OHV vs OHC
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You are currently reading a thread in /o/ - Auto
Why is it that everywhere I look online that everyone says OHV is outdated?
Honestly it does have it's cons (not the ones you think but usually just valve float, pushrods can actually go up to 13,000rpm if it's built for it) but it being smaller in size and simpler to work on in general kind of outweighs those. It can also be 4 valves per cylinder if the designer so chooses.
Tell me /o/, what's your opinions on this?
Pic related, a 4.6L DOHC next to a 302 OHV
![arao16b[1].jpg](https://i.imgur.com/NCrlL5F.jpg "arao16b[1].jpg")
>>14907346
here's an example of a 4 valve pushrod aftermarket setup.
(as far as I know Arao was a scam artist and copied this design from an older company)
Ohc is superior in every single application. It's an undeniable fact
> inb4 cherry picked bullshit
>>14907346
Can't do anything like VTEC or other variable valve timing on a pushrod, aka invalidating like half of engine development of the last couple of decades. Oldtech is badtech.
![ilmor_pneu-std_valve_comparison[1].jpg](https://i.imgur.com/wcesi9t.jpg "ilmor_pneu-std_valve_comparison[1].jpg")
>>14907355
except for size, simplicity and weight distribution.
The only thing that OHC has over OHV is that IF it's directly acting on the valves it eliminates valve-float, and you can get into 20,000rpm in race applications (which is being superseded by pneumatic valves which don't use cams at all)
>inb4 they don't make power per liter compared to DOHC
They can, companies that make OHV don't make them for performance per liter but performance to overall size.
A decent aftermarket head and cam will get you over 100hp/l NA with a stock bottom end.
![hrdp_1007_01_o%2Bgms_vvt%2Bsystem[1].jpg](https://i.imgur.com/JJBCCBM.jpg "hrdp_1007_01_o%2Bgms_vvt%2Bsystem[1].jpg")
>>14907363
You can, GM has VVT on some of their pushrod engines already (which is about as good as a SOHC VVT system). If it used two cams in the block (Like GM planned but didn't do) you can get comparable performance to a DOHC VVT system.
>>14907374
And why would I want that?
>>14907365
Pneumatic valves only refers to replacing the valve springs. A engine with pneumatic valves still will be OHC or OHV etc.
>>14907365
> except for size simplicity and weight distribution
A 3l dohc v8 can make 500hp weighing under 300lb
Compared to a 7l v8 making the same power at 500lb and being almost twice the size dimensionally :^)
![116_0302_GM_5_z[1].jpg](https://i.imgur.com/1nF0YYj.jpg "116_0302_GM_5_z[1].jpg")
>>14907374
>>14907363
here's the dual cam system I was talking about.
It can be done it's just never been done because GM make their V8s to be cost effective, this would've added too much cost for them apparently
>>14907365
>pneumo valve
>Merc had hydro valve in the 90s
>in a V12 DOHC 4valve per cylinder
>that never broke and made 400 HP on 6 liter
pls
![Camless_Valves1[1].jpg](https://i.imgur.com/LwK8gmQ.jpg "Camless_Valves1[1].jpg")
>>14907379
>>14907389
I said in race applications, it hasn't gotten to the regular mass market as of yet. F1 has already done away with cams altogether.
>>14907380
it's what the company wants to do, how many NA DOHC 3L V8s that run reliably make that amount of power for under 10 grand? I'll wait.
Also, you just swap out the stock GM heads and you get your 700hp for about 400lb (which is about how much the LS7 weighs)
>>14907392
>about 400lb which is about how much the LS7 weighs
[citation needed]
>>14907346
>4.6L
The bright side is that newer mustangs have a big enough engine bay to bolt in a 385-series big block for serious performance .
>>14907413
https://www.youtube.com/watch?v=WlI-apfSKTg
Here's an example of an NA LS7 making 800hp.
Also.
http://gmauthority.com/blog/gm/gm-engines/ls7/
>454lbs
>>14907414
Yea, this is what I'm talking about, DOHCs take up lots of space. So much so you can fit an LS2/LS3 into the enginebay of any ricerocket nowadays.
Fresh out of WATs research facilities, the Dual Underhead Camshaft. Combining the power of pushrods and double cams into one great exotic package!
![2lbgykw[1].jpg](https://i.imgur.com/eiAprBU.jpg "2lbgykw[1].jpg")
>>14907433
Isn't that basically a flathead?
>>14907346
Tell me /o/, what's your opinions on this?
Any OHC engine could be improved by fitting DOHC heads and anyone who says different is a fanboy. A small tradeoff in size for more power, a massive improvement in high rpm reliability and a wider power band.
>>14907352
You don't even have to go aftermarket for multivalve pushrod engines. Most famous examples are the Cummins 24v and Honda (!) CX500.
>>14907379
Maybe he was referring to camless systems that use magnetic, pnuematic or hydraulic to individual ly control each valve
As far as ohc vs ohv, ohv is usually lighter, smaller and cheaper. Ohc will usually have more flow and better controlled flow.
Both setups in modern engines produce about the same amount if power for unit of fuel consumed. The ohc will generally rev higher and the ohv will have larger displacement ment. The same amount of air and fuel is generally being consumed to produce the same amount of power.
>>14907363
Dude, intake variation can do 80% of what fully variable valve timing does, so just phading the cam is enough. Besides that, Dodge already uses cam-in-cam full VVT, and they'll probably spread it across their engine range soon. Now show me a DOHC engine that's as easy to disable cilinders on - on a pushrod engine, you just cut oil pressure from the lifters, done.
>>14907431
>about 400lb which is about how much the LS7 weighs
>in response to 500lbs
>citation comes back closer to original claim
Did you suffer any oxygen starvation as an infant?
>>14907392
> swap heads and ls7 makes 700hp
Sure thing bud
> 400lb
In your dreams
>>14907465
Powerstroke and Duramax are also 4 valves per cylinder.
>>14907462
I don't think you'll be changing much in size with a SOHC compared to a DOHC conversion. So yea, any DOHC conversion to SOHC would be an improvement.
>>14907471
>>14907472
>does not know what about 400lbs means
>thinks it means exactly 400lbs
>still didn't show me a 3l V8 that can finish thunderhill without breaking down
>>14907474
>>14907462
OHV* to DOHC my bad.
>>14907478
It depends on the RPM range and the flow of the heads you're using.
Mercury Racing does LS DOHC conversions and the heads have really good flow for what you're getting, but I think that has more to do with how much valve area you're getting rather than the DOHC setup since ARAO heads had similar flow from more than 10 years ago.
>>14907476
>retorts "about 400lbs" in response to "500lbs"
>thinking at all
Maybe you have an extra chromosome.
>>14907486
I'm still waiting on that 3L V8 that costs less than 10 grand that can finish thunderhill.
>>14907483
The Mercury OHC conversion for LSx is mainly for valvetrain reliability. It's designed for off shore boats where you have sustained high RPM usage that is hard on a pushrod valvetrain with very high spring pressure. There are several traditional LSx heads that flow better than Mercury OHC conversions. You'll see some OHC converted Big and Small Block Chevy engines at Bonneville for the same thing. Valvetrain reliability for sustained high RPMs over 5 miles. In all out NA pushrod engines the weakness is often the valvetrain trying to balance weight and durability against extremely high spring pressures in the 0.750-1.000"+ lift cams.
>>14907483
This is one thing I don't get about pushrod fanboys. When manufacturers and race teams want more power they abandon pushrods, 427 sohc, banned 426 hemi dohc, the original ZR-1 ( also assembled by mercury iirc?) also pretty much every sports car and bike manufacturer on earth.
What do you guys know that the best automotive engineers on earth don't?
Both are outdated.
https://www.youtube.com/watch?v=OZWeNPi2XkE
>>14907346
pushrods push gods
>>14907492
>I'm still shifting the attention away from my own outlandish claims
Keep doing that broski.
>>14907439
T head flatheads are best flatheads.
>>14907462
SOHC to DOHC conversion are great.
Converting pushrod OHV to DOHC means you've got mass in places where you don't need it, a useless camshaft gallery, and negligeable gain because pushrod engines' bottom ends are hard to adapt to the high-RPM running where there would be a difference. It's not a small tradeoff either, you're adding ablot of mass and complexity - for the same money, you could probably build a stable high-RPM OHV valvetrain. Power band would still be dictated by cam choice, you'd onoy shift it up.
>>14907502
Don't get me wrong DOHC is better, but when there's a readily available DOHC V8 I can grab in the US and make 400 who or more for less than $3k in a 425 lb package that I can stuff in almost any car, then sign me up.
I'm surprised more modern small high speed diesels aren't pushrod based.
![Ilmor_500I_1[1].jpg](https://i.imgur.com/MUUciyb.jpg "Ilmor_500I_1[1].jpg")
>>14907501
I would say it's more for the elimination of valvefloat than just overall reliability. Since Nascar has engines that can rev past 10,000 RPM and they use exclusively pushrods.
There's also the Mbenz 500l used in indycar to get around the rules that was pretty reliable as well.
Reliability with pushrods has more to do with pushrod thickness and spring strength for the valves and putting return seat valves along the pushrods over the lifters.
>>14907502
>raceteams
They abandoned cams altogether lately.
>>14907507
I'm still waiting, it's like you didn't read the original post either.
>>14907505
I brought that up but they said it was just for valve spring replacement.
>>14907476
Ariel atom 500 nerd
Better than an ls7 that drops it's valve after 5k miles
>>14907512
What 400hp 425lb ohv v8 can you get for under 3k?
>>14907518
Nascar only use it because they're forced to. If they were allowed to use DOHC they'd switch so fast your head would spin.
The mercedes engine was probably reliable because pushrod engine were allowed more displacement and didn't have to work as hard.
Yeah the high valve seat pressures is what increases the load on everything and kills reliability.
>>14907518
If you look back to around 2006, the last time NASCAR really allowed teams to go wild with RPMs then you'll see a lot of engine failures due to valvetrain failure. Back then teams were sustaining 9,000-9,500 RPM regularly. Now gear rules and other RPM restrictions are in place. Engines don't even peak over 9,000 RPM that often, and it's very brief. Engine failures are down a huge amount. In an off shore engine or land speed engine it's easy to run enough spring pressure to avoid valve float for sustained high RPMs. The tough part is keeping it together. You don't want to make a land speed pass and frag a valvespring and engine so you can't make your backup pass.
>>14907529
A year ago I had a car with a 400 whp cam only LS1. $2,750 for the engine. Bought a used cam kit off Craigslist for $250. $3k didn't include the headers. I already had them, but they only cost $350. I sat the engine on a corner scale, because I was tired of seeing all the back and forth on LSx weight. Mine was 426 lbs complete with accessories alternator, PS pump, long tube headers, air filter, ecu, harness, flywheel.
>>14907529
If you can deal with a bit under 500 lbs you can build a 400 whp SBC with aluminum heads all day for $3k or less these days. A bit old school, but it works. Same for the Vortec 5.3 more or less.
>>14907525
>Ariel atom 500
>Cheap
>car literally costs more than 200k
>engine costing under 10k
good job
>>14907502
pushrod engines have won half of the GT Class 24 hour of LeMans races in the past 15 years.
So.. are you saying Vipers and Vettes are so awesome they don't need the best automotive engineers to win.. or just shit posting?
>>14907571
That's like winning the special olympics. When was the last time the overall winner was pushrod?
>>14907392
Fiat has engines with no intake cam at all, but it is not pneumatic but hydraulic. Those engines can operate without butterfly valve in throttle body.
>>14907552
That's probably the lightest weight for a dressed ls1 in existence
Piss off
>>14907587
Last year
>>14907589
Had no idea Fiat already started. Thanks for that one
>>14907562
Where'd the limit for cost come in? Stop with the goal posts
>>14907571
Too bad pushrod shit doesn't even exist in gt3 it's so uncompetitive
>>14907587
1966-1969 when it was dominated by the Ford GT40,
>>14907599
I doubt it. It was only about the same as Ford small blocks I've weighed with cast iron blocks. The long tubes save about 30 lbs over the cast iron logs. I threw on a tiny parts store Denso alternator that saved about 9 lbs over stock. The LS1 usually comes from the factory with a 30 lb flywheel that adds a shit ton of unnecessary weight too.
>>14907615
> overall winner of Le mans within 40+ years
> pushrod
pick one
>>14907616
see >>14907392
>it's what the company wants to do, how many NA DOHC 3L V8s that run reliably make that amount of power for under 10 grand? I'll wait.
>>14907620
>Le Mans only has 1 class
http://autoweek.com/article/24-hours-le-mans/chevrolet-corvette-add-growing-24-hours-le-mans-legacy-gte-pro-win
>>14907624
See >>14907380
Price was never mentioned, you brought it up after the fact
Try harder
>>14907618
The biggest engines in regulated european racing at that time were 3.0L and their lemans entries were usually derivatives of these small engines. They weren't interested in developing a larger engine that they could only use in one race.
So ford showed up with a new 7 version of the gt-40 liter and wiped the floor with them. It's a childish strategy but they won, give credit where credit is due.
>>14907631
Overall refers to overall buddy, not one specific slowfag class where gm uses an engine isn't even the same one in the production vehicle (last gen sbc used in the c7r)
![JEF2203-L[1].jpg](https://i.imgur.com/m6YnBwo.jpg "JEF2203-L[1].jpg")
>>14907644
It's just a destroked LS motor.
>>14907641
That's like saying the Mazda 787 only won because everyone else broke down (this is 100% the truth BTW). If you're okay with that then I'll accept your statement. Otherwise, just getting a relatively high revving 7 liter pushrod engine to survive the 24 hour race on 1960s tech is amazing. BTW regardless of their engine size the competition was trying very, very hard to stop Ford. It's one of racing's greatest rivalries so to say one side didn't care is pretty dumb.
>>14907531
>If they were allowed to use DOHC they'd switch so fast your head would spin.
A switch to DOHC would be new territory, with completely new rules, and it'd increase frontal area because the engines would be taller. A few teams would stick with pushrods, hoping to outlast the experimental DOHC guys.
>allowed more displacement
No, just more boost.
>>14907535
>You don't want to make a land speed pass and frag a valvespring and engine so you can't make your backup pass.
Which is why you keep backup engines.
>>14907655
amazing that you can get 600hp worth of air through those little restrictors
>>14907670
and 5.5L (since 2010)
>>14907666
>Which is why you keep backup engines.
Even professionally organized teams with deep pockets like Speed Demon are against the clock and a budget with back up engines. They usually show up with 3 different class engines and only a back up of the class they are most after for the record. At 4 engines that's $200k or more. They even have their streamliner setup for quick swaps in and out and they're still up against a very tight time window.
>>14907657
In 66 every other car to finish were in the 2l class. Big accomplishment for a 7l v8..
>>14907644
>beating 458s and 911s means nothing guys
>>14907670
Look what a Viper had to breath through!
>>14907657
The situations are completely different. Euro race teams building cars out of their sheds weren't giant corporations like ford motor co. They can't just take a 7 liter engine off their parts shelf and put it in the car like ford.
Developing a new engine they can't use in their other racers just to counter ford in one race out of the season is a tall order. They had to stretch their 3.0 engines to the max which is far from ideal.
>>14907679
I feel sorry for you if your world view is as tiny as your appreciation and understanding of getting any car no matter the competition to survive the 24 heures du mans.
>>14907688
BS the Ferrari backed teams spent more on each car for any given race than the whole GT40 program spent in any given year. Ford came in with a relatively low budget, lower tech car and trounced the gentleman racing aristocracy that had unlimited resources. Face it. Ford basically beat F1 level competition with a Model T. It truly was Ford David versus Euro Snob Goliath.
>>14907688
>Ferrari and Porsche
>not having big racing budgets
what?
>>14907691
Ooh big boy autist using frog speak for no reason! The cars are made to run for 24 hours, finishing the 24h race is no big accomplishment by itself.
Want to know what is though? The marathon De la route. 84 hours of nurburgring. 24h le man ain't shit in comparison.
>>14907705
>the Ferrari backed teams spent more on each car for any given race than the whole GT40 program spent in any given year.
cool story bro
>>14907708
Nowhere near fords. Fords original strategy for winning lemans was to simply buy ferrari. Ferrari refused, ford got butthurt and went all-out to beat them.
>>14907705
>Ford basically beat F1 level competition with a Model T. It truly was Ford David versus Euro Snob Goliath.
People are actually this retarded.
>>14907712
You need to spend more time holding a wrench and less time holding a game controller or TV remote
>>14907712
That must be why a huge portion of modern purpose built race cars still fail to finish or finish tens of laps down. Just finishing Le Mans takes a fuck ton of work and luck.
>>14907718
Nice rebuttal friend. A purpose built endurance racer completing an endurance race is no great accomplishment. Keep jerking over that insignificance.
>>14907737
>endurance racer beats other endurance racers at a time where technology was limited as fuck
>not an accomplishment
>>14907705
Back in the 60s Ford paid Cosworth £100,000 to design what went on to be one of the most successful racing engines ever.
That was a small change to Ford but a huge amount to Ferrari or Climax or BRM.
>>14907737
>A purpose built endurance racer completing an endurance race is no great accomplishment
wowsers.. you could make alot of money helping ford, porsche, chevy, and ferrari overcome the DNFs they have. Or maybe those factory teams just want to not finish sometimes.
>>14907737
Unless it's one designed for
>The marathon De la route. 84 hours of nurburgring.
That's different. Obviously.
>>14907944
not to mention they spent chump change on the Dallara chassis as well and the car in total ended up being really cheap in the end.
>>14907970
>>14907944
I meant to say Lola, my bad
![tumblr_maxh0oRhcp1qk65n6o1_1280[1].jpg](https://i.imgur.com/5mA6jF6.jpg "tumblr_maxh0oRhcp1qk65n6o1_1280[1].jpg")
>>14907365
>except for size and weight
nope
>>14908092
prove that engine would not be smaller and lighter if it was designed from the outset as a pushrod ohv type
>LS engine weights 425lbs
oh boys its another "rtarded LS fanboy" post
http://forum.miata.net/vb/showthread.php?t=129304
>>14908101
ez, motorcycle pushrod engines are not smaller than ohc motorcycle engines
ohc car engines are bigger because weight and size are not a major concern
>>14908121
if OHV was so great for making a small, light powerplant you'd think motorcycles is where they'd shine but it turns out the opposite is true.
>>14908121
which mc pushrod engines are you thinking of?
>>14908137
anything above 1 liter, since that eengine is made out of a literbike engine
>>14908156
I don't know much about bikes so tell me which ones had pushrod i4s
>>14908092
>RPA
>Reliable
>breaks down in qualifier
>breaks down every 10 laps
https://youtu.be/SdcZkQa3k5k?t=637
>>14908186
none that I can think of (not that anon) but they did have pushrod i3s and Vtwins and a few V4s.
Got changed to DOHC for RPMs
>>14908186
older 1930's ones
however, if you compare a pushrod v-twin to an ohc, v-twin, the pushrod one isn't smaller, same with v4s
>>14908200
>Got changed to DOHC for RPMs
but not size and weight?
>>14908194
nice buzzwords
>>14908223
>not for size
technically yes, because you would need bigger displacement to make as much power as the following OHC designs
>>14908233
>does not know what RPA is
https://en.wikipedia.org/wiki/Powertec_RPA
>>14908223
Nope, mostly for higher revs
>>14908233
nice butthurt
![Suzuki-Le-Mans-24-Hours-2015[1].jpg](https://i.imgur.com/8OfROW5.jpg "Suzuki-Le-Mans-24-Hours-2015[1].jpg")
>>14908246
>>14908242
>24 hours of suzuka
>24 hours of lemans
>hundreds of other endurance bike races
tell me again how a high revving motorcycle engine can't do endurance racing pls
>>14908253
>somehow that's the V8 you posted
>>14908257
yes, that v8 is made out of two motorcycle engines
it was also made by a couple of guys without a multi million dollar budget, as opposed to big car manufacturers
>>14908260
It's also unreliable as fuck in cars.
In a bike it would do fine since it doesn't have the gearing of the rear end diff to deal with, but with that gearing it eats that engine whole.
Honestly you can't put it in anything over 700kg and be reliable because it would be too hard on the engine (which was the issue they had at thunder hill).
It's also not mass produced and is built to make mad power for displacement. If someone were to make a comparable engine out of pushrods it may have higher displacement and rev lower to about 8500 but may make the same power for the same weight.
>>14908271
>It's also unreliable as fuck in cars.
totally doesnt have anything to do with the fact that they don't have a multi-million dollar budget
>Honestly you can't put it in anything over 700kg and be reliable because it would be too hard on the engine
>(which was the issue they had at thunder hill).
what the fuck are you talking about
http://northamerica.radicalsportscars.com/newsitem.aspx?id=16
>may make the same power for the same weight.
>bigger displacement engine makes more power
no shit einstein
>>14908291
the Radical SR3 is a 570kg car, the car they built was heavier (which isn't an SR3 by the way).
>>14908186
http://www.motusmotorcycles.com/files/v4.pdf
Forgot about this pushrod V4
>>14908260
Yes anon a hartley/powertec V8 is basically the exact same thing as a hayabusa i4.
I sometimes mistake them myself too.
>>14908315
no, i forgot they are completly different, the hartley/powertec v8 doesn't share any parts with a hayabusa inline 4 either, silly me
>>14908326
it only shares running gear and heads, the crank, block, cooling and oil system are completely different and the last two are unreliable.
>>14908326
you share 90% of your DNA with a banana, so are you a fruit?
![960[1].jpg](https://i.imgur.com/ZvtNdA3.jpg "960[1].jpg")
>>14908334
the crank and block is obviously different because one is a v8 and the other one is an inline 4
>the last two are unreliable.
then why did they finished 2nd and 3rd place in thunderhill?
high revving small displacement bike engines do endurance racing just fine aswell
>>14908341
yes
pic related, me
![rIeUz3v[1].jpg](https://i.imgur.com/y3rFCNk.jpg "rIeUz3v[1].jpg")
>>14908341
>he isn't a banana
>>14908356
Because they had the advantage of grip compared to most other cars.
It had an insane amount of downforce that on the qualifying lap they threw water from the track 20 feet into the air.
It's overall car design that brought them 3rd and 2nd place, not the engine.
![endurance-25-hours-of-thunderhill-2014-race-winners-17-davidson-racing-norma-m20f-bmw-alex[1].jpg](https://i.imgur.com/nnsQrvv.jpg "endurance-25-hours-of-thunderhill-2014-race-winners-17-davidson-racing-norma-m20f-bmw-alex[1].jpg")
>>14908372
>pic related doesn't make a shitload of downforce
![IMG_0174[1].jpg](https://i.imgur.com/CWnZ33G.jpg "IMG_0174[1].jpg")
>>14908396
That isn't the car I'm talking about
http://jfcracing.com/portfolio/wolf-gb08s-v8
>>14908429
I know that isn't the car with the hayabusa v8, thats the car that won the 25 hours of thunderhill
>>14908437
Did you read the link?
>Built Special with RPE, 2.7 Liter V8 (1hr on new RPE refresh engine)
>Spare RPE 2.7 engine, new bearings and refresh assembly, complete with throttle bodies and flywheel
I don't think you can read, why are you even here?
>>14907346
Only shitposters make a big deal out of valvetrains.
>>14908448
That's what I'm saying, both valvetrains have pros and cons and are both going obsolete, but the advantages of DOHC are overblown.
>>14908443
when i said " i know that isnt the hayabusa v8 car" i am talking about this one >>14908396
you, or someone else said the teams using the hayabusa v8 got 2nd and 3rd just because of an aero advantage, yet the car that took first place >>14908396 doesn't look like a fucking brick with high drag and no downforce
you need to learn how to read anon
>>14908463
the only advantage ohv has is cost
>>14908463
So don't make a thread about it.
>>14908473
The one I posted above did win thunderhill last year in spite of the engine failures.
That was the one I was talking about, and it was unreliable because it was heavy as fuck for the engine.
>>14908476
probably not even that if the only two manufacturers still using it went bankrupt.
>>14908476
Cost, size,power to torque density, weight and weight distribution.
>>14908485
No, it's much cheaper since you only have to make one cam and less complex parts like chains etc.
The companies that went bankrupt did so because they didn't make decent enough econoboxes and the japs and koreans owned them.
>>14908491
Don't respond.
>>14908501
You're not even my real dad
>>14908485
All except two (Ford and Tesla) American car manufacturers have gone bankrupt. Pushrods or not has nothing to do with it.
>>14908481
>did win thunderhill
i honestly don't know what the hell you are talking about anon
i cant any info of it winning thunderhill
http://racehero.io/events/nasa-norcal-25-hrs-of-thunderhill/results/1073743877#show:detailed-info-overall-D8fffe917:detailed-info-overall-Dff185850:detailed-info-overall-D8af4d770:detailed-info-overall-D2b36d150:detailed-info-overall-Da765cc0d:detailed-info-overall-Dbffe6dc8:detailed-info-overall-Ddcd495ac:detailed-info-overall-D6e34bc98
>>14908491
>weight and weight distribution
but thats wrong
>power to torque density
what the fuck are you talking about
power and torque are related to bore and stroke, if anything a 2 valve pushrod engine will make less power and torque than an OHC engine with similar specs
>>14908532
as in, it's small as fuck and makes decent torque and power for it's dimensions.
>>14908532
OHV engines have less parts, and thus weigh less.
Ohv engines don't have cams up high, and therefore their weight is distributed lower.
OHV eengines have superior airflow and therefore better torque.
>>14908541
>OHV eengines have superior airflow and therefore better torque.
Airflow depends on the heads, not valvetrain.
![tappetsystem[1].jpg](https://i.imgur.com/ICEsB5V.jpg "tappetsystem[1].jpg")
>>14908541
but it doesnt have less mass in parts, i mean the difference is not significant considering a SOHC engine just have 1 less camshaft, it doesn't have pushrods and sometimes rocker arms in the case of shim on bucket valetrain
sure you have 1 less camshaft, but that camshaft is bigger and you still have a more complicated valvetrain
> engines don't have cams up high, and therefore their weight is distributed lower.
that doesn't necessarily makes the engine center of gravity higher
>eengines have superior airflow and therefore better torque.
>ohv
>most of them are >lol 2 valves per cylinder
>better airflow
good meme
>>14908546
>not valvetrain.
it does though a 4 valve dohc is a lot more simpler than a 4 valve ohv, meaning less intake restriction because of the pushrods
>>14908541
a dohc 4v engine of similar design and displacement should make more torque than an ohv type.
ohvs tend to make more torque through more displacement, not better head flow.
>>14908589
That's still head design though. You have potentially more flexibility with an OHV setup, but a well-designed OHC head will flow just as well as a similarly well-designed OHV head.
>>14908589
>4 valve dohc is a lot more simpler than a 4 valve ohv
Depends on how it's made
You can make it with 16 pushrods and have it 1 rod per 2 valves or 1 rod per valve.
Wouldn't have to deal with those chains to the heads however.
![Ford67valvetrain[1].png](https://i.imgur.com/0pF6uC4.png "Ford67valvetrain[1].png")
>>14908619
>You have potentially more flexibility with an OHV
you have 32 fucking pushrods coming from the cam to the top of the head
you can't tell the pushrods to fuck off, you have to design the intake side considering you have to leave enough room for them
that is a massive disadvantage
pic related, a 4 valve pushrod engine takes a shitload of space, unless we are talking about a design in which 1 pushrod moves 2 valves, but that adds a lot of compelxity
>will flow just as well
no it won't
>>14908546
2 valve pushrod heads tend to outflow 4 valve OHC ones though.
>>14908578
Show us a comparable SOHC that weighs less than it's OHV counterpart.
Unless the engine is designed with a set of pants on the engineer's head, yes, it will effectively lower the CoG.
2 valve pushrod heads have simple valvetrains, and therefore have great flowing ports. You show me a head that outflows the 3rd gen Hemi, or an LS7 for that matter. 300cfm like it ain't a thing.
>>14908617
A DOHC 4V engine of similar displacement and design would be heavuer though. An equally heavy, larger displacement OHV engine would produce more torque.
>>14908619
>a well-designed OHC head will flow just as well as a similarly well-designed OHV head.
Hah. No.
See above. You show me a 400cfm DOHC 4 valve head then - I'll probably be able to show you 10 OHV heads in return.
![1zbz9d0[1].jpg](https://i.imgur.com/MZm4nwb.jpg "1zbz9d0[1].jpg")
>>14908657
yeah, but at that point i font see why an OHC wouldn't be better
you have almost the same amount of mass at the top of the heads and they are just as big
also you can always use a belt
>>14908664
Haven't you seen a CX500 head? Shit's simple as fuck. Single rocker arm operates two valves. Stable to almost 10000 RPM from the factory, too.
>>14908677
>also you can always use a belt
God no. Chains or gears.
>>14908682
>gears
enjoy fucking the rest of the valvetrain just to save on a chain or belt change
>>14908674
>Show us a comparable SOHC that weighs less than it's OHV counterpart.
a honda j series weights 500 lbs with the transmission
which should bring the weight of the engine at 380
a chevy 4.2 v6 weights almost 500 lbs alone
> it will effectively lower the CoG.
it wont though, cog has a lot more to do with deck heaight and total height
the advantage in a lower cog that pushrod engines have is completly irrelevant in flat engines for example
>2 valve pushrod heads have simple valvetrain
no they dont, the pushrods are in the way of the intake ports
>A DOHC 4V engine of similar displacement and design would be heavuer though. An equally heavy, larger displacement OHV engine would produce more torque.
post a pushrod engines that makes as much power per lb as this >>14908092 then
>>14908678
easy to do when it's one cylinder per bank
>>14908678
well thats a single cylinder, i don't really see the point of having a dohc single cylinder engine 2bh
>>14908745
>a chevy 4.2 v6 weights almost 500 lbs alone
no the 4200 vortec is a lot less than that
![1405289789131[1].png](https://i.imgur.com/UcHjEFJ.png "1405289789131[1].png")
>>14908682
>wanting higher harmonics at high rpms
its like you dont like to rev
>>14908677
the heads are wider, not higher
>>14908754
It's a twin though.
>>14908677
The mass isn't comparable, it'll just be about as wide as a hemi head. that's about it.
>>14908682
ive seen and had chains break just as easily as a belt. atleast with a belt you can readily change it and inspect it for wear.
Plus, a belt has less harmonic vibration transfer to the valvetrain.
![gallo12_or_gallo24-55282f78cd3fb[1].jpg](https://i.imgur.com/7HWUkyo.jpg "gallo12_or_gallo24-55282f78cd3fb[1].jpg")
>>14908674
>le cfm meme number
>completly ignoring displacement
shoudl i put a 600 or an 800 cfm head in my 600cc sportbike, according to you the 800cfm will make losts of power right
>>14908907
hemi heads ARE fucking massive, in both weight and size, prob weight as much as a coyote head
>>14908799
well yeah, but it has just one cylinder on each side, my bad
>>14907954
They were production vehicles, not race cars built specifically for the 24h le mans
>>14907346
They are not Outdated.
It's mostly people like this asshat >>14907363
that don't know that OHC is actually an older design than OHV. As for OHC being better than OHV It's debatable.
>>14911270
Are you really saying that if you get more air to burn more fuel in the engine you won't get gains in power?
I mean it's an oversimplification of it, but the more air you get into an engine is the more power you will make.
>hemi heads ARE fucking massive, in both weight and size, prob weight as much as a coyote head
>110lbs compared to 74lbs
http://www.jpcracing.com/rgr-jpc-cnc-stage-3-coyote-5-0-cylinder-heads/
http://www.shophemi.com/c-1170-ported-hemi-heads.aspx
It's also way shorter and will fit into the same space as an LS, because the heads are wide, not tall.
>>14912646
Honestly, the only advantage of OHC is that you can get higher RPMs and you get less valve float because of that.
That's it, there's not much else I can find.
>>14907346
>Why is it that everywhere I look online that everyone says OHV is outdated?
People like to parrot memes because they don't know any better and can't be bothered to research it themselves.
The truth is OHC is almost as old as OHV.
>>14912770
>Are you really saying that if you get more air to burn more fuel in the engine you won't get gains in power?
not him but yes, the engine is not using more air simply because the heads flow better
you need the displacement and the cam to be able to suck that much air, otherwise the velocity of the gasses will be slower than the velocity achieved with a smaller head
those are modern hemi heads aswell u massive gaylord, they aren't hemi heads at all
>>14912770
>http://www.shophemi.com/c-1170-ported-hemi-heads.aspx
You're a moron.
A coyote head with a similar bore size to a hemi would absolutely destroy it in terms of flow and that flow would occur with much lower valve lifts.
The cfm numbers on the coyote are largely limited by its small bore size (92.5mm vs 107.95mm).
Also, OHV hemi headed engines are very octane sensitive and require heaps of advance due to the fact you need massive domes to get any sort of decent compression and that forms a crescent shaped combustion chamber resulting in the flame front having to travel far.
A modern pentroof 4v design is far superior to a 2v hemi head. Even worse a hemi 2V head doesn't come with the packaging & weight advantages of a wedge/bathtub OHV style engine.
>>14913223
>A coyote head with a similar bore size to a hemi
Can a coyote engine have larger bore with its current dimensions? If it can't your argument isn't very good if you need to increase the bore size you will need to increase the head size, and you end up with an engine that is unreasonably large do to the space requirements of OHCs.
>>14913223
Are you retarded? that link was posted for weight, not airflow.
Hemi heads weigh 74 pounds while Coyote Heads weigh 110 pounds.
>>14913087
>chrysler V8
>not still called the Hemi
>not realizing it's just for a weight comparison
>that part has nothing to do with CFM
>not reading the whole post to see that I said just saying CFM = more power is a gross undersimplification
>moving goalposts
>>14913223
>anon posts link to show you hemi heads weigh less than coyote head
>completely ignore it and think he posted it for CFM
