm)
- OHC engine: 3.6L V6 SFI (252 hp [188 kW] @ 6300 rpm, 251 lb-ft [340 N-m] @ 3200 rpm)
Which makes more torque (and power) at a lower rpm? The OHC engines, or the pushrod engines? Also notice that the OHC engines don't even need more displacement to make that torque.
Why are speculative quotes such as this one below allowed without reference?:
Currently few pushrod type engines remain in production, a result of the fact that it has become difficult to achieve competitive engine performance with the configuration.
- Because it's a fact. IJB TA 17:10, 27 December 2006 (UTC)
According to whom???
- If you can find a better way to explain why pushrod engines are almost completely phased out of production by all but a few manufacturers please do so. IJB TA 00:48, 3 January 2007 (UTC)
Since you appear to be actively moderating this page, I'd much prefer you to back up your statement of fact with a citation, something other than an appeal to popularity as an authority. The tyranny of power, and all that.
- Just look at the performance of OHC engines compared to similar pushrod engines, that should be all the proof required. There is a reason something becomes popular. Also there are some examples above, one being the DOHC engine for the Pontiac G6. It not only makes more power over its entire rpm range compared to the pushrod engines but it also achieves greater fuel efficiency. But like I said, if you can find a better way to explain why pushrod engines are being phased out of production please do. IJB TA 23:23, 4 January 2007 (UTC)
Considering that the G6's base OHV engine just received a power boost, and that you not only appear to be comparing fuel economy when one engine is mated to a 4-speed transmission while the other is mated to a 6-speed, but also specific hp/l without mention of developmental dollars spent on each engine (you are, after all, comparing GM's High Feature and High Value engines), I would like to see something a little more technical.
- I compared the 3.9 with a 6 speed manual to the 3.6 with a 6 speed auto. Even with a less efficient transmission the 3.6 has greater fuel efficiency, it also has lower emissions output. So it's more powerful, more fuel efficient and cleaner, pretty hard to beat that. With the amount of driving I do the 3.9 liter would cost me almost $300 a year more to operate compared to the 3.6. So even if the 3.6 is more expensive to begin with (I haven't looked yet) it would easily pay for itself during the time a person would own it. There are plenty of other examples like that as well, like Toyota and Honda V6 engines. Developmental cost is completely irrelevant. IJB TA 23:36, 5 January 2007 (UTC)
The Toyota is not only a good deal more powerful, but also quite a bit cleaner and more efficient. IJB TA 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 http://automobiles.honda.com/models/specifications_full_specs.asp?ModelName=Civic+Sedan&Category=3, 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: R&T Technical correspondence.
- 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. IJB TA 00:19, 9 January 2007 (UTC)
Comparison Table (Removed)
editI 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 NPOV policy, as it was obvious astroturfing for the title engine. --156.143.89.87 01:34, 5 January 2007 (UTC) KeplerNiko
The 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. IJB TA 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. Crazym108 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. Crazym108 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.
IJB TA 15:49, 14 April 2007 (UTC)
- I think the chart looks great as of the revision by 68.35.101.191 Crazym108 00:23, 15 April 2007 (UTC)
- Agreed. IJB TA 16:19, 15 April 2007 (UTC)