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Old 07-09-2013, 06:30 AM   #1 (permalink)
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Rear Mounted rad n other trickery!

Hi guys, I am from the UK I have been browsing your forum for over a year now, I have an active interest in making my car as slippery and fuel efficient as possible on top of chasing HP numbers. I have recently performed an engine swap into my car: A 1996 Honda Prelude Type S, this is the lightest version of the Prelude range tiping the scales with a full tank and all fluids at 1330kg, since the swap it now weighs 1270kg. The weight saving is simply down to engine swap, air con delete & lightweight battery and a few brackets here and there.

I decided to do the engine swap as its different, its more economical (37mpg v 41mpg Extra Urban Imp), has a 6 speed box, is lighter, and has more room for mods in the future.

So here is a nice side profile of my car:



A photo of the new engine, this is quite old so there are a few things missing:



An image of the UltrGauge mounted in the Double Din unit:




So currently the engine bay is absolutely cooking, 60c intake temps and everything is just very very hot under the bonnet. I need to fit a cold air intake to prolong the life of the supercharger, overly hot intake air can reduce service life. So my plan was why not remove the source of heat altogether and move the radiator to the boot, I am thinking I can fit 2 smallish radiators either side of the number plate with a nice black inconspicous grill allowing the air to escape.



I do not have a huge amount of space so I don't think a duct would do much good & would be rather tight, so perhaps just utilise the low pressure side at the back of the car to draw air through. I think as long as I can get the car to cruise on the motorway without having the electrical drag of 2 radiator fans then it won't matter if the flow isn't sufficient at WOT and the fans come on to keep the engine in check. Apart from moving a bit of weight rearward I could also pretty much run a full grill block at the front allowing for some opening just to vent the engine bay, I am fairly confident the grill will help increase my motorway FE but I am not so confident if my rads at the back will be aiding or working against me?

Let me know if I am wrong but you would want the rads to draw from an high pressure area, using a diverging duct to the rad and vent it using a larger opening of a calculated size to an area of low pressure. I would be venting to a turbulant low pressure area but also picking up air from a turbulent but not as low pressure area with no ducting in,just on the exit. Would it be more beneficial if I vent the air at the centre of the rear bumper and move the number plate?

Please excuse my grammer as I am just thinking outloud at the mo and have written this really quickly!

Thanks for your help, Mudgey

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Old 07-09-2013, 06:30 AM   #2 (permalink)
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I need to post a couple more times to post pictures, my thread is obviously useless without pics.
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Old 07-09-2013, 06:32 AM   #3 (permalink)
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Almost there...
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Old 07-09-2013, 08:44 AM   #4 (permalink)
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Quote:
Originally Posted by Mudgey View Post
supercharger........ radiator to the boot
The radiator or new twin radiators, they are coolant fed for the engine block, or are they the air to air heat exchangers for the supercharger?
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Old 07-09-2013, 08:47 AM   #5 (permalink)
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Quote:
Originally Posted by kach22i View Post
The radiator or new twin radiators, they are coolant fed for the engine block, or are they the air to air heat exchangers for the supercharger?
Hi,

The radiator would be the engines radiator, the supercharger is not cooled in any way.
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Old 07-09-2013, 08:53 AM   #6 (permalink)
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Quote:
Originally Posted by Mudgey View Post
Hi,

The radiator would be the engines radiator, the supercharger is not cooled in any way.
Sounds like a bit of engineering either way to me.

Mid-engined cars with rear radiators are notorious for overheating problems. The front mounted radiators fair better.

Most of this poor "record" is pre-electric cooling fan technology though.

A cool-air intake for the supercharger would be the rational/economical solution, don't cha think?

Something like this inlet perhaps?
https://plus.google.com/101297578708891518020/posts

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Last edited by kach22i; 07-09-2013 at 08:59 AM..
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Old 07-09-2013, 09:03 AM   #7 (permalink)
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I don't think there will be any issues with overheating as long as the radiators are specced accordingly, some maths are required here..

I cannot fit a CAI with the radiator in its current position, its a large standard radiator that takes up all the available opening into the engine compartment.

I have to either remake the front radiator to allow a gap on one side to allow a 3" pipe to pass infront of it, or run radiators in the rear, both are going to require some design and fabrication time, though for a little extra effort I could run a rad at the back, hence my questions about whether the aero is worth the little extra effort.
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Old 07-09-2013, 09:17 AM   #8 (permalink)
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I gave you my opinion, and will let others chime in, some parting thoughts.

I think you need to be more creative about the cold air intake location.

From the photo, you could run it to the headlight location and switch to any number of tiny headlight lamps now available.

Alternately, piping the CAI to the windshield cowl similar to an air induction hood facing backwards would also work.

It does not have to be as massive as the Mustang example attached.

http://s184.photobucket.com/user/kac...?sort=3&page=1
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1977 Porsche 911s Targa
1998 Chevy S-10 Pick-Up truck
1989 Scat II HP Hovercraft

Chin Spoiler:
http://forums.pelicanparts.com/off-t...effective.html

Rear Spoiler Pick Up Truck
http://forums.pelicanparts.com/off-t...xperiment.html

Roof Wing
http://ecomodder.com/forum/showthrea...1-a-19525.html

Last edited by kach22i; 07-09-2013 at 09:25 AM..
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Old 07-09-2013, 10:36 AM   #9 (permalink)
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Simple solution (relatively) ... move the ABS control unit and the washer reservoir elsewhere in the engine bay and move the cone behind the headlight. Build a n insulated box to isolate that area from the rest of the engine bay and poke a hole in the fender liner to let cooler air in.
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Old 07-09-2013, 11:03 AM   #10 (permalink)
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Hi guys,

I appreciate your thoughts but lets take a step back a minute so if we ignore the CAI side of things for a minute, how would a rear mounted rad effect aero as I proposed along with an almost full rad block?

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