Lotus Europa Community
Lotus Europa Forums => Garage => Topic started by: Pfreen on Tuesday,June 19, 2018, 06:45:59 AM
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I recently measured the intake air temperature at the carburettor inlets. My car is a tcs with the stromberg head, but two SU carbs with individual air cleaners. The front carb measured 115 degrees and the rear carb was 125 degrees on an 82 degree day. This was measured at highway speed. At idle, the temperatures rose 10 degrees. This amount to about 7% loss of theoretical power.
Has anyone measured the air inlet temperature, especially with the stock air filter? Also, has anyone done anything to reduce it, like a cold air inlet, or a cooling fan?
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Air flow in the engine area is the #1 problem with the Europa in my books. The only solution I know of, that actually works, are forward-facing scoops directing air into the engine area. These significantly alter the aesthetics and require major body work. The NACA ducts commonly fitted do help but they don’t actually flow much air.
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I was considering two things. An airbox with the air filter located down by the bottom half of the fuel tank. I was also thinking about mounting a fan down by the fuel tank blowing cool air over the carbs.
Has anyone done any of those things?
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Air intake down low there would pick up a lot of road dirt, plus water off a wet road if you drive the car in the rain.
Any air from the front or the top would be very difficult to direct to the carb air intakes, or would look strange and would affect the aerodynamics/air drag.
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I have heard that leaving the chassis open at both ends helps but that may also allow lots of crap and moisture to enter as well.
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Forum member Peter Boedker has written an article in the files section of the Yahoo Europa mail list titled:
"How to make a colder air intake on the Europa and gain some HP (Peter Boedker, 3904R)".
Unfortunately the article is in, I believe, Danish? Been meaning to ask Peter for an English translation. His dyno chart appears to show the effectiveness of his modification. I copied the piece to my Dropbox account, hopefully it will work.
https://www.dropbox.com/s/w475ercj88pptlo/Peter%20Boedker%20cold%20air%20intake.doc?dl=0
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I think you have to share it, it's asking me for my username and password.
While you work on that, I'll study up on my Danish! ;D
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It took me a while but I believe it can now be viewed with the link.
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Thanks Joji! That works. I'm assuming his duct work "connects" to the vent in the engine cover (I still haven't found my Danish book!).
I hope he translates for us. It looks like another of Peter's clever mods.
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Looking at the photos, it seems to me that the entire carb and filter assembly is enclosed with the ducting being directed to the area just in front of the rear wheel. Hopefully Peter can explain the setup.
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Dimly remember that as being a high pressure area. Sounds like a good idea. Might pick up some of the hot air from the rad but anything is better than the existing situation.
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Here is a Google Translate barf-up of Peter's article. Sorry, all formatting was lost, but the message get through.
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Very interesting, thanks.
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Thank you for the interest and kind words. It is bedtime now in Denmark, so only a short note from me at this time.
I did see the original post/question earlier today, and spent some time searching for an english version of my document. But, since I was at work I had to give up after few minutes, and the evening was spent on other things. I am not sure I even did a translation to english at the time or later. Hmmm... I will need to look it up tomorrow evening on my own server.
I willl return with more information. Your thoughts on the solution are not that far from the actual facts.
+1 for the Google translation. ;D
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Ha! I knew I had already translated it. Not into a Word document but into a page on my not-so-fancy website which has now long been removed. I found it on my server and then it was fairly easy to import into a new Word/PDF doc (attached) with enlargened pictures.
To answer a couple of questions in the thread so far: :D
- Yes, the two air intakes down low does pick up some dirt and water but far less than I feared. This is now 15 years and maybe 30000 miles ago, and the power blanket and filters are dirty but not filled with dirt. Of course a daily driver would have needed some cleaning, or a cleaner air but it has not been a problem with my use until now.
- The duct work (or power blanket) does not connect fully to the vent in the engine cover as the rim of it is flush with the fiberglass lip, so about 2 inches below the inside of the engine cover.
- Yes, the carb and filter assembly is enclosed with the ducting which stretches from the top of the chassis and up close to the engine cover. This duct is not part of a pressurized ram-air solution but more of a way of shielding the intake from hot air from the engine and at the same time collecting the cold air from below until it goes into the filters. So it is not sealed at the edges.
- The flexible tubes are connected to the edge of the opening in the floor below the fuel tank.
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Thanks Peter! This is very helpful.
With regards to the dirt that is collected from the air intakes, did you try anything to reduce the amount of trash they pick up, for example, stretching an old stocking over the opening or putting some open cell foam in the entrance?
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Very interesting article Peter. Initially I thought that the air box enclosed the Strombergs looking at the small photos in the original article. From your large pictures, it now appear that only the filter section is enclose.
A couple of thoughts came to mind reading your piece. The location of the stock filter does not appear to be too bad of a choice. It's in a fairly open area with probably some air flow from under the car. I wonder how much of that was forethought and how much circumstance.
My other thought was to move the filter to the inside of the luggage box. Totally seal it off and run ducting directly under the car. You'll lose some luggage space but not much. Just thinking out loud here :BBQ:
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Thanks for posting the article, Peter. Very interesting.
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Because of all the road debris thrown up by the rear wheels, air filters do not last long. This was noted in a period long-distance road test back in the day. I run my twin-sidedraft crossflow with the stock TC set-up. Works fine but I notice the filter starting to affect performance at about 1500 to 2000 km. I live in a dry, somewhat-dusty climate. You may go considerable further in a moist climate. Adding filtration inline just has things plugging up sooner elsewhere. Better would be to fit an air cleaner that takes an air filter with a larger surface area.
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With regards to the dirt that is collected from the air intakes, did you try anything to reduce the amount of trash they pick up, for example, stretching an old stocking over the opening or putting some open cell foam in the entrance?
No, because the dust problem is really very small. :)
The location of the stock filter was where I measured the highest engine bay temperature. It was a simple measurements and e.g. didn't take into account how the air was moving around inside the engine bay.
Oh, and I also need to add again, that all the work was done by the two guys from DOT Engineering. I did the temperature measurements and saw the need but the solution and manufactoring was thought up by them. 8)
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Peter, by any chance did you measure the temperatures in the section where the petrol tank lives ?
This has been an interesting topic and pushed me to look critically at my car with the result that I came away thinking, "hmm, yeah" after seeing the exhaust route and silencer distance from the intakes.
It got me wondering if the RHS tank could be relocated backwards a few inches and an air filter assembly mounted in front of it with an air scoop to drag cold air from underneath the car in similar fashion to your tubing. If the air box was remade/reversed it could end up being a neat installation ?
Brian
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That is exactly what I am doing after reading the comments on this topic. i will let you all know how it works. I did not have to relocate anything on my tcs. Just making a new airbox, hose, and filter. I am not fitting a scoop initially until I measure the results.
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Ah, now that is interesting. I did some quick measurements of the available space but it seems tight, whereas the tank itself could move backwards a couple of inches with some juggling of the filler pipe. That might be enough to allow a modern housing (and filter) to fit in without having to custom make something although I'm not averse to that route.
I'd be interested in seeing any photos of your progress and snags/solutions that you come across.
Brian
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I have completed my tc airbox and filter assembly. It works very well. With an air temperature of 100 degrees F under the car, the air inlet temperature at the carburetor was 105 degrees F. Previously, with no airbox, I measured about 30 degrees warmer than ambient at the carb inlet. I made the airbox from an aluminum bread pan (Vollrath 5216) which measured 4-1/2" x 16" x 4-1/8". I epoxied in a 3-1/2" diameter aluminum tube from Spectre Performance angled down at 30 degrees. I fabricated an aluminum backplate from .090" aluminum. The filter assembly was also from Spectre, part number 9831. I cut the bottom of the filter housing at 20 degrees so it would be flush with the bottom of the car. The connecting hose was from Mcmaster.
If you have any questions, please let me know.
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Thanks for posting, the airbox is inspired ! I'm about a week behind you with my conversion which uses a different filter, a flat rectangular one as used on the UK Ford Puma but otherwise we're on very similar lines.
I've made a new fibreglass airbox molded off the original but it looks exactly the same as yours with the inlet pointed down towards the fuel tank well.
Temperature measurements are encouraging and I've been wondering if when you're on the move you'll get an even match with the ambient air due to a slight pressure flow into the filters ?
Brian
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i attributed the temperature rise to heat transfer through the aluminum airbox. i tried to find an alternative airbox, but didn’t have the dimensions to see if it fit. The Elan airbox may have fit, but I just wasn’t sure.
BTW, I measured the pressure drop between the cabin and the airbox, It was less than 2” h2O (0.5 kpa).
Please post pictures of your system when you can. Thx.
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You could well be right on the heat transfer causing a bit of temperature lift, although compared with the data that Peter originally provided I think you're doing well. I would be happy with those numbers anyway.
As I said, I'm probably a week away from assembly and so things might change but this is where I'm at. The Airbox is finished, it's basically the OEM one with a new inlet and looks remarkably like yours ;)
The filter has more surface area than the round one and the casing for that is still in the "scrappy" state while I tidy up the GRP. Today I have been learning how to make louvres in Al which I hope will both channel air into the filter and also cut down on water/spray ingress. That's what's been taking the time, trying to come up with a way to protect the paper filter from direct water splashes from underneath. I don't deliberately take the car out in the rain but in England it's a given that you'll get very wet at some point.
Dumb question time, how do you get your temperature and pressure measurements ? Is it specialist or DIY kit ? Pressure measurements is sounding high tech !
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I have a two channel thermocouple readout made by Omega. For pressure, I have a digital manometer, but a simple clear tube with water in a “U” and a scale will make a water manometer.