New GT40 on the way

Time to introduce myself to the group. I recently finalized my order for P2388. A Superformance Mark I RHD, Sill shift, Widebody in Gulf colors.

Timing should see the car in my hands (for install), May 2018.

Still a few details (ok more than a few) to decide. At this stage a Roush 427IR is likely, with an RBT transaxle.

I have a number of extras on the order that i will share in time. I'm also looking at custom ratios in the gearbox as i plan to put as many miles on the 40 as I do on my MkIII (my third Cobra). Think low RPM at 80 Mph for long haul fun.

Looking forward to adding this to the toybox and getting to meet many of you at events across the globe.

Congrats on the new gt40!!

I would shoot for 1800-2200rpm @80mph. I drive my cobra all over Florida 2500rpm @80mph. (it is immediately ready to jump to 100mph, but fuel consumption with a small-block is prob 10-14mpg. The gt40 tachs about 2800rpm at 80mph, and that is a little high for sustained (more than an hour) jaunt on 95. (10mpg)

Post some pics when you get it, and have fun!! S
Cameron, congrats on the GT-40. A year or so to get it on the road won't be too bad compared to about 8 yrs to build mine.

Like Scott's, my Cobra putts along at 80 and turns about 2000 in a tall 5th gear. It's fuel injected so I can manage 22-25 mpg on the highway on a long trip. The GT is geared lower and turns about 2900-3000 @ 80 mph, with the throttles cracked at 3%, burns about 24-26 lbs per hour, which is about 4 gallons and roughly 18-19 mpg.

This morning I drove the GT from 5400' up to about 11,000' elevation. It was slow going with all the traffic so I managed between 15-17 lbs per hour. That's about 3 gallons/hr. In fairness, there was a fair amount of downhill coasting, too. I run stacks with EFI and can change my AFRs with a flip of a switch for a more conservative tune but haven't spent much time dealing with it.


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Are you flying or driving? :)

I'd have to check mine but I am rarely in 5th even at 80 as it would not be in a happy spot at that low of RPM. I don't see the appeal of a tractor GT40?

Congrats on the new GT40 Cameron!
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Actually yes.....flying NOE. This fancy EFI computer rather tell me how much weight I'm burning off per hour so makes me feel in better shape at the end of the drive. ;-)

LOL, so I guess you'll need a granny gear installed to keep your motor 'happy' at 7000 rpm as you drive through the Cars and Coffee parking lot or you'll end up stalling it!


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Did that once Labor Day weekend. Not my cup of tea. It is very happy at 7K but it starts getting happy around 3K. It will cruise at 1800 but it just seems like it wants to be spinning a little faster. It's more fun with the 302 than the 427 I think.
Cameron, I'm thinking you'll enjoy the IR if it's tuned right. My trumpet orchestra starts playing at 3000 rpm!
Thanks all.

[email protected] in 5th feels about right to me. My Cobra is 2850 and that's a bit much. As for fuel economy, don't really care unless I can't get from one gas station to the next. After 250+ miles in these cars, any excuse to get out and stretch for a few minutes is welcome.

Photo's will start coming as the build get's underway.

Welcome Cameron!

You will find this forum invaluable for all the questions that will come up during your build.

Cameron and I have been communicating for quite some time about his build. We finally met this summer when he drove his Cobra to Ann Arbor to test drive my SPF GT40 P2248. I am very excited to be involved in his build. Cameron is a great guy and will be a real asset to this community.

Robert Kay


Lifetime Supporter
I'm of the opinion 2200 rpm @ 80 mph is on the low rpm side. In my Pantera with modern rubber (26.2" tire dia.) and stock 4.22 R&P I installed the taller 0.642 5th, which acts as an overdrive gear and is good for 80 mph highway cruising at 2600 rpm.

The next usual step is a 3.77 Ring & Pinion coupled with the tall 5th which will provide 80 mph at 2300 rpm.
Robert, thanks for the kind words. It's going to be another adventure!

Joules. Interesting. Thanks for the POV. I have a 289/65 Mustang and I changed the diff to get to 2300 @ 80 Mph and it feels very happy at that speed. My Cobra (Roush 402) is supremely happy at 2200, just too slow! What is your thinking on the low RPM's? Response, laboring engine, something else?


My personal experience (with a 347) has been that 3,000+ rpm is too busy and noisy for sustained driving jaunts. I swapped out the gearbox on my CAV in order to drop rpm (and add an LSD) to the 2,600 rpm level for comfortable highway cruising at around 75mph. Made a world of difference - engine seemed much happier....and so was I.