 Flat fan for T4 engine |
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| mepstein |
 Feb 10 2026, 07:03 PM
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#1
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914-6 GT in waiting  Group: Members Posts: 20,427 Joined: 19-September 09 From: Landenberg, PA/Wilmington, DE Member No.: 10,825 Region Association: MidAtlantic Region 
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| worn |
Feb 10 2026, 07:05 PM
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#2
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Winner of the Utah Twisted Joint Award Group: Members Posts: 3,544 Joined: 3-June 11 From: Madison, WI and North Bend WA Member No.: 13,152 Region Association: Upper MidWest
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QUOTE(mepstein @ Feb 10 2026, 05:03 PM)  I liked how they hid the belt and idlers. I also suppose that one can calculate air movement needed and delivered. Sweet. |
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| TRP |
Feb 10 2026, 07:12 PM
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#3
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Member Group: Members Posts: 206 Joined: 2-September 23 From: Morgan Hill, CA Member No.: 27,559 Region Association: None
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Don't imagine that would fit under a LJet/DJet set up. You carb guys have all the fun.
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| mepstein |
Feb 10 2026, 07:17 PM
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#4
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914-6 GT in waiting Group: Members Posts: 20,427 Joined: 19-September 09 From: Landenberg, PA/Wilmington, DE Member No.: 10,825 Region Association: MidAtlantic Region
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QUOTE(TRP @ Feb 10 2026, 08:12 PM) Don't imagine that would fit under a LJet/DJet set up. You carb guys have all the fun. I was thinking it would be cool with ITB's and EFI. |
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| worn |
Feb 10 2026, 08:09 PM
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#5
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Winner of the Utah Twisted Joint Award Group: Members Posts: 3,544 Joined: 3-June 11 From: Madison, WI and North Bend WA Member No.: 13,152 Region Association: Upper MidWest
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QUOTE(mepstein @ Feb 10 2026, 05:17 PM) QUOTE(TRP @ Feb 10 2026, 08:12 PM) Don't imagine that would fit under a LJet/DJet set up. You carb guys have all the fun. I was thinking it would be cool with ITB's and EFI. (IMG:style_emoticons/default/agree.gif) Me too. Not that I plan to spend that on my four. |
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| Jack Standz |
Feb 10 2026, 09:32 PM
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#6
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Senior Member Group: Members Posts: 704 Joined: 15-November 19 From: Happy Place (& surrounding area) Member No.: 23,644 Region Association: None
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Type IV flat fan
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| TRP |
Feb 10 2026, 09:38 PM
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#7
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Member Group: Members Posts: 206 Joined: 2-September 23 From: Morgan Hill, CA Member No.: 27,559 Region Association: None
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This one looks like a Corvair.
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| Superhawk996 |
Feb 10 2026, 09:43 PM
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#8
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914 Guru Group: Members Posts: 7,672 Joined: 25-August 18 From: Woods of N. Idaho Member No.: 22,428 Region Association: Galt's Gulch
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I must be missing something. The T4 was an improvement over the T1 engine by having the fan driven directly off the crank and eliminating the possibility of fan loss due to a broken belt.
Lose the electrical fans due to some sort of electrical issue or temp sensor issue and you just bought a new motor (IMG:style_emoticons/default/confused24.gif) Sure it frees up maybe 5hp by removing fan parasitic loss but at the expense of losing an engine, no thanks. Surely it has a place within a T4 conversion on a Bug, Ghia, etc but I’m not seeing an advantage within a 914 other than just being different for the sake of being different. |
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| Montreal914 |
Feb 10 2026, 10:00 PM
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#9
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Advanced Member Group: Members Posts: 2,026 Joined: 8-August 10 From: Claremont, CA Member No.: 12,023 Region Association: Southern California
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Yes, it has always been the issue with the electric fans. Nevertheless, not the first one to play with that concept.
Maybe it provides better cooling distribution (cyl 3) and more cooling overall? (IMG:style_emoticons/default/confused24.gif) This racecar at Rennsport V was setup with two dual outlet fans in the cabin with two ducts each going to the engine tins in redundancy. At least if one fan goes, one is still pushing air. Unfortunately I wasn't able to picture the engine bay but the standard engine fan wasn't there, just the ducts. (IMG:style_emoticons/default/driving.gif)   |
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| emerygt350 |
Feb 10 2026, 10:01 PM
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#10
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Advanced Member Group: Members Posts: 3,457 Joined: 20-July 21 From: Upstate, NY Member No.: 25,740 Region Association: North East States |
That's just what I was thinking. If the engine is spinning the fan is moving.
I would have to suspect the physics also don't work out for the dual electrics but I can't do the math. Again, I will defer to those with the thermodynamics chops or the vw Porsche engineers. It definitely looks cool though. |
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| emerygt350 |
Feb 10 2026, 10:03 PM
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#11
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Advanced Member Group: Members Posts: 3,457 Joined: 20-July 21 From: Upstate, NY Member No.: 25,740 Region Association: North East States |
Reminds us of the real value of the generator light on nontype4s
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| wonkipop |
Feb 11 2026, 03:01 AM
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#12
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914 Guru Group: Members Posts: 5,393 Joined: 6-May 20 From: north antarctica Member No.: 24,231 Region Association: NineFourteenerVille
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QUOTE(Superhawk996 @ Feb 10 2026, 09:43 PM) I must be missing something. The T4 was an improvement over the T1 engine by having the fan driven directly off the crank and eliminating the possibility of fan loss due to a broken belt. Lose the electrical fans due to some sort of electrical issue or temp sensor issue and you just bought a new motor (IMG:style_emoticons/default/confused24.gif) Sure it frees up maybe 5hp by removing fan parasitic loss but at the expense of losing an engine, no thanks. Surely it has a place within a T4 conversion on a Bug, Ghia, etc but I’m not seeing an advantage within a 914 other than just being different for the sake of being different. (IMG:style_emoticons/default/agree.gif) (IMG:style_emoticons/default/smile.gif) the crank driven fan on the type 3 and type 4 was the best move VW ever made. in terms of engine preservation and limp home mode. re limp home mode. etched in to my memory from nearly 40 years ago in the old type 3 variant i had. (IMG:style_emoticons/default/beerchug.gif) |
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| wonkipop |
Feb 11 2026, 03:04 AM
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#13
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914 Guru Group: Members Posts: 5,393 Joined: 6-May 20 From: north antarctica Member No.: 24,231 Region Association: NineFourteenerVille
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QUOTE(Montreal914 @ Feb 10 2026, 10:00 PM) Yes, it has always been the issue with the electric fans. Nevertheless, not the first one to play with that concept. Maybe it provides better cooling distribution (cyl 3) and more cooling overall? (IMG:style_emoticons/default/confused24.gif) This racecar at Rennsport V was setup with two dual outlet fans in the cabin with two ducts each going to the engine tins in redundancy. At least if one fan goes, one is still pushing air. Unfortunately I wasn't able to picture the engine bay but the standard engine fan wasn't there, just the ducts. (IMG:style_emoticons/default/driving.gif) cylinder 3 not an issue on a type 4? not really. sure its further back but the oil cooler is out of the equation in a type 4. sure is on a type 1 and a dead cert on a type 3 due to lay down oil cooler. (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/biggrin.gif) don't ask me how i know (twice). (IMG:style_emoticons/default/biggrin.gif) |
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| GregAmy |
Feb 11 2026, 07:20 AM
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#14
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Advanced Member Group: Members Posts: 2,631 Joined: 22-February 13 From: Middletown CT Member No.: 15,565 Region Association: North East States
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Chris at Tangerine has had a downflow cooling system for decades, based around a Corvair fan. Used it on his Weber-equipped race cars, it evens the cooling flow across all cylinders.
It implements an HVAC sensor to set a light when the fan isn't creating pressure in the ducting. He has one of his customer cars with it in this shop right now, with an ITB Megasquirt setup (we're tuning it before shipping the car to the owner in Hawai'i; I've asked if it needs a chaperone for the trip...) |
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| barefoot |
Feb 11 2026, 08:31 AM
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#15
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Senior Member Group: Members Posts: 1,471 Joined: 19-March 13 From: Charleston SC Member No.: 15,673 Region Association: South East States
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QUOTE(worn @ Feb 10 2026, 08:05 PM) QUOTE(mepstein @ Feb 10 2026, 05:03 PM) I liked how they hid the belt and idlers. I also suppose that one can calculate air movement needed and delivered. Sweet. You miss the point, no belt needed, these are ELECTRIC fans. Note that the kit comes with high output alternator. Barefoot |
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| barefoot |
Feb 11 2026, 09:14 AM
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#16
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Senior Member Group: Members Posts: 1,471 Joined: 19-March 13 From: Charleston SC Member No.: 15,673 Region Association: South East States
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QUOTE(Superhawk996 @ Feb 10 2026, 10:43 PM) I must be missing something. The T4 was an improvement over the T1 engine by having the fan driven directly off the crank and eliminating the possibility of fan loss due to a broken belt. Lose the electrical fans due to some sort of electrical issue or temp sensor issue and you just bought a new motor (IMG:style_emoticons/default/confused24.gif) Sure it frees up maybe 5hp by removing fan parasitic loss but at the expense of losing an engine, no thanks. Surely it has a place within a T4 conversion on a Bug, Ghia, etc but I’m not seeing an advantage within a 914 other than just being different for the sake of being different. I aint sure it would represent more usable horsepower in racing applications as the alternator now has to work harder to keep up with fan wattage compared to power consumed by the engine driven fan. Barefoot |
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| stownsen914 |
Feb 11 2026, 09:26 AM
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#17
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Senior Member Group: Members Posts: 982 Joined: 3-October 06 From: Ossining, NY Member No.: 6,985 Region Association: None |
The idea of using electric fans has come up for 911 motors too. I've understood that a couple challenges have prevented it from being effective.
It's hard to get an electric fan to flow enough air to properly cool the motor. 911 fans flow a LOT of air. There are some higher output fans out there that have high flow numbers in FREE air, but the flow goes way down when there is stuff in its path (as is the case when it's sitting on top of a motor). Maybe the challenge is less on a type 4? The power savings are questionable. Yeah, belt-driven fans do take some hp to drive. If you can get an electric fan to flow enough, you have to deal with the physics of losing some energy (hp) with the phase transitions of converting physical energy to electric at the alternator, and then back to physical again with an electric fan. If you could do the above for short-duration runs like drag racing or autocross, or maybe even a sprint race (and run without an alternator and charge between runs), then I could see some advantage if you can get fans that actually flow enough. |
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| mepstein |
Feb 11 2026, 09:27 AM
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#18
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914-6 GT in waiting Group: Members Posts: 20,427 Joined: 19-September 09 From: Landenberg, PA/Wilmington, DE Member No.: 10,825 Region Association: MidAtlantic Region
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The flat fans that are belt driven use a lot of hp. They have advantages of very even cooling and low profile but on a type 4 that doesn’t have gobs of ho, they are going to cost you.
I just like the idea of alternatives if they work well. |
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| 73-914 |
Feb 11 2026, 11:07 AM
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#19
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Senior Member Group: Members Posts: 650 Joined: 24-April 10 From: Albany UpstateNY Member No.: 11,651 Region Association: None
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QUOTE(worn @ Feb 10 2026, 08:05 PM) QUOTE(mepstein @ Feb 10 2026, 05:03 PM) I liked how they hid the belt and idlers. I also suppose that one can calculate air movement needed and delivered. Sweet. 2 electric fans (IMG:style_emoticons/default/lol-2.gif) no belts or idlers (IMG:style_emoticons/default/idea.gif) (IMG:style_emoticons/default/popcorn[1].gif) |
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| 73-914 |
Feb 11 2026, 11:11 AM
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#20
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Senior Member Group: Members Posts: 650 Joined: 24-April 10 From: Albany UpstateNY Member No.: 11,651 Region Association: None
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Everyone forgets that a higher output Alternator needs more HP
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