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Author: Subject: Weird fan problem (airflow, not electrical)
nobrakes

posted on 15/7/16 at 11:44 PM Reply With Quote
quote:
Originally posted by nobrakes
All in all, I'm reasonably confident that the cooling will be ok although I haven't been out on the road yet (first time on the road will be a trip to the MOT station this week), its just that I'd like to try and get as much air from the fans as possible through the radiator for those stuck in traffic in a heatwave moments.

Well, it looks like the radiator isn't up to the job after all because when I tried driving at a steady 60-ish the fans came on and were running on full blast continuously so going to see about getting a bigger rad this weekend.

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02GF74

posted on 16/7/16 at 06:15 PM Reply With Quote
quote:
Originally posted by nobrakes

Well, it looks like the radiator isn't up to the job after all because when I tried driving at a steady 60-ish the fans came on and were running on full blast continuously so going to see about getting a bigger rad this weekend.


post a photo of your current section so we can all laugh, sorry, I meant advise.

Bear in mind a car has body work with an opening at the front to channel air to the rad - I expect you don't have that on your v8 trike.

what is the radiator from and approx. size of the matrix?






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rachaeljf

posted on 16/7/16 at 10:34 PM Reply With Quote
You can't avoid some small leakage back past the blade tips. It happens because there is a gap and there is a pressure difference between front and back. The shroud massively reduces the loss round the ends of the blades but will never completely eliminate it. It sounds like you have quite a high pressure ratio front to back as a result of your setup. If you ran the fan in free air you should find that leakage round the blade ends would be negligible.

As someone has said, make sure the blades are orientated correctly for the desired airflow. If they have a curved aerofoil shape, the concave side should face the intended air flow direction.

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nobrakes

posted on 17/7/16 at 11:40 AM Reply With Quote
Pic as requested. Looking at it, I've just noticed something. The top hose, running up from the middle of the inlet manifold the across to the nearside and forwards into the rad, is higher than the top of the rad. That can't be helping.
- the core is about 520mm wide & 370mm tall
- the old engine was from a 1972 Rover p6, I've misplaced the measurements but they had a rad a little bigger than this
- I believe it cooled the old 3.5 v8 but the rad in a P38 with a 4.6 like mine is 570 x 500, thats nearly 30% bigger
- the side plates used to be 'U' shaped, I straightened out the front bend so I could use it to mount the electric fans, the top offside one is just showing (maybe I could extend them outwards to make scoops, like on the Honda GL1100 model without a fairing?)
- there's an overflow bottle, not an expansion tank
- it looks like there is a lot of room behind the rad but its an optical illusion, there isn't space for a puller style fan



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mark chandler

posted on 17/7/16 at 04:00 PM Reply With Quote
I cannot see the bubble pipe, is it running SU's

On the lump the carbs bolt to there is a 1/4 barb pointing forward that carries water, this needs to go to the top of the rad, if it's blocked (quite common, have a good poke in it) as it takes the air bubbles that come off the water boiling in the head.

Missing the car will quickly blow out water and overheat,

Rad looks quite big, p38 is designed to tow heavy loads up steep hills, your time on WOT will be very limited so I cannot see this being an issue if in good condition.

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