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#61 Rybags

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Posted 20 March 2017 - 10:37 PM

His point is it's not mechanically sound.

It can't handle large amounts of power and also remain compact in size.

It seems to have nowhere near the durability of a manual or auto.  Suffers with smoothness/refinement compared to both.

 

I remember reading about concepts and small scale implementation of it in the 1970s.

Fact of the matter is, there's been little in the way of widespread adoption.

Compare that to turbos.  In the mid 1980s there might have been half a dozen cars available with a turbo, these days they're an option on almost everything.



#62 Master_Scythe

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Posted 21 March 2017 - 08:44 AM

 

The idea behind it of course is great but I've got doubts there'll ever be a decent implementation.


Since the idea behind CVT is to keep the engine at max torque regardless of output shaft velocity (ie: vehicle speed), yes that's brilliant. Which makes me wonder what in hell MS was on about back there.

 

 

But it doesn't for two reasons.

 

1. technically, most are tuned for max EFFICIENCY, which while in theory is where max torque is, if you lead-foot the gas in an emergency situation, it'll still rise above the, say, 3000rpm.

2. There is always a climb from no torque, to max torque every acceleration. (from 600rpm idle to 3000rpm), so this is where you feel shudder.

 

Bonus 3. They give drivers flappy paddles to 'limit' the gearbox manually if wanted (bad idea).

 

Lets not even look at the problems with running an engine at near the exact same RPM for its entire life. No visits to redline at all must mean hella amounts of carbon.


Edited by Master_Scythe, 21 March 2017 - 08:44 AM.

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#63 smadge1

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Posted 21 March 2017 - 08:57 AM

I haven't had any issues with my CVT. It doesn't seem to be as responsive as a normal Auto, but I put that down to computer/software.

 

The main limitation of the CVT is the belt, the stronger the belt, the more torque you can transmit. As time goes on, I don't doubt they can improve the belts.

 

Ideally, given a properly engineered belt and software, the CVT would be the perfect transmission. But there are still engineering hurdles to jump.


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#64 Master_Scythe

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Posted 21 March 2017 - 09:11 AM


The main limitation of the CVT is the belt, the stronger the belt, the more torque you can transmit. As time goes on, I don't doubt they can improve the belts.

Ideally, given a properly engineered belt and software, the CVT would be the perfect transmission. But there are still engineering hurdles to jump.

 

138 years they've been trying.

Ever since saw mills first started using them, and quickly went back to fixed speed belts.

1920's-ish was the first decent car attempt (there had been some before that).

 

And 1970-something was the modern wet band style implimentation IIRC....

I suppose it's only been 47 years they've been trying with the modern design.

Maybe they'll perfect it just in time for hub driven electric motors to take over?


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#65 Xen

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Posted 21 March 2017 - 11:52 AM

CVT is mostly unheard of outside small vehicles, and for good reason.

 

The idea behind it of course is great but I've got doubts there'll ever be a decent implementation.

Given that autos with mad amounts of ratios are becoming common, there seems not much reason to pursue improvements.

 

Stupidly Subaru have gone with a CVT even on the 3.6R Outback whereas previously it was only on the 2.5.

 

A decent 8 speed would have been a much better choice.



#66 Master_Scythe

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Posted 21 March 2017 - 12:19 PM

 

CVT is mostly unheard of outside small vehicles, and for good reason.

 

The idea behind it of course is great but I've got doubts there'll ever be a decent implementation.

Given that autos with mad amounts of ratios are becoming common, there seems not much reason to pursue improvements.

 

Stupidly Subaru have gone with a CVT even on the 3.6R Outback whereas previously it was only on the 2.5.

 

A decent 8 speed would have been a much better choice.

 

 

I "drove" a Levorg around a.... "privately owned mountain course"..... with the CVT in aggressive mode.

That turbo really makes a CVT shine!

I was actually impressed. But it was also near brand new....

 

Just because they feel great now, they'll need another 5+ years to prove they're reliable before we trust 'their design'.


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#67 @~thehung

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Posted 21 March 2017 - 12:38 PM




the idea is brilliant, but looking at this video i am amazed it works acceptably for high torque applications.

 

the sheeves pinch the belt!  thats it?  0_o  with the force transferred non-uniformly across the bottom edge towards the top edge of the belt — a factor which also appears to vary across the range of angles* at all sheeve positions.  i dont know anything about the stiffness and resilience of the belt material, but that type of contact just seems so obviously imperfect.  not only does it have to respond to diameter changes with minimal non-linear losses, its behaviour has to be precisely constant with the diameter changes at both axles or else forces would be lost through the belt itself.  why arent friction and slippage ever-present problems?

 

 

* i say range of angles, even though it appears the sheeves may have constant angles. i am allowing for some kind of tapering.  i guess i am thinking about the effects of there being more contact along the circumference of the belt at larger diameters, and that this would need adjusting for. 


Edited by @~thehung, 21 March 2017 - 12:52 PM.

no pung intended

#68 Master_Scythe

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Posted 21 March 2017 - 12:48 PM

 why arent friction and slippage ever-present problems?

 

They are. That's what we've been discussing.


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#69 smadge1

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Posted 21 March 2017 - 01:46 PM

It's important to note that belts for high-torque applications are made completely of metal.

 

 

They refer to them as "push belts" because they are designed to push the pulley, rather than pull it.


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#70 Rybags

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Posted 21 March 2017 - 03:42 PM

Get a reliable durable CVT that handles high power without huge space or cost increase, then after your lunchbreak devise a standard type railway line that doesn't buckle in 40 degree heat (with similar proviso on low cost etc).



#71 ReapermanRS

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Posted 21 March 2017 - 09:34 PM

Currently my cars are

 

Gwen

 

Tx6hEie.jpg

 

2003 FPV GT-P (Number 254)

 

5.4 ltr V8 4 spd Auto with everything. All I've done is chucked 10 grands worth of Kicker IQ speakers, subs and amps as well as custom audio work including a yellow top optima auxilary in the boot to run everything, chucked in an aftermarket head unit under the factory one, did my own take on the factory gauge pod and gauges (Factory one costs 4 grand with gauges, and is ugly, not even colour matched with the GT interior) and put some pretty bits under the bonnet. She's a goddamn monster and drinks like one too.

 

And Natasha

 

wgznBP0.jpg

 

1998 Ford Falcon XR-6 Longreach Ute 4.0 ltr 5 spd Manual. The back wheels are 15" x 10" and the fronts are 15" x 8", rear rubber is 295 by 65. Hence the huge ugly flares that will be done properly eventually.

She's had the front sway bar replaced and the rear one installed with Whitelines. Had a Ceramic cushion button clutch installed. I hand rebuilt the motor

 

BFc920b.jpg

 

In preparation to bolt this on the side of it

 

kwMDV2p.jpg

 

I've also got a more or less bespoke front bar to go on it as well as proper XR ute sideskirts. Got 850cc Bosch Deatschwerk Injectors a Proflow fuel pump, Drift BOV and an FG XR 6 Turbo Intercooler to go on her as well. Need to save up for a good Haltech, Bonnet bulge and a few other bits and pieces before she can all go together. Interior will be mostly custom built by me and my old boss. Plan on doing a cab extension and a few other bits and pieces to her. Have a host of high end Vibe Audio to go in her as well.

 

Edited because I forgot this place has the worlds worst image handling and 6000 x 5000 pictures are bad.


Edited by ReapermanRS, 21 March 2017 - 09:42 PM.

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#72 Rybags

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Posted 21 March 2017 - 09:48 PM

Nice XH... what's the expected improvement with the blower?

And, given you're probably throwing a bunch of bucks at the engine, did you consider grabbing a newer twin-cam one?

 

Nice BA GT too - I did a couple of hundred km a few years back driving one.  Complaints I had was it was a little asthmatic (dual-fuel and I think it was before he'd put an ECM upgrade in), and the 4-speed auto just couldn't make up it's mind what it wanted to do.

They cop a right whack too with poor resale value, especially considering the new 5.0 just makes everything before it seem stone-aged.

 

I had my XF Falcon for almost 13 years... put LPG on it for free thanks to the subsidy, it was cheaper to run than a Camry and nowhere near as boring.  Engine died prematurely though.  Cooling issues + LPG not real good for gaskets especially if you don't run petrol as often as you should.



#73 ReapermanRS

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Posted 21 March 2017 - 10:10 PM

I'm expecting to more or less double the output. Stock it's supposed to have 162 Killer Wasps, and I've had the head decked, ported and polished so it should already be up on that. Every tuner I've talked to said a good Haltech or similar with a daily tune should run at about 300 and I'll have a button to push that will give me closer to 500. Hence the foot of rubber on each side at the back. After I bought the kit and got halfway through the build I thought it would be easier just to go with a Barra but the kit will actually bolt onto a Barra if I shorten one of the brackets by 25mm anyway so I'll try this and if it kills the motor I'll dump a Barra in. Probably a late model one out of an FG. I'm already think that the T5 wont stand up to Drag mode very well and that I may need to upgrade to a T56, which means I need to get a custom two piece tail shaft made up and get a centre bearing engineered for it. It's been done before on them so there's nothing to learn it's just all money.

 

As for Gwen she drinks nothing but BP Ultimate and I forgot that the previous owner had put a genuine BF Gt exhaust and rear bar on because it gives you a second pipe and better performance as well as a B & M washable filter which makes her thirstier but prevents weezing. I don't really notice the 4spd suffering from indecisiveness all that much and if it does find a rev range where it wants to keep changing pushing sideways into sports sorts it out pretty well.

 

LPG is basically not an option in Tassie unless you live in Hobart or Launceston. There are 4 servos in a 140km radius that have LPG pumps and none of them are 24 hr.


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#74 Rybags

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Posted 21 March 2017 - 10:22 PM

It's amazing the progress they made with that engine, it became one of the world's great inline 6's from essentially being an evolution based on the bore centres of the classic 250 of the 1970s.  Supposedly the bottom end of even the old ones was/is good for 7,000 rpm without modification - though one of the weaknesses of the old pushrod ones was the valve train.

 

The added advantage of the XH is from the get-go it has a big weight advantage of anything from 50-450 kg over EF through FG-X.

Though I have to wonder how it'd behave with leaf-springs although for power delivery they'd probably be easier to setup to control axle tramp than modern types.







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