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pete k said:
Thanks Bruce, that explains a lot. First, I have never heard it come on, and probably won't. 110 C is the same as 220 F, which is probably possible to reach after turning off a hot engine
110 C is 230 F I think. Toyota doesn't use the heat soak on any of their 2ZZ cars. It's peculiar to Lotus. But I guess some Elise get driven harder than Toyotas.

But I have another question about the Lotus Heat Soak procedure. Why do the fans come on at 115 C? That's not the circuit the water is flowing through. I definitely know my fans have never come on after the car has been off. An interesting experiment would be to bypass the heater core up front by just switching the hoses and see if the cooling fans ever come on. That would indicate that enough cooling isn't getting done just flowing through the pipes and hoses.
 

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Discussion Starter · #82 ·
Randy - Your certainly welcome

I hope it helps your car...I would agree with you that it's messy and that the anti-freeze is slick which can make it b*tchy to get those clamps on. I went throug 3-4 pairs of nitrile gloves during that part just to keep some grip.
 

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So I finally finished installing tonight. Haven't had a chance to drive car. Test of the setup works good so far though. Valve comes right on with the switch, and shuts off quickly when the car is shut off.
I actually use an Audi air solenoid instead of the one Tony was suggesting. Why? Because I had a couple spare ones lying around :) The are of 99 A4 2.8. You can use these, but you'll also need a Bosch 2 wire plug to plug into it. Regular push on leads won't work.
This mod was more of PITA than I thought. Working in tight crammed spaces sucks like no tomorrow.

For getting power to the switch, their is 12 volts switched power right in the AC control head. The fan switch has 1 lead that is hot with ignition. It is the lead labeled C on the back of the switch. I just used that to grab my power for my solenoid.
 

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Discussion Starter · #84 ·
A Mod I forgot

Wow, this was wayback in Oct 04:huh: ....I took the grill off the car and opened up the fresh air intake for the climate system. Just used a cut-off wheel and opened up the intake considerably wider and extended it onto the top of the vent rib as well. Then I siliconed new screen over the holes to keep small children out.... I completely forgot I did that until just now. The idea was to cut down on the freezing by getting more air through the system. I recall this did increase the air flow noticeably. Sorry it just occurred to me now...:wallbang:
 

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This morning...I actually saw my windshield fog up from the cold air coming out of my vents. I couldn't believe it :)
This is definitely worth doing.
 

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Discussion Starter · #87 · (Edited)
Bigger Climate Control Intakes

What I was going for was to cut down freezing (more air flow = less freezing..at least when not in recirc)and also to increase air flow in general for all climate modes. It’s pretty straightforward mod and can’t really hurt anything. If you take the grill off, you can see they’ve just got screen over the climate system intake openings (on the ends of those 3 big ribs) with a bunch of tar-like goop holding it on. I just peeled them off exposing the intakes to the climate system. I used a 3” cut-off tool to slice the sides off the existing opening to make it wider and taller. I also extended the opening on to the top of the rib a bit (inch or so). I think I probably increased the square area of the inlet by 40%-50%. Just seemed to make sense to make it less restrictive on the intake side. That’s why we pay for all those cool air cleaner elements.



Procedure:

1) Remove plastic “bolt” in middle of grill (pic 1)

2) Release 4 brackets at top of grill my gently pushing on the tab at the bottom of bracket while simultaneously pulling the top of the grill towards you (pic 2)

3) Once all four bracket are loose, pull the top of grill toward the front of the car and work the grill pegs out of the holes in the bottom of the grill “mouth”

4) Peel off the existing screens over the fiberglass ribs to expose the climate control inlets. Widen these as you see fit to maximize air flow.

5) Use black silicone and new screen (if your old screen is no longer able to cover the opening) and glue it back in place like it was originally. I came up with new galvanized screen from a gutter cover with almost the identical pattern as the original screen. Most any expanded metal or hardware cloth will do. (pic 4)

6) Replace grill.

7) Feel the bigger breeze…..

NOT MY BEST LOOKING WORK!! What a real hack I can be, but not usually. I meant to come back to this and smooth it up, but it just fell to the wayside…. I think I’ll fan a little flat black while I’m in here….although the Lotus OEM one looks just as bad or worse (far right).

As usual, no guarantees, no warranty, your mileage may vary, your responsibility, I am rubber, you are glue, etc.....:wave:
 

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Discussion Starter · #89 ·
CFM

I think the appropriate southern scientific term is "scads" more CFM;)
 

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Discussion Starter · #90 ·
Rob - did you route the cool air to the firewall area yet?

let me know.
 

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Sorry haven't gotten around to that yet.
My car is blowing really cold, just need to get more CFMs now :)
 

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I am not sure what I am looking at exactly on the intake mod. Do those openings go back imediately into a larger plenum? If not, it looks like the ribs are the "duct" and the cross sectional area of the ducts which did not change is now the pinch point so not sure how you would get more air flow to the fan..
 

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Discussion Starter · #93 · (Edited)
Gary - Plenum observation

The ribs form three plenums that feed the intake to the climate control system. The openings to those plenums (at least on my very early car) were considerably smaller than the plenums themselves. The holes just weren't cut with much care. One other sort of jungle math bit - I'm pretty sure the vent hose on the output side of the climate control is 4" diameter yielding 12.5 square inches of area. For my car (the only example I have:) ) the inlets in the ribs probably had more like 8 or 9 square inches (approx. 1.5 *2* 3) of total area. Again the cut-outs did not "port match" to the plenums very well. I widened the openings as much as possible without getting into the corner fillets which still left some restriction at the opening. I extended the opening onto the top to get more square area Imagine a big carb vs. small carb. Bigger venturi gives more CFM or try drinking coffee through a coffee stirrer. I think I'm on solid ground here, but am open to opinions.
 

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I have always thought the air flow was too weak on my car so I took a look through the grille on my '05 (late production) and only two of the intake plenums were opened and covered with the mesh. The middle plenum was uncut and totally sealed while the two open plenums were completely plugged with bugs, leaves and road crud. I cleaned all the crud off the mesh with a stick and a wet rag, but I need to pull the grille and clean everything thoroughly when I have more time. This looks like another cleaning chore that I will need to add to my list on a yearly basis. When I pull the grille should I cut open the center plenum or did the factory leave it uncut for some reason?

Tonywa28 said:
The ribs form three plenums that feed the intake to the climate control system. The openings to those plenums (at least on my very early car) were considerably smaller than the plenums themselves. The holes just weren't cut with much care. One other sort of jungle math bit - I'm pretty sure the vent hose on the output side of the climate control is 4" diameter yielding 12.5 square inches of area. For my car (the only example I have:) ) the inlets in the ribs probably had more like 8 or 9 square inches (approx. 1.5 *2* 3) of total area. Again the cut-outs did not "port match" to the plenums very well. Imagine a big carb vs. small carb. Bigger venturi gives more CFM or try drinking coffee through a coffee stirrer. I think I'm on solid ground here, but am open to opinions.
 

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Has anyone checked that this doesn't impact structural integrity (extending the hole to the top?)

Hate to rain on a parade...
 

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Arno said:
Correct. Part of it, yes.
I had the same thought when I looked at the structure. I wouldn't open up the plenums on the top, but I can't see why enlarging the existing holes to their edges would be any different than the crude holes Lotus cut into the face of the plenum structure. I am mainly curious as to why the photo on this thread shows three open plenums while my car has only the two outer plenums open and the center plenum uncut.
 

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Discussion Starter · #99 · (Edited)
I don't actually remember if I had two or three cut-outs

I think three, but again, my car was very early (#62) and I made the mod almost two years ago:crazyeyes . I'd like to believe they did a better job on the openings on later cars, but I'll have to hear from others on that subject.

OPINION - As far as crash structure, look at the rib, be your own judge. You can feel the thickness of the top of the rib through the factory opening. You could conceivably say the beam is not as strong due to the removal of fillet corner on the front edge.....My opinion is fiberglass is a LOUSY impact material (well that's just fact). It's brittle and shatters right away without absorbing much enegy. Strong within its limits, but sudden and ugly in failure (my family had a boat company when I was young, I saw lots of fiberglass failure boats vs docks, briges, piers, etc). I believe the desirable quality of any impact absorption device is to deform and absorb energy over distance and sacrifice itself, not shatter and be of little consequence or be so rigid as to deliver an impact shot right to the footwell/frame. Remember, its that sudden stop that sends your brains out though your nostrils:no: ....The change I made is miniscule (this is the opinion part), but again be your own judge. Heck, it might have improved the crash absorbing cabability for all I know by introducing a new shape that deforms better before it shatters:D .

A bit off topic but sort of relevant...Chapman recognized this way back in the early cars. I can remember updating my Elan with nice shiny big tubular a-arms over the original stamped steel channels because I thought strong and heavy was always good. Then a revered Lotus tuner pointed out that now any curb impact that I had was going to send the shot straight to the stressed skin frame rather than the orignal a-arms sacrificing themselves.....much more expensive proposition to replace a frame than replace a-arms...Chapman was a genius because everything was sized correctly for the job, no more, no less and he tried to get multiple uses out of parts (frame sections carrying vacuum is an example). He seemed to more get more performance (at least the kind of performance I like) from the sum of the parts than other manufacturers.

I'm sure there are some structural, civil or mechanical engineers with the proper education that can weigh in on this subject.


Good Luck
 

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I posted thinking it was CF, not fiberglass.

It's a toss up for sure, I'll check mine today/tonight to see if only 2 are open.
 
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