unfinished cars ?

[Rune]

I see lots of unfinished cars, mine is "finish" I got my registration and is allowed to drive on public roads. But up in my head the car is not finish. Every time i look on the the car , the brain cells start to vibirate, I see lots of small things that could be more perfect. So I make me a list of things that I can do to make the car better in many ways. Things that was not done in the 60's. Then I ask me a question , will someone see the changes and correct me, if so I think of let it be as is. But one thing I will do are the exhaust I will change to stainless, not for the eyes, but only due to reduce the heat around the engine. It is also a challenge to make it all alone from some lengths of 1 3/4" tubing. All other changes on my list will undergo some study before hey see daylight .
Does some of you out there have the same feeling about your "40"

 

[Neil]

I see lots of unfinished cars, mine is "finish" I got my registration and is allowed to drive on public roads. But up in my head the car is not finish. Every time i look on the the car , the brain cells start to vibirate, I see lots of small things that could be more perfect. So I make me a list of things that I can do to make the car better in many ways. Things that was not done in the 60's. Then I ask me a question , will someone see the changes and correct me, if so I think of let it be as is. But one thing I will do are the exhaust I will change to stainless, not for the eyes, but only due to reduce the heat around the engine. It is also a challenge to make it all alone from some lengths of 1 3/4" tubing. All other changes on my list will undergo some study before hey see daylight .
Does some of you out there have the same feeling about your "40"

A builder never sees the car as "finished".

 

[Ian Anderson]

I see lots of unfinished cars, mine is "finish" I got my registration and is allowed to drive on public roads. But up in my head the car is not finish. Every time i look on the the car , the brain cells start to vibirate, I see lots of small things that could be more perfect. So I make me a list of things that I can do to make the car better in many ways. Things that was not done in the 60's. Then I ask me a question , will someone see the changes and correct me, if so I think of let it be as is. But one thing I will do are the exhaust I will change to stainless, not for the eyes, but only due to reduce the heat around the engine. It is also a challenge to make it all alone from some lengths of 1 3/4" tubing. All other changes on my list will undergo some study before hey see daylight .
Does some of you out there have the same feeling about your "40"

Hi

Why not have your current exhaust ceramic coated? It will greatly reduce your under fiberglass temperature.

Stainless steel exhaust may look nice but transmits even more heat to the engine bay.

Ian

 

[Scott]

I agree that ceramic coating will make a difference. I've recently discovered Zircotec's ThermoHold solution. It's applied with robotic plasma-spray robotic system, baked at 550°C (1,022°F) and is suitable for applications of up to 1,400°C (2,550°F). This results in a thicker 0.3mm (0.012″) textured coating that allegedly has 2x the heat retention of the smooth-finish ceramic coatings that I'm familiar with. I've ordered some sample parts, but I'm not sure I want to ship my headers to the UK. Does anyone have experience with it?

I disagree that stainless steel will transmit even more heat. If you look at the table below, carbon steel has a thermal conductivity (TC) that is 2.8x higher than 304 or 316 stainless steel. The 2.8x won't be fully realized in an exhaust system because stainless steel's TC increases as temperature increases whereas carbon steel's TC decreases. That said the cross over point is around 1,000°C (1,832°F) which is pretty much the top end of a turbo application, so stainless steel should have a lower TC across your entire EGT range.

Note that stainless steel's TC is lower than both Inconel and Titanium (I have seen titanium as low as 14.2), but those materials are lighter and more durable. I also assume that their TC performance doesn't drop off the way that stainless steel does.

If you're serious about heat mitigation, you fabricate in stainless steel and then ceramic coat it. I didn't use stainless steel for looks, I did it because it's significantly more durable and it transmits less heat. I haven't decided which ceramic coating I'll use.

If you decide to go stainless, you'll need to choose which type. Here's what my fabricator recommends:

*304 Stainless Steel: 16 for street and 18 for race
*321 Stainless Steel: 18 for street and 20 for race

The logic is that if you're racing, you'll likely trade off long-term durability to save weight. 321 will cost 30-40% more than 304, but it allows you to go up a gauge (i.e., lighter tube) for similar durability.

 

[Mark Boyers]

Just finished ours rune 304 stainless ceramic coated inside and out with 30%less under body heat to be expected

 

[Joel K]

I agree that ceramic coating will make a difference. I've recently discovered Zircotec's ThermoHold solution. It's applied with robotic plasma-spray robotic system, baked at 550°C (1,022°F) and is suitable for applications of up to 1,400°C (2,550°F). This results in a thicker 0.3mm (0.012″) textured coating that allegedly has 2x the heat retention of the smooth-finish ceramic coatings that I'm familiar with. I've ordered some sample parts, but I'm not sure I want to ship my headers to the UK. Does anyone have experience with it?

I disagree that stainless steel will transmit even more heat. If you look at the table below, carbon steel has a thermal conductivity (TC) that is 2.8x higher than 304 or 316 stainless steel. The 2.8x won't be fully realized in an exhaust system because stainless steel's TC increases as temperature increases whereas carbon steel's TC decreases. That said the cross over point is around 1,000°C (1,832°F) which is pretty much the top end of a turbo application, so stainless steel should have a lower TC across your entire EGT range.

Note that stainless steel's TC is lower than both Inconel and Titanium (I have seen titanium as low as 14.2), but those materials are lighter and more durable. I also assume that their TC performance doesn't drop off the way that stainless steel does.

View attachment 127816

If you're serious about heat mitigation, you fabricate in stainless steel and then ceramic coat it. I didn't use stainless steel for looks, I did it because it's significantly more durable and it transmits less heat. I haven't decided which ceramic coating I'll use.

If you decide to go stainless, you'll need to choose which type. Here's what my fabricator recommends:

*304 Stainless Steel: 16 for street and 18 for race
*321 Stainless Steel: 18 for street and 20 for race

The logic is that if you're racing, you'll likely trade off long-term durability to save weight. 321 will cost 30-40% more than 304, but it allows you to go up a gauge (i.e., lighter tube) for similar durability.

Scott, I just received some Zircoflex Form to fabricate some heat shields. It’s embossed stainless sheet with their coating applied on both sides. The main reason I purchased it was due to how tight the clearance from each cat is, So far I like the product. Easy to cut and form. Hopefully it does the job.

FYI,

Hector used this company in NY that applies Ceramic .015” thick on his headers. They only spray that thickness on in white, but I think you can coat it with a color coat on top.

White Lightning Exhaust Coatings – Swain Tech Coatings | Industrial Coatings | High Performance Racing Coatings

 

[Duncan Horlor]

I've recently discovered Zircotec's ThermoHold solution

I used Zircotec to coat a few exhausts on my old race cars. It made a huge difference in getting the heat to the outside of the engine bay compared to just a wrap. It does chip though if you aren't careful.

 

[colin artus]

Anyone with experience of Cerakote?

 

[Neil]

Anyone with experience of Cerakote?

Yes, my long-tube headers are Cerakoted. The coating is holding up nicely even though I've run on the salt flats of Bonneville a few times.

 

[Scott]

Joel, I plan to use both ZircoFlex and ZircoForm for heatshields. I had spoken with SwainTech a long time ago. Their solution will retain heat much better than the smooth ceramic coatings because it's a thicker coat of actual ceramic material rather that a paint with ceramic flakes in it. That said, they're 100% clear that it's an "ugly finish that get's uglier with use." When I asked about painting them, they indicated that they've had customers pain them black to hide finger marks, discoloring, etc.

Colin, my fabricator Cerakotes all his stainless parts that get hot. He's never had a problem including with headers or turbo manifolds that look great after years of use.

Colin, which ZircoTec product did you use? The Performance Coating or ThermoHold? The Performance Coating is a polymer-based liquid with ceramic flakes in it that provides a smooth finish. I assume that it's similar to Cerakote and other smooth ceramic coatings. ThermoHold is sprayed plasma and seems similar to SwainTech. They offer multiple colors, but white is their highest performing color. The finish is textured, but it looks pretty nice in the pictures so I ordered a few samples. SwainTech has been doing their coating since the 70's and I'm hoping that ThermoHold is a more modern version.

 

[Joel Heinke]

I have used Cerakote and SwainTech on 2 different cars both with good results.

This Cobra side pipe is Cerakote.

It was originally ceramic coated by JetHot when the car was initially built in the mid-90s. After about 40K miles, the muffler rotted out and thus needed replacement. After welding a new mufflers in, the pipes were coated with Cerakote. The Cerakote looks as good or better than JetHot, has held up well and shows no signs of issues. I can't really say if the heat retention of Cerakote is any different than JetHot because it's a different type of muffler (double walled so it's much cooler for that reason). I don't really worry about "Snake bites" anymore but that's due to muffler difference more than coating difference.

I also have a home built replica of a Ferrari 250GTO with a supercharged LS engine and C5 drivetrain. The headers and head pipes are coated with SwainTech coating. I don't have pictures of the after coated exhaust and haven't taken heat measurements so I only have subjective information to provide. Here's a picture of the pre-coated exhaust that's all in 304 SS including the mufflers.

I don't sense too much heat coming off the headers with the engine idling in the garage/driveway but I do know the headers get hot during driving as a plastic piece with cylinder number on one of the spark plug wires melted from a position between the header tubes. Only 1 of 8 has done this so far but it's a good indication of the heat being radiated from the headers. The white coating has discolored to light grey where some oil has leaked from a valve cover on it but I sort of expect that.

There is an issue of too much exhaust heat entering the car's interior that I haven't addressed yet. Again, the SwainTech coating is on headers and up to mufflers but not beyond. The engine is positioned at the rear of engine compartment (harmonic balancer a few inches rear of front wheel centerline) so scatter shield is just inside the tunnel. The tunnel is covered inside and out with aluminum sheet with 1 1/2" of industrial ceramic oven insulation in between. The aluminum sheet passes heat right through it but the insulation should be stopping it but not sufficiently so. The mufflers are located adjacent to the drivers and passenger seats in the tunnel as that was the only open space that could accommodate them (C5 transaxle and fuel cell take up all chassis space rearward of them). In driving during California summer heat, the A/C couldn't keep the interior cool at outside temps over 90 degrees. My guess is that there is heat radiating from the headers, head pipes and mufflers causing this. My plan is to put DEI exhaust heat barrier on the head pipes and mufflers when I get the chance.

Given what I've experienced so far, the SwainTech coating seems to work better than typical ceramic coating at slowing heat radiation but it's not a cure all either. Given the GTO is a very challenging application to address (5.7L of supercharged front engine heat generation in a very tight space), I'd say from what I've seen so far that if you have concerns with radiated heat it should be considered. I think the rough white finish looks fine but that's more of a personal opinion than anything. Stains on smooth ceramic coat can be cleaned with metal polish but the only option for "refreshing" the look of SwainTech is high heat paint.

I don't know if this long winded reply helps but there you have my experience.

 

[Oliver]

Hello,

just finished mine with Zircotec

Rgds

 

[Neil]

Hello,

just finished mine with Zircotec

Rgds
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The headers have an attractive finish. Are those all-metal locknuts?

 

[Oliver]

Hi Neil
If you mean between the primary and the collector, yes those are full metal locknuts.

 

[Neil]

Hi Neil
If you mean between the primary and the collector, yes those are full metal locknuts.

Good idea! I'd hate for you to lose such beautiful collectors somewhere on the roadway.

 

[Brian]

Despite most chinese V band clamps being supplied with them, this wouldn't be a good application for a nylock nut.

 

[Oliver]

it is regular - not nylock

 

[Doc Watson]

If yours is 'finished' Bune, then pop over to mine and help me with a little fettling.... ;-)