Peter Cobbold Posted May 3, 2021 Report Share Posted May 3, 2021 15 hours ago, Peter Cobbold said: Yes, one HS6 (1.75 inch) is fine according to Allard. Slide 48 is from his book: https://supertrarged.files.wordpress.com/2015/08/supercharging-trs-for-the-road-iwe-shorter-for-wordpress.ppt Peter HS6 predicted piston lift with hp at full throttle. Slide 32 https://supertrarged.files.wordpress.com/2017/07/final-pdf-how-does-an-su-carburettor-work-iwe-2017.pdf Full lift ca 60 hp, hence twin carbs used for normally aspirated engine. A single SU on a supercharger can either be weighted or fitted with a stronger spring to give max lift at say 100 hp or the carb can be left standard configuration. If downforce is left standard the piston will lift max at 60 hp and above that deliver an increasingly rich mixture because the depression at the jet will increase, it is no longer constant. Holley works on entirely different fluid mechanics - a venturi at full throttle. Quote Link to post Share on other sites
Z320 Posted May 3, 2021 Report Share Posted May 3, 2021 Hi Peter, today back on my computer I can open your links, thank you very much for the explanations. Marco Quote Link to post Share on other sites
ctc77965o Posted May 4, 2021 Author Report Share Posted May 4, 2021 I am so vane, thanks to George Folchi in the US... They arrived yesterday, they are a weird impregnated-canvas like construction. I stripped and cleaned the Holley carb, new seals and a check that all passages were clear. I didn't dismantle the economiser block as the internet said it's best left alone. On-top is a Hellings&Stellings pancake with an oiled copper mesh filter...these have a reputation to flow quite well but have mediocre filtration. Still available for your Holley despite its performance limitations... I might need to find a modern alternative. Waiting to get the rotor back from the machine shop next week (fixing that bearing damage), I will also fabricate a heatshield to hang off the base of the charger to provide some protection against radiated heat off the exhaust manifold. Quote Link to post Share on other sites
ctc77965o Posted May 4, 2021 Author Report Share Posted May 4, 2021 I also stripped down my marvel mystery oiler. It's a simple thing with one special contraption and a simple oil filler plug. When it works the oil droplets appear in the little window as they drop down into a chute attached to a manifold vacuum source (just under the carburettor). The contraption has a spring steel plate that I believe vibrates up&down in response to the vacuum pulses of the engine. In the top of the contraption is an adjustable spring-loaded needle valve: So, the top of the contraption is connected to manifold vacuum, that vacuum forces the dip tube assembly up and it's seat on to the needle valve...at lower vacuums the dip tube drops down, lowering the seat away from the needle and allowing oil to be sucked up, into a little spout (seen thru the window) and then drops into the chute above the manifold vacuum line...sucking the oil into the inlet. Seems to rely a lot on gravity.... Judson recommended straight 10W oil, and warned against using Marvel Mystery Oil (!) ... I might use ultra modern 0W20 semi synthetic...it's got a nice low viscosity and good lubricity for my flailing canvas vanes.... Quote Link to post Share on other sites
Peter Cobbold Posted May 4, 2021 Report Share Posted May 4, 2021 Dave, Good idea when looking for an air filter to have one suitable for a cold air intake duct. Heat is the enemy of supercharging ! Peter Quote Link to post Share on other sites
ctc77965o Posted May 10, 2021 Author Report Share Posted May 10, 2021 The cast iron body is honed & painted: The rotor has machined to fit an undersize bearing (correcting the previous spun bearing damage) and cleaned-up ready for new vanes. Plus I got a new 3-belt drive pulley fabricated, as I was missing the original Judson one. Here it is loosely positioned on an old water pump for reference. (Charger pulley lower right, standard water pump pulley left) I found the exhaust manifold, need to cut off one inlet manifold mounting tab, per the Judson instructions. I thought I had gaskets, but they turned out to be low port ones...will need to make some. Should be ready-to-fit in a week or so. Quote Link to post Share on other sites
Peter Cobbold Posted May 10, 2021 Report Share Posted May 10, 2021 Dave, Is there a back-fire valve in the manifold? Its best to have one to protect the blower. Peter Quote Link to post Share on other sites
Nigel C Posted May 10, 2021 Report Share Posted May 10, 2021 all great info, thanks Dave and all.... Quote Link to post Share on other sites
Peter Cobbold Posted May 10, 2021 Report Share Posted May 10, 2021 Backfire valves made by Danbury (Essex) Hydraulics, and they sell weld-on ali boss too. https://www.ebay.co.uk/itm/SHORROCK-C75-C142-supercharger-relief-valve-NEW-/273969754972 Peter Quote Link to post Share on other sites
Z320 Posted May 15, 2021 Report Share Posted May 15, 2021 Just read the preview fror the next (German) Oldtimer Markt (06/2021), in 2 weeks in the shops. "Matter of Pressure, 40% more power: Judson offered supercharger kits. Does that work?" I'm very interested to read this article, but sadly they are indeed for interested readers and not very special... Quote Link to post Share on other sites
Peter Cobbold Posted May 15, 2021 Report Share Posted May 15, 2021 40% more power is unlikely. We might think that 40% more pressure will deliver 40% more power but that is wrong. Compressing gas always heats it up and that reduces the air density and hence the amount of fuel that can combust. Heating the mixture has to be avoided by all possible means,stsrting with a cold air intake. But the worst heating occurs in the supercharger as a result of turbulence. My old Wade is dreadful, the turbulence as atmospheric air suddenly meets boosted air at the edge of the rotor is bad. The Judson by contrast sqeezes the gas gradually, and this true compression heats much less. This property of superchargers - inherent in thier design -is called "adiabatic efficiency". More here. slides 28- 36 https://supertrarged.wordpress.com/2015/08/10/iwe-tech-seminar-supercharging-trs-for-the-road/ Intercoolers can be used to reject heat but below ca 6 psi more pressure is lsot in the matrix than density gained by cooling. And for our "wet blower" installtions fiitng an intercooler amounts to driving with a grenade under the bonnet, triggered by the first backfire. Peter Quote Link to post Share on other sites
Z320 Posted May 15, 2021 Report Share Posted May 15, 2021 Due to the short text of the preview I expect Judson promised +40% Quote Link to post Share on other sites
ctc77965o Posted June 22, 2021 Author Report Share Posted June 22, 2021 (edited) After some delay due to international shipping, I got the Garlock Klozure shaft seals that fit in the endplates of the charger. That's the old seals underneath and the new-old-stock seals I got from the USA. Interestingly, the pulley-end of the shaft has space for two seals of the same size that are mounted in opposite orientations. These seals run against a tube that slides onto the rotor shaft and is clamped between the bearing and the main rotor body by the pulley nut. I guess they did this to protect the seals during assembly when being pushed over the threaded end of the rotor. The vanes were soaked in 0W20 light engine oil: I painted some assembly lube inside the body (as recommended by the Judson Guru George Folchi) and then rotor was mounted in the rear end-plate: The the vanes were slid into their slots, before the end plate was fitted with a homemade gasket. The tensioner mounts on the front end-plate before the pulley is fitted to clamp down the tube/washer stack to the rotor body. I got a new "Supercharged by Judson" decal from an obscure US site and refitted the original serial tag: It spins freely, I can hear the vanes clattering around as they do when the pulley is spun fast. I have the exhaust manifold ready - with the front carb mounting bracket sawn off (as explained in the original Judson instructions). I have a ex-aircraft boost gauge mounted on-top of the dash, it's got a 1943 date scratched on the back and a hand-painted dial...the type of gauge used with early supercharged British aircraft V12s. Max 8PSI boost indication should suit the Judson. Currently we are locked-down again here, so I need to wait a bit before assembly to the car, as I need to fabricate an exhaust downpipe and can't do that at home...maybe July... Edited June 22, 2021 by ctc77965o Quote Link to post Share on other sites
Hamish Posted June 22, 2021 Report Share Posted June 22, 2021 (edited) great update its exciting for us, can’t wait for the firing up of the beast from the east !! Edited June 23, 2021 by Hamish Sp Quote Link to post Share on other sites
Tim D. Posted June 22, 2021 Report Share Posted June 22, 2021 2 hours ago, ctc77965o said: After some delay due to international shipping, I got the Garlock Klozure shaft seals that fit in the endplates of the charger. That's the old seals underneath and the new-old-stock seals I got from the USA. Interestingly, the pulley-end of the shaft has space for two seals of the same size that are mounted in opposite orientations. These seals run against a tube that slides onto the rotor shaft and is clamped between the bearing and the main rotor body by the pulley nut. I guess they did this to protect the seals during assembly when being pushed over the threaded end of the rotor. The vanes were soaked in 0W20 light engine oil: I painted some assembly lube inside the body (as recommended by the Judson Guru George Folchi) and then rotor was mounted in the rear end-plate: The the vanes were slid into their slots, before the end plate was fitted with a homemade gasket. The tensioner mounts on the front end-plate before the pulley is fitted to clamp down the tube/washer stack to the rotor body. I got a new "Supercharged by Judson" decal from an obscure US site and refitted the original serial tag: It spins freely, I can hear the vanes clattering around as they do when the pulley is spun fast. I have the exhaust manifold ready - with the front carb mounting bracket sawn off (as explained in the original Judson instructions). I have a ex-aircraft boost gauge mounted on-top of the dash, it's got a 1943 date scratched on the back and a hand-painted dial...the type of gauge used with early supercharged British aircraft V12s. Max 8PSI boost indication should suit the Judson. Currently we are locked-down again here, so I need to wait a bit before assembly to the car, as I need to fabricate an exhaust downpipe and can't do that at home...maybe July... Love the guage.. most modern gauges read much higher boost which means that the modest boosts we use (mine is running 4psi) don't really move the needle much. Your guage looks perfect! Quote Link to post Share on other sites
Peter Cobbold Posted June 22, 2021 Report Share Posted June 22, 2021 57 minutes ago, Tim D. said: Love the guage.. most modern gauges read much higher boost which means that the modest boosts we use (mine is running 4psi) don't really move the needle much. Your guage looks perfect! Yes, I'm also green with envy. I get 8psi at 3500 rpm. Peter Quote Link to post Share on other sites
2long Posted June 22, 2021 Report Share Posted June 22, 2021 (edited) Saw this little tidbit on offer. Dang, that is pricey (your gauge looks great!) Your Judson project is awesome. Cheers https://www.ebay.com/itm/174687425011?hash=item28ac2e91f3:g:Q1oAAOSw1eBgUYJz Dan And this too: https://www.ebay.com/itm/174687445893?hash=item28ac2ee385:g:cI8AAOSwJy5gUYQ5 Edited June 22, 2021 by 2long Quote Link to post Share on other sites
stuart Posted June 23, 2021 Report Share Posted June 23, 2021 If anyone fancies going down that route there is this one for sale in the US Judson supercharger Stuart. Quote Link to post Share on other sites
ctc77965o Posted June 24, 2021 Author Report Share Posted June 24, 2021 (edited) https://www.raf-surplus.co.uk/main-panel-flight-instruments.php Edited June 24, 2021 by ctc77965o Quote Link to post Share on other sites
ctc77965o Posted July 4, 2021 Author Report Share Posted July 4, 2021 (edited) All, To try to quantify the benefits of this flailing vane supercharger, I want to record some 'before-&-after' power & torque figures. I am using PerfExpert https://www.perfexpert-app.com/ some of you may not believe that an app can be trusted to measure these figures, but the accelerometers in a cellphone are an accurate and direct way to measure acceleration...the gearing mathematics is the same as any rolling road, the only complication is drag factor - you do the run on a flat road in 2nd gear, meaning you get up to 60mph: wind, Cd and Frontal Area are factors.....However, overall i think it should be at least as good as some contraption with rollers and brakes and who-knows-what-other-losses and fudges. This is what I got for my 'mid-life' TR engine, its got about 50K miles on the pistons, less on the cam and valves....i havent touched the ignition timing or mixture in 6-9 months. Road was flat, no wind, I did two runs in opposite directions and got almost identical figures, here's one run: Peak power is 96 HP at 4600rpm, peak torque is 118lbft at 3500 (Factory figures 104 BHP @ 4700rpm & 132 lb/ft @ 3000rpm) I think thats not bad for a bog-standard mid-life TR4A running on RON95, around 90% of factory figures for a properly tuned fresh engine. I will record a similar set of runs after fitting the Judson with no changes in the app configuration data (Tyres, Gearing, Weight, Drag) - still waiting for Pandemic to fade in order to get the exhaust fabbed. Does anyone have the factory power/dyno curve for the TR4A engine?? I'd like to overlay the factory data with the above and the blown version so we can see the full picture. Edited July 4, 2021 by ctc77965o Quote Link to post Share on other sites
Tim D. Posted July 5, 2021 Report Share Posted July 5, 2021 This doesn't look half bad.. How does it get info on RPM? Tim Quote Link to post Share on other sites
ctc77965o Posted July 5, 2021 Author Report Share Posted July 5, 2021 20 minutes ago, Tim D. said: This doesn't look half bad.. How does it get info on RPM? Tim It calculates it from the gearing and tyre info you enter....just like on a rolling road, actual rolling radius is a potential source of error in the overall gearing calculations (maybe not for revs on a dyno, but certainly for estimating engine HP from the specific wheel HP) Quote Link to post Share on other sites
JohnC Posted July 6, 2021 Report Share Posted July 6, 2021 (edited) On 7/5/2021 at 9:42 AM, ctc77965o said: wind, Cd and Frontal Area are factors.... Hi Dave, What Cd did you use? I've been using 0.47, which I got from a GT6 dyno simulation spreadsheet somebody on here (sorry!) shared with me years ago. I'm guessing the GT6 is a little slipperier than my TR6, and probably your 4A as well. <edit> Just found this post on another forum suggesting the TR6 is 0.44 and the TR250 (and so I expect TR4/4A/5) is 0.45. Any thoughts?</edit> John Edited July 6, 2021 by JohnC additional info Quote Link to post Share on other sites
ctc77965o Posted July 7, 2021 Author Report Share Posted July 7, 2021 Hi John. The app requires 'Drag Area', Cd.A, which it says can be approximated as Cd*Height*Width*0.82 I also struggled to find a number, eventually on an MGB site I found Cd 0.54... so I am using Drag Area=0.54*1.27*1.47*0.82 = 0.83m2 Your figure of 0.45 Cd is significantly more 'slippery' than my 0.54 https://en.wikipedia.org/wiki/Automobile_drag_coefficient Cars in the Cd 0.5+ range are 2CV, Merc G Class, VW Camper...so certainly seems on hi side for a TR. A Cd.A of 0.82 is same as Citroen DS! And a Lotus Elise is 0.59 Cd.A Anyway, I am gonna stick with my figure for now in order to get a solid comparison when I add the supercharger, these settings are on the conservative side so my actual power likely slightly higher than the app shows..... Quote Link to post Share on other sites
JohnC Posted July 7, 2021 Report Share Posted July 7, 2021 I've ended up with CdA of 0.72. As you say, best to keep a consistent number otherwise you won't know much change there has really been. Same with rolling road dynos - I got significantly different results from two, only a few weeks apart, with no tuning changes. With PerfExpert, it seems to me that finding a really flat and straight stretch is critical. Straight more so than flat, assuming you take averages. It's nice to be able to compare before & after changes though, even if the absolute number may be a bit off. John Quote Link to post Share on other sites
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