teach me about corvette engines

EDIT: OVERHEAD VALVE != OVERHEAD CAM; I should have read more carefully.

I'm revealing my ignorance about engines by asking this, but.......

http://www.leftlanenews.com/chevrolet-corvette-c7-to-feature-5-5l-v8.html

Drew Johnson said: Seemingly confirming one of the worst kept secrets in the industry, a General Motors insider has revealed that the next-generation Chevrolet Corvette will be one of the first road-going vehicles to feature GM’s new 5.5L V8. According to one of Motor Trend’s inside sources, the Corvette C7 will come equipped with GM’s new 5.5L small block V8. The new mill will feature a number of technical advancements — including direct-injection and a new combustion system – but will retain its old school overhead valve design to cut costs and keep the engine compact. Power for the new engine will likely total 440 horsepower, which would be a slight improvement over the 436 horsepower currently available in the C6 Corvette. However, thanks to the 5.5L’s smaller size and its advanced features, expect a noticeable jump in overall fuel economy – improving on the C6’s already impressive 26mpg highway rating. Chevy’s new 5.5L has already made its world debut, appearing between the fenders of the C6.R racecar. GM has also committed $890 million to develop and produce the new small block. Expect to see the C7 Corvette in 2012.

When I hear "old school" I think of NASCAR with pushrod. What's the new nifty design that makes overhead cams seem so old fashioned?

It says overhead valve, not overhead cam...

Doh! Thanks.

Interesting. It doesn't really bother me because A) It's still a V8 and B) it's still a pushrod. So I take it this is the 5th generation SBC?

probably

i figured this would be a thread lauging at CL adverts that claim anything with a small block has a "350 vet moter"

saw an ad for a p71 with "its a cop package so has corvette engine"

the new engine sounds impressive - theyre doing some cool things with the direct injection systems - 300hp v6's that get 30+mpg in porky camaros and mustangs are good no matter how you slice things.

unfortunately in the 19 years since my vette was built they have jumped 200hp on the base models - i need to do some catching up.

New motor, same stigma...

In reply to GR40RACER:

If you mean the pushrod setup, I prefer they keep it that way. It makes it unique. There are tons of other OHC V8s out there; if every V8 were built the same, it'd be kinda boring. If an engine is still matching (and beating) comparable engines, it's not outdated in my book. Anyway, the OHC is older than the OHV, so if the OHV configuration is outdated, than we surely can't go to the OHC, which would supposedly be even more outdated by that logic.

JeepinMatt wrote: In reply to GR40RACER: If you mean the pushrod setup, I prefer they keep it that way. It makes it unique. There are tons of other OHC V8s out there; if every V8 were built the same, it'd be kinda boring. If an engine is still matching (and beating) comparable engines, it's not outdated in my book. Anyway, the OHC is older than the OHV, so if the OHV configuration is outdated, than we surely can't go to the OHC, which would supposedly be even more outdated by that logic.

i'm just waiting for someone to come out with a modern interpretation of a flathead engine...

Remember, OHV engines are much smaller overall. Here's a pic of a 302 Ford and a 4.6 Ford side by side:

ZOO wrote: Remember, OHV engines are much smaller overall. Here's a pic of a 302 Ford and a 4.6 Ford side by side:

Wow! They should have shown the 5.4 too.

So true. If you've ever looked under the hood of a Corvette, you know there is barely enough room for the OHV engine, let alone an OHC.

The OHV designation confuses me, aren't the valves overhead in pretty much ALL modern car engines? The cams are in different places, the plugs are moved around, but the valves are all overhead.

MrJoshua wrote: The OHV designation confuses me, aren't the valves overhead in pretty much ALL modern car engines? The cams are in different places, the plugs are moved around, but the valves are all overhead.

Not on flatheads; the valves are not overhead but off to the side, in the block. The OHV designation was meant to differentiate them from the flathead, which is a simpler design, with fewer moving parts, but doesn't offer the efficiency of a dome (hemi) or wedge combustion chamber.

It's true that overhead valve engine as well as overhead cam engines have valves in the head, but in this case, cam placement trumps valve placement.

All you need to know about a Corvette engine is.... Someone will put it in a Miata.

In reply to NYG95GA:

I guess my confusion is why they use a name meant to differentiate it from a Flathead to differentiate it from an OHC engine. The two commonly used designs in modern vehicles are both overhead valve and typically referred to by cam placement. Actually, I guess the common descriptions are OHC and pushrod, so the names come from cam placement and parts required by cam placement, but basically they are all about cam placement.

and yes Rotary fanatics, I know all about the magical spinning triangles.

Josh, you got my bizzare mind to thinking (I hate when that happens), and I figure that an OHC flathead engine could be designed (and likely has, by some obscure company), with a chain or belt driven cam in the head that operated pushrods going into the block to rocker arms to activate the valves which run parallel to the pistons up to the CC. It would be an engineering nightmare, with too many moving parts, and the efficiency would likely be poor, but it could be done.

Damn, I'm weird..

Don't forget the "F" head engine.

NYG95GA wrote: So true. If you've ever looked under the hood of a Corvette, you know there is *barely* enough room for the OHV engine, let alone an OHC.

I just read a short bit from an engineer involved in the C4 Corvette ZR-1 and he said a key factor in ditching the LT5 and going with the LS1 was the size. They built the C5 Corvette's engine bay just big enough for the LSx, figuring the smaller size and lower weight would overcome the difference in power.

JeepinMatt wrote:

NYG95GA wrote: So true. If you've ever looked under the hood of a Corvette, you know there is *barely* enough room for the OHV engine, let alone an OHC.

I just read a short bit from an engineer involved in the C4 Corvette ZR-1 and he said a key factor in ditching the LT5 and going with the LS1 was the size. They built the C5 Corvette's engine bay just big enough for the LSx, figuring the smaller size and lower weight would overcome the difference in power.

that, and the LT5 was a mechanical nightmare that required 12 quarts of oil because they couldn't figure out how to get the oil to drain back to the pan fast enough. sure, it looks cool, but it's easier and cheaper to get the same amount of power out of a similarly sized pushrod V8 by adding some sort of forced induction.

a couple of years ago, i saw a C5 Corvette that had a 502 crate motor in it. it looked right at home. so we know that the engine bay isn't just big enough for the LS engine..

you just can't beat the simplicity of a single cam in the block- it is compact, light, has less moving parts, is easy to manufacture, and easy to work on and modify. that's why it was the most common engine layout in domestic cars and trucks from the 20's to the 90's.

novaderrik wrote: you just can't beat the simplicity of a single cam in the block- it is compact, light, has less moving parts, is easy to manufacture, and easy to work on and modify. that's why it was the most common engine layout in domestic cars and trucks from the 20's to the 90's.

so all those rockers and pushrods aren't moving parts?

i have to believe there was some other reason for using such a convoluted valvetrain setup...it seems much more straightforward to have the valves work directly on the camshaft.

You have to add in the non-valvetrain parts though. For example, my 4.6 SOHC has some giant honking timing chains ($$$), a bunch of timing chain guides ($$$), an extra cam, and still has all the hydraulic lifters and followers/rockers. The only thing I lost compared to an LSx is 16 pushrods and about half a freaking engine bay. The rocker/cam covers have to be larger as well and now the engine has to have a giant clamshell front cover.

iceracer wrote: Don't forget the "F" head engine.

And "L" head engines.

novaderrik wrote: a couple of years ago, i saw a C5 Corvette that had a 502 crate motor in it. it looked right at home. so we know that the engine bay isn't just big enough for the LS engine..

Did the owner do any sawing and fabricating to get that thing in there?

I thought the L-head was a flathead.

JeepinMatt wrote:

novaderrik wrote: a couple of years ago, i saw a C5 Corvette that had a 502 crate motor in it. it looked right at home. so we know that the engine bay isn't just big enough for the LS engine..

Did the owner do any sawing and fabricating to get that thing in there?

looked like it dropped right in- other than the huge freaking hole in the hood to clear the ramjet intake manifold, i didn't see any obvious signs of anything being hacked or fabricated.. i didn't talk to the owner, but looked at it for a little while. this was at the Car Craft Summer Nationals car show a few years ago.