Why is it that everywhere I look online that everyone says OHV is outdated?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 Veeky Forums, what's your opinions on this?
Pic related, a 4.6L DOHC next to a 302 OHV
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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
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.
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acting on the valves it eliminates valve-float, and you can get into 20,000rpm in race applications (which is being superseded by pneumatic valves which don't use cams at all)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.
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.
And why would I want that?
Pneumatic valves only refers to replacing the valve springs. A engine with pneumatic valves still will be OHC or OHV etc.
> 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 :^)
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
>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
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.
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)
>about 400lb which is about how much the LS7 weighs
[citation needed]
>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 .
youtube.com
Here's an example of an NA LS7 making 800hp.
Also.
gmauthority.com
>454lbs
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!
Isn't that basically a flathead?
Tell me Veeky Forums, 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.
You don't even have to go aftermarket for multivalve pushrod engines. Most famous examples are the Cummins 24v and Honda (!) CX500.
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.
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.
>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?
> swap heads and ls7 makes 700hp
Sure thing bud
> 400lb
In your dreams
Powerstroke and Duramax are also 4 valves per cylinder.
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.
>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
OHV* to DOHC my bad.
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.
>retorts "about 400lbs" in response to "500lbs"
>thinking at all
Maybe you have an extra chromosome.
I'm still waiting on that 3L V8 that costs less than 10 grand that can finish thunderhill.
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.
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.
pushrods push gods
>I'm still shifting the attention away from my own outlandish claims
Keep doing that broski.
T head flatheads are best flatheads.
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.
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.
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.
>raceteams
They abandoned cams altogether lately.
I'm still waiting, it's like you didn't read the original post either.
I brought that up but they said it was just for valve spring replacement.
Ariel atom 500 nerd
Better than an ls7 that drops it's valve after 5k miles
What 400hp 425lb ohv v8 can you get for under 3k?
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.
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.
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.
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.
>Ariel atom 500
>Cheap
>car literally costs more than 200k
>engine costing under 10k
good job
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?
That's like winning the special olympics. When was the last time the overall winner was pushrod?
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.
That's probably the lightest weight for a dressed ls1 in existence
Piss off
Last year
Had no idea Fiat already started. Thanks for that one
Where'd the limit for cost come in? Stop with the goal posts
Too bad pushrod shit doesn't even exist in gt3 it's so uncompetitive
1966-1969 when it was dominated by the Ford GT40,
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.
> overall winner of Le mans within 40+ years
> pushrod
pick one
see >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.
See Price was never mentioned, you brought it up after the fact
Try harder
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.
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)
It's just a destroked LS motor.
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.
>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.
>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.
amazing that you can get 600hp worth of air through those little restrictors
and 5.5L (since 2010)
>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.
In 66 every other car to finish were in the 2l class. Big accomplishment for a 7l v8..
>beating 458s and 911s means nothing guys
Look what a Viper had to breath through!
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.
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.
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.
>Ferrari and Porsche
>not having big racing budgets
what?
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.
>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
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.
>Ford basically beat F1 level competition with a Model T. It truly was Ford David versus Euro Snob Goliath.
People are actually this retarded.
You need to spend more time holding a wrench and less time holding a game controller or TV remote
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.
Nice rebuttal friend. A purpose built endurance racer completing an endurance race is no great accomplishment. Keep jerking over that insignificance.
>endurance racer beats other endurance racers at a time where technology was limited as fuck
>not an accomplishment
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.
>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.
Unless it's one designed for
>The marathon De la route. 84 hours of nurburgring.
That's different. Obviously.
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.
I meant to say Lola, my bad
>except for size and weight
nope
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
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
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.
which mc pushrod engines are you thinking of?
anything above 1 liter, since that eengine is made out of a literbike engine
I don't know much about bikes so tell me which ones had pushrod i4s
>RPA
>Reliable
>breaks down in qualifier
>breaks down every 10 laps
none that I can think of (not that user) but they did have pushrod i3s and Vtwins and a few V4s.
Got changed to DOHC for RPMs
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
>Got changed to DOHC for RPMs
but not size and weight?
nice buzzwords
>not for size
technically yes, because you would need bigger displacement to make as much power as the following OHC designs
nice butthurt