LocostUSA.com

Learning how to build Lotus Seven replicas...together!
It is currently September 23, 2018, 6:57 am

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 4 posts ] 
Author Message
 Post subject: midi coolant pipe size
PostPosted: March 5, 2018, 12:21 am 
Offline
User avatar

Joined: March 30, 2011, 7:18 am
Posts: 1409
Location: central Arkansas
My original plan was to place my radiator in the back. Short coolant path, low pressure zone in the back to help pull air through, etc. But the radiator would have to compete for space with other stuff, so I've been revisiting the idea of putting it in front. So I've been checking up on coolant tube sizes, etc.

Some searching turned up these tube sizes:

1-3/8 Pantera
1-3/8 Fiero
1-1/8 X1/9 (iffy)
1-1/2 some GT40 replicas
1-1/4 hot, 2 cold New GT40

Those are probably the closest inch equivalents to metric sizes, since all of those cars were metric.

A somewhat contentious but informative thread on gt40s.com:
http://www.gt40s.com/forum/gt40-tech-en ... tions.html

There's one comment in the thread about the weight of the filled GT40 cooling system that was a real eye-opener. Also that Ford determined the need for such a large return line through CFD.

And another very detailed thread on a Pantera forum:
http://pantera.infopop.cc/eve/forums/a/ ... /346105744


Top
 Profile  
Reply with quote  
PostPosted: March 5, 2018, 12:51 pm 
Offline
User avatar

Joined: March 30, 2011, 7:18 am
Posts: 1409
Location: central Arkansas
There turned out to be a lot of interesting information in the intarwebs after I found the correct search term - "rear mounted radiator."

It doesn't matter so much that the radiator is in the rear, as that it's at the other end of the car.

Two main groups of builders do it - the 4x4 guys and the rally guys.

The 4x4s move the radiator to the back because they're often running narrowed noses, big winches, and the radiators are not only fighting for space, but are also susceptible to impact damage or simply being packed with mud.

The rally guys are going to rear mounts because current intercooler thinking has moved from "large" to "yuuuuge" to "Brobdingagian." The poor radiator gets shunted to the back. And they like being able to move some of the weight off the nose as well.

What's interesting is that the air ducts and vents on some of those 500+hp rally cars are both tiny and in more or less "dead" air. Some of them don't even have any particular ducting. I'm not sure how some of them work...

The 4x4 guys usually cool fine at low speed and in town, but sometimes have trouble on the freeway. I'd already wondered about that, having seen the "horizontal cyclone of debris" orbiting behind the cab often enough. Coupled with the ever-popular Locost CFD airflow drawing, the air direction and pressure on the back of a Locost could be a problem. And the air flow would be noticeably different depending on if front and/or rear wind shields were fitted.

If you already had a running car it would be fairly easy to figure things out empirically with yarn tufts and a homemade manometer rake, but that's a chicken-and-egg problem...

Most OEM mid-engine cars seem to put the radiator in front. A few of the supercars use sidemount radiators.


Top
 Profile  
Reply with quote  
PostPosted: March 5, 2018, 2:45 pm 
Offline

Joined: January 18, 2015, 2:34 am
Posts: 45
Location: Los Angeles
Years ago, when I was running a Formula Ford, I met a fellow who had used "airfoil shaped" aluminum tubing for the supply and return lines for a front-mounted radiator on a FF. I believe that they were sourced from discarded wing struts from a Luscomb or some such. He "pounded to shape" tubular adapters at each end and welded them on. He claimed that this added no weight and the greater surface area allowed him to run a smaller radiator; less weight and less drag. This was around the time that Harvey Templeton (age 69 then, the brother of Templeton Funds founder John Templeton) was running a FF of his own uniques design and and winning on all of the speedway courses in the Southeast against the young guns. His was a a very narrow car with a horizontally suspended cooling grid fabricated from ½" copper tubing. No radiator other than that!

I always liked the idea of the aerodynamic aluminum tubing for it's greater exposed surface area when mounted on the outside of the chassis. Now that I have been running an electric coolant pump in my Duratec powered Birkin for a year, I would remove the engine driven pump (if allowed) and run larger battery if needed. The Davies-Craig pump controller only runs the pump as needed to maintain the commanded coolant temp. It's pretty low draw as well.

Any rear-mounted radiator is going to need a larger cooling fan with serious attention paid to which side would have the lower pressure at speed. If you look at current commercial buses, they mount a series of smaller fans across the entire surface of the radiator. there are several temperature sensors on the radiator that drive specific rows of fans as needed. How about large computer cooling fans mounted like this? They only run on 5 volts as well.

Just my .02


Top
 Profile  
Reply with quote  
PostPosted: March 5, 2018, 3:31 pm 
Offline
User avatar

Joined: October 23, 2010, 2:40 am
Posts: 1040
TRX, here's another data point:

1-1/2 o.d. tubes. Ultima. Mid-engine, front radiator, one tube hot side, one tube cold side. This is on a 1995 chassis. Those typically have 350 Chevys or small block Fords, many in the 500 hp range.

_________________
Cheers, Tom

My Car9 build: viewtopic.php?f=35&t=14613
"It's the construction of the car-the sheer lunacy and joy of making diverse parts come together and work as one-that counts."

Ultima Spyder, Northstar 4.0, Porsche G50/52


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 4 posts ] 

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
POWERED_BY