Any advantage to the series 5 mechanical fan over the series 4 one?
 

I see that the series 5 fan has more blades, would it be at all advantageous to install a series 5 fan on a stock or nearly stock series 4 car, assuming the series 5 fan was cheap and the engine is already out with the fan hardware easily accessible?

That sucks, it says in the notes -more blades for better cooling but you cant use it because we are better than you, haha s4 fan. That was a good question. now because the book says no, has anybody tried it or have done it. Is there a way to make it work?

I think the fan bolt pattern is the same... just swap the blades onto your fan clutch. You can technically fit an s5 fan clutch on an s4 but not the other way around. The center bore on the s5 is larger than that of the s4, so the s4 fan clutch will not mate with the s5 waterpump nose.

I'm not sure the extra blades equate to *that* much more cooling though. I could be wrong.

Thanks for the info.

That's a good idea. I may try that if I come across an S5 fan.

it is probably a small difference, power only went up by 10%

fyi the s5 fan doesnt fit with the s4 fan shroud

I'm not saying you're wrong, but I have never run into this issue or heard of it.

Additionally, I used an s5 fan with my s4 shroud many years ago. Unless someone had swapped the shroud years before I bought it, but it was a completely stock and unmolested car with it's original radiator even..

^He probably ran into some tolerance build up/fitment issues. Not at all uncommon, as there is a bit of slop in the shroud mounting fasteners (i.e., some are just threaded clips), and the plastic shroud is flimsy to begin with. Way to deal with this is mount shroud loosely, position it so the fan doesn't rub anywhere, then snug down all the fasteners a little at a time in sequence. It helps to have a 2nd set of hands to hold the shroud while snugging down the bolts.

hmm i realized i have a koyo rad which propably doesn't help fit it. but my s4 fan fits fine

I have a Koyo N-flow radiator in my S5T2, and when I was still running the mechanical fan with it (also S5), I had to do a bit of trimming of the fan shroud to get it all to fit. Due to the extra thickness of the Koyo radiator, I recall I had to trim a bit off the left & right side edges of the shroud along the radiator side.

I'm currently running the s5 fan blades on an s4 fan clutch. This is with stock radiator and shroud.

As mentioned above there are a couple extra blades and it seems to move a little more air. NOTE: You cannot put the s5 fan clutch on an s4 water pump because as someone else pointed out the shaft in the pump is a different diameter. This means that the s5 fan will have some slop when you put it on and will result in high rpm vibration. I checked....