5 replies to this topic

[Puddlian]

Kind of a newb here when it comes to VTEC minis. I have just purchased a '76 Mini with a D15 VTEC and I am already having fun with it but it seemed to me that it was running hotter than normal when I tootled around town.

I checked the electric fan connections and got it running when I made a ground connection to the relay. So the fan is fine... but... after one of my test drives, I pulled into the driveway and sure enough, the electric fan was buzzing away ..... I thought "great, it's working like it should." But when I walked around to the front of the car, a healthy blast of hot air was blowing against my legs as I stood infront of the grille.

My initial thought was that the fan must be running backwards (drawing hot air from the engine compartment, through the radiator core, and out the front.) But is that backwards? When I checked on several forums I saw that heavy machinery like bulldozers and earth moving equipment, actually uses this setup. I know a regular car setup draws outside air through the radiator core and into the engine bay but could this reverse setup actually be intentional?

So far the engine hasn't actually over-heated, even when I drove it around at 90 degrees ambient. The temperature gauge shows it peaking at around 210 degrees and it hasn't pushed any coolant out over the driveway..... any thoughts?

 

[Steam]

At speed air will want to flow into the front of the car. If the fan is forcing air in the oppsite direction there be no effective airflow hence no cooling.

[stuart bowes]

it's supposed to mimic, or assist, air flow through the rad when the car isn't moving fast enough to provide the air movement itself

 

therefore, sucking in from outside in towards the engine

 

although theoretically when you get up to speed again it should just cut out anyway

Edited by stuart bowes, 07 September 2022 - 09:23 AM.

[Ethel]

The direction the air goes should make little difference. The objective is to cool the water that's cooling the engine, not heat the air. The best efficiency is when you're shifting the air quickly to replace it with air that's at an even lower temperature & able to absorb heat at a higher rate. For vehicles it makes sense to stick the radiator at the front and have the vehicle's motion contribute to the flow.

 

Your Mini was a bit different when it had a transverse engine driven fan & it was mechanically simpler for it to assist in blowing air through the radiator in to the wheel arch. Some fans are designed to go in front of the radiator & blow - similar, but opposite the auxiliary fan on later Minis. Could yours be one of those?

[Kam]

Welcome to the forum

 

Do you have a picture of your engine bay? You will have a small amount of heat if you stand in front of any car but not blowing heat even with these engine swaps and tight clearances. Your d15 will have a little bit more space in the bay compared to full on packed bay like b16's etc and you will feel heat but again definitely not blowing heat against you 

 

It actually doesn't matter if you have a "push" or "pull" fan, I've used both, no difference found in temps, its all down to the size of the rad and how its mounted for clearance you then put the fan in. Even then I have a personal preference for a push fan so will aim to always mount rad if possible with a fan behind. I feel better knowing when you come to a standstill (more important than on the move!) the fan is pushing air into the rad then through it regardless of what crazy temps are building up behind the fan. Driving forward you have auto ram air into the rad, its when your not driving is what your trying to cater for here, pushing cooler air into the rad without pulling in any hot air already sitting there

 

Main things with cooling is, is the size of your rad upto the job, if you can't get the large surface area then make up for it by making it thicker

 

Is your fan upto the job? 

 

Is your rad/fan upright? Having it leaning or tilted for clearance is a no no, any crucial air being passed through the fins will just bounce over and go to waste 

 

If your temp readings are good then your rad/fan setup must be ok? Are you running a turbo or boosted as you say across the pond 

 

Can't see why your pushing out hot air unless your setup is drawing engine air over to the rad side, your rad must be super hot to touch (please don't)    obviously we do get crazy high temps under the bay

 

I did have a picture somewhere on my build taken with a temp gauge to show the different areas and there temps, once after a drive I had a slice of bread already waiting for me in the garage so when I got back I put it on the rocker cover and when the fan kicked out after a minute or so it was lightly toasted, bit of flora and it tasted fine 

 

Like I said crazy temps under there, must be a reason why yours is pushing it out, a picture might help, if you can't post up due to post count see if you can PM it to me and I'll try and put it up 

Edited by Kam, 10 September 2022 - 10:19 PM.

[Kam]

Here you go, these are the under bonnet crazy temps taken with a laser thermometer of a build running spot on temps and no cooling issues. Obviously these are not normal accepted figures but there is a lot of heat build up under that bonnet so your always gonna be working against the grain with an engine swap and a lack of routing of things of where you would like but there is always a way around