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Posted: **Tue Apr 01, 2014 7:47 pm**

Lets have a talk about engine design and theory. I had to learn about about motors to rebuilt my 364 in my 59 so lets see what I can remember! I remember hearing from a well respected Buick expert tell me the optimal bore to stroke ratio (not sure if its for pushrod or every gas engine) is 2/1. He also said the less timing advance needed the better because it has a good combustion chamber. We all know a good motor means having a very strong bottom end. The crank in the GM 3.8 is actually a nailhead crank with 2 cylinders cut short hence why both the V8 nailhead and 3.8 V6 are bullet proof (I actually used 3.8 crank seals on my 364).

Valve Train

On pushrod engines you want adjustable pushrods when using rocker shafts to adjust for wear, or standard pushrods with adjustable rocker studs. The advantage of rocker shafts is that they are much stronger and handle high rpm much better. down side is they don't tend to flow as well as studded rockers.

With pushrod engines there are 2 main types of lifters (flat tappet and roller). Flat tappets were used extensively until the 80s due to the decrease in friction with roller lifters. The advantage of flat tappet design is they tend to give you better lift, while also increasing wear (especially with very high performance grinds)

More things will come to mind, but this is all I can recall of the top of my head :roll:

Posted: **Wed Apr 02, 2014 12:21 am**

I loved my 3800, I cannot wait for the v6 calculations come out so we can design that in game.

Posted: **Thu Apr 03, 2014 12:52 pm**

JayZee88 wrote:Lets have a talk about engine design and theory. I had to learn about about motors to rebuilt my 364 in my 59 so lets see what I can remember! I remember hearing from a well respected Buick expert tell me the optimal bore to stroke ratio (not sure if its for pushrod or every gas engine) is 2/1. He also said the less timing advance needed the better because it has a good combustion chamber. We all know a good motor means having a very strong bottom end. The crank in the GM 3.8 is actually a nailhead crank with 2 cylinders cut short hence why both the V8 nailhead and 3.8 V6 are bullet proof (I actually used 3.8 crank seals on my 364).

Valve Train

On pushrod engines you want adjustable pushrods when using rocker shafts to adjust for wear, or standard pushrods with adjustable rocker studs. The advantage of rocker shafts is that they are much stronger and handle high rpm much better. down side is they don't tend to flow as well as studded rockers.

With pushrod engines there are 2 main types of lifters (flat tappet and roller). Flat tappets were used extensively until the 80s due to the decrease in friction with roller lifters. The advantage of flat tappet design is they tend to give you better lift, while also increasing wear (especially with very high performance grinds)

More things will come to mind, but this is all I can recall of the top of my head

I'm kind of sad that more time wasn't spent on pushrods.
For example, we can't choose between lifter types - implementing them wouldn't be hard (at least I think so) - Hydraulic and solid tappet or roller lifters.
Creating a high-revving pushrod engine is usually also very expensive, even when the aftermarket parts needed to do so aren't THAT expensive - I remember a 302 build on Super Chevy that revved over 7500rpm without losing a lot of power.
I understand that we will have research points, but they're going to come when the tycoon part is completed IIRC.

Posted: **Tue Apr 08, 2014 2:20 am**

If the game sells good I am sure they will revamp the engine builder. Few Europeans realize their perspective on pushrod engines is very, VERY outdated :lol:

A fact. The Buick nailheads weakest point was the valve springs that were safe to rev to 4,800 rpm (1953-1966), but those engines were designed for low rpm, high torque driving. The valve springs used on them were the weakest used on ANY GM V8, yet the motors have the Gold Trophy for being one of the most reliable V8s no longer made. Heck my worn out 56 Chevy with the 265 stock revs over 6500 rpm. In fact 90% of US pushrod V8s can rev safely to 5500-6000 rpm even in the mid 50s! Pushrod engines do tend to have more friction, but few parts to go wrong.

Aside from my personal opinion I do see pushrod engines becoming more scarce because of the lack of breathing (in general) compared to other valve train designs, and MPG laws getting more stern. However when a manufacturer can make a modern V6 or V8 as reliable as the Buick 3800 or the Buick Nailhead then I will be impressed with multi cam and roller cam designs. The only thing they proved IMO is they can breath better, but at the cost of reliability, and repair costs going through the roof. :lol:

Posted: **Tue Apr 08, 2014 2:37 am**

American pushrod tech would be about +10 quality in the game, which on a 1950 car means the tech is on 1970s standard, you need to keep that in mind. Also, I have to call you ignorant if you think American pushrod tech is "standard", it is definitely not. If Americans know one thing it is how to build pushrod engines.

Posted: **Thu Apr 10, 2014 11:57 pm**

I know pushrod valve trains aren't the standard globally. Top Gear made me (and many others) sour toward Europe's distaste toward US automobiles. The Hennessy Venom GT (worlds 'fastest' production car) has a hopped up Chevy 350 powering it.

I am glad to hear there is a adjustment for a good quality pushrod design in the game. We are all gear heads after all 8-)

Posted: **Wed May 28, 2014 2:14 am**

General Motors 427 used in the Z06 corvettes until recently can rev to 7500 reliably while still making great power all while being a pushrod engine. Any technologies shortcoming can be overcome with ingenuity and money. GM said the reason they stick with pushrod v8's is to reduce the height of the engine so it can be placed lower for better center of gravity; they also say reliability comes into play.

Now I would love to see what GM could do if someone said take this 427, make it direct injection, DOHC, VVT on everything and go to town. Its crazy to think they got 505 hp and 475tq with just displacement and a large camshaft. They said to hell with it for modern technologies at the time and went back to the old day saying of "no replacement for displacement".

Posted: **Wed May 28, 2014 3:28 am**

Correct me if I'm wrong but isn't the new ls series using direct injection, vvt, and active intake? It's not that gm is against modern tech, it's just that like porsche they decided to engineer their way past a design limitation.

Posted: **Wed May 28, 2014 3:37 am**

The latest/newest LS engines seems to have added DI, VVT is on some engines (not high performance).

Posted: **Wed May 28, 2014 3:44 am**

The one I mentioned (LS7) they do not.Tthe new LT motor does not use VVT just direct injection and DoD or displacement on demand. For us here on the receiving end it seems silly to avoid such technology, however they face the same things we do when designing engines, cost, reliability, man hours ect.

I think with a little work and tuning they could have gotten more out of the engine, and I'm sure third parties have and will, but they had a mark and in my eyes hit it. I read in an article that the corvette achieved over 34mpg highway when in eco mode and in 7th gear, that's crazy for a car of it caliber.

Posted: **Wed May 28, 2014 4:07 am**

Damn meant LT not LS, and yes the LT does use variable valve timing, DoD and a few other goodies to make a powerful efficient and compact block. http://m.motortrend.com/wot/next-gen-lt ... 80365.html

Posted: **Wed May 28, 2014 4:35 am**

Seems like the only LS engines with VVT is the Vortec 6000 (based on Holden L76) and the L99.

http://en.wikipedia.org/wiki/Chevy_LS_e ... present.29

Posted: **Mon Jun 02, 2014 11:16 am**

Irkie500 wrote:The one I mentioned (LS7) they do not.Tthe new LT motor does not use VVT just direct injection and DoD or displacement on demand. For us here on the receiving end it seems silly to avoid such technology, however they face the same things we do when designing engines, cost, reliability, man hours ect.

I think with a little work and tuning they could have gotten more out of the engine, and I'm sure third parties have and will, but they had a mark and in my eyes hit it. I read in an article that the corvette achieved over 34mpg highway when in eco mode and in 7th gear, that's crazy for a car of it caliber.

The LT1 DOES have VVT.

Unlike previous generations, the base LT1 will come standard with continuously variable valve timing (CVVT)

http://www.superchevy.com/news/ghtp-121 ... z33QrTDdaN

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