Turbocharger

Can we add banjo music to individual posts?

Steve Hiatt's hit the nail on the head - hassle. My parents have stored cars for my mates for free in the past but it's sometimes turned sour when cars outstay their welcome, tools go walkies, you find random people wandering round etc, and it's more awkward to turf out friends. They've come to the conclusion that it's not generally worth the hassle, even for a price - it takes a lot of months to offset a missing welder / set of spanners / farm gate etc. That said, they store a car and a boat for our plumber for free - he's never been a hassle, just him visiting once a month and he comes to the house first so we don't shoot at him. We've not seen a plumbing bill in years either ...

Did a few more miles today, very pleased with most of it. The torque off the line is excellent, then it settles down to around 1.25bar. Transient response is good too, it overshoots briefly and then comes smartly back to the required level - the car picks up instantly and catapults strongly out of bends, roundabouts etc. There is a hole in the torque curve just where the torque converter locks which is irritating but there's plenty of toys left to play with. The only down side is that it appears to be quite "thirsty" when driven enthusiastically...

This thread's approaching twelve months old, and I believe I now have the type of response I was looking for. I had an epiphany from a conversation with Rusty Wingnut. I've been playing with different springs to change the response of the turbo vanes. The differing springs have been changing the gradient and y-intercept of these lines: This would bring the turbine into surge at low revs, because the vanes remain in the 'zero' position until the unit is boosting at around 1 bar - that limits me to set the zero position to that which will allow surge-free running at ~1800 rpm, which means the response is very similar to a wastegated turbo. So, I reasoned, I needed a response which would give some movement at lower pressures, maybe from zero. I'd need a very weak spring. I specced up what I wanted, and rang up a bespoke company in Bristol to get a spring made specially. £54. Since I wasn't certain that my numbers and reasoning were right, I bodged something up, using a tension spring outside the pressure capsule (this was the epiphany...) This gave some very promising results, with a much more instantaneous response although the spring wasn't stiff enough to quickly return the vanes against the friction in the system. It gave me enough confidence to look at the other springs I had in my assorted bag from the £10 minimum order from said spring company. If the spring is 30mm long, it will sit in the capsule with no preload and give a response nearer to zero boost.There was one spring with a rate of 1.77N/mm and a free length of 100mm. I cut this down to 30mm, which means the rate is now nearer 6N/mm - not as stiff as some of the other springs I'd specced, but the bodge-spring effort from earlier suggested that might not be a problem. Here's the chopped spring: I tidied the ends and built it up again. Before I ran it out of the garage again, I measured the extension: Just what I was looking for - time for a roadtest. Result - :D Happy John :D There's a real 'shove' as it lifts off tickover, and it comes up to ~0.8 bar and holds steady, as it's working in a feedback loop. 0-60 is around twenty seconds with this boost level, which is really surprising as it 'feels' much quicker. I daresay this will come back as I work on it a little more to get the steady-state boost back to factory levels (or slightly greater), but the torque at lower revs is very pleasing, and it's exactly the effect I intended when I built it, rather than out-and-out power. In a show of abuse of my vehicle, I revved the engine with my left-foot on the brake, to see what boost it'll make at low revs. For the viewing public's pleasure, . Sorry about the unsteady camera work, the car kept moving despite discs all round...

I think the remote t-box opens up a range of exciting options from 2WD vehicles. Toyota/Lexus diesel? VAG 2.5TDi? Cummins 6BT? Supra engine? Rover KV6?

Oh aye, many thank yous. Wouldn't want to interrupt a gig schedule with some early-90s has-beens I guess my key question is how easily the vane actuator moves - I can't move mine by hand but I guess yours might move quite easily?

Wherever all four branches join, before the turbo and with the probe into the gasflow. I put my probe in the main manifold tube, between #2 and #3. I think there's a photo in my VGT thread of my build.

Good stuff, and considerably faster project than my own VGT lash-up. I'm particularly interested in the control diaphragm - my impression of the turbo I have is that the spring pressure needs to be quite weak (or the diaphragm needs to be quite large). Any chance of some close-ups of the pressure diaphragm?

Excellent stuff, really informative. I hadn't appreciated how much movement the prop etc went through. It'd be interesting to see some rough roads, bumping over kerbs, axletwisters etc. Not demanding, are we?

The load that dominates the alternator power consumption at higher speeds is the fan power to draw cooling air through the machine. You can actually control the mechanical load that the alternator draws by manipulating the "battery sense" voltage (since the load of the headlights etc induces a voltage drop in the battery and that's what the alternator compensates for). BMW's EfficientDynamics package has a clever computery thing between the battery and the alternator, so the alternator only 'sees' the need to charge the battery when the engine's in overrun - micro-mini hybrid!

For what it's worth, I think you're right. The peak torque when driving is decided by the engine and gear / transfer box ratio. (I'm ignoring inertial effects of the tyres when they spin/slip and 'grab' at the floor). However, with a higher ratio final drive, you'll see more time at these high torque values are sustained for longer periods (because with a lower ratio, the torque gives higher acceleration, and so torque x seconds equates to higher speed. If it's peak torque that will break components, I say there's no difference. If the parts can fail through fatigue or wear out through sustained high-torque running, it'll break quicker with a higher ratio eg RR diff.

Perhaps not the best website but we spent two weeks camping and touring Cornwall last summer and this was the best thing we did, not too expensive either: Geevor tin mine. Not the most polished or H&S/cotton wool attraction but it was really interesting. Our trip was rather curtailed by horizontal rain so we're making a series of day trips from Bristol to fill the gaps. Tintagel Castle is a pretty day out, Goonhilly was interesting and mostly indoors too - to be honest there's so much beautiful countryside and empty roads out there, you'll enjoy yourself no matter what.

I'm going to run the gauntlet of the forum here and say that there is a place for KERR ropes. If you find you need to 'snatch' a recovery (as above, straight pull has failed and no winch / no winch anchor) then you're better to snatch with a KERR than a static strap or rope - the instantaneous forces on the recovery points will be lower. It goes without saying that recovery points should be in top condition and all equipment is tested or rated to the dynamic loads and a bridle used to distribute the load if possible, but the momentum of the recovery vehicle can be an asset and the KERR captures this momentum. In the wrong hands, deadly and it's certainly not an automatic option, but it's another tool in the kit to use at the appropriate moment. They're also very handy for towing a rolling load on the road, where you don't see big forces but a bit of 'give' as the tension is taken up at junctions etc is very welcome. As for selling KERR ropes without a licence or competency test, that's a different matter...

>>> add a battery to a diesel-electric and it's a hybrid = automotive flavour of the month.

VGT control is definately a goer - I can provide some info on the type of response you're likely to want too. Don't be fooled into thinking that the mechanical route is just a bit amish and fitting a box of wires means it'll run perfectly - there's still plenty of calibration work to be done to get all the maps right. I want mine to run underwater (it IS a diesel... ) but I'm not sure if there's a closed-loop feedback VGT in the mainstream automotive world? You could use a commercially-available knock sensor to detect surge (or just d(pressure)/d(time) over a certain threshold?) and assess strategies which achieve maximum boost across the rev range, minimum back pressure across the rev range etc etc. As a control project this one's a goer in my opinion - remember the marks aren't for creating something useful, they're for hardcore maths. You can fill pages and pages with Bode, Nyquist and PID and probably not even get as far as cutting metal If you want a test bed, I'm not too far away.

Let me Google that for me Seems Mr Electron has to find a way back too - a strong argument for keeping the truck coated in wet, sloppy mud year-round

Umm - are we all missing something really obvious, or is it just me?. Since it's all in electrical contact, won't the galv on the rest of the chassis act as a sacrificial anode for the exposed bit that you weld on, or is that only if the whole thing is immersed in an electrical substrate (ie the sea)?

I shall be helping out on the Imagineering stand on the Saturday - might well pop over for a looksie as I tour the showground

That's "warneographic" :D

Nothing too hard in this job, so long as the bolts come undone. Try them first - if you need to take it to someone to get the bits drilled out, it's easier if you don't have to put the whole car back together again first...

I rather like the Bentley lookalike (it somehow looks a bit military too) and the white Cater-Rover looks like a right hoot Who's for Tdi power, eh?

Nice work, and less restriction too Does that leave you with any silencers at all? How loud is it?

I wombled down to Chepstow today to have a poke around some of the old stuff in a field in Wales. Not a large turnout but some really interesting stuff there - Diamond T, Scammell Explorer, plenty of classic cars and a number of stationary engines. One was trailer-mounted, a big lump with a flywheel on the end, spinning pretty quickly but just a quiet clicking noise, nothing more. It was so quiet myself and a mate (a diesel engine designer) couldn't work out whether it was a piston engine or a steam engine - turned out to be a marinised Kelvin sleeve valve petrol engine, obviously. There was also a 4WD-converted T35 - anything look familiar here? My mate lives nearby, he has some rims which he found at an autojumble. I think I've asked this before - they're LR stud pattern, but what are the lugs on the bead?

Night Train - how do you arrive at a 2:1 walking beam ratio required? Not disputing, just interested. I'm guessing the torque reaction around the halfshaft has to be less than the moment going into the walking beam 'box' from the two wheels (to stop the front wheel lifting off the floor and the rearmost wheel climbing under it), but I think this would be much less if the wheels were well spaced, which they necessarily would be because LR wheels are quite large. I can see that a larger ratio here is better (high speed / low torque would give least torque reaction and would protect the halfshafts more too), but if you could make do with a 1.35 ratio at the walking beam, you could have a 4.77 diff in the front and a 3.54 diff in the rear. I'm not going to build anything like this but the physics of the mechanism interests me.

That's really interesting to see all the whirly working bits that you don't normally get to see - thanks for posting up!