Running Twin Radiators ..

**lexsmaz** · 03-05-2010, 03:05 AM

Hi,

I'm pondering fitting a 1jz into a old E30 BMW that i have, but due to the fact that i dont have a lot of room up front & dont want to chop up the radiator support panel i was thinking of fitting the biggest Radiator in between the Radiator upright supports that i can but it will still be too small, so i was thinking of also running a smaller Radiator off to the side & running a Y piece top radiator pipe, so basically one side of the Y will feed the main radiator all the time & i thought if i put another thermostat inline to the side radiator ( in the other section of the Y pipe ) so the side radiator would only work when required, so basically the main Radiator would be used until the temp gets high enough & then the thermostat will open up the water flow to the smaller side Radiator as well ... Both radiators would share a common Y piece return pipe to the engine ..

Obviously i would put bleeders in the line where required ..

Has any one done a similar job & also is there any issues that i have not foreseen ?? & what are the thoughts as to will it work ??

Thanks in advance ..

Regards ..

Rob ..

**Bananaman** · 03-05-2010, 07:44 AM

Can't say i have any experience with fitting twin radiators, but with the thermostat on the engine, why not simplify things and run them in series? There isn't a need for complicated Y pipes and additional thermostats surely?

**river** · 03-05-2010, 08:06 AM

Hi,

Agreed.

Running them in series and with the one standard thermostat makes things a lot simpler.

seeyuzz
river

**Dangerous Beans** · 03-05-2010, 10:23 AM

However you will get better performance running them in parallel like you were thinking about (lower pressure drop and greater temp difference at each radiator).

I would just run the one main thermostat though, having 2 thermostats is unnecessary complex. Unless your thermostat is slow to respond there shouldn't be any issues.

**allencr** · 03-05-2010, 11:23 AM

How about a thicker 3/4 row radiator, or a heater core from something big, mounted up front.

**lexsmaz** · 03-05-2010, 01:09 PM

Thanks for the feed back,

I was thinking of running a secondary thermostat as i mentioned because the second radiator would be smaller than the main one & so less heat exchange ( less temp drop ) than the main one hence the reason for it only working as required otherwise the temp going back to the motor might be higher than ideal, or on second thoughts i could run a restricter or just smaller pipes in the smaller radiator so basically less flow through it instead of using the secondary thermostat ?

As the second radiator would be smaller & possibly tucked out of the way is why i thought running them in series might not be ideal ..

Along the line of what allencr mentioned i was just thinking about maybe running a motor bike radiator as a secondary radiator ..

Regards ..

Rob ..

**LeeRoy** · 03-05-2010, 04:55 PM

In Audi's where they cram big motors in small engine bays they use a dual radiator - one on each side. Not sure how they work the plumbing and temp control but maybe check one out.

**toymaz** · 03-05-2010, 04:59 PM

Hi
You should be able to fit 1 decent radiator in. I had an E30 with a rb20 which is slightly longer than a 1j
and it fitted ok check with the guys on here who have 1jz in their E30's.