Potentially Stupid Question - Overhead Cam Engines
Discussion
My main car produces 566 bhp @ 6750 rpm. Plus it will do 28 mpg on a long run.
It costs less than half to service over 3 years compared to a Nissan GTR, for example and has a power band to die for, just sheer grunt from virtually tickover to the rev limiter at 7,100 rpm. It has pushrods and an underneath cam!
My previous 2009 Corvette C6 had 430 bhp and as of last month the new owner told me it had gone past 100,000 miles with only normal servicing, 2 sets of discs and pads and a new rear exhaust section. The plugs were only changed twice also.
The beauty of the old ohv engines is simplicity, plus just about anyone can service them, they are strong as hell and you can get 1,000 bhp out of 5.7 litres very easily and relatively cheaply.
Top Fuel drag cars have pushrods and they produce 3,000 bhp.
Finally there is a Dodge Viper i get to drive now and then in Orange County, California and it stands the owner, all in, at circa $140,000. £90,000.
For the price of a new BMW M5 he has a sports car with 1237 bhp and 1168 lbs-ft of torque. 0-200 mph 2 seconds faster than a Bugatti Veyron (high power version).
With pushrods! :-)
It costs less than half to service over 3 years compared to a Nissan GTR, for example and has a power band to die for, just sheer grunt from virtually tickover to the rev limiter at 7,100 rpm. It has pushrods and an underneath cam!
My previous 2009 Corvette C6 had 430 bhp and as of last month the new owner told me it had gone past 100,000 miles with only normal servicing, 2 sets of discs and pads and a new rear exhaust section. The plugs were only changed twice also.
The beauty of the old ohv engines is simplicity, plus just about anyone can service them, they are strong as hell and you can get 1,000 bhp out of 5.7 litres very easily and relatively cheaply.
Top Fuel drag cars have pushrods and they produce 3,000 bhp.
Finally there is a Dodge Viper i get to drive now and then in Orange County, California and it stands the owner, all in, at circa $140,000. £90,000.
For the price of a new BMW M5 he has a sports car with 1237 bhp and 1168 lbs-ft of torque. 0-200 mph 2 seconds faster than a Bugatti Veyron (high power version).
With pushrods! :-)
Max_Torque said:
And as all those^^^ pics up there prove, being able to copy and post a picture from Google does not the truth make. Even when people post pictures with no dimensions, from different angles, with nothing to judge the sense of scale, and with clearly half the engine missing, you'll still get the usual trolls moaning, "oh but this engine is soooo small" etc etc.
People can go look for themselves... there are many many examples. The compact nature of the small block engines is well known and one of the reasons it's such a popular fit to small car's such as the Mazda MX5
Max_Torque said:
And finally, if the american V8 is such an amazing engine, being hugely powerful, being so fuel efficient as to actually make fuel and put it back in the tank whilst you drive, and clearly being so small that the first time you open the bonnet it gets accidentally blown away by a small gust of wind, if ALL those things are true, how come no OEM outside of the US actually uses one?
You know, those car companies who spend literally millions of pounds developing a new car, employ the best engineers, spend millions of man hrs on simulation, calculation and benchmarking, when silly them, they could just fit a Yank V8 and hurrah, sit back and watch the money roll in..........
Plenty of people outside of the USA use small block engines. It's one of the most popular motors for kit car builders due to it's compact size, high performance and value for money.You know, those car companies who spend literally millions of pounds developing a new car, employ the best engineers, spend millions of man hrs on simulation, calculation and benchmarking, when silly them, they could just fit a Yank V8 and hurrah, sit back and watch the money roll in..........
Let's not forget that GM is one of the largest manufacturer's on earth with some of the best engineers money can buy and facilities all around the world.
They chose the small block design because it suited their purpose best, along with not facing displacement based legislation such as manufacturer's in Europe have to contend with.
Lets not forget the Aussie's love their small block's as much, if not more than the Yanks.
Edited by skyrover on Sunday 2nd August 18:00
Max_Torque said:
Well, if you knew anything, which you quite clearly don't, you'd know who i was, and what i do, and have done for the last 20 years, and for whom i work (and have worked).
But, you know, keep sitting their typing behind your keyboard, and you'll be fine..........
And as all those^^^ pics up there prove, being able to copy and post a picture from Google does not the truth make. Even when people post pictures with no dimensions, from different angles, with nothing to judge the sense of scale, and with clearly half the engine missing, you'll still get the usual trolls moaning, "oh but this engine is soooo small" etc etc.
And then you get the posters, with clearly no technical background or experience saying things like "oh but car x is hevaier than car y so it it's celarly amazing to even be using just 20% more fuel" even those same people are unfortunately not in a position to understand the (minimal) direct effect of vehicle mass on fuel consumption.....
And finally, if the american V8 is such an amazing engine, being hugely powerful, being so fuel efficient as to actually make fuel and put it back in the tank whilst you drive, and clearly being so small that the first time you open the bonnet it gets accidentally blown away by a small gust of wind, if ALL those things are true, how come no OEM outside of the US actually uses one?
You know, those car companies who spend literally millions of pounds developing a new car, employ the best engineers, spend millions of man hrs on simulation, calculation and benchmarking, when silly them, they could just fit a Yank V8 and hurrah, sit back and watch the money roll in..........
To be honest I doubt most of us know who you are and probably don't care that much. If you do know lots, why not share and educate instead ? I do know GM spend quite a bit developing engine technology too and they are one of the world's biggest car manufacturers. Do you think they don't employ decent engineers? But, you know, keep sitting their typing behind your keyboard, and you'll be fine..........
And as all those^^^ pics up there prove, being able to copy and post a picture from Google does not the truth make. Even when people post pictures with no dimensions, from different angles, with nothing to judge the sense of scale, and with clearly half the engine missing, you'll still get the usual trolls moaning, "oh but this engine is soooo small" etc etc.
And then you get the posters, with clearly no technical background or experience saying things like "oh but car x is hevaier than car y so it it's celarly amazing to even be using just 20% more fuel" even those same people are unfortunately not in a position to understand the (minimal) direct effect of vehicle mass on fuel consumption.....
And finally, if the american V8 is such an amazing engine, being hugely powerful, being so fuel efficient as to actually make fuel and put it back in the tank whilst you drive, and clearly being so small that the first time you open the bonnet it gets accidentally blown away by a small gust of wind, if ALL those things are true, how come no OEM outside of the US actually uses one?
You know, those car companies who spend literally millions of pounds developing a new car, employ the best engineers, spend millions of man hrs on simulation, calculation and benchmarking, when silly them, they could just fit a Yank V8 and hurrah, sit back and watch the money roll in..........
GM like all the other OEMs are spending the lion's share of their powertrain development kitty on small capacity, high specific output forced induction engines for the national markets which don't enjoy fuel as cheap as water. Like all the other OEMs, they're shifting thousands of front wheel drive transverse engined compact and midsize cars and vans. That they continue to use the LS series of engines, which are clearly quite effective in large cars in markets where fuel is cheap, isn't really indicative that the LS is all the engine GM will ever need and they, like everyone else, will be gearing up for 3/4 cylinder forced induction engines and hybrid systems.
CorvetteConvert said:
Loads of cars use pushrod engines still.
Not many in Europe.wormus said:
I do know GM spend quite a bit developing engine technology too and they are one of the world's biggest car manufacturers. Do you think they don't employ decent engineers?
There some pretty damning evidence in the shape of millions of Vauxhalls.skyrover said:
Plenty of people outside of the USA use small block engines. It's one of the most popular motors for kit car builders due to it's compact size, high performance and value for money.
Yeah, but those people aren't looking for tenths-of-a-percent of profit. They are engineering with different constraints.PH has a few resident experts. Rog does the advanced driving talk, Max_Torque tells you how engines work, and INS1GHT makes you jealous about how awesome his job is. These are almost universal constants. They've got embedded well in their niche ad are not known for talking b
ks, which makes me think that their views on their field might have some merit to it.A lot of the replies to Max_Torque here are bloody mumsnet "Well as a mother..." grade tripe.
wst said:
eah, but those people aren't looking for tenths-of-a-percent of profit. They are engineering with different constraints.
PH has a few resident experts. Rog does the advanced driving talk, Max_Torque tells you how engines work, and INS1GHT makes you jealous about how awesome his job is. These are almost universal constants. They've got embedded well in their niche ad are not known for talking bks, which makes me think that their views on their field might have some merit to it.
A lot of the replies to Max_Torque here are bloody mumsnet "Well as a mother..." grade tripe.
Perhaps then, you can tell us why GM dropped it's DOHC engine relatively recently for the pushrod engines instead?PH has a few resident experts. Rog does the advanced driving talk, Max_Torque tells you how engines work, and INS1GHT makes you jealous about how awesome his job is. These are almost universal constants. They've got embedded well in their niche ad are not known for talking b
ks, which makes me think that their views on their field might have some merit to it.A lot of the replies to Max_Torque here are bloody mumsnet "Well as a mother..." grade tripe.
I'll just leave this here:
http://speedsociety.com/crazy-1001-cubic-inch-stre...
Imagine how big that would be with an OHC setup
http://speedsociety.com/crazy-1001-cubic-inch-stre...
Imagine how big that would be with an OHC setup
Coatesy351 said:
CorvetteConvert said:
Top Fuel drag cars have pushrods and they produce 3,000 bhp.
More like 9000hp.Most purpose built drag race engines are pushrod overhead valve engines as it's far easier to work on them, for instance you can take the heads off to inspect the pistons and the combustion chambers without having to worry about re-setting the timing. It just bolts back together.
wormus said:
wst said:
hy the hell would I know, I'm not a bloody engineer. Duh. That was sort of the point of my comment.
Perhaps you should refrain from posting then?Yes LS engines are great because they are simple and cheap, but try squeezing one into an Aygo or Smart car. They have small capacity OHC engines and rely on the OHC to give them the tractability they need to be useful small engined city cars.
Do the LS engines ever get near the 100hp/litre+ mark in a N/A engine like we've seen European engines do?
TheAllSeeingPie said:
So he should stop because had gave an honest answer? I think you've completely missed his point.
Yes LS engines are great because they are simple and cheap, but try squeezing one into an Aygo or Smart car. They have small capacity OHC engines and rely on the OHC to give them the tractability they need to be useful small engined city cars.
Do the LS engines ever get near the 100hp/litre+ mark in a N/A engine like we've seen European engines do?
It's the pointless, angry rants I find irritating. If one has knowledge, share it, if not, ask questions. No point antagonising others, making loads of noise whilst saying apparently nothing. Yes LS engines are great because they are simple and cheap, but try squeezing one into an Aygo or Smart car. They have small capacity OHC engines and rely on the OHC to give them the tractability they need to be useful small engined city cars.
Do the LS engines ever get near the 100hp/litre+ mark in a N/A engine like we've seen European engines do?
Anyway, your point is valid but if you take it to a logical conclusion, the engine from an Aygo or Smart car won't fit in a motorbike and won't work as well either. I don't think anyone would argue OHC engines don't have a place and as stated earlier, they enable the multi valve heads required to extract power from small capacity, high rpm engines. LS engines like any other are built for a purpose balancing reliability vs torque x rpm. My 6.2 LSA revs to 7000 rpm and makes 133hp litre. Ok, it has FI but to say it won't rev or make power because of its valve train configuration is just not true.
wormus said:
... say it won't rev or make power because of its valve train configuration is just not true.
What I think many people argue is that it wont rev or make power whilst with the same configuration returning decent economy when driven gently. That's probably not true, but it's certainly the argument you see used.
calibrax said:
Most engines are OHC based nowadays. Can't think of a current car that has a pushrod engine... there probably are some, but they will be niche.
lot of US stuff is still pushrod.some of the LS V8's for example.
it's much cheaper to make, the engines ends up smaller and lighter, and less top-heavy.
only real downsides to pushrods is the reciprocating mass of the valvetrain (rods and all) will limit ultimate RPM, and also it's hard to have variable cam timing etc with a single cam pushrod engine.
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