Triumph Sports Cars

This "might" be bodywork, but its specific to TR 7/8. I'll be fitting the "Maxton Nose" on my Huffaker TR8 coupe, "Wheeler Vortex Generators" above the rear window and a belly pan. Question is, what flat plane rear spoiler is easiest to mod/install ? I envision something like drag cars use for minmal drag and perhaps small downforce ?This is only a temporary configuration, for the GT1 car, (will get me to Mohave Mile quickest).Tallest ring and pinion I can find is 3.08/1. This means fitting the tallest tires, without scrubbing tops of wheelwells. Cheers, roverman.

> This "might" be bodywork, but its specific to TR 7/8. I'll be fitting the
> "Maxton Nose" on my Huffaker TR8 coupe

If you get the chance, send me a picture of the Maxton nose.

> "Wheeler Vortex Generators" above the rear window

You may want to test the vortex generators. We tufted a 1987 Mustang
hatchback and installed vortex generators. Didn't make any improvement
because the boundary layer was already fully turbulent. The TR8 coupe
rear window angle is much more abrupt so I'm sure you'll be seeing
pressure separation over the top. You may have some flow around the
sides (we did), though. Remember, 200 lbs of lead acts just like 200 lbs
of downforce without the drag penalty (but with added inertia).

> and a belly pan.

Under the nose the nose, something to divert flow around the car will
reduce the pressure under the car. You'll likely need flexible side
skirts to keep the flow from taking the path of least resistance.
These can be inboard to be less visible.

> Question is, what flat plane rear spoiler is easiest to mod/install?

Why a flat plane? What you want is a wing that produces the most down force
for the least induced drag.

> I envision something like drag cars use for minimal drag and perhaps small
> downforce?

Wings do not reduce drag, they increase it (at least when producing lift
or downforce). Are you considering mounting at the rear of the trunk lid
or on the roof. To work, the wing needs to be in clean air (above the roof
ala Plymouth Superbird) or way back behind the car where the flow reattaches
(nature abhors a vacuum). A rear diffuser is good if you have a relatively
clean flat underbody.

> This is only a temporary configuration, for the GT1 car, (will get me
> to Mohave Mile quickest).

Roger that.

> Tallest ring and pinion I can find is 3.08/1.

Rover SD1 Vanden Plas EFI and Vitesse with an automatic gearbox had a 2.84:1
ratio. Rimmers lists it on their website:

[www.rimmerbros.co.uk]

> This means fitting the tallest tires, without scrubbing tops of wheelwells.

What gear box are you using? Consider a T5 with a 0.63:1 overdrive or
I can loan you my Hone-O-Drive 2 speed planetary gearbox.

Dan Jones

Dan and clan, What I have read about the coupe rear window configuration, is much separation thickness, rendering a conventional rear spoiler, compromized on effectiveness. This is likely why "Tullius" used the BMW roof diffuser to render rear spoiler, more effective ? Since the application is good paved, I'm not sure traction will be an issue. In other words, will I need additional downforce ? Seems like reducing lift should be enough. Isn't a skilled belly pan, less drag than front spoiler and side skirts ? My assumption is a longer flat extension, off the trunk lid, would reduce rear drag of negative pressure at rear ? Plan is to use an M22, rock crusher, up to the hp task, (maybe 580+ ) and relative low drag.A 2.84/1 SD1 r&p should help. I suspect the "coupe" should max out 170-180 mph ? Nose is what Craig Lineike ran at former Maxton Mile,(118mph/108rwhp). I have a Lenco 2 speed, 29% overdrive, I may use in the roadster,(similar in aero package to Craigs roadster).I'll be using a diff cooler in the coupe, so as not to cook the TR re.1 mile run is maybe 30 sec. ? Afterall, the fastest sports car in the world, is now a GT6/Black Salt Racing? Thanks, roverman.



Edited 2 time(s). Last edit at 09/05/2012 09:18PM by roverman.

Re:
> Tallest ring and pinion I can find is 3.08/1.
>Rover SD1 Vanden Plas EFI and Vitesse with an automatic gearbox had a 2.84:1 ratio. Rimmers lists it on their website: [www.rimmerbros.co.uk]

Yah, but try to order it...... unobtainium. Easier to find an SD1 with the auto and "re-purpose" the diff. :)

> This means fitting the tallest tires, without scrubbing tops of wheelwells.

Top of the wheelwells really isn't the problem. The horizontal opening is. I'm running 215-55ZR16"s. This leaves you about 1/2" clearance to the rear of the front wheels and front of the rear wheels. I had to trim back the rear bottoms of my front wheelwells to enable the tires to rotate in and out for turns. They were just binding. Any tires bigger will require major surgery to your wheel arch openings.



You probably already know this, but you also have to consider your wheel offset or the tire will hit the top edge of the wheel arch. I had to roll up the lip to avoid rubbing or cutting my tires.



Regards,

Martin



Edited 1 time(s). Last edit at 09/05/2012 09:12PM by bsa_m21.

Martin, problem with the GT1 car is not width, but diameter,(car is lowered perhap 3") ? Car road raced with 23x10.0x15" slicks, so overall tire width perhaps 11.5" ? I may use something like the Goodyear Funny Car fronts, as they are working well at Bonneville. Thanks, roverman.

The Group 44 TR8 did use a roof deflector from a BMW 3.0 CSL that in the end did not do any more good. From talking with Lanky only about the top two inches of the spoiler actually gave the down force needed. Best bet would be a high mounted spoiler like on the Group 44 Jaguar XJR 5 & 7 IMSA GTP cars. There is a Canadian GT1 TR8 using an elevated rear spoiler. In late 1979 at Daytona the 44 TR8 hit 178 mph prior to the roof spoiler. The front end is a great design but the back window and short deck...........

Mike, is the stock chin spoiler of any partcular significance in cooling? I've heard comments about it but I'd like to know what you think. On Edith's car that has been removed and cooling at highway speed with the A/C on is marginal. That is with a smog era 2bbl Buick V6 and the stock radiator however.

Jim

The front chin spoiler for the TR7/8 was installed for the extra cooling requirement of the V8 and Bigger Radiator. It helps a lot! For added insurance with AC a smaller little defelector was added on the lower radiator mount to get more air between the radiator and the condensor.

Clan, So as far as we know, no one has used "Wheeler Votex Generators", over the rear window ? RE the Tullius coupe, 178 mph on an oval, with listed 380 hp. ? That is impressive ! Onward, roverman.

Art,
Why not modify the rear glass like those NASCAR "Aerocoupes" did in the 80ies?

Mike and clan, I have recently considered not installing polycarb side windows, and just removing the polycarb rear window. I have no idea how much turbulence, or the lack of it, will be induced by this . Wind tunnel, not in the budget this year. Thanks, roverman.

The Group 44 wide body TR8 probably got much of its flow over the rear wing
from around the sides of the body. Not sure if a stock width TR8 would do
the same but it would be easy to attach a pole at the decklid with yarn tufts
to see the height at which the flow reattaches. For stability, you need
front to rear balance plus some overall down force. Air dams and side skirts
keep pressure from building under the nose of the car, reducing front end lift.
If you're installing a rear diffuser, you'll need flow under the body and a
flat floor or belly pan.

> So as far as we know, no one has used "Wheeler Votex Generators", over the
> rear window ?

Vortex generators help keep flow attached by tripping laminar flow boundary
layers in turbulence )turbulent boudary layers resist pressure separation
better than laminar layers and pressure separation is what causes the large
drag increase). If the boundary layer on the roof is already turbulent,
introducing turbulence won't help any. Also, if the angle is abrupt enough,
I doubt it will do any good.

Dan Jones