914-4 vs 914-6...heat exchangers, Trying to understand Dansk's price disparity Options

[horizontally-opposed]

Personal choice, but, IMHO, stainless is always the right choice for exhaust components. We've all pretty much forgotten how quickly mild steel rusts out in an exhaust since stainless has become the norm on OEM exhaust systems due to 10 year mandate w.r.t emissions integrity of the system.

Exhaust sytems constantly have condensation in them combined with an corrosive mix of emission particles. Rots mild steel from the inside out.

Back in the day of mild steel, in the mid-west rust belt, it wasn't uncommon to have to replace mufflers and pipes every 4 years or less due to corrosion.

Now stainless exhaust systems largely last the life of vehicles.

^ Good perspective—thank you! (IMG:style_emoticons/default/beerchug.gif)

I think 1 heat exchanger would be enough for most climates.. Also keep in mind when I developed mine the market was 1.625 versus oem which is 1.5" .. I do now make a stepped version of 1.5 to 1.625.. So I guess an apples to oranges comparison

I remember when your exchangers were 1.625 only, and thus not ideal for the 2.2 in my car. The 1.5s change that.

You make the point that Dansk is a big company in another post, and this puts you and other small vendors at an advantage in my view, as you are more agile. Imagine trying to buy a one header/one heat exchanger setup from Dansk? That option is very interesting to me—but I suspect it would have to be timed to a production run so you don't end up with orphans? Would solve the heat issue (at least here in CA), saves a bit of weight, and a bit of money too. (IMG:style_emoticons/default/idea.gif)

Every time this discussion comes up I wonder why no one has tried this “heat muff” method in conjunction with any of the less expensive headers readily available You only need some straight section of exhaust header to mate these to. https://www.ebay.com/i/153814316540?chn=ps&...rRoCzSUQAvD_BwE

These are used extensively on light aircraft, they come in a variety of sizes and can be adjusted to desired length with a pair of tin snipes.

I have a single 10” long heat muff on my RV 6 experimental aircraft. It puts out a lot of heat. Enough to knock the chill off of a very drafty cabin in the below freezing temperatures common in winter at 10’O00 feet.

Here is a much more sophisticated version. https://www.aircraftspruce.com/catalog/eppa...eat05-15249.php. (They must be good - they are “turbo”)

No doubt in my mind two of these mated to the OE heat system would provide plenty of heat to defrost windows and knock the chill off of a cold cabin, which is what most of us need since generally these are not cold climate driven cars.

They would not provide as much heat as the OEM design but when I turn on my stock six ones, I always end up just cracking the air diversion valves because generally the OE ones are way too hot.

These small ones also would not interfere with access to the exhaust studs for installing the headers. And they are readily removable so you can inspect for leaks in the header, unlike a set of old OEM ones that always make me cringe when I fire them up, not being fond of sleeping the big sleep.

You know, I have never seen those. Thought something like these would be smart, but didn't think about aviation as a source for them. This is why these discussion threads are a great thing—exchange of ideas. This is an interesting option, though I suspect it would require a header design with enough space around said tube to accommodate one or two of these. I guess you could try to put them very far back, but the plumbing to the heater valves would have a long ways to go—especially with driveshafts and/or any oil coolers around. So headers that leave some room for these up front, near the engine, would be a lot better...and probably more efficient too. Next thing to think about would be ground clearance. But this is another avenue to consider. Big thing is coming up with some good alternatives. Right now, I am liking Ben's stainless HEs (two or one) and MSDS if heat can be added somehow. What's cool with both is the ability to support businesses so active in this community.

[mepstein]

Every time this discussion comes up I wonder why no one has tried this “heat muff” method in conjunction with any of the less expensive headers readily available You only need some straight section of exhaust header to mate these to. https://www.ebay.com/i/153814316540?chn=ps&...rRoCzSUQAvD_BwE

These are used extensively on light aircraft, they come in a variety of sizes and can be adjusted to desired length with a pair of tin snipes.

I have a single 10” long heat muff on my RV 6 experimental aircraft. It puts out a lot of heat. Enough to knock the chill off of a very drafty cabin in the below freezing temperatures common in winter at 10’O00 feet.

Here is a much more sophisticated version. https://www.aircraftspruce.com/catalog/eppa...eat05-15249.php. (They must be good - they are “turbo”)

No doubt in my mind two of these mated to the OE heat system would provide plenty of heat to defrost windows and knock the chill off of a cold cabin, which is what most of us need since generally these are not cold climate driven cars.

They would not provide as much heat as the OEM design but when I turn on my stock six ones, I always end up just cracking the air diversion valves because generally the OE ones are way too hot.

These small ones also would not interfere with access to the exhaust studs for installing the headers. And they are readily removable so you can inspect for leaks in the header, unlike a set of old OEM ones that always make me cringe when I fire them up, not being fond of sleeping the big sleep.

I know at least one person tried it and said they got very little heat out of it. The surface area covered around the pipe was very small compared to the 4 & 6 heat exchangers.

[gereed75]

Key is matching the airflow to the heat transfer capacity. Restricting it a bit will get the temp up. Total btu capacity won’t match that of the much larger surface area of OEM exchangers but I am sure it could be made to work.