In reply to rslifkin :
They mentioned piston oil squinters in the video.
In reply to rslifkin :
They mentioned piston oil squinters in the video.
Cooper_Tired said:alfadriver said:Cooper_Tired said:In reply to Knurled. :
Like the Mustang after the Camaro and the Ranchero after the El Camino.
Everyone copies. All the time
Huh? Last I checked, the Mustang came first. by 2.5 years.
Not that I disagree with the copying. Happens all the time.
It was sarcasm. The Ranchero came before the El Camino by ~2 years as well.
And the Barracuda beat the mustang by 16 days.
So glad to see a pair of big blocks hitting the market that were actually designed within the last half century. It will be even better once they start hitting the junk yards 
That video was great.
Guy did seem like he was stressing about the pushrod question, obviously from a engineering standpoint, im sure he can tell you the advantages of both, and Im sure hes been spent a big chunk of his recent history talking about and realizing the advantages of OHV, but he seemed to preface all that, when asked, with the advantages of OHC, before answering the question.
MadScientistMatt said:Brake_L8 said:I've heard (and someone please correct me if I'm wrong) that the current V10 stuck around partially due to UHaul's need for gigantic medium-duty trucks that didn't run on diesel - because they can't trust their customers to find and fill up with diesel fuel. This will be a good replacement for the V10 and fit that use case, alongside RVs and whatever else needs a big ol' gas motor.
Last time I rented a U-haul, a couple years ago, they claimed the reason they weren't offering diesel trucks was that apparently they weren't offered with a conventional automatic in a medium duty chassis. Seemed a bit odd that you couldn't get a Duramax and Allison transmission on these chassises.
Oh, you absolutely can get a diesel/automatic combination on both GM and Ford offerings. As someone else said, take your average human and realize how blithely unaware they are of their vehicular surroundings. Then look below that 50th percentile and rent them a diesel moving truck. It will not go well.
Brake_L8 said:MadScientistMatt said:Brake_L8 said:I've heard (and someone please correct me if I'm wrong) that the current V10 stuck around partially due to UHaul's need for gigantic medium-duty trucks that didn't run on diesel - because they can't trust their customers to find and fill up with diesel fuel. This will be a good replacement for the V10 and fit that use case, alongside RVs and whatever else needs a big ol' gas motor.
Last time I rented a U-haul, a couple years ago, they claimed the reason they weren't offering diesel trucks was that apparently they weren't offered with a conventional automatic in a medium duty chassis. Seemed a bit odd that you couldn't get a Duramax and Allison transmission on these chassises.
Oh, you absolutely can get a diesel/automatic combination on both GM and Ford offerings. As someone else said, take your average human and realize how blithely unaware they are of their vehicular surroundings. Then look below that 50th percentile and rent them a diesel moving truck. It will not go well.
This. I cannot tell you how many times we had fresh EMT-Bs that would put gasoline into diesel ambulances- even had one time where one of them got offended we were angry at her for it, and tried to lie out of the problem claiming we only needed to "run it out".
he seemed to preface all that, when asked, with the advantages of OHC, before answering the question.
Well, he did talk a lot about the advantages of the engine being so much narrower than it would be in an ohc configuration, so in that sense he talked it up quite a bit. Also agree, that video was great. I admit when i first saw the link i didn't click it because, as much as i love the TFL guys, i have definitely seen videos that were... mostly speculative chit chat and didn't expect it to be a whole interview with a very knowledgeable insider. Pleasantly surprised!
Meh. Fords version of a LSx.
(and no, I did not read all 4 pages before writing this.)
In reply to noddaz :
There's only so many ways to configure a pushrod V8.
4 pages in and nobody's said how they want to stick a pair of eBay-special beijing airbenders on this thing and crank the boost up as high as it can safely go?
In reply to G_Body_Man :
Once they get cheap, and maybe by then the chinesium metallurgy will be on par with the "real" stuff and someone can have 1000hp swapped into their Twin or new Supra. Gonna happen, just needs time.
alfadriver said:A more likely reason was that U-Haul got tired of dealing with gasoline in the diesel tanks. You can fit a gas nozzle into a diesel tank, but you can't do the other way around, and dealing with a typical consumer, which may have never bought diesel in their life, well.... it would be an easy mistake to make.
Many gas stations use the same size nozzles for gas and diesel pumps, so yes, you can do it the other way. Convention may be that diesel nozzles are bigger than gas, but AIUI there are no actual regulations about it, so many gas stations don't bother. It's only leaded vs unleaded where it's required (not that anyone sells leaded any more, but...)
That said, most people are used to buying gas and are no more likely to put diesel in a rental than they are in their street car. Also, diesel in a gas engine does a lot less damage than gasoline in a diesel (modern diesel, at least)
Vigo said:he seemed to preface all that, when asked, with the advantages of OHC, before answering the question.
Well, he did talk a lot about the advantages of the engine being so much narrower than it would be in an ohc configuration, so in that sense he talked it up quite a bit. Also agree, that video was great. I admit when i first saw the link i didn't click it because, as much as i love the TFL guys, i have definitely seen videos that were... mostly speculative chit chat and didn't expect it to be a whole interview with a very knowledgeable insider. Pleasantly surprised!
OHC engines give better specific power (power per displacement). Thing is, specific power is really only interesting if you've got some regulation limiting how much displacement you can use, either a sanctioning body for racing or a government tax scheme. Pushrod engines with a bit more displacement give the same power in a more compact and lighter package, which has actual real-world, user-noticable benefits.
In reply to codrus :
The advantages of OHC designs are really only evident at higher rpm. That's not super beneficial for an engine destined for work trucks.
I understand all these things, it just struck me as odd. This guy has probably spent a good amount of his recent history researching and building this motor, it's his baby.
When asked a question about why he broke the norm, and went pushrod, in any other scenario id expect an engineer to geek out and gush about the benefits of his chosen path.
But here his response seemed very metered and prefaced with, well OHC is better
I assume because if he gushed about how awesome OHV was someone at Ford would be not so happy
noddaz said:Meh. Fords version of a LSx, which is GM's version of every good Ford engine all rolled into one.
(and no, I did not read all 4 pages before writing this.)
FTFY
I still don't understand why overhead cam engines need to turn faster to make power. Is it simply because they can, so they are tuned to? I mean, it seems like cam placement really shouldn't matter, if the engine had long, small runners, little valves, and small ports and header tubes, it should be just as torquey as anything else.
The advantages of OHC are mainly tied up in having an easier time doing 4 valves per cylinder, and having less reciprocating weight in the valvetrain at high rpm. All the weight of everything between the valve face and the cam lobe is mass that the valvespring has to accelerate to close the valve. The heavier you make all that, the stiffer a spring you need, the more power it takes to open it, and that power comes out of your fuel economy and accelerates wear on the valvetrain. An ohc setup on a 2v cylinder head is not inherently better at making power unless it's also spinning really fast.
In reply to Vigo :
I get that, but it should be able to be just as good on the bottom. Hell, even a little better, since the valve train eats less power.
I think OHC inline engines make more sense than OHC V engines on the low end.
Less machining on the block, run a slightly longer timing chain/belt to the head, directly mash the valves open instead of using push rods. There have been some shockingly crude OHC engines built because it was just easy. As soon as you do that to a V motor you've doubled the number of cams just as a start.
The other advantage of OHC is that you can now throw two cams on there and vary cam timing individually to achieve better emissions or performance or both.
I think modern transmissions are starting to eliminate the need for engines to be efficient over a wide range of RPM as well making all of that cam timing nonsense unnecessary.
snailmont5oh said:noddaz said:Meh. Fords version of a LSx, which is GM's version of every good Ford engine all rolled into one.
(and no, I did not read all 4 pages before writing this.)
FTFY
It's the circle of life 
Although to me it still screams mirror-image 8100 without that goofy water pump or 80 pound aluminum intake manifold. (Maybe not 80, but YOU try setting one into the engine bay of a Topkick and see where your opinion is)
The 8100, or Mark VI, is of course the good old Mark IV BBC that looks like they threw as many of the Gen III, or Series II 3800, improvements at it without actually going to a crank snout oil pump. Symmetrical ports, barrel style intake manifold, coil near plug ignition, all gaskets are either captivated O-ring or metal/rubber composite. I'd like to say that the oil pan surface is flat, too, but I only had the oil pan off of one once. No sheetmetal in it, the oil pan and valve covers are castings. Iron heads, though, which is also fun to wrestle in and out of a medium duty truck.
The 385 looked like Ford's answer to the Mark IV, or "Wow, we didn't realize how crappy the FE is" Not a fan of the timing cover arrangement that Ford had, but at least they didn't stick the distributor up against the firewall.
mazdeuce - Seth said:I think OHC inline engines make more sense than OHC V engines on the low end.
Less machining on the block, run a slightly longer timing chain/belt to the head, directly mash the valves open instead of using push rods. There have been some shockingly crude OHC engines built because it was just easy. As soon as you do that to a V motor you've doubled the number of cams just as a start.
The other advantage of OHC is that you can now throw two cams on there and vary cam timing individually to achieve better emissions or performance or both.
I think modern transmissions are starting to eliminate the need for engines to be efficient over a wide range of RPM as well making all of that cam timing nonsense unnecessary.
GM's MO has been pushrod V engines, OHC inline engines, for a while. Then they discontinued the pushrod V6s in favor of the High Feature and turbo fours.
We will always see variable cams. It's an integral part of engine management now. Having a fixed camshaft position is like having a cable operated throttle, it is a huge limitation in what you can accomplish! Might as well have a distributor with mechanical timing advance.
Vigo said:An ohc setup on a 2v cylinder head is not inherently better at making power unless it's also spinning really fast.
This is where things get interesting.... the biggest issue with pushrods, from a cylinder head design standpoint, is getting the air in past the pushrods. Ford got around this twice for the 427. In one case, they actually had the intake pushrods going through the intake ports through little tubes (the Tunnel Port), and in the other, they just made a SOHC engine. (And with the 385 and Cleveland, they said "Hey, if we cant the valves like Chevy did, we can spread the pushrods apart and make LOTS of room for an intake port!" I figure they went with those actually-too-large intake ports because they didn't know what to do with this newfound freedom )
GM made a pushrod Midget (inline four) engine a short ways back that broke from all norms by putting the camshaft on the exhaust side. Not only did this put the valvetrain weight on the "down" side of the engine, but it freed up the world for intake port placement, and the smaller, relatively unimportant exhaust ports could snake through the pushrods just fine. It's a shame no production engines did that. I suspect none did because it would probably cause issues with oil longevity and possibly even cylinder head life, with nothing to cool the necessarily long exhaust ports but oil drainback. Not much of a problem for a sprint engine on methanol.
Knurled. said:This is where things get interesting.... the biggest issue with pushrods, from a cylinder head design standpoint, is getting the air in past the pushrods. Ford got around this twice for the 427. In one case, they actually had the intake pushrods going through the intake ports through little tubes (the Tunnel Port), and in the other, they just made a SOHC engine.
Not necessarily a Ford solution, but still on a Ford engine, Mickey Thompson built some hemi OHV heads for Ford 427s that used a 3-piece articulated pushrod to snake around the massive intake ports.
snailmont5oh said:In reply to Vigo :
I get that, but it should be able to be just as good on the bottom. Hell, even a little better, since the valve train eats less power.
You CAN get the exact same low end torque with an OHC cam engine, heck, even a 4V engine.
The thing is that you deal with what compromises you are handed to you. While you CAN make an OHV engine spin really fast (NASCAR engine spend hours and hours at 9000 rpm), it's a whole lot cheaper to not. Which means you time the cams to be better at lower speeds. Then add in the packaging issues Knurled points out, and before you know it, you have a low revving 2V OHV engine.
The exact opposite applies to an OHC engine-there's no obvious compromise to limit engine speed, so you don't. And after a while, you end up wiht a 5.4l OHC engine instead of a 6.xl OHV engine that does the same thing (in a package, I mean, not matched outputs).
And this particular engine has an extra bonus that Joel didn't mention- but it's part of the cert law, so I can put it out. The Dyno Cert cycle is actually matched to the engine speed where the engine makes max power/torque. For example (and this is NOT real data- just made up)- you can have a 500hp 6.2l OHC engine that does that at 6000 rpm, but that means max engine speed/output on the cycle something like 4500rpm. And that's problematic for many reasons. Whereas a pushrod 7.3 with the same power, but at 5000rpm, that lowers the tested speed to 3600rpm- which is a lot easier to deal with.
So for the real HD gas trucks, really big gas engines are the way to go, and there's no real advantage to having OHC, so you go with the simpler, cheaper, and easier to package OHV design.
The common on line OHC vs OHV debate misses a lot of the compromises that have to be balanced for production.
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