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Ideola's Ultra Wide Body 931 Build (Master Thread)
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ideola  



Joined: 01 Oct 2004
Posts: 15509
Location: Woodstock IL

PostPosted: Fri May 22, 2009 2:10 am    Post subject: Reply with quote

john h wrote:
My calculations (which couldbe wrong) showed that at 160kpm (which I get to at some circuits) the alternator would be turning over at 30,000 which is about 12,000 more than Bosch suggest. That was majorily under driving the alternator.



John, here's the reply from my supplier:
Quote:
Peak RPM on the alternator you purchased would be around 18,000 RPM which with a 3:1 pulley ratio would be 6,000 RPM at the drive pulley. You axle driven setup should not be that close to this revolution.

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15 981 GTS | 88 924S SE | 82 931 Holbert | 82 931 Rallye | 81 937 | 81 Euro 931 | 81 Weissach | 80 US 928 | 80 US 931 '941' | 80 US 931 | 80 931 GTR | 79 Sebring | 78 D-Prod Replica | 78 w/D-Prod kit | 78 Poli-Form | 78 Limited Edition | 77 Martini
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john h  



Joined: 06 Nov 2002
Posts: 827
Location: Wellington New Zealand

PostPosted: Fri May 22, 2009 9:38 pm    Post subject: Reply with quote

My calculations were based on running a 225/50 x 15 tire,
I might be wrong but I've just recalculated my speed calculations and it might not be too bad
225 x 50 x 15 = 23.7inch dia
20800/23.7(tire dia) x 100 (speed mph)= 88,000 revolutions
pulley alternator 5 inch, [pulley axle 1.5 inch. ratio = 3.3
Alternator speed = 26,500.
The 12,000 overspeed was based on the assumption that if I get enough hp out of the car I could get to 130 + mph on one of our circuits so I would have to have a margin of safety.

As I said I could be wrong in my calcualtions so am willing to be corrected. And yep it would be great to see the way the D production was done.

In the past I looked at a Triumph Stag that had the alternator running of the driveshaft so it was running at less revs than the axles.
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if you take it to pieces slowly it can provide anguish all year long!
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RC  



Joined: 25 Mar 2007
Posts: 2624
Location: Australia

PostPosted: Mon May 25, 2009 10:36 am    Post subject: Reply with quote

john h wrote:

As I said I could be wrong in my calcualtions so am willing to be corrected.


OK then.

Change the batteries in ya calculator John and remember there is a factor of 60 between miles per HOUR and revs per MINUTE.

Bit slower now, I bet!

I fail to understand why any sane person would consider driving their alt off the axle, even if they read on the www that its better than a wind turbine on the roof.

IMO it is a band-aid compromise even in a race car that is always rolling and can be put on a charger in the pits. Far from practical in a street car and bordering on ludicrous if its intended to drive at night or in cold weather. Obviously if you`re not moving above a certain speed, determined by the alt specs and gearing/ tyre diameter, the battery is not being charged and is draining according to the load. Lights, heater fan, demister draw considerable current. So does rad fan(s), fuel pump(s), and I believe in this case an electric water pump, IC pump perhaps?, what else?

Comparatively speaking, the electronics is more efficient regarding power displacement. What is there - ECU with injector drivers, ignition unit/coils, WBo2 reader/ controller (with heated sensor), water pump controller, a fancy LCD dash, datalogger (flash or HDD). What else - stereo, amp, sat nav, neons, LEDs, flux capacitor?

Problem with electronics is that it needs a regulated system voltage. For automotive applications a good designer will utilize a 8 or 9V maximum supply with 5V for micro/ computer supply. This allows for the regulators internal voltage drop. BUT even with a low drop regulator on a 12V system there is bugger all leeway on a an uncharging lead acid battery.

Even with knowing all the various specifications and figures of all systems as well as battery specs, along with some serious estimation and calculations there is a very good chance of at least one system just dropping out unexpectedly. Do you know how long you have while stuck in traffic, at a hold up (accident, roadworks, police), what about exiting a large sporting function or concert carpark, crawling along your local perv boulevard strip, whatever, particularly at night?
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ideola  



Joined: 01 Oct 2004
Posts: 15509
Location: Woodstock IL

PostPosted: Mon May 25, 2009 11:00 am    Post subject: Reply with quote

This car will not be using a lead acid battery, nor will it be driven at night (at least not much), nor will it be driven during cold weather. No heater, no demister, no A/C, no radio, no "street" luxury items whatsoever.

Currently (no pun intended), I'm planning to run the Odyssey ER40 which has a 87 minute reserve capacity with 25amp load. The alternator I've selected, which just arrived on Saturday, will provide 110A charging at 600 RPM, and 160A at normal speeds. All of the in-cabin accessories will be switchable, so any superfluous functions can be selectively turned off if battery charging becomes a significant concern.

I would never run an axle-driven alt on a daily driver type of vehicle.
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ideola  



Joined: 01 Oct 2004
Posts: 15509
Location: Woodstock IL

PostPosted: Wed May 27, 2009 5:43 am    Post subject: Reply with quote

Here's a couple of photos of the alternator:


Next step is to take the aluminum slug over to my buddy's house...yeah, the one with the big lathe. Bwahahahahah!

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15 981 GTS | 88 924S SE | 82 931 Holbert | 82 931 Rallye | 81 937 | 81 Euro 931 | 81 Weissach | 80 US 928 | 80 US 931 '941' | 80 US 931 | 80 931 GTR | 79 Sebring | 78 D-Prod Replica | 78 w/D-Prod kit | 78 Poli-Form | 78 Limited Edition | 77 Martini


Last edited by ideola on Sat Jul 18, 2009 12:05 am; edited 1 time in total
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flosho  



Joined: 01 Jul 2004
Posts: 3158
Location: Eau Claire, Wisconsin

PostPosted: Wed May 27, 2009 8:58 am    Post subject: Reply with quote

Your interior is going to look like the cockpit of a 747!


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ideola  



Joined: 01 Oct 2004
Posts: 15509
Location: Woodstock IL

PostPosted: Wed May 27, 2009 11:40 am    Post subject: Reply with quote

Ooooh! Buttons! Lights! Switches!
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15 981 GTS | 88 924S SE | 82 931 Holbert | 82 931 Rallye | 81 937 | 81 Euro 931 | 81 Weissach | 80 US 928 | 80 US 931 '941' | 80 US 931 | 80 931 GTR | 79 Sebring | 78 D-Prod Replica | 78 w/D-Prod kit | 78 Poli-Form | 78 Limited Edition | 77 Martini
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ideola  



Joined: 01 Oct 2004
Posts: 15509
Location: Woodstock IL

PostPosted: Thu Jun 25, 2009 5:30 am    Post subject: Reply with quote

Lots of progress to report from late May through mid-June!In addition, a couple of other projects are in the works:
  • Gear reduction starter should arrive within days
  • Head is at EMW and should be completed within a week or so
  • Brembos have been shipped off for rebuilding

_________________
15 981 GTS | 88 924S SE | 82 931 Holbert | 82 931 Rallye | 81 937 | 81 Euro 931 | 81 Weissach | 80 US 928 | 80 US 931 '941' | 80 US 931 | 80 931 GTR | 79 Sebring | 78 D-Prod Replica | 78 w/D-Prod kit | 78 Poli-Form | 78 Limited Edition | 77 Martini
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Joes924Racer  



Joined: 03 Nov 2002
Posts: 11966
Location: Oregon, Denver Colorado native!

PostPosted: Thu Jun 25, 2009 2:53 pm    Post subject: Reply with quote

Gosh dang alright then. awesome
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1980 porsche Turbo 931GT Replica
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ideola  



Joined: 01 Oct 2004
Posts: 15509
Location: Woodstock IL

PostPosted: Thu Jul 16, 2009 2:09 am    Post subject: Reply with quote

Wow! Look at all the BLUE in the OP! That means we're getting REALLY close fellas! Still TONS to be done of course...

Here's the update:
  • Jorge called last night, the head is done, and will be shipping out this week, so I should have a bunch of thexthy new pix by mid next week. Can't wait !
  • Brembos should also be shipped out this week or early next from the rebuilder. Pix to follow as soon as they arrive!
  • Snagged a pair of the GT Racing teardrop race mirrors last week, they should arrive this week. Only thing left on the body to acquire now is the lexan door windows and the D-9 dual projector fixed headlight kit.
  • Pace Products have apparently sorted out their mixup, so I hope to have the correct dry sump pump, bracket, and oil-in assembly within 4-6 weeks
  • Just finished the hybrid Audi-G31 shift linkage prototype. Next step is to bolt up the torque tube and check clearances, make final tweaks. When that's done, I'll redo everything with much higher quality components.
  • I got the front suspension all assembled and bolted up, with the exception of the steering rack. Next on the shopping list is an Atsco rebuilt rack for an 89 944/951, which will give me the correct late offset tie rods.
  • Once I have the steering rack bolted up, the next step will be to get the torque tube, gearbox, shift linkage, and rear suspension into the chassis. This will allow the chassis to finally roll again(!!!!), as well as pave the way for final fabrication of brackets for the FMIC, radiator, hood pins, and axle-driven alternator. Hope to get that work scheduled and completed by end of August.

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15 981 GTS | 88 924S SE | 82 931 Holbert | 82 931 Rallye | 81 937 | 81 Euro 931 | 81 Weissach | 80 US 928 | 80 US 931 '941' | 80 US 931 | 80 931 GTR | 79 Sebring | 78 D-Prod Replica | 78 w/D-Prod kit | 78 Poli-Form | 78 Limited Edition | 77 Martini
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Rasta Monsta  



Joined: 12 Jul 2006
Posts: 11356
Location: PacNW

PostPosted: Wed Sep 02, 2015 4:15 pm    Post subject: Reply with quote


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  • Shaggy (1980 931) - Got Boost?
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  • Weiße Scheiße (1987 924S) - In Progress
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ideola  



Joined: 01 Oct 2004
Posts: 15509
Location: Woodstock IL

PostPosted: Thu Sep 03, 2015 1:13 am    Post subject: Reply with quote


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15 981 GTS | 88 924S SE | 82 931 Holbert | 82 931 Rallye | 81 937 | 81 Euro 931 | 81 Weissach | 80 US 928 | 80 US 931 '941' | 80 US 931 | 80 931 GTR | 79 Sebring | 78 D-Prod Replica | 78 w/D-Prod kit | 78 Poli-Form | 78 Limited Edition | 77 Martini
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Power Tryp  



Joined: 16 Apr 2009
Posts: 427
Location: Calgary, Alberta

PostPosted: Thu Sep 03, 2015 3:15 am    Post subject: Reply with quote


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Melanie - 1980 931
Scrappy - 1980 924 shell
NoName - 1980 931 (seeking rebuild)

Green tartan interior, you don't see that on a Civic.
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