BiTurbo228

Perhaps something a little like this fabrication nightmare: So your regular primary diameter, which expands into a gradual cone before it reaches the collector. At the collector there's a little plate that extends the merge (the longer it is, the narrower the jump in diameter but the narrower the exit), and then into the secondary. Probably a very complicated way of making KPR's 'collector-into-narrow-into-gradual cone' design...

On the exhaust merge collector front, my mate's Kawasaki ZZR1100 once had a terrible jangling noise from the exhaust for a while and then spat out a little twisted plate of stainless from the back of the exhaust. We think it was welded into the 2-1 merge part of the exhaust to better blend the transition. It looked like it was welded into the point that they merged where your red arrow is pointing, and then the free end was twisted slightly to impart some rotation to the gas. No idea if it works or not, and it'd be more complicated on a 3-1 merge than a 2-1, but it was always a bloody fast bike... I suppose the question would be whether a gradual taper down to a smaller diameter than the runners themselves is better or worse for flow than a sudden increase in diameter.

Yet more nice work! Like the idea of using the aircraft titanium for something. I went to the Silverstone Grand Prix back in 2012 or something and there was a prang on the corner where someone's front spoiler got obliterated. After the race I picked up a bit of the carbon fibre and used it to bond over a little rust hole I'd cut out of my Spitfire, so now I can say it's 0.01% F1 car

Yeah I was appalled at how much wiring is in an X1/9 when I started poking around mine. I tihnk half of the issue is that there's a whole bunch of wires that probably fit really neatly for LHD drive car, but they've got massive linking looms over to the switchgear and back for RHD. I had a similar 'can I just rip it all out and run my own, much simpler wiring' when I saw the snakes nest for the first time! Also, I can thoroughly recommend an Uno Turbo swap. Mine went great, even if it was running on 3.75 cylinders. Engine they were supposed to come with, in my opinion. Mine was a 1.3 Mk1 engine with a boost valve to a smidge under 1 bar, until the last dodgy cheap jubilee left from the PO that I hadn't changed snapped and it dumped a load of coolant and overheated, popping the headgasket. I had the replacement in the passenger's footwell for a month! Lesson in deferred maintenance... Edit: also, on a wiring related note, if you have rear foglights I'd recommend pulling them out. They were retrofitted to UK cars to meet our regulations, but were done cheaply with wiring that clearly wasn't up to the job. This was mine when I found it while tracing a battery drain. That was melted through all along the length of the interior, sandwiched between the tunnel and the carpet. Not often you find a car fire moments before it happens! Edit edit: also also, I expect you've come across the advice before but if you're keeping the original wiring it's worth putting some extra relays in for the dip beams. Main beams are off a relay, but dips go straight through the switchgear and like to burn stuff out. There's also another unused main power in spade somewhere on the fusebox I can't remember. It helps to run another power feed there if you're running more electrical load than usual (say with electronic management).

I'm guessing the strut tower has captive studs pointing down towards the wheel-well and is bolted on from underneath? Rather than whittling up a new set, could you get a plate plasma cut? I've used sites like xometry before who do automated quoting for simple parts (which this would be). Not sure if they cater to the antipodes, but I'm sure there's local companies who can help out. Nice work on the steering tie rods. I'm looking at a mill this weekend as I sense a similar thing in my future...

Dead interesting graphs, as usual. Not that it's terribly relevant for 1/4 mile, but I wonder what the splits look like from 100 to, say, 124mph (200kph).

Man that's impressive! A mate of mine has a 106 GTi race engine which is a not entirely dissimilar 1.6l, great flowing high revving engine. I thought his one was doing well making 197hp @ 8300 crank (147kw). On the VVT front, I wonder if you knew off the top of your head whether the pulley diameters were the same for the 16v and 20v VVT cams. If it is, then there's a slight chance that I might be able to pinch a 4AGE pulley for my 70s Rover 2600 engine (seems to be the same OD as the 16v 4AGE pulleys). I've been searching around but found a lot of conflicting information, usually regurgitated by people who haven't come across the real versions themselves.

First off, excellent that it's staying! Second, on the topic of diesel SD1s, I've been on the eye out for a cheap 2300/2600 or 2400D over here as the basis for an M57 swap. Seeing how well it goes in my XJ40 I thought it'd suit the character of an SD1 down to the ground. All it'd be lacking is the V8 burble...

They might be close... I've got some on my car I need to whip off and test against the manual ones I've bought. Can see if I can do that before you're finished. Looking at where yours need to be you might not need to flip them at all. I need to flip the ball joints on mine though. The plan is to TIG the taper up enough that you can redrill and ream it out to roughly the original dimensions. Not sure if that's allowed in your regs.

Here's a question you've probably already considered, but how different is the geometry of your shiny new machined steering arm to that of the factory power steering dropped arms with the balljoint fitted to the opposite side of them... From the pic on your thread it looks like you've got manual ones on your car.

Ah so it's like a switchable baffle. Clever! Is it switched through boost or vacuum? You can get little vacuum solenoids off diesel BMWs (and I expect a lot of other cars), which you could tap into the ECU to get it to trigger under whatever conditions you want.

Interesting... lower relative to the rack is exactly what I want it to be! Have dropped it by 2.5" with the front-steer rack so I can fit the tie rod ends upside-down on the original steering arms, but I've got about an inch of space between the rack and the sump in that setup. Would be nice to tuck it up a bit more out of the way as it'll be the lowest point of the car. If the LHD-flipped-rear-steer setup means the suspension arm is, say, 1.75-2" lower then I could pop the balljoint in the original location and job's a goodun (aside from ackerman).

Where's the butterfly thing going in the exhaust and why do you want a bypass? If it's just poking out the side of the exhaust bypassing a silencer then it'll probably function like a J pipe resonator. I've just fitted one of those to my Jag to combat a nasty boom around 2600rpm. Exhaust pulses travel up the tube and reflect off the end. If you size the length right you can make them return at the opposite frequency of your boom, cancelling it out. If you've got issues with boom then that might help, with the bonus of having a straight piped section if you want to give the game away Worth noting that at double the rpm you set it at the waves will match each other and make more noise. Not an issue for me with my M57 and its 5500rpm redline, but yours might pass through that a couple of times!

Yeah and it happened when you were at moderate rpm didn't it? If it was a sudden failure due to a failed ignition event at high rpm you'd expect it to go bang as you were near the limiter...

It could well have contributed to the engine failure. Didn't it look like your piston had pulled itself apart? Combustion adds a little cushion to the upward force on a piston zinging over TDC (and then a whole lot more pushing it down afterwards). If that cushion is missing then the piston would be subject to a whole lot more force than it would otherwise have done. Not a done deal though as it would still have had compression cushioning it, and AFAIK the point where the most upwards force is exerted on a piston is during the exhaust stroke (where it's only cushioned by whatever restriction is offered by the exhaust port/valve). I wonder if unburnt mixture does less cushioning than burnt mixture. I bet it does as there would be a hell of a lot less energy/pressure in it trying to force its way through the valve. Really there's no way of knowing for certain, but it's suspicious at least...

Haha had not considered that! Makes the decision of what to do easier (don't do the thing that will make it turn the wrong way!). Could possibly get a LHD rack and flip it upside-down, but LHD T2000s aren't exactly common! Yeah I'm in the UK where our testers probably wouldn't be fussed so long as they don't look completely sketchy.

Old thread, but coming across similar issues with the steering rack on my Mk1 and the AJ6 I'm wedging into it. Firewall is quite thoroughly clearanced which has let me drop the engine way back, but there's a little bump at the front of the sump which houses the oil pump and is fouling on the rack (which I already plan to lower by flipping the balljoints upside down). On the off chance anyone's heard of this before, an idea I've had is to fully flip the front crossmember around so the rack sits behind the subframe rather than in front of it. From an initial look it seems like the subframe mounts are symmetrical, and the front wishbone mount is on the same plane as those mounts. The front spindles are also symmetrical, so could be flipped around to have the steering arm point backwards. From there it's a case of bending a set of steering arms to sort ackerman and bump steer (hopefully you can use manual rack ones as they're shorter which might help ackerman).

On the crank front it's not wholly unusual to have 4 counterweights in 4-cylinders, especially as you say with light components. The main way I4 cranks bend is around the middle bearing. The other side of the first throw is balanced somewhat by the 2nd throw (and number 3 to number 4), which leaves a rocking couple between the 1-2 half and the 3-4 half as the crank wants to bend like a skipping rope through the middle. You get it a lot with inline 6 cranks, like the one in my AJ6 which is counterweighted on the outermost and innermost cylinders, missing out throws 2 and 5. High performance cranks like S54s or 4G63s tend to be fully counterweighted to sort rocking couples at the expense of greater inertia (which affects resonance), and compensate through making them super-stiff. For small engines with light components it doesn't seem like a major drawback. BMC A-Series will happily rev to 8500rpm with 4 counterweights and only 3 main bearings!

While simpler is definitely quicker, I quite like these Jag XJ40 exhaust mounts that locate things in a triangle. I did make sure there was a flexi upstream of them so the engine could move around without twisting the exhaust though.

Ooh the fart noise VW DSG gearboxes make between gear changes. Exhaust is looking sweet man!

I've made a silencer before using perforated pipe, fibreglass wadding and a large aluminium tube. Weld up some stainless end-caps onto the perforated tube and pop-rivet them together. Piccy - be gentle on my ropey welds My supply of large OD thin wall aluminium tube seems to have dried up though, but if anyone can think of a cheap domestic supply it was a fairly easy way to make a lightweight silencer.

No worries man I guess I've got a lot of the whole 'reality not meeting expectations of theory' stuff coming up A lumpy dyno graph and a measurement of your intake length for it would be dead useful yeah! Back of closed valve to the open end of the bellmouth would be perfect. Could probably have a stab at guessing your cam timing and then if you do end up measuring it for any reason (not sure why you would TBH), could see if it's anywhere near close. Although lord knows what VVT does to tuned length intakes. Probably makes them somewhat redundant I expect as you can move your cam opening and closing time around wherever you like it (although your engine seems to have responded better to some lengths of inlet compared to others.

Haha I expect you're right, although without a working engine (or a working car for it to go in) all I have at the moment is mucking about with spreadsheets! Interesting to see if they can point me in some sort of direction for when the other bits start falling together. Would be interesting to see if it bears any semblance to reality or not. Very familiar with @kpr's videos. Awesome stuff. Was just as surprised at how well the peach slices did same with how poorly the super long intakes did, although that was before I knew about the water hammer theory being junk. To answer some questions about the scribblings, yes it does account for the offset of the crank (and the piston pin, which moves things back in the other direction). No, it doesn't do anything with working out how far the atmospheric pressure migrates down the runner, nor determines when in the intake cycle is a good idea for the charge to be targeted. All far too complicated things to determine with my level of maths! Best leave that to the empirical testing. What it does do is give you an intake length range where the pressure wave will enter the cylinder between 3/4 and 7/8ths of the inlet cycle. Anything more precise is way too complicated man

Hey man, @yoeddynzpointed me in the direction of your thread over on Retro Rides. What a read! I was wondering if you might want to be a guinea pig for some of the stuff I'm working on around tuned length runners. It's got calcs and stuff, and I'm sure there's a graph or two that could be knocked up from it For a long time, I bought into the idea that inlet pressure waves were caused by air piling up against the back of the inlet valve as it closes and bouncing backwards and forwards along the inlet at the speed of sound until it reaches an open valve again. Apparently, according to the bods on Don Terrill's Speed Talk who are much smarter than I am, that's not how it works at all! (or, rather, that does happen but it's nowhere near being the dominant effect). What actually happens is the piston creates a strong negative pressure wave as it reaches its point of fastest acceleration (usually somewhere around 84-90 degrees of crankshaft rotation). This propagates up the inlet until it reflects off the atmospheric pressure at the end of the inlet and returns as a positive pressure wave back towards the inlet. What you want to do is size the inlet tract so that positive pressure wave arrives back at the tail end of the same stroke that created it, when the piston has slowed right down at BDC, or has even started coming back up the bore. So far, so easy to calculate. The issue is that the atmospheric pressure the wave bounces off at the open end migrates down the runner a distance that's dependent on the strength of the negative pressure generated by the downward movement of the piston and the diameter of the runner. As this is the complicated stuff that programmes like Pipemax does and I haven't worked out yet, the best I can offer is to get into the rough ballpark for trial and error, with the possible suggestion that if it's not possible to fabricate a short enough runner, you can step up the runner diameter to make it appear shorter to the pressure wave. I've made a little calculator so people can plug in their engine's specs and get a rough idea of what inlet lengths to aim for, and which ones to avoid. You'll need to know your target rpm, your stroke, your rod length, and your cam timings (actual measured cam timings, not advertised as they're often quoted in deliberately obfuscated or incorrect ways). Ideally your inlet temp would be useful too, but that's not too tricky to estimate. It's a little crude at the moment as I've no idea how far the atmospheric pressure travels down the inlet, but it should give you a rough range to aim your inlet tract length to. Would be dead interesting to compare the numbers the calculator spits out to the various different lengths of trumpet you've used. I think the only thing that would need to be measured is the length of the inlet tracts and the opening and closing times of your cams/valves (would need to be measured using a dial gauge and degree wheel, published specs are usually junk). If I can work out how exhaust length tuning works then it'd be interesting to see how that matches up as well. The usual aim with exhaust runner lengths is to tune them for the trough caused by your tuned inlets so you get minimal reversion and a smoother torque curve. If one or other of your inlet or exhaust runner lengths are dictated by packaging then you could try and tune the length of the other one to compliment the length of the one you're restricted on... Sorry for the wall of text!