Author Topic: Exhaust and Oil temp solutions  (Read 1834 times)

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Offline BDA

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Exhaust and Oil temp solutions
« on: Tuesday,February 26, 2019, 11:45:56 AM »
I didn't really consider documenting what I've been doing on my car lately because it's such a unique situation and probably not very useful for others but then I opened my big yap about my trying to do something about my exhaust and keep my trunk tray on matmacwac's thread here: http://www.lotuseuropa.org/LotusForum/index.php?topic=2894.45. Then matmacwac opened up his big yap saying he was curious about what I had done so here it is.

To start with, I had two oil problems on my car. First, if the car set up for more than five or so days, all the oil would drain from my oil tank into the oil pan and I would have to start on no oil pressure. The second problem was that on long trips, my oil would get very hot. There were two reasons for this. first, my exhaust pipe was beneath my oil tank. The second was that I mounted my oil cooler so that it exhausted out the rear of the body. I found out later that all the air flows up through the screens in the engine cover and almost through my oil cooler and out the cool looking  :) louvers next to my license plate.

Since I was adamant about keeping my trunk tray, I didn't have a lot of options for routing my exhaust. In fact, when Dave Bean was building my engine (BDA for those who didn't know already), he suggested I take a set of headers from a Formula Atlantic, get a rear screen from an S2 and route the exhaust out through the hole like an S2. I didn't want to do that (sanctified trunk tray, remember!) so a couple of years later when ordering some parts from DB, I asked if they had headers for a BDA in a Europa - yes!, routed like the stock TC exhaust? - yes!, in stainless? - yes!, send me a set!

Years later I found out about some cool kits that Richard at Banks Service Station in England had so I got, among other things, front vented disks, rear disks, rear twin link suspension. From one of the attached pictures, you can see the BIG rear cross member. It's a neat piece (too bad I had to cover up the nice chassis punched holes in the top) but something I didn't appreciate was that it limited the width of a muffler if it was placed under it which is the only place I have for a muffler given all my restrictions (header and exhaust routing and trunk tray). I was able to get a very compact steel muffler with 2 1/4" ports that fits there pretty well. It is the smallest muffler with 2 1/4" ports I've seen anywhere. It's pretty loud but it's not terrible around town, it doesn't wake neighboring pets, or rattle windows, but it does add to the fatigue when taking long trips and conversation with a passenger requires raising your voice a bit.

I've included a picture of the area under my carbs showing the snake nest of wires and hoses that was made a big worse because of the Accusump. It required a 'T' to connect the Accusump to the oil hose and add a check valve.

Well, I guess I've rambled enough. Now on to what I've been doing about the problems mentioned above. To solve my oil pressure problem, I finally after thinking of probably a dozen ways to solve this, came up with a one quart Accusump with an electric valve. I already had a switch on my console that was originally to be used in the event I got driving lights, then I hooked it up as an override switch for my fan controller. The obvious place for the Accusump seemed to be on my rear cross member. The valve has to be protected from heat. So I made a heat shield to go between the exhaust and the oil tank and Accusump valve. I made the heat shield from some aluminum from the hardware store and added some insulation from DEI (http://designengineering.com/floor-tunnel-shield-ii-extreme-heat-shield/). I also put some on the bottom of the oil tank. Originally, I intended to ensure there was an air gap between the different parts. It turned out that the oil tank does contact the heat shield but I don't think that will be significant. If it is, I can move the heat shield lower on that side. I also wrapped the exhaust pipe up to the muffler. I used the titanium heat wrap, again from DEI (http://designengineering.com/titanium-exhaust-wrap/). I didn't want to wrap the headers because I like the way they look though they need to be polished again. Besides, I was more concerned about the heat going into the oil. My wrap started under the engine so there should be a bit less heat going into the oil in the oil pan.

You might be able to see that I tilted the muffler a bit front to back and side to side. It would fit where it is in the horizontal dimension but this gave a bit better angle for the tail pipe and give more clearance for suspension arms.

I have to plug my chisel and file fabricating job on my exhaust mounts. You can't see the front one because it's under the heat shield but you can see the back one a little. It's from 16 ga stainless steel. I had to cut it out with a dremel tool and cut-off wheel, bend it on my vice and clean it up with files. I had trouble drilling a hole - maybe because I didn't didn't dimple the sheet enough for the carbide drill bits I had but I found out that those Unibit step drills do a great job with making holes in fairly heavy stainless steel sheet. They are shorter than most drill bits so they were handy making holes in my frame where the space was tight.
« Last Edit: Tuesday,February 26, 2019, 12:03:37 PM by BDA »

Offline Certified Lotus

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Re: Exhaust and Oil temp solutions
« Reply #1 on: Tuesday,February 26, 2019, 01:40:08 PM »
I’ve had several accusump’s in my Exige S track car. They work amazingly well. The worst part of the device is the switch valve. They fail on a regular basis. Especially if you don’t use it on a frequent basis. There is a fair amount of info on this on the Lotus Talk forum. Someone custom built the control valve because of regular failure. I kept a spare all the time because it would just stop working without any warning.

I would not install one on a street car. Just saying........

Offline BDA

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Re: Exhaust and Oil temp solutions
« Reply #2 on: Tuesday,February 26, 2019, 03:55:12 PM »
Thanks Certified. That's good information to know. My Accusump is only to be used for pre-oiling and only then when the car has been sitting up for a few days. It's only real job is to provide oil long enough for the scavenge pump to catch up. In the event of a failure of the valve, I would only be back where I was originally. Not a place I'd prefer to be (after all I went to some trouble to get out of where I was) but not catastrophic.

In any case, I'll look into other options. I appreciate the heads up!

update: I started looking at some posts on LotusTalk and it appears there was an option from Lotus for an Accusump (I think it was for the Exige! Did I read that wrong? Also, from the few posts I have seen that mention a problem with the electric valve, they talk about the EPC electric valve. That is designed to maintain oil pressure within a range. That's not the valve I have. Mine is designed to open when the valve is switched on and when switched off, it is a one way valve that allows the Accusump to be recharged. I suspect it is a lot simpler and less likely to fail - however it is more likely than a manual ball valve! I think I'll be ok but I'll be watching out for ways to install and control a manual ball valve in the event.
« Last Edit: Tuesday,February 26, 2019, 04:50:26 PM by BDA »

Offline jbcollier

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Re: Exhaust and Oil temp solutions
« Reply #3 on: Tuesday,February 26, 2019, 06:15:21 PM »
Do you need an accusump when the engine has a dry sump?  Seems a bit of a work around for the actual problem which is the oil draining back into the sump (wet dumping).  Why not a one-way check valve?  Or, a pump to put the oil back before starting?

Offline BDA

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Re: Exhaust and Oil temp solutions
« Reply #4 on: Tuesday,February 26, 2019, 06:57:34 PM »
I thought about several different ideas such as an electric ball valve turned on with the ignition, a electric pump that would "prime" the oil tank in the event of a low oil level in the tank, moving my oil tank to a lower position that should so that it wouldn't drain, a manual ball valve, and a check valve, and probably a few others. I wanted something that would be like getting into any other car where you hop in, turn the key and go. Electric ball valves have a finite duty cycle, I couldn't be sure that the failure mode would be to fail open and not closed. Extra electric pump to fill the oil tank didn't require but suggested a means of determining the level in the oil tank. IIRC electric oil pumps that were appropriate were pretty expensive. A manual ball valve required a "remove before flight" flag. There is a company that makes check valves for the same purpose for Porsches but they were ridiculously expensive and much too big for my application. I didn't think I could reliably modulate the spring tension to be strong enough to hold up enough oil and not restrict the flow.

I may have underestimated some of the opinions but the Accusump was pretty much a canned solution. True, I will have to flip a switch before starting after the car sits up but I was willing to live with that. Keep in mind the Accusump is only for pre-oiling which for me means oiling the motor till the scavenge pump catches up. It's not for maintaining oil pressure which, as you noted is taken care of with the dry sump system.

Offline gideon

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Re: Exhaust and Oil temp solutions
« Reply #5 on: Wednesday,February 27, 2019, 07:12:19 AM »
Just a thought about the oil cooler.  One option is to use an oil to water heat exchanger to cool the oil with engine coolant on it's way back from the radiator.  It would cost more than just relocating the existing oil cooler, but there are some advantages in terms of balacing oil and water temperature.  I recall that Jim Hall explains the advantages in one of Jay Leno's Elan 26R videos on youtube, but I couldn't quickly find the exact point.  Here's one source of such heat exchangers (at the bottom of the page)

https://www.crracing.com/product-category/oil-coolers


Offline BDA

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Re: Exhaust and Oil temp solutions
« Reply #6 on: Wednesday,February 27, 2019, 07:25:47 AM »
I think you're right although the changes required would probably have to be done with the engine out of the car.

Boy, do they think a lot of their heat exchangers! I did a search and they are all pretty expensive! They don't seem like they would be so expensive!

Offline jbcollier

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Re: Exhaust and Oil temp solutions
« Reply #7 on: Wednesday,February 27, 2019, 07:35:55 AM »
Here's my oil cooler:

https://jbcollier.smugmug.com/Lotus-Europa/i-SjHwgt2/A

It is off to the side but the front compartment pressurizes so air flows through into the left wheel well.

Add AC and a hydraulic clutch and it starts to get busy:

https://jbcollier.smugmug.com/Lotus-Europa/i-43VtjPt/A

Pretty much had to convert to a cable shifter:

https://jbcollier.smugmug.com/Lotus-Europa/i-hwdj25w/A

Oil in the sump never rises above 80°C though it gets there fairly quickly.

Have ports in the back so I can flush the cooler during oil changes, and, fill and pressurize the system afterwards:

https://jbcollier.smugmug.com/Lotus-Europa/i-3p66rHx/A

Offline BDA

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Re: Exhaust and Oil temp solutions
« Reply #8 on: Wednesday,February 27, 2019, 07:51:57 AM »
Amazing work, JB! Well thought out and executed! I didn't want to mount my oil cooler in front of my radiator as many do because I didn't want to add any heat to the water that I didn't have to. I thought about mounting the oil cooler in the front on the driver's side similarly to the way the water radiator was mounted but I wanted to maximize air flow through the water radiator. I was obviously way too worried about water temperature.

If I take the motor out, rethinking oil cooling will be part of the plan.

Offline gideon

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Re: Exhaust and Oil temp solutions
« Reply #9 on: Wednesday,February 27, 2019, 10:01:55 AM »
For what it's worth, I found a more reasonably priced source of oil to water heat exchangers :

https://www.cantonracingproducts.com/categories/oil-cooling-heat-exchanging/water-to-oil-heat-exchangers.html

Offline BDA

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Re: Exhaust and Oil temp solutions
« Reply #10 on: Wednesday,February 27, 2019, 10:06:05 AM »
Good find! That's a lot more reasonable!