DuPuis Family Cobra Build

[Ted]

My cousin just took delivery on the F350 with one of these. This is the motor that converted him from diesel.

Honestly the modern diesels don't make a ton of sense. I might've bought a 6.4 Hemi if they'd offered a manual transmission with it.

 

[MIFlyer]

Late to the response on this, but I tend to think you're right. The last time I wrapped headers was in college, and to be honest I have no idea if I did a decent job or not back then. I've already installed the headers so removing them would be annoying to wrap them, but I suspect that keeping that heat out of the engine bay is probably the way to go.

I have to think some more on this, but what might be the thing to do would be get at least past first start and into the Go-Kart stage a bit and then pull them off to do it, when I may have to do some other work anyway.

What about doing Jet Hot?

 

[MIFlyer]

Last night I walked around the Cobra some, trying to look at where I was and figure out what I need to do next in the quest to keep moving forward. The reality is none of it is going to happen too soon just because my bandwidth is absorbed on RV and Disco projects (and trying to get the shop built). But maybe I'll get some time here and there.

My next steps can end up in one of three areas:

1) Electrical. Need to make more progress on the main wiring both around the rear of the car (where I have the main power distribution and relays) and also from the front to the rear.

2) Dashboard. The dash aluminum panel is ready to be covered and then have the gauges installed. I could argue doing this either before or after the main wiring above. Ultimately I think this is sort of a six of one half dozen of the other sort of choice, but I'm thinking the dash might make more sense, that way when I run wires up it'll just be the appropriate power wires, sort of a subsystem of the electrical.

3) Dynamat and carpeting for most of the interior and the trunk. I do still have to do some metalwork related to the trunk because of the AC compressor location back there, and how it sticks above the floor pan. This is one that doesn't really need to be done at this point, but is something I might do anyway because it's something that I can do relatively easily without needing a more significant block of time.

Truthfully the biggest problem I have with getting progress done on this right now is the garage. After tearing down one of our outbuildings in preparation for the new shop (not to mention RV/Land Rover projects and other projects that we have stuff for) the garage is really packed. I can't even get to working on it without moving things around. Maybe I'll get motivated enough to piddle on it some evenings and move enough around to get at it.

It would be nice if I could get the car running in time to get it driven into the shop, but I just don't see that happening. Really at this point it's just wiring and some clean-up to make that happen, but it's a good amount of wiring. Theoretically the shop should be done sometime in December, but between weather and general contractor delays, who knows when we'll get the thumbs up from the county for occupancy. I want it done but maybe if it takes longer that'll actually make it more likely I can get the Cobra driving in time.

One alternative to dynamat is to spray Al's Heat and Noise reducer. I'm doing this both underneath and inside my project. It's supposed to be worth about 40% reduction in heat and noise transmission.
https://alsliner.com/shop/heat-and-... heat reflection and sound deadening properties.

 

[Ted]

What about doing Jet Hot?

That would be another option. My understanding is that wrapping headers will insulate them better than a ceramic coating, and also cost less. Given the purpose of the build, I think it would work well.

One alternative to dynamat is to spray Al's Heat and Noise reducer. I'm doing this both underneath and inside my project. It's supposed to be worth about 40% reduction in heat and noise transmission.
https://alsliner.com/shop/heat-and-noise-reduction/#:~:text=Al’s Liner Heat and Noise Reducer (HNR): Al’s,incredible insulation, heat reflection and sound deadening properties.

That would be an option. But I already bought the stuff I'm using. I'm calling it Dynamat but it's Rockmat - Dynamat clone that's cheaper but seems to work just as well. I used it on the Kenworth for noise reduction and it worked well.

 

[SoonerAviator]

Honestly the modern diesels don't make a ton of sense. I might've bought a 6.4 Hemi if they'd offered a manual transmission with it.

Lol well they make sense if you use them for their intended purpose: towing heavy loads long distances. If you need a truck to run across town, the modern diesel is a waste. The new 7.3 Godzilla is great for those short runs and hauling whatever will fit in the bed. They won't get the fuel mileage of the diesel, or the power, but they make up for it by being cheaper to purchase and maintain.

 

[Ted]

Lol well they make sense if you use them for their intended purpose: towing heavy loads long distances. If you need a truck to run across town, the modern diesel is a waste. The new 7.3 Godzilla is great for those short runs and hauling whatever will fit in the bed. They won't get the fuel mileage of the diesel, or the power, but they make up for it by being cheaper to purchase and maintain.

I should've elaborated some. For the normal buyer these days modern diesels add a lot of complexity and reduced reliability. If you're using it for local driving the emissions equipment on diesels will be really unreliable. If you're one of the relatively low percentage that uses it as it's designed almost exclusively, then yes, you'll see better mileage and probably be happier with the diesel.

It used to be that diesels were more expensive when they broke, but they basically never broke. Think the PowerStroke 7.3, 12-valve and early 24-valve 5.9 Cummins. Yeah the 6.2/6.5 diesels were junk but that was the exception. In the late 2000s it was obvious that the emissions were not ready for prime time and I advised against buying diesels for pretty much anyone. They've definitely gotten better and I had hoped that they'd be good to go by 2017 when I bought mine, but then at 40k miles I got a check engine light for the SCR (DEF) system. Really? Yeah, I still advise against the diesel for most people.

 

[Bill]

To me a really good truck value is something like an F250/F350 in base trim with the 7.3 gasser or similar. Very capable for most uses and relatively inexpensive and simple compared to a modern diesel. Something like that would be a 20yr truck easy with decent MX.

 

[Ted]

To me a really good truck value is something like an F250/F350 in base trim with the 7.3 gasser or similar. Very capable for most uses and relatively inexpensive and simple compared to a modern diesel. Something like that would be a 20yr truck easy with decent MX.

Yeah, I think it's definitely questionable how maintainable my truck will be in 20 years. I'll still be able to do it, don't get me wrong, but I don't see it having the level of bulletproof reliability that @denverpilot 's Ram was known for.

 

[SoonerAviator]

Yeah, I think it's definitely questionable how maintainable my truck will be in 20 years. I'll still be able to do it, don't get me wrong, but I don't see it having the level of bulletproof reliability that @denverpilot 's Ram was known for.

Agreed. I'm hoping my "bulletproofed" 6.0 PSD in the Excursion keeps itself running without any major issues. EGR deleted, o-ringed heads, coolant filtration/bypass oil filter and ARP head studs. I'm not running any tunes on it, but do have an SCT Livewire programmer to monitor various parameters. Get to do the first 2 oil filter/2 fuel filter/15qt oil change here in another week or two, lol.

 

[Ted]

Agreed. I'm hoping my "bulletproofed" 6.0 PSD in the Excursion keeps itself running without any major issues. EGR deleted, o-ringed heads, coolant filtration/bypass oil filter and ARP head studs. I'm not running any tunes on it, but do have an SCT Livewire programmer to monitor various parameters. Get to do the first 2 oil filter/2 fuel filter/15qt oil change here in another week or two, lol.

My 6.0 didn't hold up, but I think it was a stock long block with some of the items you listed. However in retrospect, I think that engine had a significant turned up tune - wouldn't surprise me if it was +120 tune, and that's why it blew a cylinder. Of course, I also had a 7.3 F-250 that I took on trade with a dead cylinder (no compression), and that one I do think was a stock engine.

 

[SoonerAviator]

My 6.0 didn't hold up, but I think it was a stock long block with some of the items you listed. However in retrospect, I think that engine had a significant turned up tune - wouldn't surprise me if it was +120 tune, and that's why it blew a cylinder. Of course, I also had a 7.3 F-250 that I took on trade with a dead cylinder (no compression), and that one I do think was a stock engine.

Yeah, I believe this one probably had the typical EGR/oil cooler failure so they went the bulletproof route while doing the repair. The o-ringed heads are aftermarket (Kill Devil Diesel), but they are supposedly factory spec so it's not been set up to make big power, just reliable power. Has a new-ish Ford turbo and Ford injectors/glow plugs as well, so it *should* hold up pretty well. It's not going to spend much time towing, and when it does it will typically be 6K lbs and below (half the tow rating). However, when doing my research on the Excursions the diesels hold their value EXTREMELY well, and the 6.0L gets the best fuel mileage/acceleration/power out of all of the available options so I decided to take a chance. If the 7.3L Godzilla had been an option, I probably would have went that direction. I did just put 39 gallons of diesel in it the other day after having gone a bit over 620 miles on the tank. At that rate, I'll fill it up once a month, lol.

 

[Ted]

Yeah, I believe this one probably had the typical EGR/oil cooler failure so they went the bulletproof route while doing the repair. The o-ringed heads are aftermarket (Kill Devil Diesel), but they are supposedly factory spec so it's not been set up to make big power, just reliable power. Has a new-ish Ford turbo and Ford injectors/glow plugs as well, so it *should* hold up pretty well. It's not going to spend much time towing, and when it does it will typically be 6K lbs and below (half the tow rating). However, when doing my research on the Excursions the diesels hold their value EXTREMELY well, and the 6.0L gets the best fuel mileage/acceleration/power out of all of the available options so I decided to take a chance. If the 7.3L Godzilla had been an option, I probably would have went that direction. I did just put 39 gallons of diesel in it the other day after having gone a bit over 620 miles on the tank. At that rate, I'll fill it up once a month, lol.

Yeah, whoever bought my F-350 got a whole lot of good parts that went on an engine that needed to be replaced since I did most of those. I think if you sort through it well it should be reliable. I was close to just putting in a new engine instead of buying the Ram, especially after I'd done some of the other upgrades (like the King Ranch interior), but that truck had enough other problems that it didn't make sense, plus it didn't have a manual and the sound of the 6.0 is... well... not to my taste let's say.

The Fummins swap (Cummins in an F-350) would've changed things around, and I've even seen a couple folks try to shoehorn a Cat 3126 into some F-350s. There's even a guy who put a Detroit Diesel 4-53T into a 2009 F-350, which I think is ridiculous but he did a good job with it. In all cases, though, more work than I felt like doing.

 

[Bill]

plus it didn't have a manual and the sound of the 6.0 is... well... not to my taste let's say.

Nothing beats a straight 6 diesel for sound...

 

[Ted]

Nothing beats a straight 6 diesel for sound...

That's why I like my straight piped Cummins. Although even I'm starting to think that a muffler of some sort (small) might not be a bad idea.

 

[denverpilot]

Yeah, I think it's definitely questionable how maintainable my truck will be in 20 years. I'll still be able to do it, don't get me wrong, but I don't see it having the level of bulletproof reliability that @denverpilot 's Ram was known for.

I hope the rancher is still using that truck.

 

[Zeldman]

Although even I'm starting to think that a muffler of some sort (small) might not be a bad idea.

I have a 36 inch glass pack on my Duramax which a lot of folks tell me they like the sound. The exhaust exits behind the right rear wheel, and I have a turndown to prevent the exhaust from blowing into other vehicles. I also don't have the annoying exhaust drone inside the cab while at highway speeds.

 

[SoonerAviator]

Yeah, whoever bought my F-350 got a whole lot of good parts that went on an engine that needed to be replaced since I did most of those. I think if you sort through it well it should be reliable. I was close to just putting in a new engine instead of buying the Ram, especially after I'd done some of the other upgrades (like the King Ranch interior), but that truck had enough other problems that it didn't make sense, plus it didn't have a manual and the sound of the 6.0 is... well... not to my taste let's say.

The Fummins swap (Cummins in an F-350) would've changed things around, and I've even seen a couple folks try to shoehorn a Cat 3126 into some F-350s. There's even a guy who put a Detroit Diesel 4-53T into a 2009 F-350, which I think is ridiculous but he did a good job with it. In all cases, though, more work than I felt like doing.

Yeah, mine has a pretty good turbine whistle at idle. I think they changed turbine wheels to a 13-vane from the 10-vane in mine, which quieted it down some.

 

[Ted]

I have a 36 inch glass pack on my Duramax which a lot of folks tell me they like the sound. The exhaust exits behind the right rear wheel, and I have a turndown to prevent the exhaust from blowing into other vehicles. I also don't have the annoying exhaust drone inside the cab while at highway speeds.

With the 5" straight pipe I get a drone at around 1900-2100 RPM, which equates to about 77-86 MPH. 90 is quieter than 85, for instance.

For most of my driving, which is 75 or less, I only get the noise/drone when I'm accelerating through the gears through that rev range. When I'm on a longer highway trip and want to go 80-85, that's a problem and it does get annoying.

However, the other issue I have is the exhaust brake. On this truck the exhaust brake closes up the VGTs so that the turbo provides a restriction. This also causes the turbo to spin fast, and the end result is that the exhaust has a turbine engine exhaust sound. The ECU will engage the exhaust brake at idle on cold days to help warm the engine up faster.

Let me tell you, I am not kidding when I say that exhaust with that on at idle is rivaling a TPE-331 in volume and sound type. It is really loud and obnoxious if you're standing near that outlet. If I'm driving with the windows down the exhaust brake also seems obnoxious.

I don't drive in city traffic a lot, but it's a consideration. I'm not going to do a muffler yet, but I may. The rest of the time I'm happy with the exhaust, but those two items may cause enough grievance for me to do something about it.

 

[3393RP]

Nothing beats a straight 6 diesel for sound...

If you're speaking of the first generation Cummins in Dodge trucks, I think you mean noise. Jeeezus those things were loud.

 

[3393RP]

A 7 liter cast iron block engine isn't going to do anything good for the car's weight distribution.

It worked OK with the seven liter 427 FE.

 

[denverpilot]

If you're speaking of the first generation Cummins in Dodge trucks, I think you mean noise. Jeeezus those things were loud.

Second gen weren’t any quieter. Switching from the mechanical fuel pump to the Bosch made no difference. Ha.

 

[3393RP]

Late to the response on this, but I tend to think you're right. I've already installed the headers so removing them would be annoying to wrap them, but I suspect that keeping that heat out of the engine bay is probably the way to go.

I have to think some more on this, but what might be the thing to do would be get at least past first start and into the Go-Kart stage a bit and then pull them off to do it, when I may have to do some other work anyway.

It's worth the effort. If it was my decision, I would wrap them now. I understand the Go-Kart stage reference, but the A/C hoses, electrical and ignition wiring, and other systems will be partially or fully installed by then. It will be easy to rationalize not doing the wrap.

I'm sure you realize that minimizing underhood temperature is critical, especially because of the induction system you are using.

The last time I wrapped a set of headers, I used DEI Titanium wrapping. It has ground lava in the material, which has excellent heat absorption properties.

https://www.designengineering.com/titanium-exhaust-wrap/

It's also available in black:

https://www.designengineering.com/black-titanium-exhaust-wrap/

I prefer the classic look of the original color wrap.

Removing the headers would also allow you to paint the entire engine more easily. The last photo I saw, it was not a uniform color, which I believe was due to installing some accessory parts after the block was in the car. With all the effort you're expending, it would be a shame to have an engine with a bit of a barnyard look to it.

 

[Ted]

It's worth the effort. If it was my decision, I would wrap them now. I understand the Go-Kart stage reference, but the A/C hoses, electrical and ignition wiring, and other systems will be partially or fully installed by then. It will be easy to rationalize not doing the wrap.

I'm sure you realize that minimizing underhood temperature is critical, especially because of the induction system you are using.

The last time I wrapped a set of headers, I used DEI Titanium wrapping. It has ground lava in the material, which has excellent heat absorption properties.

https://www.designengineering.com/titanium-exhaust-wrap/

It's also available in black:

https://www.designengineering.com/black-titanium-exhaust-wrap/

I prefer the classic look of the original color wrap.

Removing the headers would also allow you to paint the entire engine more easily. The last photo I saw, it was not a uniform color, which I believe was due to installing some accessory parts after the block was in the car. With all the effort you're expending, it would be a shame to have an engine with a bit of a barnyard look to it.

You make really good points on all counts. Removing the headers will also give me the chance to more easily put a sort of heat shield around the brake line to the rear that I routed poorly, which should get done.

Painting, that's my own fault and stupidity/impatience. The reality is I should've painted the block when I was building the engine in the first place. I have no desire to paint the aluminum heads (I think that those look good just in their natural color), but trying to get the rest of the block would be good. The problem is, at this point I wonder if I haven't gone too far with the engine to be able to do that without a more thorough removal and tearing into. I have to think about that some more I guess. The engine is pretty well covered up at this point in many ways. If I'd had dummy/slave components then I would've been able to easily paint the block before. Now? Ehh...

 

[3393RP]

Removing the headers, intake, driven accessories, and ignition components would probably be less work than you think. Your familiarity with the engine will speed the process. It'll be worth the effort, and in the long run you'll be unhappy with your car unless the engine is painted.

I think by now you've realized building the car is a marathon, not a sprint. Your earlier estimates of a completion date made shortly after you began the project were unrealistic, and now you know that.

Being an active and driven person, you have made a lot of commitments to your time. With your high personal standards, excellence is important. Take the extra few hours and paint that engine!

 

[Ted]

Well, I finally decided to make some progress.

I've worked on this on the past couple nights. Previously I'd gotten all the holes cut in the aluminum part of the dash, but I hadn't attached the vinyl front covering and then cut the holes in it for the gauges. All of that actually went easier than I thought it would. I did get the alignment a bit off of the vinyl when gluing it to the front from ideal, which gave me not as much extra up top as would've been ideal to wrap around the back side of the aluminum. In the end I still was able to get it completed. I may add some Rockmat to the back, especially around the top where the dash will attach to the frame since the vinyl there isn't entirely uniform. Next on this will be getting the lights and switches in and then starting to wire up the dash as a subsystem.

 

[Ted]

Removing the headers, intake, driven accessories, and ignition components would probably be less work than you think. Your familiarity with the engine will speed the process. It'll be worth the effort, and in the long run you'll be unhappy with your car unless the engine is painted.

I think by now you've realized building the car is a marathon, not a sprint. Your earlier estimates of a completion date made shortly after you began the project were unrealistic, and now you know that.

Being an active and driven person, you have made a lot of commitments to your time. With your high personal standards, excellence is important. Take the extra few hours and paint that engine!

I looked at the engine some last night to think about what I'd need to remove for paint. What I came up with was the starter, ignition coils, the distributor replacement, headers, and alternator. I could remove the water pump and the harmonic balancer to make things more "correct" for painting too, although both of those would be annoying to remove between needing a balancer puller (hmm... do I have one of those?) and breaking the seals on the water pump since I put that all together.

The intake manifold I'm not taking off and I wouldn't take off. I'd just tape that up, especially when you figure that the inside of the block and the heads I wouldn't be painting. Also, taking the intake off is not a simple task on this engine, mainly because of the heater location. But that intake isn't coming off. So I think if I paint the block, the real questions will be:

1) Do I take off the water pump and harmonic balancer? Leaning towards yes for the latter if I have a puller, no for the former.

2) What color do I paint it? (I think the answers are black or red, probably black))

What I really should have done is bought a few slave components cheap that I didn't care about (heads, intake, oil pan) and painted the engine with those slave components before installing it.

 

[MIFlyer]

You make really good points on all counts. Removing the headers will also give me the chance to more easily put a sort of heat shield around the brake line to the rear that I routed poorly, which should get done.

Painting, that's my own fault and stupidity/impatience. The reality is I should've painted the block when I was building the engine in the first place. I have no desire to paint the aluminum heads (I think that those look good just in their natural color), but trying to get the rest of the block would be good. The problem is, at this point I wonder if I haven't gone too far with the engine to be able to do that without a more thorough removal and tearing into. I have to think about that some more I guess. The engine is pretty well covered up at this point in many ways. If I'd had dummy/slave components then I would've been able to easily paint the block before. Now? Ehh...

HI Ted, I am struggling with similar decisions on mine. How much to do "while you've got this exposed" vs wanting to get back on the road, even if you're missing a lot of things.

That said, I do think that insulating the headers now is probably worth it. The bolts will come out easy, there's not much in the way, and it really shouldn't take very many hours. At that point, you can put them back in and be "done forever" for all intents and purposes.

 

[Ted]

HI Ted, I am struggling with similar decisions on mine. How much to do "while you've got this exposed" vs wanting to get back on the road, even if you're missing a lot of things.

In your case, you've still got the engine out (when I should've done painting).

That said, I do think that insulating the headers now is probably worth it. The bolts will come out easy, there's not much in the way, and it really shouldn't take very many hours. At that point, you can put them back in and be "done forever" for all intents and purposes.

Yeah. I think I've decided that wrapping the headers does make sense to do before first start. So I should look at some of that exhaust wrap (I think the titanium color is best, like @3393RP ), and figure out the paint (if I'm going to do it, and how I'm going to go about it).

 

[Zeldman]

Well, I finally decided to make some progress.

.

WOW.!!! 90 MPH...that thing is fast just sitting still.!!

You didn't like the ''backwards'' speedometer.??

 

[Ted]

WOW.!!! 90 MPH...that thing is fast just sitting still.!!

You didn't like the ''backwards'' speedometer.??

Yeah, most people go with the vintage replica gauges with the counter-clockwise speedometer. Most people also reverse the speedo and tach locations because they say the speedo is more useful (such people are not true drivers, in my opinion). I'm just not a fan, and don't think they're practical for a car you actually intend to drive.

 

[Bill]

Most people also reverse the speedo and tach locations because they say the speedo is more useful (such people are not true drivers, in my opinion).

Present GS, note tach, center top, speedo, lower left.

The RR I used to own, tach big, analog, speedo, small, digital

 

[Ted]

Present GS, note tach, center top, speedo, lower left.

The RR I used to own, tach big, analog, speedo, small, digital

View attachment 91371

More and more these days, tachs are afterthoughts as drivers no longer need to shift or think about when to shift. Looks like BMW has sort of shifted that way with your current GS having the tach smaller than the speedo, but at least it is further up so I suppose more readable when riding.

I'm a fan of how the tach is the biggest instrument in Porsches, and the speedo is more of an afterthought. That's how a performance vehicle should be.

 

[Bill]

Most new bikes now have TFT digital displays, the new GS uses this display, with a graphical tach.

It has many new capabilities, but the same old argument of needles vs digital displays goes on.

 

[Ted]

Most new bikes now have TFT digital displays, the new GS uses this display, with a graphical tach.

It has many new capabilities, but the same old argument of needles vs digital displays goes on.

I considered something similar for the Cobra before deciding to go with the traditional style gauges. Really, those digital displays are pretty amazing. I was very impressed by the one on the C8 Vette for instance. But they don't have the same sort of "feel" of a normal analog gauge.

 

[3393RP]

I could remove the water pump and the harmonic balancer to make things more "correct" for painting too, although both of those would be annoying to remove between needing a balancer puller (hmm... do I have one of those?) and breaking the seals on the water pump since I put that all together.

Autozone and O'reilly's have loaner balancer pullers.

 

[Ted]

Autozone and O'reilly's have loaner balancer pullers.

I’m aware, I’m just used to not leaving the house anymore.

 

[Bill]

I’m aware, I’m just used to not leaving the house anymore.

Ted DuPuis Hughes lol...

 

[Ted]

Ted DePuis Hughes lol...

Come on man, my last name is literally spelled out for you when you quoted my post and you still spelled it wrong!

 

[Sac Arrow]

It's about time we are able to gauge the progress on Ted's Cobra!

 

[Bill]

Come on man, my last name is literally spelled out for you when you quoted my post and you still spelled it wrong!