Who said OHVs have problems at high revs?

SSbaby · 09-02-2005, 12:14 PM

:hihi:

The new LS7 7.0-liter OHV (overhead valve) V-8 engine for the 2006 ZO6 Corvette will not only achieve 500 horsepower but will be capable of running up to 7100 rpm. The previous limit was 6600 rpm in the 6.0-liter LS2.

With this new engine GM is showing multi-valve overhead cam performance is achievable with a two-valve cam-in-block engine. For the new ZO6, higher rpm allows the driver to remain in first gear to just over 60 mph, contributes to higher top speed and improves overall vehicle performance. The LS7 is one of the first automotive OHV production engines in the industry capable of over 7000 rpm.

...

"For a production engine to run at this high of an rpm blurs the lines even more between OHV and OHC (overhead cam) design," said Dave Muscaro, assistant chief engineer for small block engines. "We took a complete systems approach to achieve the high rpm. We have a tight valvetrain design along with some race-inspired materials for the reciprocating components like titanium intake valves and connecting rods."

OHV engines use pushrods to activate the valves via rocker arms, whereas with OHC engines the valves are typically actuated directly via finger followers. The extra mechanical movement and weight of the components of an OHV valvetrain present challenges to higher rpm. The LS7 design and use of lightweight, stiff components, along with GM's economy of scale, make higher rpm obtainable in a production OHV engine.

"The new LS7 cylinder head gave us the opportunity to design a new high-revving valvetrain," said Jim Hicks, LS7 valvetrain design engineer. "The new valvetrain had to be as stiff and light as possible to assist meeting the engine's aggressive performance targets without compromising idle quality and low emissions. Stiffness is increased with larger diameter pushrods and rocker arms optimized through extensive finite element analysis."

The LS7's 1.8:1 rocker arm ratio and titanium intake valves contribute to a lower effective mass (compared to the LS2 base Corvette engine) in spite of larger and stiffer valvetrain hardware. Idle quality and emissions performance is achieved with the help of a more aggressive cam that provides more lift and duration while still keeping overlap area to a minimum.

More here.

Homer1 · 09-02-2005, 01:09 PM

Like it or not, the new LS2 and LS7 are rippers (as long as they don't use oil!). What Ford needs is a sports car oriented V8 like these and not a truck based design which I think is the main performance problem with current Ford V8s.

tickford2001 · 09-02-2005, 01:14 PM

yep definately going to be and absolute weapon of an engine - i still wouldnt buy one though, ill just keep saving for my GT40...uh huh ill keep telling myself that :hihi:

XplosiveR6 · 09-02-2005, 06:20 PM

there is no doubt that OHV engines can make serious power, just remember the old 351 clevos and 350 chevs, they made around the same power as our V8s do now, and that was 30 odd years ago they may have drank a whole lot more juice then our v8s do now, but never the less the power was there.

i like how GM has had the guts to stick up the the rest of the motoring world and said 'there is nothing wrong with ohv engines' and they keep proving it time and time again

MrSparkle · 09-02-2005, 06:53 PM

Aaah, GM... forever pushing the boundaries of "technological cost cutting"!!!!!

I can see it now.. the 2010 Corvette C9... 8.5L of V8 muscle, and revolutionary QUAD-CAM-IN-BLOCK™ technology! See it rev like a 10 year old OHC V8! Watch as it expires after 50,000km! Marvel at the marketing effort and acronym count that accompanies its release! Be astonished at the total lack of other manufacturers being interested in adopting its design principles!

I love the line, "blurs the line between OHC and OHV engines"... truly hillarious, that's made my day!

Bossxr8 · 09-02-2005, 08:31 PM

Quote:

Originally Posted by MrSparkle

Aaah, GM... forever pushing the boundaries of "technological cost cutting"!!!!!

I can see it now.. the 2010 Corvette C9... 8.5L of V8 muscle, and revolutionary QUAD-CAM-IN-BLOCK™ technology! See it rev like a 10 year old OHC V8! Watch as it expires after 50,000km! Marvel at the marketing effort and acronym count that accompanies its release! Be astonished at the total lack of other manufacturers being interested in adopting its design principles!

I love the line, "blurs the line between OHC and OHV engines"... truly hillarious, that's made my day!

The thing has a short stoke so piston speeds are kept low, and it runs titanium rods, valves etc. Big deal. Bathurst Clevos revved to 7000rpm in the Ph3 back in the 70's without the fancy components. Most engines could be made to rev to 7000rpm with the right parts.

Sox · 09-02-2005, 10:35 PM

Quote:

Originally Posted by MrSparkle

Aaah, GM... forever pushing the boundaries of "technological cost cutting"!!!!!

I can see it now.. the 2010 Corvette C9... 8.5L of V8 muscle, and revolutionary QUAD-CAM-IN-BLOCK™ technology! See it rev like a 10 year old OHC V8! Watch as it expires after 50,000km! Marvel at the marketing effort and acronym count that accompanies its release! Be astonished at the total lack of other manufacturers being interested in adopting its design principles!

I love the line, "blurs the line between OHC and OHV engines"... truly hillarious, that's made my day!

Well said, and I agree totally.
I can't help but laugh at people who take all this propaganda in, they just don't seem to realise how much better a 7L engine could be with OHC and multi valve technology.
They obviously have no idea of the inner workings and limitations of pushrod operated valves.

We have the likes of BMW producing 500hp with 2L less capacity.

GM is a joke, much like Harley Davidson were for many years, they only just saw the light recently with a multi valve OHC engine in there sports model.

Rick.

SSbaby · 09-02-2005, 10:51 PM

Quote:

Originally Posted by MrSparkle

Aaah, GM... forever pushing the boundaries of "technological cost cutting"!!!!!

I can see it now.. the 2010 Corvette C9... 8.5L of V8 muscle, and revolutionary QUAD-CAM-IN-BLOCK™ technology! See it rev like a 10 year old OHC V8! Watch as it expires after 50,000km! Marvel at the marketing effort and acronym count that accompanies its release! Be astonished at the total lack of other manufacturers being interested in adopting its design principles!

I love the line, "blurs the line between OHC and OHV engines"... truly hillarious, that's made my day!

You've said absolutely nothing constructive there... only bagged the hell out of a well proven design. How sad cynics can be.

:

A big block that's really a small block that's dimensionally smaller and lighter than the blue team's 4.6L DOHC donk (just a friendly reminder)!!! So who's behind the times? I've made my point. :thebirds:

MrSparkle · 09-02-2005, 11:05 PM

Quote:

Originally Posted by SSbaby

You've said absolutely nothing constructive there... only bagged the hell out of a well proven design. How sad cynics can be.

:

A big block that's really a small block that's dimensionally smaller and lighter than the blue team's 4.6L DOHC donk (just a friendly reminder)!!! So who's behind the times? I've made my point. :thebirds:

It's so good that ALL the big players are adopting cam-in-block designs! I can see that now... shame on me and my sarcasm...

:

Seriously, haven't you EVER wondered what GM could achieve if they just GOT OVER IT and put even HALF the effort into an all-new OHC design? Can you possibly comprehend the idea of a high tech V8 made of quality materials sitting in the engine bay of your precious SS? Seriously? Or would you stubbornly refuse such a sweet unit, in favour of the "Holiest of Holies" cam-in-block?

SSbaby · 09-02-2005, 11:11 PM

Quote:

Originally Posted by Bossxr8

The thing has a short stoke so piston speeds are kept low, and it runs titanium rods, valves etc. Big deal. Bathurst Clevos revved to 7000rpm in the Ph3 back in the 70's without the fancy components. Most engines could be made to rev to 7000rpm with the right parts.

I suppose you consider 101.6mm (4" in the old measure) of stroke a 'short stroke' design'? The LS7's bores are almost as wide as the stroke of the 5.4L Boss. And we're talking big!

bore: 4.25"
stroke: 4.00"

Looks almost square to me. For a big capacity engine of 7.0L to rev past 7000rpm is saying something - even for an OHC of similar capacity to rev that high, is quite remarkable!

SSbaby · 09-02-2005, 11:20 PM

Quote:

Originally Posted by MrSparkle

Seriously, haven't you EVER wondered what GM could achieve if they just GOT OVER IT and put even HALF the effort into an all-new OHC design? Can you possibly comprehend the idea of a high tech V8 made of quality materials sitting in the engine bay of your precious SS? Seriously? Or would you stubbornly refuse such a sweet unit, in favour of the "Holiest of Holies" cam-in-block?

As a matter of fact, Sparkie, I have.

Let me tell you that the BMW V10's torque peaks at around 5500rpm for an engine that has 2L less capacity and weighs over 50kg more (240kg total) while the LS7 produces the same torque as the V10 at just over idle, at 1600rpm. Technically, you have no real argument. You remind me of a school kid who likes to make fun of the kid who pulls all the chicks...

:

BTW, GM do make DOHCs but its performance V8s are all OHVs... and Chrysler obviously believes in what GM has done in the last decade as it's HEMI is doing great things in the states.

FYI, the LS7's block is a slightly different alloy to that of the LS2... speaking of alloy... when are Ford going down that path (on a mass scale)?

MrSparkle · 09-02-2005, 11:44 PM

Quote:

Originally Posted by SSbaby

As a matter of fact, Sparkie, I have.

Let me tell you that the BMW V10's torque peaks at around 5500rpm for an engine that has 2L less capacity and weighs over 50kg more (240kg total) while the LS7 produces the same torque as the V10 at just over idle, at 1600rpm. Technically, you have no real argument. You remind me of a school kid who likes to make fun of the kid who pulls all the chicks...

:

The LS7's block is a slightly different alloy to that of the LS2... speaking of alloy... when are Ford going down that path (on a mass scale)?

So you aren't at all interested in a modular Ford engine (including the Yank GT and all-alloy "Cammer"), any of the BMW V8 range (including the new 4.8 Valvetronic), any of the Merc V8 range, any of the Ferrari V8 range, any of the Audi V8 range, ... etc. etc. purely on the basis that they have overhead cams? And following, would you then go on to conclude that the LS7 is superior to each and every one of these engines? If that is the case, then I would love to see your breakdown and criteria, addressing each one in terms of its inferiority, and consequently, a concluding comment directed to each manufacturer perhaps giving them a few tips on how they could improve these units.

Finally, I'm not going to dignify your comment on what I apparently remind you of, and I'm really not sure exactly what kind of statement you are trying to make there, but feel free to continue along whatever path you wish to on that front.

SSbaby · 09-02-2005, 11:54 PM

Sparkie,

I'm a simple man with not a lot of money, who knows the meaning of bang for buck... I'm surprised you left the best performance marque in the world out of your argument - Porsche. I would lust after a GT3 or GT2 and would never settle for anything less if I had the cash... and lots of it!

But if the Corvette (Z06) LS7 were available in AUS and in all probablility were half the cost of a GT2, it would be hard to decide between the two. In a nutshell, it wouldn't come down to your technology argument... it's about raw performance, it's about fun and it's also the amount of pride you get in owning such wonderful machinery.

MrSparkle · 10-02-2005, 12:18 AM

Yes indeed, the TT V8 in the Cayenne is a worthy unit and I was negligent to have missed it.

Well I'll wrap up my rant by letting you in on a secret - the pushrods wouldn't stop me from having a new (or near new) 'Vette! I have no doubt that I'd absolutely love it, and I also have absolutely no doubt that I'd continue my opinions on OHV vs. OHC! You can love a car and be happy with it, and still long for more! Hell, isn't that the entire life of an enthusiast?

needturbo6 · 10-02-2005, 12:39 AM

well if the opinion on the longer lasting, better designed engine than the Mr sparkle is on the right track but if the argument is about cheap power than i think SSbaby has the arguement won.

The main thing though is that IF GM used an OHC design on the LS7, it would have been a way better motor than it already is. more responsive, more power, possibly longer life .etc.

If using pushrods to keep the cost down and power up than it is ok, but i think in the next few years GM will have to build a hi-po OHC v8.0

10-02-2005, 01:47 AM

Disregarding the OHV vs OHC arguement for a moment, you have to say a 7100rpm limit on an OHV is something. Personally I prefer the OHC layout for the obvious benefits but the LS7 will be one hell of an engine.

G&D PERFORMANCE · 10-02-2005, 02:15 AM

As a lover of GM & Ford pruduct I will say that there is NOTHING like a big capacity V8 for pure adrenilan pumping excitement & it's good to see a modern day production version of good ol fasion muscle car engine.I love high tech multi valve stuff as much as anyone but I think this new GM engine is a good thing,I've seen amazing things from our current LS1 & we continue to see it time & time again.As much as I love & own Fords I take my hat off to GM for having the balls produce some exciting tyre shredding machinary like this.I'm not taking anything away from the new GT40 either,I'd have one of those babys in a second.

I look forward to the day when we may see a bigger version of Fords V8 with a decent bore to stroke relationship so we can rev them up safely to see the true potential available from their 4 valve cylinder head instead of it being wasted.

galaxy xr8 · 10-02-2005, 10:28 AM

Quote:

Originally Posted by G&D PERFORMANCE

As a lover of GM & Ford pruduct I will say that there is NOTHING like a big capacity V8 for pure adrenilan pumping excitement & it's good to see a modern day production version of good ol fasion muscle car engine.I love high tech multi valve stuff as much as anyone but I think this new GM engine is a good thing,I've seen amazing things from our current LS1 & we continue to see it time & time again.As much as I love & own Fords I take my hat off to GM for having the balls produce some exciting tyre shredding machinary like this.I'm not taking anything away from the new GT40 either,I'd have one of those babys in a second.

I look forward to the day when we may see a bigger version of Fords V8 with a decent bore to stroke relationship so we can rev them up safely to see the true potential available from their 4 valve cylinder head instead of it being wasted.

Here,here, well said mate.

SSbaby · 10-02-2005, 11:22 AM

Quote:

Originally Posted by MrSparkle

Yes indeed, the TT V8 in the Cayenne is a worthy unit and I was negligent to have missed it.

Well I'll wrap up my rant by letting you in on a secret - the pushrods wouldn't stop me from having a new (or near new) 'Vette! I have no doubt that I'd absolutely love it, and I also have absolutely no doubt that I'd continue my opinions on OHV vs. OHC! You can love a car and be happy with it, and still long for more! Hell, isn't that the entire life of an enthusiast?

Well said! Ditto!

:

CAMS290 · 10-02-2005, 04:59 PM

Good onya GM for making affordable performance available to the masses, ala LS1,LS2 and the new LS7, lets face it if it wasn't for GM's lead, we would all be driving 200kw Windsors around still. Nuff Said !

10-02-2005, 05:19 PM

Well, horses for courses. I see nothing wrong with the way the LS2/LS1 series respond when I put the foot to the carpet. Same with the Boss290. Personally I can't care what is under the bonnet as long as it has 8 pots and sounds good and goes like stink.

But I ask you this. As good as the Boss 290 is (we won't even acknowledge the 220), what's better right now? yes, you are correct. The lowly OHV LS2. Simple. And it carries no penalties in weight, fuel consumption or performance. In fact it is better in all three.

So what's the point in rubbishing the GM choice?

galaxy xr8 · 10-02-2005, 05:51 PM

Quote:

Originally Posted by CAMS290

Good onya GM for making affordable performance available to the masses, ala LS1,LS2 and the new LS7, lets face it if it wasn't for GM's lead, we would all be driving 200kw Windsors around still. Nuff Said !

And what's wrong with the 200kw windsor my friend, LOL.

:

XplosiveR6 · 10-02-2005, 06:38 PM

talking about fuel consumption, the herald sun got 13.7l/100ks out of the GT with the new 6 speed they had, which is pretty dam good and would be better then any LS1/2

12-02-2005, 12:09 PM

Quote:

Originally Posted by galaxy xr8

And what's wrong with the 200kw windsor my friend, LOL.

:

Nothing if you haven't driven a 220kW WIndsor. Fact is there may only be 20kW in it, but the way Tickford livened up the engine overall was fantastic. Sorry, the 200 ain't the best bit of gear, although it still sounds damn good.

buickman · 12-02-2005, 12:27 PM

I question I have to ask is why is it in the V8 mtrs Chevs are used more for drag racing in the US & Australia. Excepting the Mustangs & F150 lightnings. Ford are behind GM & Chrysler in v8 & v10 performance mtrs.

buickman

RED_EL_XR8 · 12-02-2005, 12:31 PM

Quote:

Originally Posted by buickman

I question I have to ask is why is it in the V8 mtrs Chevs are used more for drag racing in the US & Australia. Excepting the Mustangs & F150 lightnings. Ford are behind GM & Chrysler in v8 & v10 performance mtrs.

buickman

Most of what is called Chev is aftermarket chev pattern kit & crate stuff, cheap simple and bangs for bucks.

SSbaby · 13-02-2005, 11:45 PM

I don't wanna start a riot folks... I'm just the messenger ;)

Quote:

Chevy's small-block V-8 turns 50
And is still packing a big punch
Saturday, February 12, 2005
By TERRY BOX / The Dallas Morning News

Hot-rodders call Chevy's little reddish-orange V-8 the "mouse motor."

These days, though, 50 years and 90 million engines after its introduction, it is the mouse that roars.

Small-block Chevys live and breathe deeply under every kind of hood imaginable, from 1940 Ford street rods to 5,000-pound sport-utility vehicles.

In fact, many in the industry say the mighty mouse – whose 50th anniversary is being honored at the Dallas AutoRama this weekend – may be America's most significant motor.

"Someone once said time will tell, and in this case it has," said Brian Brennan, editorial director of Street Rodder magazine, which is marking the anniversary with a display at the car show at Dallas Market Hall. "Fifty years down the road, Chevy has a real winner."

Automakers such as Toyota and Nissan built modern overhead-cam V-8s, which are more efficient in some ways than the overhead-valve small-block, but General Motors Corp. is sticking with its middle-aged mouse.

Variants of the engine, now in its fourth generation, can be found in new GM pickups, SUVs, sedans and muscle cars. The most recent descendant was introduced at the North American International Auto Show in Detroit in January: a pumped-up 7-liter, 500 horsepower V-8 that will power the 2006 Z06 Corvette to nearly 200 mph. The Z06 is the fastest and most powerful car GM has ever built.

"And we're not done with the small-block yet," said Tom Stephens, group vice president of GM Powertrain. "It will be with us for a while."

The engine's nickname, by the way, distinguishes it from a family of big-block Chevy V-8s in the 1960s that enthusiasts called rat motors.

GM believes its decades-long commitment to the muscular mouse gives the company a competitive advantage because it is simpler and cheaper to build than overhead-cam motors but produces about as much real-world power, Mr. Stephens said.

"Albert Einstein said the best design is the simplest one that works," he said. "I don't have one piece of data that says I should abandon the small-block."

Even better for GM, mouse power extends beyond the company's assembly lines and dealer showrooms.

At a time when GM sometimes struggles with its image, many hot rodders revere the small-block Chevy and have generally positive opinions of GM because of the engine, industry officials say. It is the billion-dollar hot rod hobby's engine of choice, powering perhaps 80 percent of street rods and custom cars, said Mr. Brennan of Street Rodder.

Even people who drive Chevy-powered Fords are probably more loyal to GM than to Ford, Mr. Brennan said.

"The small-block Chevy was a genius invention," said Tom Williams, vice president of Championship Auto Shows, the promoter for the O'Reilly Auto Parts AutoRama in Dallas. "To hot rodding, it has been our staple engine. There are more Fords in hot rodding with Chevy engines than there are Fords with Ford engines."

**russellw** · 14-02-2005, 05:23 PM

I'll pass on the OHV vs OHC debate - I personally couldn't care less as long as it goes hard.

However on the topic that was started here I am surprised that anyone thinks 7,000 rpm is that high for an OHV design. Those who follow the Nascar circus will have noted the gradual increase in RPM limits on the super speedways to the point where RPM in excess of 9,000 is now a common sight - and for 4 hours on end. This is up over 1,000 RPM on a year ago and some of their engine builders are predicting a similar increase in the next 2 years. There are also surprisingly few failures in either the top or bottom end of these motors although when they do fail they do it in a big way.

Cheers
Russ

SSbaby · 14-02-2005, 06:17 PM

Quote:

Originally Posted by russellw

I'll pass on the OHV vs OHC debate - I personally couldn't care less as long as it goes hard.

However on the topic that was started here I am surprised that anyone thinks 7,000 rpm is that high for an OHV design. Those who follow the Nascar circus will have noted the gradual increase in RPM limits on the super speedways to the point where RPM in excess of 9,000 is now a common sight - and for 4 hours on end. This is up over 1,000 RPM on a year ago and some of their engine builders are predicting a similar increase in the next 2 years. There are also surprisingly few failures in either the top or bottom end of these motors although when they do fail they do it in a big way.

Cheers
Russ

Yes but they're only designed to last 5-6 hours... true. The lighter-weight components they use in their qualifying engines help the engines rev even higher but they'll blow within an hour under race conditions.

In F1, it's much the same story.

Brute33 · 14-02-2005, 07:29 PM

Does Ford Cosworth DFV mean anything to anyone .
As long as GM stick with pushrods , Lemans and F1 will always be out of touch , and thank god for that.