First peek at Gen V

[feistl]

Have a Google of BMW valvetronic, it makes a LS1 look pretty ordinary

Agree with most of your post, but the one thing worth pointing out is LS create engines are around the $6k mark (retail pricing). Im not sure what the BMW V8s go for, but im willing to bet its a damn sight more than this. The whole beauty of the LS engines is the are relatively low tech, meaning cheap and reliable. If they go to some super technical engine design its going to push the price up... And people already bitch about how expensive GMs performance cars are. So in the new Gen5 i would be hoping for more of the same, coupled with direct injection and more efficient design. Basically i dont want to see the engine become overly technical, expensive or fragile.

[Marco]

The Euro engines make incredible power and are highly effiecent. The 4.0L BMW M3 V8/ 5.0L M5 V10 are good examples, but Audi with it`s 4.2L V8 makes 331kw!

Efficient in what sense, though? Perhaps in terms of kW/litre but I didn't think the Euros were particularly better than GM when it came to kW vs fuel consumed?

Also, what's all this talk of 3 valve heads - is that confirmed for the Gen V?

[macca_779]

The power/litre comparisons I aways find amusing. If it makes as much power and returns similar fuel economy to a smaller engine it's a nonsense to consider it a poorer design.


iPad 2 HD

[Xjas]

The power/litre comparisons I aways find amusing. If it makes as much power and returns similar fuel economy to a smaller engine it's a nonsense to consider it a poorer design.

I agree, power/litre is great for comparing engines in a racing class that has capacity limits but rego has no such limits so power vs weight or power vs total engine volume (ie. the space it takes up in the engine bay) are more relevant.

[Phillshz]

Feistl: That is a good point, no doubt one of the reasons GM still continue with pushrod engines. It was the same case with the LS1 vs the LT5.

Marco: Another good point, the euros are better at overall efficiency (they have to be given the relative fuel cost over there) but the performance engines are comparatively as thristy as the larger GM engines. A 3 valve head was under development to fit the LS7 but was shelved,it`s not confirmed but if it was going to come out it will end up on the GEN V at some point.

Macca: Also a good point, as long as GM can keep the total design advanced enough and cost effective to be close to the euro`s specs then i`m sure they will stick with it.

Ford US pulled the plug on pushrods back in the mid 90`s, perhaps seeing the writing was on the wall.
It even happened in the airline industry. State of the art,expensive big 4360ci (71.5L) 28cyl radial pushrod turbocharged engines making massive power with good economy were immediately overshadowed when turboprop/jets were released. The airlines all dropped the "old" piston motors virtually overnight.

GM might still solder on with a excellant pushrod motor but for how long??

Cheers Phill

[Evman]

Ford US pulled the plug on pushrods back in the mid 90`s, perhaps seeing the writing was on the wall.
It even happened in the airline industry. State of the art,expensive big 4360ci (71.5L) 28cyl radial pushrod turbocharged engines making massive power with good economy were immediately overshadowed when turboprop/jets were released. The airlines all dropped the "old" piston motors virtually overnight.

You can't compare a mass shift from radials to jet engines to a shift from pushrods to OHC. Jet engines are fundamentally different. OHC is not fundamentally different to pushrod, its just a reshuffle of the components.

[Kotso]

This looks the 5.5L Supercharged Small block from the corvette. HSV is planning to use it in the next gen GTS R8 and Grange. Was talking to a few mates in the industry who have been testing them.

[Toddler78]

It even happened in the airline industry. State of the art,expensive big 4360ci (71.5L) 28cyl radial pushrod turbocharged engines making massive power with good economy were immediately overshadowed when turboprop/jets were released. The airlines all dropped the "old" piston motors virtually overnight.

I think(know) the reason in the airline industry was so that planes could fly at higher altitudes thus be more efficient There is a height limit a piston plane can fly at before it falls out the sky because there is not enough air

[Phillshz]

I believe there is a altitude ceiling that piston engines (no matter how advanced) could safely reach,but i don`t know the figure.

The piston engine planes kept on getting bigger ie more cyls and larger displacement combined with more/larger turbos and eventually turbo compound systems. All to climb higher and fly faster and it also allowed larger planes to be built. The engines were pushed to the limit of the times and prone to failing regularly ie catching fire, bending conrods, o/heating, seizing, eating exhaust valves etc etc

The jet engined planes could/can not only climb higher to beat the weather than the piston planes but could fly much much faster without blowing up a motor or two. This made the switch to jets very rapid.

Yeah comparing a radial to a jet is a big difference compared to OHV to OHC, they are totally different designs entirely. Perhaps i should have said flathead to OHV instead.
If the flathead was a better engine then it would still be around today, but everyone went to OHV, then onto SOHC & DOHC. GM are still using the OHV but they are alone, but if they can keep it in the "ring" with DOHC then cudos to them

Cheers Phill

[swingtan]

OK, so let's get down to grass roots levels for cam locations.

Advantages Of OHC:

• Reduces valve train weight: No need for lifters and push rods, this reduces the total weight that the valve springs need to control.
• Following on, lighter valve springs required: Reduced losses from friction and overcoming spring tension, less wear on components.
• More available space for components: Allows for separate inlet and exhaust cams. This then allows for better component alignment ( valve angles and follower / rocker angles)
• Ability to vary the timing of inlet and exhaust cams separately: Provides for optimisations for both economy and power / torque.
• "May" return a smoother running engine: Given the infinite adjustment possibilities for the cams, the engine may run smoother through the RPM range.

Disadvantages of OHC:

• requires more complex drive mechanisms: rotational forces need to be transfered from the crank shaft, down low, to the cam/s up top.
• Longer drive path can increase timing variances: The longer the belt / chain, the greater the valve timing variances will be.
• Higher centre of gravity: Moves weighty components to the very top of the motor.

Advantages of push rod setup:

• Low centre of gravity: Cam resides low in the block.
• Ease of upgrades: Need to replace 1 cam and not up to 4.
• direct drive from crank: or much shorter chain / belt.
• Proven long record of stability and consistency: They simply work and work well.

So what do you want to use the motor for? If you want a proven track record with a motor that develops great low down torque and has a low centre of gravity, a push rod V8 is a very good choice. It's simple, reliable, gets the job done and returns huge power and economy for very little outlay.

If on the other hand you want a motor that develops it's power high up in the RPM range and runs really smoothly, then the OHC version might be a better choice ( at an increased cost ). Don't forget the bang for buck, the LS series motors and been one of the outstanding stayers. Just because they still run push rods does not mean they are out dated.

Simon.

[macca_779]

I think(know) the reason in the airline industry was so that planes could fly at higher altitudes thus be more efficient There is a height limit a piston plane can fly at before it falls out the sky because there is not enough air

Not quite right. Forced induction takes care of the air pressure problem. Jets even in turbo prop config come into their own for other reasons.


iPhone 4

[SUPERH2377]

then how come the 5.7 gen 3 had its torque very high in the rev range compared to gen 4 or holden 5.0
i dont understand
thanks

[macca_779]

then how come the 5.7 gen 3 had its torque very high in the rev range compared to gen 4 or holden 5.0
i dont understand
thanks

Cam, tune, inlet manifold mainly.


iPad 2 HD

[Nutter]

The holden 5.0 has smaller throttle body, very long runners in the manifold, smaller port heads and a smaller cam so even with its pathetic static compression ratio all the power is down low, of course they don't go very hard up top.

HTC One XL 2

[Evman]

Don't forget the bang for buck, the LS series motors and been one of the outstanding stayers. Just because they still run push rods does not mean they are out dated.

This is the reason I think the LS series are truly world class. They might not be the most refined or more efficient, but they are one of the most versatile motors out there. Stroke, supercharge, turbocharge, twin supercharge, twin turbocharge, twin turbo+supercharge, boat, plane, car, motorbike, lawnmower, anything. Anything that can be done to an engine has been done and almost anything that can have an engine has had an LS conversion. Absolutely awesome engines for that exact reason.