Trombone cooler: Making it more effective.

[Jdub]

Since I've been taking weekly drives of 45-minutes plus in the hotter weather (80degrees plus) here in the Northwest I have been thinking hard about how to make the trombone cooler work better for those of us with this cooler type. I see several options, discussed below:
= Air scoop via Pelican
= Modify bodyparts to permit more air:
1) Valance, fog light or holesaw a hole
2) Bellows: Cut, refab with tin in tasteful manner
3) Bumper/valance slot: add horizontal "helper" scoop to dish more air into this slot.

First off, I have a valance without fog lights. I like that. However, it means I cannot use a fog light hole to channel air to the cooler. I also have a lip spoiler, which may or may not prevent air flow.

I have determined that I have the option of purchasing an air scoop to put in place of the side marker light. But I like that light, so that's out.

I'd like to see if the rubber bellows on the passenger side can be reworked to route air to the cooler. This would be done in concert with a metal sheet that would wrap around the backside of the cooler, the tin curving towards the front at the other side of the cooler. This would cause the air to move to the cooler directly, with the sharp curve end throwing air forward before exiting.

Next option of course is to holesaw a nice round hole in the valance and route the air directly to the cooler via hose and tin.

Finally, the slot between the lower section of the alum. bumper and the upper section of the valance carries air into the front wheelwell. What if a horizontal scoop could be riveted to capture and dish more air into this slot?

I am convinced the trombone can be made to work better with simple fixes. My problem is simply that the air that gets to it is insufficient. As it stands, the only air that gets to it is via the slot between bumper and valance (take a look up at that slot) and whatever eddies vent in from the tire/wheelwell.

If you have an extra bellows or a trombone cooler (or both) you can lend or sell cheaply I'd be much obliged. I need these two items on my workbench to begin this project. All results to be posted here with specs. measurements etc. should they be successful in reducing oil temp overall.

None of this is a substitute for clean, proper oil and cleansing the oil lines, cooler, on-engine cooler, or proper mix/timing etc. as per my prior thread.

Many thanks!
John

[Neilk]

How about a cool collar type device for the trombone cooler?

[Chuck Moreland]

The real problem with the trombone isn't air flow, its surface area. Funneling more air in the front will make only a small improvement. The hard lines leading to/from the trombone actually provide more cooling than the device itself.

The best way to improve a trombone is to rip it out and replace it with a carrera cooler.

On the other hand, Carrera coolers do respond well to increased air flow.

[GettinHeadStuds]

I agree 100% with what Chuck has said.

[JP911]

Maybe start by simply cleaning it until you can see the brass (the lines too)? All of the gunk that builds up on these probably hurts the ability of the metal to conduct heat.

[Bill Verburg]

You could always braze Cu. or Bronze strips between the existing tubes. That would have the effect of increasing surface area.

[banjomike]

Chuck is right, and elephant racing sells a great carrera cooler with big inner diameter fittings (some aftermarket carrera style coolers have big restrictions in the fittings). There is also a company called Engine Builders Supply (or EBS Racing) that sells a cooler very similar to the carrera cooler, but about 2x as deep. It isn't listed on their website but if you call and ask about the Austrailian cooler they'll tell you about it. They told me that for ~$350 it comes with mounting parts and the baffles that go around it to prevent air flowing around it. Sounds like a hell of a deal with me. They had one of the coolers at the Parts Heaven swap, and it looked really nice with big ID fittings. I was going to buy it last month but the money went into new ball joints. Oh well.

When my mechanic replaced my clutch he spent some time and tuned up my engine really well. Since then I have never had it go over ~225 (and that was with hours of non-stop high speed with lots of full throttle speed changes, in ~100deg temps in the Central Valley) Even multiple laps at autocrosses haven't given me trouble since then (and they used to get the motor REALLY hot).

[targa80]

Why not mount some sort of heatsinks between the trombone to assist in drawing the heat away from the oil. Copper or brass bars could be clamped to the trombone from one side to the other. A fan could also be mounted to the bars to pass cooler air across the heatsinks

[Jdub]

The finned approach is very intriguing. I spent many years building steel bicycle frames and am very good with brass/silver brazing.

Tell me, what thickness of copper/brass strips would be ideal? Would angling these strips be more effective in "catching" air than leaving them perfectly horizontal?

Many thanks!
John

[juanbenae]

get the copper or broonze threaded before brazing to the loop cooler. that would act much like chucks finned lines. i might also drill a couple holes front and back or the newly attached tubes to allow air to flow throught them too??

[Jgordon]

what about that scoop that fits in place of the right side turn signal? A couple of guys have gone with that and have had good results.

[Randy Webb]

yes, angling would be better

for fin design you need to go look at a copy of a text -- Engineering Heat Transfer -- by Kreith (the std) or Karlekar and Desmond (better graphics)

you can pretty much ignore the eqns and just look at the optimum (or nearly so) graphs and drawings.

Just remember they are going to act as convectors, not radiators so don't worry about the latter.

I don't understand the comment re threading - really short fins like that will be ineffective.

[Paulporsche]

Aside from the above, don't forget to check the engine operation itself. Make sure your points are gapped correctly, and your timing and mixture are right. They can also contribute to keeping your engine temps where they should be.

[JMPRO]

The scoop that is available from pelican does not replace the right turn signal. The scoop replaces the right side marker light, which by the way is only on U.S. cars. R.O.W. cars have a rubber bumper in that slot.
Jerry

[juanbenae]

randy have you seen chucks finned oil line product? the fins on them appear to be much like thread grooves. is this ineffective as a whole or the short run i suggested just does not provide enough of this threading/finning to be affective due to length?

[banjomike]

Funny that this thread came up. I have been thinking about the same thing myself. I've done lots of google searches on "tube fin"

here are some interesting ones:
http://www.heftengineers.com/products.htm
http://www.kentube.com/fintruth.shtml
http://www.cyburbia.net.au/Commercial/Key/finned_tube.html
http://www.rmarmstrong.com/products5.htm

This appears to be a very common approach to increasing heat exchanger efficiency in industrial settings. 'threaded' fins like the elephant racing lines are pretty common, and big claims of their effectiveness are made. I have found nothing yet about fins that can be added to an existing tube/pipe. I would guess that having the tubes fabricated with the right connectors would easily be as expensive as a Carrera cooler, so what would be the point.

In the last link above there is a picture of longitudinal fins. If someone found a source of extruded copper or aluminum fins that could be bent to match the radius of the trombone tubing we'd have a good start. Of course you know where this is all heading don't you....

Cool Collar For the Trombone!!!! Except this one might work!

[Jdub]

I'd have to agree that just ditching the trombone and getting the Carrera cooler or the Elephant version is easiest, and probably less expensive than dicking around with the trombone.

Still, God hates a coward and I do have the skills and time to do some basic work. While fins circling the tubes would be very effective, I am thinking the easier approach is going to be running fins lengthwise along the tubes.

Wicking heat away will require good adhesion to the tube itself. Tack welds at each end just won't do. And since the tubing is brass (or is it?) this will have to be a silver brazing process. That means perfectly clean surfaces and no small expense what with the price of a decent silver braze.

But I am sure that the combination of finning and proper air ducting will have some effect, plus Noah's sage comment on simply keeping the darn tubes clean. If I had the money, I'd get Chuck's finned lines and oil cooler and be done with it. But I do love to fiddle around.

Again, if anyone has a trombone cooler I can purchase for modification so that I can continue to drive my car I would be much obliged. Cheap is good (free even better!) and I promise to post all pics and information as I progress on this.

Many thanks for your comments and support!
John

John

[Randy Webb]

"chucks finned oil line product? the fins on them appear to be much like thread grooves. is this ineffective as a whole or the short run i suggested just does not provide enough of this threading/finning to be affective due to length?"
- the latter; also I don't really think of them as "threads" so the terminology threw me at first.

You want to braze many fins 90deg to the tube -- Find some scrap and you have no costs -- but a huge amt. of labor.....

Go check out the texts ai posted. Thought is a lot easier than action and often cheaper - prototype in your head or on paper.

[SC-targa]

Actually, I messed around with this idea a few weeks ago. I took an aluminum heat sink/cooling fin set up for some electronics and cut it in two. I then formed some brass sheet stock to make some straps. I pretinned the cooler and the brass with tin-lead solder, then pop riveted the heat sinks on. Then I back filled the gaps around the brass sheet stock and the heat sink with solder.

The heat sinks get very hot, but the oil temps don't seem to have changed. Now that I've got fins on the cooler, I made need some more air flow now.

Regards,

Jerry Kroeger

[unclebilly]

Banjo Mike has the right idea. We use fintube (available from fintube products) on the back of our fuel cell test stands that have humid hydrogen and air flowing through them. I realize that the specific heat of these gases is much less than the oil but over a 4' length, we see a delta T of roughly 600°C or more depending on the flow rate and amount of humidity in the gas. You could easily build you own trombone cooler out of fin tube and connect the bits with swagelok connectors so it resembles the trombone cooler.

We've also has a good degree of success with the fin wrap that you wrap around tubing which could be applied to the existing trombone cooler after a good cleaning. You should apply liberal amounts of heat transfer compound between the fin wrap and the base tube tho.

The trouble with welding or brazing fins on to your existing trombone cooler is that you have to weld the whole length of the fin to the tube otherwise you only get heat transfer (conduction) between the fin and the tube at the weld.

Has anyone ever considered putting a small 1/4" heat tracing line onto the trombone cooler and tieing it into your A/C (basically hook it up in parallel with the evaporator, provided the pressure drop was higher through this line, it wouldn't hinder the effectiveness of your AC) - this could effectively use your A/C to help cool your oil. I assume you'd really only run the A/C on hot days, these should be the only time you'd need the extra cooling...