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Project Supracharger


David P

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The DH61 ignitor plug has 2 new wires from AEM and earth.

 

That's 3 of 10 wires sorted, leaving 3 pins to swap from existing N/A to VVTI plug and 4 solder joints to the new loom from coils.

 

The ignition system changeover is now prepped as far as it can be in readiness for a pitstop swap. :)

 

 

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Whilst at it, I plumbed the pre-charger jet back into the water/meth equation ready for testing too. :)

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For several months now I've been trying to find a small leak in the charge-cooler plumbing and in hope have bought new hose to re plumb the pre rads.

 

However, the weather didn't encourage me to undertake this PITA of a job so I went to the Pub for lunch.

 

There I popped my bonnet in the car park to stop a disused w/m pipe from rattling and spotted a single drip, elusive little beggar.

 

Lunch was the correct decision and another Gremlin is found.

 

A plastic straight hose-coupling has cracked lengthways, nice easy fix for a change. :)

 

 

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  • 2 weeks later...

The cracked plastic fitting is replaced with a brass version and the car is now an ounce heavier than it was, which is a small price to pay for evicting the mystery charge-cooler leak Gremlin. :)

 

It turns out that Aquamist supply 2 different sizes of 0.4mm jets and the ones they had sent me were the larger. :think:

 

Calculating hole size areas, the 0.3's are nearly 6 times smaller than the larger size 0.4's and flow around a third of the amount.

 

Maybe it's good news they don't make tape measures. ;)

 

 

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Nevertheless, Richard at ERL responded to my plea for 0.3mm jets and has sent me a set of bottom halves to convert the large sized 0.4's to standard 0.3mm.

 

Thank you very much. :)

 

 

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Internally they're not threaded all the way so if still to large can't accommodate the reducing spinners and are around 5mm taller.

 

Usually 5mm wouldn't matter a jot, yet with this installation 5mm is a huge distance and luckily they just clear, the back one might just need a little of the bonnet grinding away to clear when the engine mounts flex under load

 

I've fitted all 4 yet for now only plumbed 3, I'll set it up when road conditions allow WOT.

 

 

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One step forwards and another sideways?

 

The supercharger has become growlier at low revs, tickover is up 250 rpm and fuel consumption has increased.

 

On inspection, I've found that the supercharger bypass-valve actuator-diaphragm has failed, this was a new unit for the build and not sure why it has died?

 

I realise that it wasn't designed for 16lbs boost, yet must stand over 20 lbs of vacuum with any installation and sure that it's not getting any hotter than it would on a Jag.

 

Fortunately, I've found an O.E. brand spanker on ebay for £25, :) when I swap it in I'll break open the dead one and inspect the rubber diaphragm to find if it has been damaged by the pre-charger 50/50 water/methanol, even though this has barely been used.

 

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The new actuator should be here on Tuesday. :)

 

Revving the engine without load would be a bad idea, yet without such antics it can be driven without one till then.

 

Now that I know this new noise is harmless it's actually really good fun around town, because at low revs it growls along like an angry big cat. :D

 

A machine that sounds like a ferocious animal, it's not loud, but menacing and intimidating.

 

Trundling along with the torque-convertor unlocked it sounds like a grumpy old liger and with a gentle tap on the throttle emits a "SNARL" good enough to scare old ladies and/or make small boys jump with joy. :)

 

Growling along in a dual traffic queue, one young lad was behaving like that in the passenger seat of his Dads V8 M3. :D

 

Rolling starts at the lights, instead of a scream from nowhere, get the full spectrum from growl to howl.

 

This new understated growl turns heads everywhere it goes and when I've nout better to do, I'll make the bypass valve on and offable so I can growl it at will. :D

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I hate the poor ride, poor traction and poor handling that result from using low profile tyres on 18" wheels and this wheel/tyre/diff combination is my answer.

 

Front 8.5J 18's with 235 45, rear 10J 18's with 285 40, using an N/A 4.083 Torsen diff gives the same final drive ratio as a T.T. auto with stock 17" wheels/tyres.

 

Now that I'm settled with the wheel tyre combo, I've gained access to a lathe and raised the front Bilsteins by 8mm to level the Old Girl up and cure the Concorde nose.

 

The suspension is 2" lower than stock yet the rear wheels/tyres raise it back up 1", resulting with the car appearing to be lowered by 3" but is actually only 1" lower.

 

There's no tyre rubbing, it looks good and clears sleeping policemen, rides nicely with good traction, no tramlining and handles well . :)

 

In C.W. lingo, maybe this 'baby bears bed' is; 'fur coat with knickers'. ;)

 

 

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Edited by David P (see edit history)
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Whilst waiting for the bypass-valve actuator to turn up I've been trundling around like a Granny, yesterday however, I gave it WOT in 3rd for a few seconds to monitor water/meth flow through the 0.3mm jets and it boosted to 20 psi and smoked the tyres!

 

In disbelief I gave it another couple of seconds of WOT and 20 psi it is?

 

Maybe the original actuator has never functioned correctly and the bypass valve has been spilling 4 psi, but I can't see how because the butterfly is held closed with a spring and opened by induction vacuum?

 

Not sure what's going on here, but hope to find out tomorrow after the new actuator has arrived, maybe I'll need to fit the 3.4" pulley to reduce boost to a useable pressure?

Edited by David P (see edit history)
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Whilst waiting for the bypass-valve actuator to turn up I've been trundling around like a Granny, yesterday however, I gave it WOT in 3rd for a few seconds to monitor water/meth flow through the 0.3mm jets and it boosted to 20 psi and smoked the tyres!

 

Quick, wack it on a dyno whilst the spark plugs are still underneath the bonnet and not in a farmer's field on the M6! :D

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I'm not planning any WOT until the new actuator arrives and is fitted and had a good look at the bypass valve.

 

20 psi is too much of a good thing. :think:

 

Spoilsport. :(

 

Think of the opportunity to contribute to our collective understanding of connecting rod ballistics. You have a moral obligation to test your engine to destruction for the sake of our safety! :blink:

 

(and viewing entertainment :D)

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My spoilsport imagination is on the other side of the Matrix :think: working on an alternative addition to our collective understanding and is growing impatient for the new actuator.

 

If that valve assembly has been bleeding off 4 psi, the supercharger would've been working harder than it needed to and sapped power, if so, I'll have found some missing torque-horses. :)

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If that valve assembly has been bleeding off 4 psi, the supercharger would've been working harder than it needed to and sapped power, if so, I'll have found some missing torque-horses. :)

 

Wouldn't the charger encounter less air resistance if boost pressure was 4psi lower and therefore be doing less work with a pressure leak?

 

Boost pressure only increases as a result of resistance to airflow and a bleeding valve (ooer!) would only mean you need higher rev's to reach a given pressure.

 

You're right to expect more power overall though. Just don't expect 4psi 'for free'. :)

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I don't yet understand how the bypass wouldn't be closed, the butterfly-valve is working perfectly and could only be held open by the actuator, yet its vacuum feed is in stock Jag location post charger and receives positive pressure under boost, yet it would be an amazing coincidence to be anything else?

 

Maybe the Jaguar O.E. actuator has a spring-seated reversing-cam 'thingy' behind the diaphragm and designed to compensate for 'overboost' by spilling some. :think:

 

I'll find out when I reduce the dead one to its component parts, but at the mo it's holding the valve closed.

 

I don't expect ought for nowt, yet the power consumption for a Roots supercharger is not pressure/resistance, but an rpm/hp equation, it's not compressing air, just moving lots of it from one place to another.

 

Removing top of the parabolic curve from supercharger parasitic-loss, would give torque gains across the full powerband, with a larger pulley and less rpm, with better belt traction, with less work to do, giving a cooler primary-charge and also a non-recirculated (non partially re-heated) charge and + 800 rpm horsepower-potential at the top end.

 

Along with some bright new sparks from the coil-packs, maybe the flux capacitor will fire? :D

Edited by David P (see edit history)
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There will definitely be a cut off as that's what the blow off valve is for. It's just a matter of finding out it's designed limit.

 

The TT's boost to about 14psi iirc but that's probably way more than the NA lump was designed for. We all know that you can get away with more than 9psi but for how long?

 

Inferior engines would have blown up at 20psi so you're lucky you got away with it.

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The primary function of this bypass-valve is; during induction-vacuum to recirculate air and free-wheel the supercharger, I can find no reference to a secondary function as blow-off recirculation-bypass.

 

Until dissection/examination it's supposition, yet if/so, this could be cured by moving the vacuum pipe to pre charger and vacuum only, maybe it was raised boost pressure that was the death it.

 

Current pulley is a 3.2" and also have 4.2", 4.0" 3.8" and 3.4" with matching belts in stock, :think: which means that should supposition be 'welcome to the real World', you can bet it'll need a 3.6". :shrug:

 

Reality is, it's mapped to match, whatever its sneaky tricks may be, so any tinkerings would mean another mapping.

 

Replacing it will do for now, unless I win a free remap in some fictitious Christmas raffle. :think:

Edited by David P (see edit history)
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My laptop and camera aren't talking to each other, so at the mo I can't post pics. :(

 

The actuator diaphragm had burst like a balloon and exposed that it doesn't have an over-pressure relief function, it was simply the diaphragm running out of space to expand enough for 16 pounds of boost and squidging around the front of it's stop, consequently, moving the operating rod in the opposing direction sufficient to open the butterfly enough to spill 4 psi.

 

I've found that without the actuator plumbed in, (valve definitely closed) a larger 3.4" pulley gives 15+ pounds of boost and the present map is happy. :)

 

When I find a road that's not a car-park and/or skid-pan I'll test it plumbed pre-charger, yet prognosis is; this should allow around 600 rpm more than the current 6,100 limit. :)

 

Also had a tinker with the water/meth to find that even with the smaller 0.3mm jets flow remained too high, however, removing one of the two ERL pumps from the system has reduced the flow and at last it's doing what it should. :)

 

With this reduction in supercharger parasitic-loss and a raised rev-limit with an operational water/meth system, after the coil packs are into the equation, with another remap I should at last have that number 500 worried. :think:

Edited by David P (see edit history)
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Yesterday the Old Girl had a Big Day Out. :)

 

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After an unhindered trundle around Bruntingthorpe, I've found that this new found power is all bottom and mid-range, the top end still hits a wall and sends EGT's OTT, 1,100°C by 120mph.

 

AFR's are 12.5 to 12 @ 15psi boost and all seems well other than the above.

 

The days activities weren't my call so I didn't get the chance to tinker, yet suspect that with the vacuum pipe now plumbed pre-charger, the slight induction vacuum at the top end is partially opening the bypass-valve.

 

I'll check EGT with the valve definitely closed and if that cures it, I'll fit a TT traction-control butterfly stepper-motor to do the actuators job and have the AEM manage it.

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Edited by David P (see edit history)
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With the actuator-vacuum disconnected so the bypass-valve is definitely closed, the EGT is reduced to 950°C by 120mph and the engine is still pulling hard.

 

Still high, but 150°C better and has exposed top-end spill by the bypass-valve.

 

Neither side of the supercharger vacuums will operate the actuator-controlled bypass-valve correctly and need to create an electronic version.

 

Does anyone have a traction-control butterfly stepper-motor I can have to tinker with?

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