1UZFE Lux cooling issues with BMW 740 radiator

[Zantus]

Hi All

My first post here. I've searched this and other forums and haven't found what I'm looking for.

I've got a '96 South African spec hilux with a 1UZFE under the bonnet, a Lexus auto/tip box, stock hilux transfer case, stock 4.88 hilux axles and 35" Kumho's at the other end.

The guys who did my conversion fitted a BMW 730 radiator with a 14" puller fan on the inside and a 12" pusher fan offset on the outside. Cooling was good but not perfect. I was too busy with work, so I had a friend fit a 740 radiator with 2x12" puller fans on the inside, to make space for the aircon condensor on the outside. Now the cooling seems to be worse. The fans deliver less airflow than the previous set-up, and they are not mounted right up against the radiator. These fans deliver about 1500CFM of airflow, the fabs on the 730 rad delivered about 2000CFM.

I only have cooling problems when driving slowly offroad, even in stop/go traffic it doesn't get hot.

We've already cut the whole front end apart to fit the 740 rad, and cannot see how to fit anything bigger. I also have a aircon condensor fitted, but so it's not connected yet, but that will make things worse when I eventually do start using the aircon.

My question is: Will changing the fans to a set-up that delivers 3600CFM be sufficient to cool it in offroad situations?

The fans are very expensive, so I don't want to spend all that money for no reason.


P.S. Here's my lux:
http://www.zantusdesign.co.za/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=15704&g2_serialNumber=2

[Tower]

try an aluminium radiator?

[Zantus]

The BMW radiator is aluminium. Like I said, not looking at a different radiator....yet, just want to know if 3600CFM instead 1500CFM of air flow will help with the current radiator. It took my friend a month of part time work to fit the current radiator, so I really don't want to start over for the 3rd time.

[boof]

Better airflow will always help if its low speed work as you said and the radiator is of a good quality then I would say increasing the fans will help.

I have a set of fans off a AU Falcon on mine and have never had a drama with slow work. Maybe see if they run them on any of your vehicles over there. Here they are cheap and readily available.

[Zantus]

Thanks. Unfortunately I haven't been able to find stock fans off any other vehicle here that are both powerfull and small enough to fit.

[boof]

This is a set here
AU Falcon Radiator Thermo Fans 1998 - 2002 BRAND NEW - eBay, Cooling Systems, Car Parts, Accessories, Cars, Bikes, Boats. (end time 21-Apr-08 21:22:37 AEST) (http://cgi.ebay.com.au/AU-Falcon-Radiator-Thermo-Fans-1998-2002-BRAND-NEW_W0QQitemZ170211840796QQihZ007QQcategoryZ33599Q QcmdZViewItem)

I have them in mine it is tight but I have not had the engine hit them yet. If your engine bay area is the same size as mine which it looks like you should be right, Not sure how they cpompare in cost to what you are already looking at?

[duza]

Increasing the size of the fans is surely going to help. However, sitting them as close to the radiator as possible will help and having them in a decent shroud will also help. Boof is right. Falcon AU thermos are considered to be ideal for these conversions. They do take up a fair bit of room. From memory they are about 110mm thick and you may have a little modding to do to get them in there, but it will be worth while. I think each fan pulls about 2000cfm and they come in a fairly efficient shroud. I had constant overheating problems with my Lux since the conversion and ended up chopping the front severely and fitting the Celsior radiator, (which is huge, skinny but copper and plastic tanks) under the front radiator support panel. This gave me the room to fit AU thermos and I think I have solved my problems. Unfortunately, virtually the day I fitted them, the weather turned cool, so I haven't really been able to test them in the heat, but so far around town and on the freeway, the temp has not gone over 92 deg.