DuPuis Family Cobra Build

So when is the Cobra's first track night?

Good question! It does need some more tweaking first. Among other things, more grippy pads (the hard long-life pads don’t stop fantastic with manual brakes). The engine needs to be tuned better. The air/fuel ratio gauge is all over the place driving. Honestly amazing it runs as well as it does.

The next goal is getting the body on, lights, etc., and making it legal while I tweak it. RX-7 remains the track weapon in the stable.
 
Now, if you wanted to be really classy, you'd tow the RX to the track behind the Cobra....

:D
 
I think the better question is when is @Half Fast 's next (first?) track night?


Did you miss the part of the story that the RX7 was originally my race car? I did track days and races in it for years before it went to Ted.

I can afford either racing, flying, or cocaine. For now, I'm flying.
 
Did you miss the part of the story that the RX7 was originally my race car? I did track days and races in it for years before it went to Ted.

I can afford either racing, flying, or cocaine. For now, I'm flying.

I have read the backstory, and was wondering if the race track has started calling you. I'm 65 years old, did 14 years of club racing, the last year being 1997, and I've been trying to get on the track ever since. Doing track nights isn't like racing, you can use your daily driver, and the entry fee for an hour's track time is just about exactly what it costs to rent an older 172 around here. Much cheaper than cocaine.
 
I have read the backstory, and was wondering if the race track has started calling you. I'm 65 years old, did 14 years of club racing, the last year being 1997, and I've been trying to get on the track ever since. Doing track nights isn't like racing, you can use your daily driver, and the entry fee for an hour's track time is just about exactly what it costs to rent an older 172 around here. Much cheaper than cocaine.


Every once in a while I feel like going racing again but I find if I take a few ibuprofen and lie down in a dark room with a damp towel on my forehead, after an hour of so the tremors stop and the feeling goes away.
 
Must be reading too much Ted, or something —

As this headline was scrolling by the words "Family Cobra" popped into my head. Do you think I need a doctor? Or a Cobra?
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Where is the video of the Cobra drive???

I do have video footage that I'll put up. Right now my focus is on wrenching rather than on processing and uploading videos. So, I will get it uploaded, but no promises on timing.
 
I do have video footage that I'll put up. Right now my focus is on wrenching rather than on processing and uploading videos. So, I will get it uploaded, but no promises on timing.

I've heard from others that processing and uploading videos is a lot of work. I laughed. Then I tried it. I am humbled.
 
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You are a *terrible* narcissist.

Thank you, I try. :)

I've heard from others that processing and uploading videos is a lot of work. I laughed. Then I tried it. I am humbled.

It definitely takes a lot of work, and I don’t put in nearly the effort that folks like @SixPapaCharlie do. But I am trying to up my game, and little things like making good thumbnails (it’s amazing how much of a difference those make) all add to the effort.

Right now I have a completed video on some lights I installed/reviewed on my BMW, but I haven’t completed the thumbnail yet so it’s not published. I should do that.
 
Ok @Sac Arrow I didn't post the Cobra driving video (yet) but I did finally finish that video thumbnail for my BMW-related video, which will drop tomorrow.
 
Interesting that my tag line ****ed him off so much, oh well, it's not my issue.

Sent from my SM-N970U using Tapatalk
 
Hmm the comment is still there last time I looked, why would that be a challenge, and how did his efforts affect me?

Sent from my SM-N970U using Tapatalk
 
Awesome to see that car out of the garage, Ted.

Thank you! It’s really a great personal milestone. Now that I can call it “a car” it’s time to go through the paperwork to complete that process.
 
The Cobra is now officially insured!

I ended up going with Hagerty on this, at least to start. For these cars, a lot of policies are "pleasure drives only", and there are some stories (probably overstated like with most things) of people getting dinged in the Home Depot parking lot and not getting covered because that doesn't count as a pleasure drive. I figured that I would just go into it saying that I was going to take my kids to school, drive it to the office, etc. and wanted it insured accordingly so there was no question.

Hagerty was willing to work with me on that. What surprised me was how much it was like getting insurance for an airplane. They wanted to know my driving history - not tickets or things like that, but what cars I'd owned and driven and years of experience driving high performance cars (they don't count old liter bikes, which I get but is funny in some ways because those are actually more twitchy). I've owned varying high performance cars my entire driving career so this wasn't an issue, but it's the first time this has happened. A lot more questions about the car itself.

I also did a declared value on the car. Nothing new to me with aviation, and I've been keeping track of spending so I came up with a number appropriate for what I have in it and what replacement would be.

Now I have to go by the sheriff's office and the courthouse to try to make it a car.
 
Oh, another thing I was definitely doing better at on the track day Thursday was trail braking. While I've been working at that some, for whatever reason it was going better Thursday. That was a nice bonus.

June 15th is the next track night, so I'll want to drive again then. Pulling the carb apart and trying to clean it further so the primaries will work properly I think is a first goal (although that will require some time dedication - and I do have a lot going on with the RV and the Cobra). But also of interest to me is working to increase rear downforce. I'm thinking about adding a universal wing on back that I can play with some there. If done right, tuning of those can be a challenge, but I think that it would help. Lemons rules would allow it. The new MSD coil will show up and I'll throw that on to see if I observe any improvement from a stronger spark (and I may increase the spark plug gap a bit since that should help too).

Horsepower, of course, is a goal - but that's also not something that has any easy options for improvement.
 
I'm thinking about adding a universal wing on back that I can play with some there.


Hmmmmm........ When is it you need more downforce? Are you spinning the tires while accelerating off a corner? (Very doubtful with Wankel torque)

If you want more rear traction while cornering, think about your corner speeds vs. straightaway speeds. A wing that will help in a corner will give you lots of drag down the straight, and with a low HP car the last thing you want is more drag. I'd chase suspension tuning and tire pressures before fooling with a wing. What do your tire temps look like? Are you getting good tire rollover (you chalk the tires, right?)?

Trail braking should help a lot with initial turn-in. The car, when it's dialed in, should oversteer while trail braking during turn-in, go neutral when you smoothly transition from brake to throttle, and finally push a bit under acceleration as you exit the corner under full throttle.
 
Realizing I made a post in the wrong thread. Correcting. :)
 
What do they consider "high performance"? More than 200hp?

They don’t specify. I used my judgement (and included the RX7 in that since it’s a dedicated track car) and they accepted it.
 
Today and tomorrow are the last two days of school for my kids. Being home solo I gave them an opportunity to pick a "slot" for driving them to/from school today and tomorrow. Surprisingly, they all agreed on which slot they wanted, and so I drove the first one to school this morning. This also got me about another 20 miles or so on the car to observe its behavior further.

The engine still needs tuning obviously, but it's running really strong. For some reason the engine has quite a high idle, 1500-2k RPMs, and that's with the idle adjustment screw all the way out. Another interesting note is that the #5 cylinder (furthest forward on the driver's side) does not seem to be pulling vacuum through the velocity stack the same as the others. If I put my hand over each of the cylinders at idle, #5 feels like nothing, the other 7 will try to suck my hand in. My first thought was that I'd wiped out some cam lobes or there were issues with rockers (which didn't make sense given how well the engine was running). Pulled that side valve cover and the rockers are on just fine, and the valve lash on that side was actually all still quite good. Loosening up a hair from where I first set it, which isn't surprising now that the engine's run a bit, but still plenty fine and not indicative of any kind of problems.

I'm trying to figure out where that sort of a leak could be coming from. I need to get a fresh bottle of carb cleaner to try to find the location of the leak, so far I've not found anything and there's nothing obvious. The fact that it's impacting that cylinder dissimilar from the others would indicate something like the intake gasket not sealing, but if that were the case I'd also expect the coolant crossover to not be sealing, and that would create a very obvious leak. I put a lot of effort into trying to seal up the intake when I put it on, and I would be surprised if there was an issue there.

Right now it seems to be running very rich, which isn't surprising given the initial tune, but 10-12:1 is richer than it needs to be, especially in cruise. I purchased the upgrade for MegaSquirt's auto-tune and I'll need to drive it around some with that to see if it makes a difference that's at all noticeable and what that difference might be.

I seem to recall there was something about the Speedmaster intake I used that was different on the #1 cylinder compared with the others, but for the life of me I can't remember what that was, and my videos on it (which I've now rewatched) haven't provided any insight on what it could be. So for now, I'll do some more investigation and work further on tuning.

Not surprisingly, the brakes need to get a more aggressive pad being manual. I had just put on the initial normal pads that the calipers came with (which are probably cheap junk) and they stop fine, but it should have more power. So I ordered some EBC Yellow Stuff pads after looking through the options, thinking those would probably work the best. One of the big things I wanted was good cold initial bite, since this is a street car first. The yellow stuff look to be pretty consistent up to higher temps than I'm likely to get these brakes too, even on the track.

There are other little notes, but for now, I'll just keep a list and chip away at the little items. At 500 miles I'll plan to pull the valve covers and do an adjustment.
 
Very cool Ted!
 
I have the EBC Yellows on my Excursion (SSBC 8-piston front/rear calipers) and they are fantastic. Lot of dust compared to typical pads, but the bite is evident. I've run them on several other sports cars as well with similar results. If you're tracking it you can look at the Redstuff lineup, but the Yellows are great for the sport-touring setup. As far as the vacuum, any chance it's just at the velocity stack and not the actual intake? Did you pull plugs on that cylinder and a few others to compare?
 
OUTSTANDING!!! Her schoolmates must be awfully jealous. I know I am!

One of the fun things I'm already seeing with this car is how many smiles it gets. The Harley riders with no helmets look at me like I have 2 heads driving a car with a helmet on, but with no windshield the wind and face protection makes wearing my motorcycle helmet natural.

We got there right as the school busses were letting out, and a bunch of the kids were looking, pointing, and smiling. I used to be that kid, so it makes me smile to see that there are still kids like that. :)

I have the EBC Yellows on my Excursion (SSBC 8-piston front/rear calipers) and they are fantastic. Lot of dust compared to typical pads, but the bite is evident. I've run them on several other sports cars as well with similar results. If you're tracking it you can look at the Redstuff lineup, but the Yellows are great for the sport-touring setup. As far as the vacuum, any chance it's just at the velocity stack and not the actual intake? Did you pull plugs on that cylinder and a few others to compare?

I used EBC Greens on my Jaguars back over 20 years ago and other than that I've only used them on motorcycles. I was originally going to go with Hawks as a lot of folks have recommended them with manual brakes on these cars (and I like them on the RX-7), but after looking through the various options, the yellows looked to me like they would fit the best. I don't want pads that have to warm up to get to a good bite, and want a high initial bite. Seemed like the yellows fit the bill better than the others. Dust is fine, for one it's a performance car, and also the rims are black. :)
 
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