Cowl airbox /AC blower delete vs. DP Ventilation kit or Classic Retrofit HiPo blower?

[famoroso]

Greetings Pelican Nation,

1989 3.2 heat delete in conjunction with:
A) Fresh air box / blower delete and / or...
B) AC blower delete
VERSUS these options:
C) DP Motorsport Ventilation kit, versus...
D) Classic Retrofit hi-power blower, or...
E)?


By way of background, I am building an '89 911 M491 / M470 Sports Purpose project. ~2,500 lbs. is the stretch goal (altho, I'd imagine I will end up closer to ~2,550 lbs.).

Current situation:





More here: Presenting "Vents," my 1989 911 M491 / M470 coupe

So far, I've executed on, and planned, the following to achieve this goal:

Euro front bumper crush tubes (altho, I am ISO aluminum versions)
Fog light delete
Antigravity lithium battery (14.19 lbs)
Fuchs Evo 7&9X16 wheels
Radio & speaker delete
Footwell blower delete
RS style door panels
Sunroof delete
Manual door locks
Manual windows
Recaro Pole Position Carbon seats (13.43 lbs per + 9.31 lbs of Al brackets & steel sliders)
Rear seat & seatbelt delete
Lightweight sound deadening
Cruise Control delete
Heat delete, comprehensive
AC delete, comprehensive
M&K tubular no-heat headers
Lightweight muffler (TBD, likely 17.7 lb 2 in / 1 out Scart)
TopTuning's 3D printed rear light housings
Euro rear bumper crush tubes (altho, I am ISO aluminum versions)
Rear bumperette (there's nothing "ette" / diminutive about 'em) delete
Etc.

Going full manual (windows, locks and mirrors) 1989 doors. Tips & tricks?


However, I need to maintain fresh air ventilation / blower(s). As such, I currently have:

A) The smuggler's box AC blower, which flows air thru the dash vents & bowtie vent. I originally planned on keeping this system, but upgrading the fan to the Kuehl Wirbelsturm / Hurricane evaporator motor




B) The factory fresh air fan in the cowl, along with the dashboard slider controls. Obviously, the heat slider control is now superfluous. As you know this fan / system flows fresh air to the defroster vent and / or underdash foot vents (I currently have Achtung Kraft Kool'n under dash ducts, which are quite efficacious).




I originally planned on keeping both of the above setups for as much fresh airflow as possible.

However, I am now contemplating removing the cowl fan system as A) the heat slider is no longer needed and B) for weight savings. If I went this route, I figured I would just maintain the smuggler's box AC blower and call it good.

Given that I am considering deleting the cowl fan system, should I consider replacing it with one of the following options? And, if so, should I then also delete the smuggler's box fan, etc.?

Also, any other options I should consider?

I suppose that, in a perfect world, one fan would provide fresh airflow to all three sets of vents (defrost, dash and underdash) with at least some fresh airflow directional zone control being a huge plus.

I see these two options and would be interested in opinions and, especially, salient btdt experiences.

1) https://www.dp-motorsport.de/en/produkt/ventilation-set-for-911-1970-1989/







Description
No heater, only fresh air blower! Without radial fan!

Replaces the original ventilation box, bowden cables and selector lever.

Set constisting of:

1x fibreglass ventilation box
1x bracket
1x T-piece
1x hose
6x hose clamps
Radial fan (911.624.044.02)


2) Classic Retrofit High Power Blower for 911 A/C Gen2 (preferably, without the AC evaporator).

https://www.classicretrofit.com/en-us/products/high-power-blower-for-911-a-c




I'll leave it at that for now. Let the fresh air box blower vs. AC evaporator blower deletion debate begin...

[Cory M]

I built a few cars with the factory fresh air system and achtung craft vents that work well. On a couple race cars we have just routed a hose from the cowl vent to the clock hole for fresh air. That only works when you're moving though. On some race cars I've seen people use a simple electric lightweight fan, like NASCAR brake duct cooling fans you can get it race supply shops. The fan was just mounted under the hood and pulled air from there, cowl was blocked off.

[Nditiz1]

It's funny to me how much people sacrifice trying to make a car weigh less, but at the end of the day it doesn't really matter much. What I mean by this:

I purchased an 83 SC track car 2 years ago. It was 2300 lbs. I domesticated it, took out the roll cage, lightweight race seats, lexan side windows/rear glass. I added all the dash components back in, front and rear stock seats, carpet, rear interior panels, side/rear glass, pop out windows, heat exchangers. At the end when I put my car on the race scales it was 2300 lbs. Also, unless my racing ability is that of the pros then weight could matter, but probably not. 2 cars where one weighs 100 lbs more could easily be compensated by a better driver behind the wheel.

Back to your question:

If you are trying to save weight, but want the best fresh air then you should keep the sunroof (maybe make it carbon fiber), add pop outs and add moveable vent windows. That will be the most airflow through the car and out which will surpass ANY blower setup while moving.

I have not had the chance to try out the hurricane blower, but it is on the build list this year for a hybrid AC retro fit. The CR AC gen 1 and 2 are more powerful than the stock blower. I have tested and provided video evidence of this. I have not tried the mini fan and dp-motorsports you proposed, but I'm not sure it will be more powerful than stock. Before I delved into adding AC to my 77 I did have the nut ducts installed on my stock setup and it was an improvement. The best addition by far has been moveable vent windows in the targa when I want a blast of sub 80F air (I won't even kick on the CR AC).

Last thing I want to harp on is the "No heat" Not sure why you wouldn't want to add free heat. What I mean by this is you could backdate the heat for almost immeasurable weight addition to have heat if you needed it. If you live in the perfect world where it is always 75F then I'll concede that arugment, so don't bother.

[famoroso]

Originally Posted by Nditiz1

It's funny to me how much people sacrifice trying to make a car weigh less, but at the end of the day it doesn't really matter much.

Thanks for the input.

However, weight is the most important operand in my Sports Purpose build equation.

When I took my ~2,000 pound Lotus Elise to ~1,775 pounds it went from great to amazing (and when I took it from 190hp to 300hp it went to utterly amazing). I tracked that car for seventeen years. I learned that light makes right. Every aspect of vehicle dynamics, and driving enjoyment, was heightened.

Similarly, Porsche's RS (and '89 Club Sport) recipe of a little less weight + a little more power (and, sometimes, a little nore suspension) is why these particular cars are greater than the sum of their parts. Much more so than their non-RS counterparts. That's where the Sports Purpose magic happens. Lighter weight is the most important operand in that equation.

I have three 911s covering the waterfront...

Mild (stock-ish, w/ killer AC),
Medium (260hp & 2,676 lbs & 34° vent temp AC)
Spicy (targeting: ~300hp & ~2,500 lbs). No heat, no AC, no radio, etc.

So, please keep the opinions / suggestions coming. I appreciate the help.

[Cory M]

[famoroso]

Oh, that looks GOOD.

[mnez]

I went for option E.
Heater backdate, and no other fans in the car.
Ran new hoses through where the footwell blowers used to be, perfect for the shoulder seasons.
The fresh air blower was so ineffective that removing made little difference. Left the gutted fan housing in place and get just as much air as long as the car is moving. Obviously none when stopped.
AC is 2/70 - 2 windows down, 70mph!

[creaturecat]

i backdated and converted to fresh air thru the vents, using the factory sourced parts.
works well at speed.

[Cory M]

Check this

https://www.stuttgart-classica.com/interior/ventilation-box?rq=Fresh%20air

[famoroso]

Originally Posted by Cory M

Check this

https://www.stuttgart-classica.com/interior/ventilation-box?rq=Fresh%20air

Oh, that's a nice option.

I just did a 450 mile drive in pretty moderate temps. For a while I was running just the fresh air blower fan. Regardless of whether I directed airflow to the footwells or defroster vents, the airflow didn't really reach me. The Achtung Kraft Kool'n vent makes a big difference in felt airflow

[Lz7w]

the stuttgart classica part looks identical to the dp motorsport part. I bought mine from dp motorsport directly and have it hooked up to the two diverter units to blend fresh air and heat (sounds like it's the same end state as mnez but with the dp motorsports plenum/box).

I never found the air blower to be all that effective in my car, and this solution provides plenty of fresh air once the car is moving.

[Cory M]

The blower is great when combined with the Achtung ducts that divert the air to the driver/passenger. Less so when using the factory ducts that point the air at the floor.

[famoroso]

Originally Posted by Cory M

The blower is great when combined with the Achtung ducts that divert the air to the driver/passenger. Less so when using the factory ducts that point the air at the floor.

Indeed. The Kool'n ducts are amazing for use with fresh airflow. If I needed to run the heat much, I might swap back to the stock vent during the winter. The Kool'n might work too well with heat. 😳

[Lz7w]

Originally Posted by Cory M

The blower is great when combined with the Achtung ducts that divert the air to the driver/passenger. Less so when using the factory ducts that point the air at the floor.

yeah, that makes sense. if I spent more time with the windows up or in traffic, I'd probably want to add back the blower.

this 3d-printed plenum done by a member on here also looks pretty nice: https://forums.pelicanparts.com/porsche-911-technical-forum/1123849-diy-3d-printing-tools-parts-thread-9.html#post12211508