Underside cooling tin

[neilca]

I am converting to an upright 911 fan. In doing so do I need to run the cooling tin on the underside of the motor?

Thanks,
neilca

[norustscott]

IMO, yes...The lower tin actually slows the air down and slightly increases the pressure around the heads and cylinders. This also helps direct air around the head. This allows for a greater exchange of heat. If the upright fan increases airflow then I would think you would have a greater need for the tin. Faster air does not necessarily mean a cooler engine.

[John Rogers]

I have a 911 fan system on my race car and we still use the tin around the cylinders to try to get even cooling. With out the tin the tops of the fins are much cooler than the bottom and this leads to some bad ring/cylinder wear. Good luck.

[Ron Meier]

A question to those of you that converted to a 911 style cooling system - Does it reduce engine temp significantly?

[John Rogers]

The rule of thumb is if it is 2.5l or over then the 911 fan system is the only way to go since the stock fan can not push enough air to do the job. This is figuring some driving at less that full throttle since the old time SCCA racers used to remove half the stock blades and run a tube through the firewall to get air at speed. The key world here is speed since at slow speeds the engines would cook. The other advantage is a lot more alternator capacity than stock too!

[maf 914]

If you're interested in Porsche 911 shroud cooling for Type 4 engines go to http://shoptalkforums.com/bbs/cgi-bin/forumdisplay.cgi?action=topics&forum=The+Type+4rum&number=1&DaysPrune=&LastLogin= and do a search. This has been discussed many times. Good info.

Mike