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Various unrealistic OHV engines balance observations


$7000 for the LS
$6600 for the DOHC

see the links in my last post.


Oh boy, not this again.

You guys have to realize there are variables to OHV that is not incorporated by Automation, two of them being the leading contributors to how they make power.

Solid Lifters vs Hydraulic Lifters (our simulation uses Hydraulic)
Roller valve train vs journal type (our simulation used Journal)

On hydraulic lifter engines the valve lifter is a hollow tube with a spring inside connecting the pushrod to the camshaft. The lifter is filled with oil pressure from the engine to act as a cushion, and the engines are run at zero lash (very quiet) because of the nature of this valve train and its low tolerance for high resistance, soft valve springs are used and this engine combination exibits early valve float.

On solid lifter engines, the valve lifter is as its name states, solid, the connection between the pushrod and cam is instant via the lifter which were manufactured with a high zinc purity. These engines run valve lash (a gap between pushrod and rocker) so the initial ramp of the cam lobe can be climbed by the lifter. Since the base between the cam and push rod is solid, heavier springs can be used in combination with longer duration and higher lifts. In the 50s-70s this was how OHVs made any power, and these engines had an upkeep which was triple the normal hydraulic engine.

Journal style valve train: This is the model our game uses, and this is the model all OHVs used up to the late 80s. The rocker arms are simply riding on a shaft which is injected with oil, the lifters are all flat tapped bottoms which ride directly on the cam lobe, the pushrods are in direct contact with the rocker arms in a polished socket and are normally oiled to prevent ware, and finally the rocker arms directly press on the valve stem. Everything is metal to metal and there are frictional loses.

Roller valve train: the lifters all ride on bearings against the camshaft, the pushrods all press against end caps on the rocker arms which are encased in a bearing, the rockers themselves ride on a bearing, and the rocker tips which press upon the valve stem are on a bearing. This setup has the lowest friction loss, and is expensive. Hybrid roller setups have been used since the 80s, and full roller setups since the late 2000s (The LS was not a full roller engine, not initially)

So, with our simulation you will never see the wild claim of power made by the US manufacteres in the 60s, this is for two reasons:

A: We are simulating the every day OHV, Hydraulic/Journal.
B: The US manufactures cheated on Dyno day. SAE Gross was measured with no equipment on the engine, in an ideal situation with ideal fuel and timing. At minimum expect SAE Gross figures to be at minimum 25% high.

As Killrob mentioned, OHC tech was banned from racing in the US, in 1964 Ford released a converted 427 FE engine which was OHC, it was banned by the NHRA, and NASCAR because it provided an un-competitive advantage

At this point in development it would ad un-needed complexity, but if for some reason we wanted to add it in, the OHV engine would need two additional options.

1: The option for Solid or Hydraulic lifters. Solid taking a reliability/smoothness/maintenance hit, with only a gain in valve float.
2: Full roller, Roller Lifter, or Full journal: Full roller would have the highest engineering and PU cost, offering a slight gain to efficiency, Roller lifter would be a smaller commitment to engineering and PU, and what we have now, Full journal.

Why did I have to read this, sorry @Killrob


Dear Lordred

If you stop using something this is not mean that it’s not exist, the full roller lifter is the standard for OHV engine since 1985 , if you conseder that as engineering fancy or a special case and it should cost to much , then you should do the same method on Direct Injection, VVL, VVT, all these technologies came way later after roller lifters do you conceder these as ( Fancy engineer thing) by the way the whole idea of OHV engine is the simplesty even the most advanced 2000s OHV engine is more simple than 80s DOHC engine, costing less and require less Faaaancy engineer effort, in fact you can fully rebuild it in your garage :grin:

So please stop underestimate something because it’s not common in your area



Learn to understand what you read, please.


Did you even read my post? Do you even know where I live?

I’ll help you.

I described both the Full roller, and the more common place Hybrid Roller (Roller Lifter) combinations. And yes, they are more expensive to produce because instead of using DAMB valves, you are using machined rockers, with sized to fit needle bearings.

Ford’s even combined the roller valve train into their OHC engines, but that is another topic for another time, as while it has lower friction losses, suffers from oiling issues.

If you doubt my mechanical background, that’s fine, this is the internet and I have nothing to prove to you, just be satisfied that it is people like you who kept us from getting a DOHC 32v Corvette, as you all cried ‘OHV is best’ and threw a temper tantrum when Chevy dared to put one in the Corvette in 1990.



Would you please show me where did I exactly cried saying OHV is the best :grin:

i’ll be more than happy to give you my glasses so you can read clearly :sweat_smile:


You’re as bad a the modern media, selecting only a segment of the larger picture. I was talking about the 90’s and the Lotus Built LT5 in the Corvette, but I could see how that could be misconstrued.


Dear Lordred

Forgive me for the misunderstanding, I thought that there is no reason to quote your all post because it’s right before mine. :blush:

I see that there is no reason for all of us to try to prove the others are totally wrong. :slightly_smiling_face:

The big picture that I see is that this post is one of the most active post in the forms at this time , this is healthy and prove that both schools have a hardcore enthusiasts a that is exactly how the automobile enthusiasm should be :smile:

For sure I can not imagine a Ferrari, Lamborghini, BMW with an OHV engine it doesn’t sound right at all :smiley:

The exact scenario you can apply on the American Muscle cars ( except the Mustang😁) and big SUV

It’s a heritage for each school that should exist to warm the competition

The bottom line let all of us have what they like and the best shall win :nerd_face:


I was about to point out that engineering familiarity helps with ET, but not with PU, then decided to test it to look at the exact figures first. And good thing I did, because the results are not at all what I expected:

(Note: In the comparison tab, the left engine is the dohc one, the right engine the ohv)

I wanted to know how much more ET, PU and material cost an OHV engine would have compared to a dohc if it was made to have the same power with comparable dimensions and efficiency (if at all possible).

Turns out that you can build an OHV engine that’s roughly on a par with a dohc one for a very similar amount of PU(!) with about twice the ET and just over 50% more material cost. It has 455 vs 380 Nm of torque, but peak power is @5200 vs 6200 rpm, I calculated torque increase to be ~+34% on both, so they should be very similar in terms of torquiness. Other than that, the ohv is ever so slightly more compact and lighter dispite nearly 1L more displacement, not as smooth, filthier (both of which make sense imo) and a lot more reliable (which kinda figures considering the superior engineering quality necessary - +6Q on valvetrain and +7Q on fuel system vs 0Q everywhere on the dohc).

My conclusions here:
I expected much higher PU for the ohv given the tech slider abuse, but I think this is quite well balanced as an ohv is inherently much less complex, so a high tech one being about as complex as a run-off-the-mill dohc makes sense to me.

Regarding MC and ET, I think cost might be too steep (I understand that the ohv should be more expensice with unobtanium pushrods and whatnot, but nearly 1000$ is a hefty chunk), while the ET penalty might actually be slightly too mild: A lot of familiarity in campaign mode can cut (iirc) nearly 40% off ET, which would bring it down to some 90-95 for the ohv, which I think would be pretty much spot on, BUT: If you lower the reliability to where the dohc would be in the engineering tab (the one where you balance funding vs reliability and total dev time), you will probably be able to get the dohc’s reliability with an actually lower ET (the filthier exhaust and lower smoothness would remain, of course).

So the long and short of it would be that the material cost penalty for tech slider use might be too harsh and the ET penalty possibly slightly too mild, but by and large I think the balance is quite good.

I don’t know how the engines in Automation are simulated, of course, but I always imagined that it is just that kind of engineering details stuff that’s covered by the tech sliders.

I’m not sure why you would want that, I mean, more rpm means more stress on the components, if it doesn’t come with any benefit in power or anything else, higher rpm will just make the engine worse (or am I misunderstanding you?).


Dear bastormonger

I almost agree with you in the points that you mentioned but "

Please notice that DOHC Have

1- Double of valves and spring 2 Vs 4 valves per cylinder

2- 4 times more camshafts

3- 4 times more camshaft gears

4- Much complicated timing belts some times 2 more timing belts in V engines

This is way OHV never be more complicated or expensive than DOHC engines


Well since OHV is so much more inefficient DOHC, you have to put in more work to make it just as powerful and efficient. In automation, that means putting more quality and better materials on the car, negating the simplicity of the design thus making it more expensive.

Anyways you can get round this problem in the campaign by getting high familiarity with OHV meaning you can put the extra quality without increasing engineering time as much


Dear Dorifto_Dorito

Please notice that it’s really nearly impossible to have an OHV engine that have the same power range as DOHC with the same displacement without expensive techs, but who said any thing about the same displacement, in OHV world there is no replacement for displacement.

Usually OHV engine should have 15% more displcement to equal DOHC power. :smile:


Exactly, to get similar power values you need more displacement. More displacement means more materials needed. But even then, you still need some expensive tech to get similar power range, and even then the fuel efficiency of an OHV would still be worse than DOHC


If you weren’t so caught up on the peak horsepower numbers, you’d realize that OHV is already borderline OP on what it does best: any application where displacement, cylinder count, and low-end torque are more important than outright performance. :wink:

I got very far with +0 OHVs in the campaign mode when I ignored the power and designed them for what they do best. 150hp 5.2L V12s FTW! :smiley:


Your argument holds true for the same displacement and quality sliders being at 0, but to get the same power and efficiency out of an ohv you need more displacement and fancy tech, just as Dorifto_Dorito pointed out. It’s not impossible, but it comes at a price and is thus viable only in certain scenarios. Afaik, the Chevy LS uses titanium pushrods, and these things are expensive as heck. That’s represented by the material cost penalty that comes with upping the quality slider. I can totally imagine that an LS with that kind of fancy stuff in the valvetrain has a higher material cost than a dohc engine with similar power because fewer parts made out of exotic materials can easily cost you more than more parts made from more mundane stuff. The difference in my example engine does strike me as pretty drastic, though.


Please check the below pictures and till me where is the more materials come from :grinning:

6.2/7.0 L Vs 5.0L DOHC

4.6L OHC Vs 5.7L OHV


I can’t understand why this thread is dragging on and on like this.

You’re basing your argument almost entirely on one engine, or at the very least one type/family of engines. If OHV was this simple and this cost effective then why is it now only used in a highly developed, high performance form in those specific engines? There aren’t a high number of pushrod ecoboxes around anymore for example.

It’s also already been mentioned a million times that you’re building these engines in the sandbox where it’s assumed you have no “familiarity” with anything. In the campaign, when all works as planned, this will not be an issue if you want to do a GM and build pushrod V8s for a thousand years.

It’s also been mentioned that OHV in it’s current form can work just fine if not expecting outright high power figures. The game is trying to cover all bases to provide an enjoyable experience for everyone, not goto extremes of specific engines, but can still get you damn close if that is the avenue you choose to go down.

I’m going to close this off now as it’s just going round in circles and it seems like the original points made have been addressed multiple times.