..seeing as Lockdown 2 looms...

For some time I've been having a devoid-of-reality fantasy of putting a supercharger on a K engine - all that room on top of the engine/it whistles like its already got one anyway/they look cool/I can imagine myself casually saying "it's got a supercharger y'know"/why not etc.

I think I understand how a supercharger works, but I'm not completely clear about the alternatives when it comes to the sequence of events - the air metering unit, throttle(s), etc. and those weird bypass valves. TBH I've no idea. The ones from the VAG 1.4TSi engines look, well, like my idea of a supercharger...

There's no ambition for monster power - I couldn't handle it anyway. The first aim would be to just get a running engine, maybe even with the OE injection system. The drive might come from a modified alternator drive shaft.

Help.

Help.

interesting idea  for sure

It's hard to get a blower small enough to do the job. When I was drag-racing we used magnusun blowers with hilborn injection but the mechanical injection didn't suit petrol well so methanol was the go but that isn't a consideration on the street.
Aircraft cabin blowers are a good option as they are rootes type blowers ans are often small enough and compact.
I would be inclined to try using the original injection ports and injectors and go with a megasquirt control. You only need a blow-off valve in case of a backfire which I can tell you from experience can be very expensive. You regulate the manifold pressure by how fast you drive the blower.

Good luck. What have you in mind for lockdown 3?

Turbo-supercharger.

With Nitrous.

Guys I'm being serious here.

Well, okay......I'm trying 

We're not.

If only there was a reliable way to capture and vacuum seal/store the copious amounts of hot air which comes from our respective pollies then release it into an engine in the way of nitrous...




"The molecules in hot air are moving faster than the molecules in cold air. Because of this, the molecules in hot air tend to be further apart on average, giving hot air a lower density. That means, for the same volume of air, hot air has fewer molecules and so it weighs less. So since cold air weighs more, it sinks, driving the hot air up."
~Scienceline.ucsb

Yeah well, next time some newcomer joins the forum and posts the 'hello it's me' message, and you lot all line up to say nice encouraging stuff - 'oh you've come to the right place', 'plenty of help here' and all that, well, I'm going to tell them the truth....
I am.

Advice for lockdown. It's a concept heard about round this particular portion of the hemisphere but not often adhered to.

So how about using an electric motor to drive the supercharger? You can run it up and shut down quicker.

Lots of nice little motors and speed controllers from RC Airplane guys for very little money. You could adjust the blower speed by percentage of throttle opening and be way ahead of engine RPM. It could also help to limit the over run?

Of course I know nothing about any of this.

Chris,
My v.v.limited understanding of superchargers and the like...In the old days, when fuel was delivered to an engine via a carburetor, my understanding is that you would adjust the carby jets to deliver an air:fuel mixture ratio of about 14:1 throughout the throttle opening range. So, the supercharger can force more air into the engine, and the amount of fuel needs to be increased (giving more power...) to maintain a 14:1 air/fuel ratio. (I've got no idea if this is barking up the wrong tree or not!)

So, with advent of fuel injection, wouldn't you need to increase the amount of fuel injected to maintain the ratio? If so, I wouldn't have the faintest as to how it's done, but I'm sure there's boffins out there who fully understand this stuff.

Interesting project!! It looks like Boris is going get heavy on the lock down this time!

Good luck!!

Rickmeister.

Rickmeister wrote:Chris,
My v.v.limited understanding of superchargers and the like...In the old days, when fuel was delivered to an engine via a carburetor, my understanding is that you would adjust the carby jets to deliver an air:fuel mixture ratio of about 14:1 throughout the throttle opening range. So, the supercharger can force more air into the engine, and the amount of fuel needs to be increased (giving more power...) to maintain a 14:1 air/fuel ratio. (I've got no idea if this is barking up the wrong tree or not!)

So, with advent of fuel injection, wouldn't you need to increase the amount of fuel injected to maintain the ratio? If so, I wouldn't have the faintest as to how it's done, but I'm sure there's boffins out there who fully understand this stuff.

Interesting project!! It looks like Boris is going get heavy on the lock down this time!

Good luck!!

Rickmeister.

I know even less about supercharging, but that's not going to stop me here.

While increasing air flow increases the fuel requirement to maintain the 14:1 ratio, I would think that adding a boost pressure signal to the injection control would make the needed correction for fuel. Problem is, pressure probably has a non-linear effect on flow rate and air mass.

How long is the lockdown going to last...? This project could take some time.

First off,  I dunno what I'm talking about, might be going through a bout of LSD.

Second,  the air fuel ratio is 14.7:1, by weight, so spose the same regardless.  Atmospheric pressure is 14.7psi. Coincidence?

Please tell me yes,  so I can take it out of the file "Things I know I shouldn't wonder about but sometimes do"

Then I can put it in the wastepaper bin,  and press the empty wastepaper bin button.

Seems to me I remember following this rabbit hole (well, in thought, at least).  What I researched seemed to point out you had to have a *lot* of air pressure to make it work correctly, so "Maker Solutions" with standard-type fans aren't likely to get you far.  There *are* some promising aftermarket options coming out now, though, like this:

https://torqamp.com/

Would be where I'd start, if I had the money to blow on this kind of project, lol.

EDIT:  Aww just read they don't recommend it for Motorcycles or under 1.6 liter engines.  Oh well!  

"Second,  the air fuel ratio is 14.7:1, by weight, so spose the same regardless.  Atmospheric pressure is 14.7psi. Coincidence?"

I'm thinking that's a very very good question. I'm filing it along with others like 'If God wanted us to be vegetarians, why did he make animals out of meat?"

Rickmeister:
"My v.v.limited understanding of superchargers and the like...In the old days..."

Point-Seven-five
"I know even less about supercharging, but that's not going to stop me here."

daveyson
"First off,  I dunno what I'm talking about, might be going through a bout of LSD."

Yep, this is going really really well 

"why did he make animals out of meat"

Cause some people love to punish a sinner?
And some people,  they never see the light, till the day they die,
And I've been this way before,
And I'm sure to be this way again.

So, atmospheric pressure is the same numerical value as the stoichiometric ratio for optimum combustion because of........reincarnation?


Have I got that right?

Gimme a clue with the song BTW.

He's Americano, known by his name, not a band name.

From an album (big CD) three words in album title,  first word; Hot, third word; Night. I've got one of his gold records. It was number one in OZ for ever.

I was hoping for the ratio to be a coincidence, but reincarnation sounds just as simple too,  I thin.

The only BMW related supercharger knowledge that I have is that they had that lovely pre-war race bike.  Maybe BMW could sell you the parts you need from their spares inventory?  

A very cool project indeed Chris - have atter'!!

I've ordered a supercharger, so here goes nuthin'! 

Shine on you Crazy Diamond, Lucy in the Sky with Diamonds, Diamonds are Forever, Diamonds & Pearls, Diamond Dogs, Diamonds are a Girl's.......August...Hot...Wind....Blows...Oh, Neil. Me Mum likes his music. Records on the player all the time in the early '70s.

Okay okay. "Alexa, play Neil Diamond".
Yep, he's good alright. I'd ask me own mum for her opinion, but she'd only start singing and dancing, and currently that's 82 years of not being able to sing a note. Painful. That kind of thing can affect your childhood.

Anyway, here's the doohickey. From a VW 1.4 Tsi engine. It's a screw type which, apparently, is a bit more efficient than a good old Roots blower? Can't say as I'm operating at that level of awareness yet  .

The weird thing on the top left is the belt tensioner. And the extended gearbox at the front hides a crafty little secret - it's geared up and overdriven, by a ratio of 27:15 to be exact. I think (a hugely inaccurate process at this stage) that this is because of the way VW deploy it in the 1.4 tsi engine. In that application the supercharger serves only to provide boost at the very bottom of the rev range: by 3400rpm it disengages altogether and is bypassed by the incoming air. In total, with the belt pulleys etc. this supercharger on the 1.4tsi is overdriven by around 5:1, and it peaks at 17000rpm. 

So I think that the overdriving gears are just part of this 'gearing-up' that VW had to do to make sure that the supercharger was doing its stuff by the time the engine reached 3400rpm. All I need to take from this (so far!) is a target rpm of around 17000, which on the K75 calls for an overdriven ratio of around 2:1 from crankshaft to supercharger rotor. At this unhindered-by-reality stage, the plan is to take the supercharger drive from something that replaces the alternator drive. So I need to work out how much the alternator shaft is overdriven from the crank and factor this in.

Then I can order some belts and pulleys!

Oh, it spins the wrong way too 

chris846 wrote:
Oh, it spins the wrong way too 

Gear drive?

Gear drive - using a spare driven gear from another alternator drive shaft, running as an idler off the OE alternator shaft would've been possible because, conveniently, the K75 has a straight cut alternator driven gear compared with the K100's helical cut crank/alternator driven gear. Dunno why that is? But, a gear drive involves a lot of work to provide the necessary oil bath. Also, using a serpentine belt drive provides facility for pulley swapping - to modify the supercharger speed.

I'm currently going with a double sided ribbed belt that'll run backwards over the supercharger pulley. I'm told that such things exist, but I'm waiting for a supplier to get back to me.

Failing that, I'll just press ahead with the supercharger running backwards. Maybe if I go down a steep enough hill with the engine in gear it'll suck petrol in from the atmosphere and fill the tank!

Anyway, it's almost finished...!

Just need a bit of 400 grit to bring out the grain in the wooden block 

Anyway, that fifth engine mounting is looking very inconveniently placed - it's right in the way of the new proposed belt route, and that can only have one result 

I know that the fifth mounting isn't necessary to hold the engine in place - the Madass doesn't have one and so far the engine hasn't fallen out of it. My simplistic (and convenient!) belief is that the fifth mounting is there to supplement the frame's ability to withstand the assymetric loading from the rear shock top mount - and possibly to overcome the fact that the front part of the frame isn't a braced triangle. I reckon that I could cut out the fifth mounting and replace it with a stay running diagonally from the front RH engine mounting up to the top frame tube near the tank rear mounting i.e. completing the triangle. Am I doomed?

Of course. Haven't you figured that out yet?

I thought about this - much the same ideas - drive from the alternator gear - but thought the Subaru type supercharger looked a better option - Aisin AMR500

've been working on exactly this for a while.
The VW supercharger is produced by Eaton (modified M24), and their specification is internal drive ratio of 1.93:1
1. Drive direction is definitely wrong as it sits. The supercharger can be driven in reverse, but drive output efficiency drops by approx. 15-40% dependant upon the inlet/outlet manifolding you use to get air into and out of the supercharger. This isn't the case with the AMR500 unit mentioned previously as it's a straight lobe design and can be driven in either direction. The drawback to the AMR is that due to straight lobes, the air output 'pulses' but if it's directed into a large enough airbox volume this isn't a real problem; the helical lobes on your current charger give a 'smoother' output.

2. You need a certain amount of 'wrap' around the pulleys; in almost all situations there would be a tensioner pulley, and positioning this in the right place might give you the 'wrap' required but there is the problem of where to put it and limited space. A double-sided grooved belt would also require a grooved tensioner/idler pulley. Some installations have used a tilting mount for the supercharger to achieve tension, but this isn't ideal.

3. The alternator/starter drive shaft rotates at 1.5 times crank rpm. With the above internal drive ratio, and a max engine rpm 0f 8500 (max S/C pulley speed of 8800 rpm), the aux shaft to S/C pulley ratio needs to be 8800/(8500x1.5)=0.69

4. The aux shaft extension will need a support bearing and supported mounting if you intend to run the alternator inline (i.e. extended rearward). I'm presently making some CAD drawings for having the shaft and 'stuff' made.

5. The standard injection system can be made to work with the S/C, depending upon boost level required. If using the VW S/C, the flap valve airflow meter can be modified/adjusted along with the fuel pressure regulator to deliver the fuel required. Given that the S/C can/will draw through the airflow meter, volume ingested can still be measured and fuel delivered appropriately. Flap valve return spring tension may need to be increased to prevent the flap valve reaching it's travel limit (again, depending on air volume 'pumped by the S/C). In the K75, (and in all engines using this injection system) there is a considerable overhead designed into the airflow capability of the airflow meter. If additional airflow capability was required, a different (larger diameter) meter from another application (car) can easily be used. Higher flow rate injectors may be required also. Ultimately, the corresponding output voltage will need to be supplied to the injection ECU. Basically, if you increase the fuel delivery capability by FPR and injector (and sometimes fuel pump capacity), the air measurement system can be made to deliver what's required. I intend to have the S/C draw directly from the airflow meter in my installation. I like the idea of using as much standard 'stuff' as possible; not for cost, but for a more integrated feel.
In the above case, pressurising the inlet box/trunking after the airflow meter/supercharger assembly is a task. Even moderate boost pressures (<10 psi) will require these areas to be tested for capability. Usually all the downstream components are in a lower than atmospheric pressure environment... think throttle shafts, injector o-rings, manifolds, oil breathers, etc.

There is another 'cheap' quality S/C that can be used, the Eaton M43 fitted to many Mercedes and also the supercharged Minis. It has higher air output per RPM, no internal gearing and can be fitted with a nose-plate/drive to reverse the input drive requirement.

Anyway, this is a great project, and I hope to see more of your progress here.

Well it's a great encouragement to me that, separately, we're reaching more or less the same conclusions. The ratios you mention seem right to me, as does the idea that the OE injection system might be able to cope with at least low boost. 
Been a few days just looking/shuffling the various components - the drive is a challenge. I was looking at a double sided ribbed belt, but it was too serpentine to achieve enough wrap around and dodge other stuff, which means efficiency loss. I think I've settled on a primary double sided 8M-20 toothed belt from the alternator drive running a short reversing pulley fitted to the rear end of a jackshaft more or less above the fifth engine mounting, with a tensioner pulley above it to achieve wraparound. The jackshaft front pulley can then run a secondary 8M-20 single sided belt to drive the charger, which will sit with its outlet almost above the inlet ports in the head. No idler/tensioner needed for the secondary belt as the jackshaft mounting will be adjustable for belt tension. The charger will sandwich a 40mm manifold block down onto the inlet ports. This leaves enough room above the engine on the RH side for the bulky AFM and single throttle.
I'm going for the order: cone filter/AFM/single throttle/charger/manifold/inlet ports. Downsides are no intercooler so only low boost for me. Throttle before charger might not be great for response, especially with the already-slow Jetronic AFM. Upsides are, compactness & simplicity - no blow-off required because the throttle is before the charger. Minimal air volume after the throttle due to the sandwich plate/manifold connecting the charger to the head. This layout should suit the Jetronic - the AFM is working at atmospheric as previously and can cope with K100 volumes/power. Dunno how the K75 FI ECU will cope with air flows above the factory range - it's not digital so maybe - maybe - that good old   analogue    circuitry will continue to calculate an appropriate injector pulse width??? (worst case of optimism I've had this week eh?) 
I'll use K100 pistons for lower comp too.
With an option to boost the fuel pressure at the upper range if necessary.
No pics - all still in my head at the mo 
Many many thanks for your post 

I should've added, I've junked the idea of removing the fifth engine mounting and altering the frame. It's not worth it for the advantages it gives, plus, it would mean me building an entire bike to run the engine in, which I don't want to do. If this thing works I can drop it in the K75k.
The downside is that things are a lot tighter on top of the 75 engine, especially when it comes to routing the air from throttle to charger inlet. This is even worse on the K75k because I steepened the front frame legs a-la K100 to achieve the short wheelbase.

Time for the scissors and cardboard again:


Currently (which means until I make the inevitable discovery that it won't work) the idea is to run a primary drive double sided toothed belt from a pulley on an adapted alternator drive shaft - that's the bottom pulley in the pic - the belt will reverse the jackshaft - middle pulley in the pic - and run over the tensioner pulley shown at the very top. This primary belt will run in a plane just rearwards of the 3 alternator mounting holes. The short jackshaft will take the drive forwards to a secondary belt that drives the charger - the belt is shown running more or less horizontally in the pic, the charger pulley is on the far left. The secondary belt runs in a plane more or less in the centre of the bellhousing. With a bit of an offset on the charger pulley, this will put the charger over the inlet ports in the head. I played around a bit more today and I think it might be possible to shuffle the pulley sizes and locations so's the primary belt doesn't run so inconveniently through the alternator top mounting. The alternator itself will be spaced rearwards to create a gap for the primary pulley and belt.
The position of the belt will just about guarantee instant castration should it break when it breaks.

Meanwhile, here's a very conveniently sized throttle from a Renault something:


Which didn't need to much vandalism in the lathe before it found a new home stuffed on the front of this:

I've absolutely no idea whether it will work...?

Renault huh? always thought there was a dark side to Papa and Nicole's relationship myself.

And now an appeal for help.
The throttle has a very usable WOT switch, which will work nicely with the Jetronic. I though it was an AMP connector (shown next to it for comparison) but it's smaller. The switch is made by Magneti Marelli, any ideas for a compatible plug please?

Suzy,
You need to stop this. Once again, I’ve signed in to research something important and completely forgotten what it was. Last time it was Madass and now this. I don’t have a hope in hell of mating a side draft weber onto a K, but I’m bloody thinking about it again.
Thanks a bunch .

Well after a week or so's sitting, looking, cutting cardboard discs, sitting, looking, drinking coffee...I've settled on a layout for the drive. Currently waiting for a handful of toothed pulleys to arrive from Chinese China, so I've used the time to start cleaning the engine down. It's another of those 'bought-it-for-a-spare-and-never-used-it-so-it's-been-living-under-my-bench/rhododendron bush/dead aunt' engines. Since I acquired it as a stand-by for the K75k, it's been living in a wheelbarrow 
Anyway..



The first pic is after the crud was removed. Typically for a K, the honing marks are all very visible. The big end and mains shells are almost unmarked, the pistons look good, the inside surfaces aren't too stained - hardly any glop in the sump, and the water galleries are clean. Overall it looks a good engine, the dead aunt must have been very weatherproof.
In fact, it seems a shame to submit this engine to what I've got in mind. So, I'll build it up and swap it with its much-abused brother in the K75k. That's the one with the health record of a medium-sized collection of roadkill.

Pretty sure your connectors are Tyco.

Just trying to make up for all the piss-taking huh?

Ohhh..... I haven't finished yet.

Are you going to add a 16v 12v head. It would breathe better.

Y'see I have this problem quite regularly. People try and take the mick out of me (which is great fun), but sometimes it kind of falls a bit flat 'cos I just don't see it. My fault entirely. My mother used to accuse me of slow-timing her and I used to ask her "what's slow-timing?" then she'd clout me. I never knew why. I'd cry and ask her why she'd hit me and she'd just hit me again. It never hurt though - unlike her singing.

My honest answer? I think it might be possible to saw the fourth cylinder off a 16v head, and shorten the cams too. But the problem would be the crank. You couldn't alter the 4-cyl crank, and the 3-cyl crank is a 120' so the shortened 16v cams would be all wrong. Project '12-Valve K' never got past this idle stage.

My other answer? Yeah, I'm going to leave the head off altogether - that's easy breathing 

Just pull the plug and injector on # four. Or if you heart is set on a twelve valve just remove the four you don't like. Way easier then mixing and matching.

Likely too easy.

Turn this challenge over to Allen Millyard.  He'll have it sorted and will have produced a DIY video of it in short order.  

Not sure of this is off-topic or what, weird 

Am currently still taking my time rebuilding the engine-that-was-going-to-be-supercharged-but-turned-out-to-be-better-than-the-much-abused-lump-in-the-K75k-so-I'll-swap-them-over-first.

Anyway, one of the piston rings was so gummed up and corroded that it succumbed to my ham-fisted disassembly. Which, in turn, led to a hunt-for-piston-rings amongst my motley collection of spare parts. 

Which, in turn, led to me noticing huge amounts of wear on a lot of the rings. The engine I'm working on doesn't seem to have gone to the moon and back - shells are unworn and it's clean inside, the only issues were caused by the water ingress into the cylinders during storage/abandonment. But, the piston rings seem quite worn and the end gaps do comfortably exceed the Haynes service limits. Some of my other spare pistons though, have rings with end gaps as big as 3mm ish, which is a tad (and the rest ) over the 0.45mm service limit. So I'm curious enough to ask - is piston ring wear commonly found on Ks, or have I just got a crap collection of spares?

Edit: I should add that the rings with the really big end gaps came out of 100K+ engine, but which still had the honing marks visible in the bores...

Maybe just Maybe, due to the Ks blocks not Reboreable,the rings are designed to wear a little more to protect the Bores. Like i said just mayb

Been a'googlin - turns out the 'sil' in Nikasil isn't there to put us in mind of silicone-the-much-loved-lubricant, it's actually silicon (no 'e') carbide, which is a hard thing amongst hard things. So yes, I imagine those rings are going to feel all the pain.

I think I've been under the illusion, after seeing unworn bore after unworn bore in all sorts of K engines, that bore wear isn't an issue. Never occurred to me about the rings...

The late Mr Jack Bailey a Manx Norton GURU had a saying when as a young boy i helped out in his workshop, Cant see Wood for Trees Lad, Smiling he would point to the bloody obvious.  

N/B HELPED, meaning got under his feet 

Yep; Nikasil/Nigusil is damn hard on the piston rings. It's meant to be. The flip side of the coin is that it takes just 100 miles to run in a new set of rings in an old barrel. Info courtesy a Moto Guzzi spares dealer who'd been in the trade for over three decades.

Good news about the running-in, cheers 

Well the engine-that-was-going-to-be-supercharged-but-turned-out-to-be-better-than-the-lump-in-the-K75k, threw up a problem. 


Which was some deep pitting on the exhaust valve seats. Grinding didn't shift it, so I replaced the head with what turned out to be a very good item from an Oohbay seller in Germany. The top of the block was pitted too, but I filled it with liquid metal, and re-used the same gasket , bear with me - I've done it before and it's worked.


And no, the bodging didn't stop there. The only alternator drive shaft that I had kicking around was the one that came to grief when I forgot to properly tighten the alternator drive flange bolt in the K75k. The front end of the shaft sort of welded itself into the needle roller bearing in the back of the engine block. At times like this I'm burdened with a childhood-induced 'you-messed-up/no-you-can't-have-a-new-one/you-fix-it' mentality. So I used the inner race from a needle roller bearing to sleeve the damaged shaft back up to 16mm:


So, this spare engine is now all buttoned up and ready to be swapped into the K75k. And that engine can get ready for 'trial-by-supercharger' !

looks nice