Triumph GT6 planned aeromods

[Stubby79]

Probably do better using forced air cooling through the motor, rather than liquid cooling the exterior. Exterior cooling will do little for the brushes and rotor.

If you need more power, I'd suggest looking for a (used) larger motor. I'd think one could be had for a few hundred bucks, since DC has gone out of style...

[The Toecutter]

I'm eventually going to upgrade the motor/controller when money permits.

Cutting the battery pack down to 144V to reduce weight and then installing a NetGain Hyper9 synchronous reluctance AC motor/controller would really do wonders for its efficiency. I'd have a system that could allow me to keep the transmission, while able to do 0-60 mph < 6 seconds and top out at almost 150 mph. 1/4 mile time would be in the upper 13s. And perhaps I'd get a range of 130-150 miles on a charge. AND the car would weigh less than it did stock. Were money no object, I could use TWO of these systems and delete the transmission, and possibly do 12s in the 1/4 mile with it.

I've also been considering all of the excellent input everyone here has added to the thread and will be working on the design of a spoiler system that doesn't ruin the greenhouse. As long as I can get a CdA of under 0.3, this could be doable! I don't think it's unreasonable considering the ADU1B LeMans Spitfire had a Cd of 0.32, and Jigsaw Racing who produces replica pieces to install on Triumph Spitfires quoted one doing 137 mph on 111 horsepower, and the math works out close.

[Stubby79]

I didn't know what a reluctance motor was until about a week ago. In my typical fashion, I didn't pay any attention to a technology that was out of my price range...none what so ever. Took one look at Paul's AC controller thread and assumed it was for induction...I mean, that's what Tesla runs as did a few others; assumed the rest were running a form of brushless DC. Oops. Very close, very similar, but not quite...

FWIW, the netgain, like most of the others these days, is not a simple reluctance motor...they call it a "Synchronous Reluctance Internal Permanent Magnet (SRIPM)" motor. The permanent magnets are equally important as the reluctance side of things.

And to make matters worse, there are other names for the same thing!

I can thank google for sniffing my searches and recommending a couple of youtube posts, including Tesla's "new" motor tech...which appears to have taken them a few years longer than everyone else to adopt, unless that was just on the model X which the video was about.

Anyway, just looked at the Netgain motors. The $4k US is prohibitive to me, at least for a just-for-the-fun-of-it project, but...nice efficiency map. You'd basically be running in the >85% area of the map most of the time, compared to a BLDC which would max out there. That's impressive. And all by hiding magnets inside of laminations...I wonder why it took so long to figure that out and bring it to the market. Ok, I know switching speeds/losses had something to do with it, but still...oh, and that Netgain controller only weighing 9lbs is also impressive, for the power output.

I gotta go, I'm drooling and this is making my head hurt to think about!

[freebeard]

Zombie thread lives again?

Have you made any decision on the aerodynamics? I see you'd liked the bat-wing towel rack idea.

I'm still hoarding a 1958 Beetle and an electric drivetrain. I also figured to make it weigh less than the stock vehicle. By using a 98lb 68hp single speed rear axle out of a Lexus. How does your Hyper9/transmission compare?

Stubby79 — Since you mention it, here's the Lexus part:



It has the anti-back EMF buried magnets. It's the one on the right.

Here's the thread: Hot-rodding the Toyota MGR

[SDMCF]

I had not seen this thread before but I find it interesting because I had a couple of Mk III GT for 20 years or so.

I made some perspex cowls to go over the headlights, modelled on the items used by the works Spitfires that competed at Le Mans back in the 1960s. At normal road speeds they made little difference but at the speeds you are talking about they would be good.

I am not convinced of the need for a dorsal ridge. The Mk III at least was quite stable in a straight line at 100 MPH. Cornering stability is another matter, particularly on the Mk II. The rear wheels were prone to tuck under if you lifted off mid corner, causing dramatic oversteer. A friend with a Mk II fitted the lower rear wishbones from a Mk III and reported that this was a major improvement, so you might consider doing that, or something similar. Note that not all Mk IIIs had the rear lower wishones - later cars had a wider track instead.

What are your plans for the underside of the car? I made & fitted some panels that smoothed things out and I think helped. It is easy to fit this sort of thing because there is no shortage of places to fix things to the chassiss.

Another oddity with the GT6 is tyres. The Mk III at least was sensitive to tyres and did not always react as you would expect to a change of rubber. Indeed it was sometimes counter-intuitive; for example, increasing tyre pressures on some tyres gave better grip in the wet on sprint & hillclimb competitions. With other cars it was normal to drop the pressures. I have no idea how you would find out what modern tyres would suit the car best without some expensive experimentation.

Do keep the thread updated; I am interested to see your results.

[freebeard]

The Mk III at least was sensitive to tyres and did not always react as you would expect to a change of rubber. Indeed it was sometimes counter-intuitive; for example, increasing tyre pressures on some tyres gave better grip in the wet on sprint & hillclimb competitions.

First two from DuckDuckGo:

Originally Posted by DDG

Hydroplaning: What it is and how to avoid it
https://www.msn.com/en-us/autos/owne...it/ar-BB1dLqJV
Tire pressure is one of the leading causes of hydroplaning because it impacts how much contact your tires have with the road. When tires are under-inflated, they are less likely to grip and hold...

How does tire pressure affect susceptility to hydroplane ...
https://mechanics.stackexchange.com/...-to-hydroplane
Clearly, the lower the tire pressure the more likely a tire is to hydroplane. There are two main reasons for this A tire with lower inflation pressure has more contact area, and it, therefore, takes less pressure to lift the tire off the pavement. A tire with lower inflation pressure presents a slightly concave profile to the pavement.

[SDMCF]

OK, I wasn't too clear: I meant wet roads rather than enough water to cause hydroplaning. In fact the possibility of hydroplaning didn't even occur to me when I wrote my post yesterday.

If you can discount aquaplaning it is surprising how much traction you can gain by dropping pressures when grip is low. In extreme conditions, such as on ice or grass, dropping the pressures very low can get you moving when you are otherwise stuck. In "normal" wet conditions a slight drop in pressures will usually improve things. I can't comment on why that is so.

[aerohead]

I believe I have a GT6 analysis at home somewhere. It's definitely a 'pseudo-Jaray form, with separated flow ( although it probably has good rear outward vision.
* If you're going to do a template comparison, use the 2013 version with the 'faster', more aggressive roofline.
* A look at as many cars shaped similarly and cars near Cd 0.25 will give you clues.
Carl Breer's DeSoto Airflow test mule of 1934, Cd 0.51- Cd 0.263- Cd0.244.
Panhard Dyna
Shelby Cobra Daytona Coupe
1968 Toyota 2000 GT
1970 Citroen SM
1973 Rovomobil
1975 Ferrari Cr 25
1980 Ford Probe
1980 VW 2000
1982 GM Aero X
2000 Insight-I
2010 KIA Ray concept
2011 Hyundai Sonata Hybrid
2012 Tesla Model S
2015 SCION FR-S
2016 Renault EOLAB
2009 Prius-III
2021 Porsche Taycan Turbo
You're kinda where CAR and DRIVER was in March,1974, with the Ford Pinto:
*wrap-around airdam
* grille-block
* cooling fan is NA, as you're going electric
* headlight covers
* rear spoiler
------------------------------------------------------------------------------------
Then Pontiac's 1983 Trans Am Firebird's:
* matching rocker panels with air deflectors ( slab-sides )
* aero wheel covers
* most 'narrow' tires that you can 'safely' operate
------------------------------------------------------------------------------------
As much belly pan as you can.
Rear diffuser.
I like Frank Lee's comment about simply extending the rear.
Flying-buttress C-pillar extensions along a more streamlined contour above the Bonneville-spoiler, to 'sculpt' the captured-vortex there.
Rear skirts.
Minimum front wheelhouse arch-to-tire gaps.
'Tesla-esque' side mirrors, or SCCA racing mirrors. Get them at least 80mm away from the body.
-----------------------------------------------------------------------------------
I got the CRX to an estimated Cd 0.235 as an ICE vehicle pretty easily. I can't imagine that you couldn't best that.

[aerohead]

I ran across my GT6 drawing last night. It's definitely pseudo-Jaray, with a very aggressive roofline contour.
By 1989, Porsche was able to get their 911 from Cd 0.40, down to Cd 0.32, with very exacting detail to cooling inlets and underbody smoothing. And it doesn't have the front cooling system penalty of the Triumph.
I couldn't find a definitive drag coefficient for the GT6.
Cds for the Spitfire are not parsed out with respect to whether measured as the top-down roadster, or with the rag-top up.
Carrol Shelby's AC Cobra roadster is estimated at around Cd 0.65.
As the Peter Brock, AC Cobra Daytona Coupe, an estimated Cd 0.42.
As an EV, losing the cooling drag, and smoothing the exhaustless belly, Cd 0.32 seems reasonable.
Skirts and wheel fairings, as with the circa 1962 Panhard Deutsche & Bonnet LeMans Coupe could push the Cd lower.
Extending the roofline, like Carl Breer did with the 1934 Chrysler DeSoto aerodynamic test mule would definitely do it. They got a Cd 0.51 car down to Cd 0.262 as a chopped-off Kammback, and Cd 0.244 with the boat-tail stinger. ( A Tesla Model S in 1934! )