Cobra gear U.S.A. style

[Naumoff]

Kevin,
I can tell you with my 427 stock stroke 2x4s 3.31 rear gear ratio 26.5" tall tire 4 speed top loader highway cruising 75-80 3600 RPM 11 MPG.

The only thing that is different now is that it is 482 cubic inches.
I will report back after this weekend as I am going on a long trip and like to check the mileage just so I know how far I can go between petrol stations.

I originally wanted a five speed just for long trips but was talked out of it by Bill at SA.
The Toploader is a sweet trans but I still would like the overdrive.

[Neil O]

Kevin, are you really sure you want to know?

Ok, my early calculations, which are not that accurate due to a lot of time spent on tickover at the SVA etc. and no long runs..........12 mpg.

I am assuming that on a decent run and with the engine getting a little more loose in time I'll be getting nearer 15 mpg. I'm off to France for a week in June, so I'll get more of a chance to work it out properly. Also, I have a diff change planned for the winter to swap the 3.31 for a 2.88 power lock.
Currently 85 mph in fifth gear is around 3000 rpm. Ok for acceleration, but as my lump pulls well from under 2000 rpm, I can up the gearing a notch.
Hope to be 2250-2500 rpm at 90 mph once it's all changed over. It should reduce the fuel consumption a bit and feel less "busy" on the motorway.

[Naumoff]

I just remembered mine is in US gallons so you can probably add a mile or two.

Neil, I have thought off a gear change too now that I have a stroker.

with the wide ratio toploader I would probably go 3.08.
If I change to a 5 speed TKO600 I would probably go to 2.88.

Tire spin is ridiculous.

[KevinW]

Thanks chaps, at least its in double figures. I'm planning on a toploader, rather than 5 speed for authenticity but with a tall diff. So maybe the smaller engine and US conversion might make 15mpg? Are your engines in the >500 bhp range?

[Naumoff]

Kevin,
If you are going with a toploader (sweet trans)and a tall diff go with the wide ratio gears.
I have a close ratio and slow traffic and parking lots even with the 3.31 you are on and off the clutch pedal to keep the speed down.

If you wan't to go from zero to 60+ without shifting

[KevinW]

was planning to get a topoader as part of a turnkey package from SA.
i didnt know there was a choice of gears for the toploader? Presume 4th is still 1:1 ?

[Naumoff]

4th is still 1:1.
It is the first, second and third gears which are different.
The first gear in a close ratio is taller than the first gear in a wide ratio.
All close ratios are big spline input/output shafts. NASCAR specs.
With Bill at SA there might not be many choices. I purchased my engine and trans from SA.
He might have more choices now. With a 406 400HP you can use a top loader wide ratio even if it is a small input shaft. Which by the way is about the same size as the TKO600 input shaft.
It is up to you but I say you will be happier with a wide ratio toploader.
What rear gear ratio are you going to use?
Anything taller than a 3.31:1
and you might not be real happy at the fair grounds trying to find a spot to park with a close ratio Top loader.

Gear Ratios

Close

firstsecondthirdfourthRatio2.321.691.291.0Tooth Count32282523Counter Gear Tooth Count15182125

Wide

firstsecondthirdfourthRatio2.781.931.361.0Tooth Count32312523Counter Gear Tooth Count15212430

Gear ratio is determined by tooth count on second gear. If it has 28 teeth, it's a close ratio. If it has 31 teeth, it's a wide ratio.

Not to take the sale away from Bill but David Kee can do both close and wide with a big spline if you want. I don't think the big spline is a big deal for a street Cobra.
Toploader Price List

[Naumoff]

I couldn't edit my post.
If you can't figure out the gear ratios to compare the wide to the close trans let me know.
They were beautifully displayed when I was writing as I copied them from Kee's website.

[KevinW]

OK, depends what you mean by tall diff. I meant 2.88 or similar, really just to compensate for the lack of 5th gear, and so eake out a bit more mpg.

[Neil O]

Kevin, tell John you want to put a Tremec in it......just for fun.
Best done face to face, then you can see his expression.