5.0 Is back
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Originally Posted by TheDonEffect,Dec 18 2009, 07:52 AM
What's wrong the GM LS motor?
And yes, I do remember the northstars, but considering how BMW and Merc V8s are maitenance/repair heavy as well, it's a wash.
And it's not that they can't, they simply don't want to, why mess with year of developlement? The Corvette ZR1 had a renowned DOHC engine (granted not completely designed in house), great motor but why bother?
But what's wrong with GM's pushrod?
It's more compact, lighter, sits lower since it doesn't have the big DOHC heads, has a pretty much flat torque curve, makes ridiculous reliable relatively low maitenance power, cheap to repair, cheap to produce, efficient, burns relatively clean, I just don't see how it's bad. We compared the engine LS against the comparable M5 V10 engine which was apparently an engineering marvel, yet aside from the fact that they reinvented the wheel, the LS made more logical sense. Why reinvent the wheel? I mean, I'd rather say it makes 400hp, I get 28mpg and I haven't seen my service writer since I bought the car and its reliable as a truck motor since it shares some of its heritage with them than it makes 240hp with 2/3s the torque, 28mpg, has a proprietary variable valve timing system which decimates all, makes over 100hp/liter, has DOHC with 4 valves per cyl, and oh the valves are bent because it revs to 9000 rpms to make power but it absolutely must be because I overrevved because that's what my service writer said and the problem isn't that common...
Oh crap I poked the stick in the hornets nest again, lol.
And yes, I do remember the northstars, but considering how BMW and Merc V8s are maitenance/repair heavy as well, it's a wash.
And it's not that they can't, they simply don't want to, why mess with year of developlement? The Corvette ZR1 had a renowned DOHC engine (granted not completely designed in house), great motor but why bother?
But what's wrong with GM's pushrod?
It's more compact, lighter, sits lower since it doesn't have the big DOHC heads, has a pretty much flat torque curve, makes ridiculous reliable relatively low maitenance power, cheap to repair, cheap to produce, efficient, burns relatively clean, I just don't see how it's bad. We compared the engine LS against the comparable M5 V10 engine which was apparently an engineering marvel, yet aside from the fact that they reinvented the wheel, the LS made more logical sense. Why reinvent the wheel? I mean, I'd rather say it makes 400hp, I get 28mpg and I haven't seen my service writer since I bought the car and its reliable as a truck motor since it shares some of its heritage with them than it makes 240hp with 2/3s the torque, 28mpg, has a proprietary variable valve timing system which decimates all, makes over 100hp/liter, has DOHC with 4 valves per cyl, and oh the valves are bent because it revs to 9000 rpms to make power but it absolutely must be because I overrevved because that's what my service writer said and the problem isn't that common...
Oh crap I poked the stick in the hornets nest again, lol.
but back to the point, for ford to go back with a cam in block heap would be a step backwards
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Originally Posted by TheDonEffect,Dec 18 2009, 09:52 AM
But what's wrong with GM's pushrod?
It's more compact, lighter, sits lower since it doesn't have the big DOHC heads, has a pretty much flat torque curve, makes ridiculous reliable relatively low maitenance power, cheap to repair, cheap to produce, efficient, burns relatively clean, I just don't see how it's bad. We compared the engine LS against the comparable M5 V10 engine which was apparently an engineering marvel, yet aside from the fact that they reinvented the wheel, the LS made more logical sense. Why reinvent the wheel?
It's more compact, lighter, sits lower since it doesn't have the big DOHC heads, has a pretty much flat torque curve, makes ridiculous reliable relatively low maitenance power, cheap to repair, cheap to produce, efficient, burns relatively clean, I just don't see how it's bad. We compared the engine LS against the comparable M5 V10 engine which was apparently an engineering marvel, yet aside from the fact that they reinvented the wheel, the LS made more logical sense. Why reinvent the wheel?
If the complications provide no real benefit, better without them.
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Originally Posted by beanseff,Dec 18 2009, 11:37 AM
i'm not knocking the LS engines, they're very technologically advanced for a cam in block, and i know about the dohc zr-1 LT5 engine BUT it wasn't designed by gm it was designed by lotus
but back to the point, for ford to go back with a cam in block heap would be a step backwards
but back to the point, for ford to go back with a cam in block heap would be a step backwards
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From: Pawtucket, RI
If you're not displacement-limited (as in most racing series'), a larger-displacement OHV (cam-in-block) V8 makes a HELL of a lot of sense. As already mentioned, here are the benefits of an OHV V8 over OHC/DOHC:
fewer parts/lower cost
lighter weight for a given displacement (or more displacement for a given weight)
lower center of gravity
smaller
better fuel efficiency
allows a much lower hoodline (in a front-engine car)
If you want to maximize power out of a given displacement, you will go to DOHC and multivalves per cylinder. If you want to maximize power out of a given engine size and weight, OHV is IMO the way to go for a V-configured engine.
Personally, I'd prefer a smaller/lighter-weight Mustang *not* based on a discontinued luxury sedan platform, with IRS, and with a smaller/lighter-weight aluminum OHV V8. Yeah, I know, not gonna happen...
fewer parts/lower cost
lighter weight for a given displacement (or more displacement for a given weight)
lower center of gravity
smaller
better fuel efficiency
allows a much lower hoodline (in a front-engine car)
If you want to maximize power out of a given displacement, you will go to DOHC and multivalves per cylinder. If you want to maximize power out of a given engine size and weight, OHV is IMO the way to go for a V-configured engine.
Personally, I'd prefer a smaller/lighter-weight Mustang *not* based on a discontinued luxury sedan platform, with IRS, and with a smaller/lighter-weight aluminum OHV V8. Yeah, I know, not gonna happen...
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From: Palo Alto
One of the great benefits to DOHC motors has been the ease of adding VVT. I'm curious if GM is going to add a Viper style VVT cam to the LS motors. The VVT cam seems a complex solution but it does work. The alternative would be a new block with twin cam shafts. This would loose some of the cost and weight advantages of a pushrod motor but would still retain the packaging advantages.
I've seen two dual cam pushrod motors. One was the Harley Twin Cam. In the case of the twin cam each cylinder has it's own cam. I guess the idea was to better align the cam lobes with the cylinders. That would make sense in a Harley motor since the pistons are in plane on the common crank. Since their in line the angles between the cams and pushrods gets strange.
The other design I've seen is the GM XV-8. That was a really cool concept engine from a while back. It's what I would like to see the LSx motors replaced with... mostly because it's cool. It was a dual cam in block motor with pushrod 3 valve heads. It was very compact and used a intake and exhaust cam stacked vertically one above the other. That allowed full VVT.
However, so long as the LS keeps delivering I can't blame GM for sticking with it. We all are techie people. We like knowing there are cool parts under the hood. However, in the end, the proof is in the pudding.
I've seen two dual cam pushrod motors. One was the Harley Twin Cam. In the case of the twin cam each cylinder has it's own cam. I guess the idea was to better align the cam lobes with the cylinders. That would make sense in a Harley motor since the pistons are in plane on the common crank. Since their in line the angles between the cams and pushrods gets strange.
The other design I've seen is the GM XV-8. That was a really cool concept engine from a while back. It's what I would like to see the LSx motors replaced with... mostly because it's cool. It was a dual cam in block motor with pushrod 3 valve heads. It was very compact and used a intake and exhaust cam stacked vertically one above the other. That allowed full VVT.
However, so long as the LS keeps delivering I can't blame GM for sticking with it. We all are techie people. We like knowing there are cool parts under the hood. However, in the end, the proof is in the pudding.
