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Post by racket on Dec 10, 2015 22:18:02 GMT -5
Hi Smithy LOL..............I'm not sure I'll be up to much more than just the first 20 yards  Do you think the gearings about right for the horsepower , the next ratio is 7.56 vs the 6.57 :1 , it'd bring top speed back to ~235 kph , maybe a tad slow ?? Cheers John |
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Post by pitciblackscotland on Dec 10, 2015 23:10:03 GMT -5
Hi John,
Yeah that sounds like a good deal. I paid well over $1,000 for the Boeing gearbox and cartridge starter including the shipping cost.
Cheers,
Mark.
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Post by racket on Dec 12, 2015 22:52:27 GMT -5
Hi Guys Work started on the turbine exducer shroud/jetpipe stub . An 85mm length of 4 inch nominal pipe , cleaned up true and the end cut and flared to roughly the exducer shape   Small rebate in other end for positioning the jet nozzle into prior to welding it on  Flare welded up ready to be fitted to the lathe for final machining to shape  Cheers John |
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Post by Johansson on Dec 13, 2015 4:26:43 GMT -5
Ah, so that is how you make your turbine shrouds! I always imagined that you machined them from solid, I can´t remember seeing any pics of the job before.
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Post by pitciblackscotland on Dec 13, 2015 4:31:05 GMT -5
Ah, so that is how you make your turbine shrouds! I always imagined that you machined them from solid, I can´t remember seeing any pics of the job before. Yeah i was going to ask John the same question  Cheers, Mark. |
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Post by madpatty on Dec 13, 2015 10:02:09 GMT -5
Ah, so that is how you make your turbine shrouds! I always imagined that you machined them from solid, I can´t remember seeing any pics of the job before. Racket has some beautiful and differently exotic ways of doing the stuff. i was confused first how is he going to assemble disassemble his engine earlier in this thread. Then later i realised that he has got some different arrangement for turbine shroud as compared to what me and you had done(machining it from solid and then bolting it on the NGV plate). cheers. Patty |
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Post by smithy1 on Dec 13, 2015 13:59:55 GMT -5
It's commonly called a "Wallis Custom Exducer Contour"...Looks rough now... but I can assure everyone that it will be perfect for the job at hand when finished.
Smithy.
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Post by smithy1 on Dec 13, 2015 14:10:01 GMT -5
Hi Smithy LOL..............I'm not sure I'll be up to much more than just the first 20 yards Do you think the gearings about right for the horsepower , the next ratio is 7.56 vs the 6.57 :1 , it'd bring top speed back to ~235 kph , maybe a tad slow ?? Cheers John With the 6.57 ratio and a pull of ~1100lbs at the axle, I'm assuming the kart will weigh ~450-500lbs-ish....another rough guess tells me you'll possibly be pulling 2g's+ on launch...either that or it will break traction, and turn the tyres... whichever comes first. With the 7.56 ratio it'll pull significantly harder off the line, traction will be the biggest issue I suspect....top speed may be down but it'll get there a helluva lot faster..!  I'd drive it for sure..!  This all assumes full throttle acceleration though, and with the gazzilion Lb-Ft of torque on tap, you'll have your tyres shredded in no time  ...there's nothing stopping you from "applying" throttle a little more sedately though. Smithy. |
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Post by racket on Dec 13, 2015 17:47:33 GMT -5
Hi Anders
The 4" pipe comes with an ID of ~105 mm and an OD of ~115 mm , not too thick and not too thin , the ID area pretty well matches up with the 106 mm TV94 exducer once the hub and blade areas are taken into account, it should even be OK with my radical clipping for this engine.
Its also thick enough to tap threads into for holding the P4t pitot tube as well as the thermocouples .
Even though its only mild steel I've never had any "thermal" problems once a coat of high temp exhaust paint is applied , also its less likely to damage the turbine wheel if theres a rub compared to a stainless shroud .
Cheers
John
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Post by racket on Dec 13, 2015 18:11:27 GMT -5
Hi Smithy
I've ordered the 6.57 ratio box, it'll help keep the N2 rpm down a tad , theres not much of a power difference between 80 and 100% N2 , 80% of power is available at 50% N2.
Yep, 500 lbs with driver would be a reasonable weight to calculate from , I used ~475 lbs for my old 2 shaft kart with its 160 lbs of static drawbar "pull" with me onboard ...........heh heh , and it pulled rather nicely getting up to ~60 mph in 7.5 seconds
Now if I do the calcs for 1,100 lbs and assuming nil wheelspin etc etc etc , acceleration will be at ~70 ft/sec/sec.
Velocity after 3 sec will be 210 ft/sec or ~140 mph ..........OH !! , must be something wrong with my calcs .
Lets try distance , 0.5 X 70 X 3 X 3 =315 feet , say 100 metres , something still doesn't seem right, Theres gunna need to be a big wind resistant component added into the calcs , Heh heh , the calcs worked out OK for the old karts "thrust" number.
Mmmm , maybe I'd better leave driving this thing to someone else :-(
Cheers
John
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Post by enginewhisperer on Dec 13, 2015 18:24:38 GMT -5
*hand up*
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Post by racket on Dec 13, 2015 19:22:28 GMT -5
Hi Andrew
LOL...........that was quick :-)
Cheers
John
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Post by smithy1 on Dec 13, 2015 20:17:08 GMT -5
Too late...I already had my hand up earlier this morning.. Smithy. |
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Post by smithy1 on Dec 13, 2015 20:21:45 GMT -5
Hi Smithy I've ordered the 6.57 ratio box, it'll help keep the N2 rpm down a tad , theres not much of a power difference between 80 and 100% N2 , 80% of power is available at 50% N2. Yep, 500 lbs with driver would be a reasonable weight to calculate from , I used ~475 lbs for my old 2 shaft kart with its 160 lbs of static drawbar "pull" with me onboard ...........heh heh , and it pulled rather nicely getting up to ~60 mph in 7.5 seconds Now if I do the calcs for 1,100 lbs and assuming nil wheelspin etc etc etc , acceleration will be at ~70 ft/sec/sec. Velocity after 3 sec will be 210 ft/sec or ~140 mph ..........OH !! , must be something wrong with my calcs . Lets try distance , 0.5 X 70 X 3 X 3 =315 feet , say 100 metres , something still doesn't seem right, Theres gunna need to be a big wind resistant component added into the calcs , Heh heh , the calcs worked out OK for the old karts "thrust" number. Mmmm , maybe I'd better leave driving this thing to someone else :-( Cheers John LOL....Nill wheelspin? Methinks you're dreaming.. ...I think wheelspin is going to be a major factor and put a damper on some of those numbers....but she's still gunna go hard. I hope the gearbox is strong enough to handle the torque...be sure to brace the gearbox and axle mounts accordingly..!  This machine is going to be something truely special....really looking forward to it becoming a reality. Smithy. |
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Post by enginewhisperer on Dec 13, 2015 22:03:12 GMT -5
Maybe it's worth doing a custom frame for it rather than using a Kart frame? I have a fair few bits already |
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I'd drive it for sure..! 
...there's nothing stopping you from "applying" throttle a little more sedately though. 
