rear rad mit ducted scoop
http://bb.bbboy.net/vwengineconversions-viewthread?forum=20&thread=16
Powered By BbBoard - http://bb.bbboy.net

moTthediesel
13:08:02 Fri
May 13 2005
rear rad mit ducted scoop
I'm looking into building a FrankenPorsche 356 with a modded 1.6L VW TD engine for power. As these engines can be built to provide 100hp and 160ft#T, I think that you could expect to get better than original performance while returning 50 mpg.
I'd rather not do the surgery that would be required for a front mount radiator, to allow for a return to original power at some later time. With the Quantum based engine inclined at 30 degrees, there is plenty of room for a tall, narrow rad from a VW Fox to be mounted alongside the engine.
It seems to me that the failing of most rear mounted rads is that their air supply is not isolated from the heated air of the engine compartment, and that they do not get a good supply of high pressure air.
What I'm thinking of doing is mounting the rad (and intercooler) in a sealed fiberglass duct/ram box, with a scoop behind the swing axle. The idea is that this would supply cool ambiant air to the cores while under motion, and would allow an electric fan to draw in the same while in traffic. Engine compartment venting would be enhanced with a custom deck lid with many louvers or rear facing scoops.
Has anyone here seen anything similar tried?
Was it successful?
moT

vw_legacy
23:37:59 Thu
May 19 2005
Re: rear rad mit ducted scoop
i had a baja with a 2.3 ford with the rad in the rear with a scoop, dual fans and it still overheated on the freeway, but around town it was fine. so i wish u luck because you cant get more isolated than that without puttin it in the front

moTthediesel
05:13:38 Fri
May 20 2005
Re: rear rad mit ducted scoop
Do you have any pics of the Baja set up that way? If so, I'd sure like to see them.
moT

vw_legacy
05:13:27 Sat
May 21 2005
Re: rear rad mit ducted scoop
no, sorry that was about three years ago when i had that now i've moved on to bigger and better projects

moTthediesel
15:54:03 Sun
May 22 2005
Re: rear rad mit ducted scoop
I guess what I want to know is did your scoop just force air into the area where the rad was mounted, or was the air ducted through the core?
My thought is that by supplying air to the core through a sealed duct, you could insure that the core would only receive ambiant air from the scoop. That would prevent the outside air from mixing with the heated air from the engine compartment before it reached the core.
A potential problem is that by using an undercar scoop, it would be ramming in air that is heated, to some extent, by the road surface. I'm not sure just how significant that heating would be?
moT

vw_legacy
00:24:36 Tue
May 24 2005
Re: rear rad mit ducted scoop
it was all forced into the core. i dont think the heated air off the road would be much of an issue because the air is about 120 deg. F. and the coolant is around 180 although the cooler the air the more efficient the radiator works so you can get away with a smaller one. on the car im buildin now i mounted the rad in the front with an electric fan pushing air through all of the core and it is sealed so weel see how it works in a month or two. (im still tryin to get pics up, no camera)

kkkango
20:22:38 Tue
Jun 14 2005
Re: rear rad mit ducted scoop
i have run my buggy with a radiator mounted longditudinally along side the engine just rear of the axletube of the l/h/r wheel with a scoop outside and fan inboard for 18 years now was so so with an 1800 fiat twin cam motor but an upgrade 4 years to 2L sport made it too borderline on running temp..

it worked ok but was always border line on temp sitting at 100 to 105C with the fans on full time and sometimes the heater on to aide cooling on long runs, the temp stayed constant and did not fall back it just steadied at maximum.

2 months ago I put a peugot 205 GTi rad up front plumbed in with 35mm copper pipe and twin fans mounted pushing air through.

using 72 degrees C fan switch in the rad, thermostat is an 82C with a 4mm hole in, the motor now runs in cycles from 85C when the stat opens fully, sometimes to fans on at 90C then cools to 80C even on long high speed runs as well as stationary in traffic where sometimes it needs the occasional blip of the throttle just to speed the water flow up again.

radiator up front is definetly the way to go i should have done it years ago.

mxman70
04:52:42 Fri
Jul 1 2005
Re: rear rad mit ducted scoop
Why can't the radiator go in the back. I saw a picture of a Beetle that porsche R&D grafted to a 914 chassis. It had louvers under the rear side windows like the 412 wagon. Seems to me if you ducted straight to the radiator you could let the hot air escape through the rear deck lid and maybe open up the vents under the window.It would also exit past the motor like every other car on the planet.Louvers, NACA ducts. There must be a reasonable way to do it.
Pat

moTthediesel
21:09:10 Sat
Jul 16 2005
Re: rear rad mit ducted scoop
I think the early series Renault-Alpines used rear rads too, I'd like to see how they were ducted/vented.
Anybody know of a good Renault-Alpine site?
moT

dreadiee
19:00:44 Tue
Sep 13 2005
Re: rear rad mit ducted scoop
do you have any pictures of the rad scoop?

hirider
02:12:07 Thu
Sep 15 2005
inside rad
Here is my setup, if it can help you guys....
Just a setup I'm still using, since I had no place to put my rad next to the engine (3 cyl suzuki swap), I just took the rad and seated at the place of the back seat, with an electric fan.

This setup means that no hot air from the engine gets to the rad, but it doesn't get fresh air neither. I drive with both windows open and it gets hot in the car, so not so fresh air to cool. I put a 1987 1.8 jetta rad. If I stop the fan, temp gets high almost instantly, past 220 deg.
Outside temp : 18 deg celcius (65F) = running temp of 180 F (ideal)(82C)
Outside temp : 25 deg celsius(77F) = running temp of 210-220 F (100-105F)
I also have a fan always running like my rad fan in the engine bay to get air to circulate next to the engine


gerrelt
19:32:42 Thu
Sep 15 2005
Re: inside rad
Hirider, did you consider building a box around the radiator, and then feed fresh air to it through ducting and an airscoop from under the car? And then let the warm air escape through holes cut in the firewall.

This is an interesting samba thread for a rear mounted radiator set-up:
http://home.tiscali.nl/~gmolhoek/kcd/kcd7.jpg



hirider
03:24:29 Fri
Sep 16 2005
Re: inside rad
Well from this setup, you get plenty of space to put ducts, but my plan is just to put the rad in front like everybody since I have a new baby that needs to seat in the back now !
But anyone that doesn't need the back seat, I think that with a good duct setup, it should be efficient.

gerrelt
05:50:07 Fri
Sep 16 2005
Re: inside rad
You still retain the back seat with this setup, you only loose (part of) the parcel shelf.


eureka
01:46:34 Wed
Jan 11 2006
Re: inside rad
Good discussion about rear mounted rads in a beetle here
http://forums.aussieveedubbers.com/viewtopic.php?tid=44693

64ghia
01:10:47 Fri
Jan 26 2007
Re: rear rad mit ducted scoop
I put a 2.2 subaru in a ghia with a rear rad. I raised the deck hinge 1.5 in &cut out back of deck , behind lic. plate. I used a jeep rad it is 10" high X 31" long with 2 10" fans have not driven in hot weather 0ver 85 deg. temp stays constent 195-200 deg. p.s fans pull out back.



rear rad mit ducted scoop
http://bb.bbboy.net/vwengineconversions-viewthread?forum=20&thread=16
Powered By BbBoard - http://bb.bbboy.net