Dial in your compression?

[kevin930t]

I was just curious if anyone has hurd about this technology? I am not sure about how it works and was wondering if any of you could shed some light on the subject.I thought it to be interesting and would be awsome on turboed motors.

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[kevin930t]

Or was i just dreaming

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[brcorp]

Variable Compression Ratio Coming to New Infiniti Four-Cylinder Turbo – News – Car and Driver | Car and Driver Blog

[copbait73]

SAAB had a variable compressor boost engine in the 2000-2001 timeframe. GM bought Saab, killed the program for cost reasons, killed Saab, sold back Saab, then GM killed themselves. The technology was different but accomplished the same.

In the 70s I worked on a variable compression diesel destined for Abhrams battle tank. Pistons moved up and down by oil pressure, worked great. Pentagon Army types wanted a turbine like everyone else, so the tank got a turbine instead.

Frankly this concept looks like a bunch of claptrap that will not be compatible with high revs. Also 1.5 seconds is very slow response when you want boost/power now. Think about that.

What is significant to me is their acceptance that 8:1 is desirable in this modern engine. Makes a good case for 7:1 being more reasonable for our 50 year old motors.

[kevin930t]

I might be wrong but believe Porsche owns the patent and is putting this in there new gt2rs its a interesting concept and thought what if any benefits it might have.Thanks copbait i also look forward to your input..

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[mark houghton]

Originally Posted by kevin930t

I was just curious if anyone has hurd about this technology? I am not sure about how it works and was wondering if any of you could shed some light on the subject.I thought it to be interesting and would be awsome on turboed motors.

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A hurd is where a bunch of animals hang out and ruminate together, much like 930 owners.

[Speedy Squirrel]

Nissan presented this at last months Society of Automotive Engineers convention. The explanation is a little detailed, but think of it as a rotating rocket arm. It is no longer the slider crank mechanism we know and love. Here are my notes:

The rod big end now makes an elliptical motion, with the long axis along the cylinder axis. As a result, the conrod remains more vertical. This means it pushes less on the cylinder walls. Piston friction is claimed to be reduced by 44%. Compression ratio can be varied from 8 to 14. (The Continental VCR referred to by Copbait had less than half that range, with no friction reduction.)

The full range switch time was not mentioned.

There are many other VCR schemes, but this is a Nissan patent. Here is a pic.

[Speedy Squirrel]

Another interesting technology was the BorgWarner eBooster electric compressor assist:

[kevin930t]

Originally Posted by mark houghton

A hurd is where a bunch of animals hang out and ruminate together, much like 930 owners.

Mark,thanks man you know how us mountain folks talk.

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[kevin930t]

What controls the system?Can it be controled manually?Can you add less compression and more boost?Sounds exciting

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[Tippy]

Originally Posted by mark houghton

A hurd is where a bunch of animals hang out and ruminate together, much like 930 owners.

Actually, it's herd.

[boosted79]

I heard there was herd of 930 enthusiasts on here.

[icemann427]

Originally Posted by boosted79

I heard there was herd of 930 enthusiasts on here.

You got that wrong, boosted. It's...I herd there was a heard of 930 enthusiasts on hear...

[Speedy Squirrel]

They use one electric motor to move all the pivots up or down together. The said they have run over one hundred engines for three million miles so far, and that there was a separate ECU just for the variable compression. No cable attached to levers between your seat to turn your CR to 11 though

Originally Posted by kevin930t

What controls the system?Can it be controled manually?Can you add less compression and more boost?Sounds exciting

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[Pat RUFBTR]

6000 tr/mn maximum with this system.

[Rawknees'Turbo]

Originally Posted by mark houghton

A hurd is where a bunch of animals hang out and ruminate together, much like 930 owners.

Like so ?!?!

[turbo owner]

Originally Posted by Rawknees'Turbo

Like so ?!?!

They all seem to have a smile on their face, Rawknees do you have raw knees?

[kevin930t]

Originally Posted by Speedy Squirrel

They use one electric motor to move all the pivots up or down together. The said they have run over one hundred engines for three million miles so far, and that there was a separate ECU just for the variable compression. No cable attached to levers between your seat to turn your CR to 11 though

This revised tech really sounds exciting to me although i know it can't work with our engines but if Nissan or Porsche can perfect this system to be instantanios may be on a switch that says really freekin fast,freekin fast,or just fast would be freekin cool.I hurd use fellas like going fast.Haha

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[Speedy Squirrel]

Originally Posted by Pat RUFBTR

6000 tr/mn maximum with this system.

I think that's right. Not really a performance system.

Here is the Saab system. It lifts one side of the whole head to lower compression. It was super-expensive, and also did not have a very big range of CR's.

Here is the Continental Engine vcr from the '60's. It used oil that came up the connecting rod shank to jack up the piston crown. This was a diesel application.



I think gas turbines won the tank engine contract because they don't need much of a radiator. Diesel tanks can be knocked out by punching a hole in the radiator.

[JFairman]

Raising compression raises cylinder head temperature quite a bit. With water cooling you have a thermostat and the headroom to control that.

With air cooling there is no extra cooling headroom.. all you can do is put a different pulley on the fan to speed it up a little and hope for the best and/or install extra oil coolers to cool the oil more.