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Discussion Starter · #1 ·
As summer is here, and the next trackday approaches, I've been giving careful thought to heat management.

My fairly heavily modified (only ylee’s has more
) 9000 does suffer from "heat exhaustion" in the summer. This is largely down to the triple radiator set up- aircon, then intercooler, then coolant. The net effect is that there is very little air flowing through the coolant radiator.

To help the high temps, I’m embarking on/have done the following mods

1. During winter, I switched to an 89 deg stat for efficiency. Over this weekend, I did some comparisons with an 89 and 82 deg stat. By 100 deg C, the 82 stat is further than the 89, so I’ll be switching back to an 82. The difference is even more noticable in the mid 90s. 89 is on the left.


2. Raising the back of the bonnet- I’m putting 20mm spacers underneath the hinges and removing the seal on the aquarium. This will allow flow through the engine compartment. The bonnet still closes no probs. Track day use only.

3. Drilling several large holes in the wheel arch liners- permanent mod to help air flow.
4. Removing the throttle body heater “coolant” circuit- I will simply insert a short tube to connect the flow and return from the throttle body, thus bypassing it. Summer use only. A further development would be to turn it in to a cooler by adding a pump (I’ve already got one) and a small aux radiator (don’t know where to mount it yet)

5. A custom grille- here it is in early stages. I’ve removed the centre bar and louvres, and added a “lining” up to 90mm deep to help form a strong, channelled stream of air heading to the top of the radiator sandwich. I’ve yet to add a mesh at the back of it, but you get the idea…



6. Removing 50% of the aircon fins in the top half of the aircon rad- they should just pull out. I’m happy to sacrifice some aircon efficiency for performance gains

Posted partly for info, partly for comment/discussion...
 

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It might be worth atempting to seal the edges of the radiators to car better and using part of the modded front grill to duct down to attempt to use the raditor behind the bumper/spiler better.

Also, do you know if the wheel arches are high of low pressure area's if you are to mod the liners?

Worthy mods for a hot car.

Andrew
 

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Wheel arches tend to be high pressure areas, hence the huge number of air slots and slats that are visible over and behind the wheel arches on the cars that were competing at Le Mans last weekend.
 

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Discussion Starter · #4 ·
Um I'd have thought low pressure actually Alex- my thinking being that the air is being forced around them quicker than other parts, thus creating an area of low pressure that will draw air out, especially when combined with the high pressure at the front of the car forcing air through the engine compartment- or have I got completely the wrong end of the stick?
 

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Originally posted by Mark E:
[qb]Um I'd have thought low pressure actually Alex- my thinking being that the air is being forced around them quicker than other parts, thus creating an area of low pressure that will draw air out, especially when combined with the high pressure at the front of the car forcing air through the engine compartment- or have I got completely the wrong end of the stick? [/qb][/b]
Would brake cooling suffer then if you opened up holes in the wheel liner?
 

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Discussion Starter · #6 ·
I wouldn't expect so too much, Mark- the brakes create their own airflow by the outer edges moving quicker, generating low pressure and drawing air in from the middle.
 

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Top tips Mark.


Where are you planning to drill the holes in the wheelarch liners Mark, front only or all over? I certainly like the Grille idea and since mine is tatty it would be worthwhile removing the slats and centre bar from mine. Which I can then replace with a "cleaner" grille from a scrapper. Of course I have the old style grille which provides a larger aperture.

I was also thinking of removing the slats from my front bumper and using some simple ducting to improve air dispersion. I will get some black mesh to fill the gaps for normal road use to prevent road-debris from destroying my A/C condenser rad.
 

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Discussion Starter · #8 ·
I've had the holes in the wheel arch liners for a while now- since before the last track day. It's too dark now to take a pic but they're all in the forward section, about 6 or 7 50mm dia on each side.

I'd think twice about removing the slats on the bottom section- they take up very little surface area and do help to reduce turbulence in the incoming air. I reckon that most of the cooling takes place through the bottom aperture.

I've long pondered how to try to get some forced air to the section behind the bumper, but haven't as yet come up with an answer. If/when I do, I'll report back.

Oh and BTW, there's quite a few hours of messing about with heat guns, PVC, glue and filler to get the front grille looking anything like decent- not to mention the hour and a half it took me to peel all the chrome plating off back to the plastic to make sure there was a sound base for filler/paint!
 

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Mark,

Have you considered heat wrap around the down pipe at all ?

This may help to keep the under bonnet temps down a little and providing you have a stainless downpipe shouldnt result in any cracking
 

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Discussion Starter · #10 ·
Yes I've thought about wrap- for the turbo and downpipe. However it's a) expensive B) difficult to fit 'cos things are so tight. All the other mods so far are cheap if not free


Stainless is more likely to crack than mild steel BTW- did you mean to say don't have a stainless...?
 

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Funny you should say about the wrap being difficult to fit, I got 50' of 1" wrap, which was around £35.00, but fitting it is a nightmare, the biggest problem was fixing it to the downpipe, tried using hose clips, but, just not enough room to tighten the clip as well as holding the wrap in place...

I have heard that demon tweaks sell some metal cable ties, which I shall order up before attempting the wrap again
 

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Something to try would be to force air through the rads. Hirsch explained to me that at high enough speed, pressure will build up at the front of the rads and spill around the side leaving little cooling benefit. A solution to this would be to put in baffling around the rads and seal it somehow so that all the air entering the grill or the area below the bumper is forced through the rads instead of being able to spill around the outside. Of course, the baffling would have to be around the entire opening to keep air from going over or under as well.
 

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If the wheel arches were low pressure then GT cars wouldn't need the slats across the top of the wheel arches or holes at the rear. In the case of the Toyota GT-One the inner part of the arch was also removed, leaving as little metal over the top of the tyre as possible.
 

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My heavily modifyed front spoiler (its not there!)
has made the car run hotter ...this hot weather you have been having down south of watford gap made my car run all rough and hot..
now its back in scottyland all is well

I expect the spoiler really manages the flow thro the rad stack..if you look at the undertray it has a heavy scallop on the front of the wheel..
I would have thought this was to promote airflow to the brakes and create some negative lift ..
I wonder if the slats on the grille are also needed for airflow management
I have not seen any heat problem bar the suspicion of a little heat soak/boost retard caused by a lack of front spoiler as described
 

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Originally posted by Mark E:
[qb]Stainless is more likely to crack than mild steel BTW- did you mean to say don't have a stainless...? [/qb][/b]
Actually it depends a great deal on the grade.

321 Stainless has continuous service temperatures of 900 degrees C in air. Which means the metal itself can be at 900 degrees continuously safely. It is stabilized against carbide formation with the addition of Titanium to the metal matrix. (Very small amount.)

The notorious reputation for stainless cracking is due to the misuse of 304 stainless, which was only designed for things like Beer kegs, kitchen sinks, etc. Unfortunately, for cost reasons and possibly ignorance, it has found its way into exhaust parts.

Those of you out there thinking of purchasing a new turbo or downpipe might consider getting everything you can ceramic coated. Because ceramic coatings are also used on the inside of the pipe/header/turbo they generally lower part temperatures several hundred degrees, and similarly usually lower radiant temps nearly the same amount.

The top of the wheel-arch tends to be high pressure, while the rest low-er pressure. Mainly because the top of the tire is moving in the opposite direction as the air at twice the speed of the vehicle. When you're doing 100, the top of the tire is doing 200, and the bottom zero.

One of the reasons NOT to wrap a mild steep pipe is that corrosion is multiplied by about 10x because the heat wrap traps moisture next to the pipe. Heat wrap is also shown to give almost no performance advantage on street cars, unless the radiant heat is affecting the intake charge.

Dubbya~
 

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After having the heat wrap for the turbo and downpipe for about 6 weeks, I finally got around to fitting attempt number two.

It was much easier with two people and with the front of the car jacked up, all went well and was done within 15 mins.

First test drive was rather worrying though, plumes of acrid smoke from under bonnet, with fears of the wrap bursting into flames !, I assume it just initially beds in, no more smoke or smell after a 15 min spirited drive

Will report back if I notice any difference with it fitted
 

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Mark, this may be 'far-out' but, it just might help. Why not utilize the latent heat of evaporation externally - sort of like cooling towers that are used for HVAC on commercial buildings. I'm thinking that some sort of misting device placed between the IC and radiator could lead to a two-pronged attack. It would lower BOTH the charge air temp' and the coolant temp'. I haven't done any calculations to figure how much it would help at the radiator, but without any calculating, I can almost guarantee that it will improve the charge air temp'.
 

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Discussion Starter · #20 ·
Robert, I have considered using a second injector hooked up to my intake water injection, and may yet go for that option.

However in the meantime, at the track day I think we sussed the problem (it was ylee who spotted it)- the lower intake air scoop on the ordinary CS is noticably smaller than on the Aero, so I will look to try to enlarge that as my next step
 
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