Pelican Parts Forums - Watercooled intercooler system on aircooled 911

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Watercooled intercooler system on aircooled 911

I have a 69 model prodject car and i am installing a 3,3 litre turbo engine in it. I want to use a ducktail on the car so there is not so much space for the standard intercooler. I was thinking about building a watercooled intercooling system with a radiator in front. When first making this water loop for the intercooler it will be easy to install a small plate heat exchanger condenser in the same loop (weights about 2-3 kg) so the air cooled condenser(s) can be removed.

Before starting on this i would like to find out more about the temperatures and capacities in intercooler and air conditioning system on the the car so i can find out if this is possible or not.

Can some one please help me with my questions below

If it is 30°C (86°F) outside and you run your car at 3500 rpm

1. What is the nominal air flow through the engine in a 930, for intance at 3500 rpm

2. what is the normale temperature before and after the intercooler, (air that flows into engine)?

3. what is the nominel air conditioning cooling capacity or refrigeration compressor flow rate?

I see that here is some advantages and some disadvantages to make this system. As i can see is now it's like:
Advantages:
- Coolder air into the engine because air is not pre heated by the intercooler or air condition condenser (more power)
- possibility to use a ducktail :)
- removes two aircooled condensers
- possibility to get more capacity out of the air conditioning system
- reduces some weight because of no need for air cooled condensers and intercoolers, also the airconditioning liquid reciver can be removed. less refrigerant needed.

disadvantages:
- Complicated system
- More weight on piping and bigger radiator in front.
- less capacity on intercooler because there is needed to have a secondery fluid to exchange heat = hotter at high ambient temperature :( ???

Please if some one have any information, please help me.

below you can se my system drawing, there will also be needed some small balancing valves

http://forums.pelicanparts.com/uploa...1192129757.jpg

Best regards
Kjell Robert

Thanks

I'm far too much of an engineering simpleton to be of any real help with devising your water-cooled intercooler system. If it were me, I'd figure out a way to make an air to air intercooler fit. In fact, I think Paul Rodelo runs a duck tail on his 930 and made the OEM 3.3L intercooler fit. It seems that you are adding a great deal of complexity to an otherwise pretty simple and proven system. Just my two cents...probably not even worth that.

I found this picture some where on the internet some months ago, but no more info. It's interesting does any one know this modification?

Kjell Robert

http://forums.pelicanparts.com/uploa...1192133910.jpg

I think it's a matter of taking the factory intercooler (which is not known to be a performer), and making the necessary mods to make it fit with your tail.

That's why I say, I think it would make more sense to funnel the money into making an air to air intercooler fit/work rather than devising something else. What kind of mods can be done to the tail to help fit an intercooler?

There's a custom intercooler to fit a duck on this car.

http://forums.pelicanparts.com/porsche-cars-sale/369078-74-911-rs-turbo.html

Lets see...you want to add a water cooled tercooler to an air-cooled car....that has had years of history using air-air charge coolers? l have to jump board here and say....NO. This air-water charge cooler idea comes up time and again and eventually air-air wins out every time. Why? it works better,is lighter,simpler and cheaper. Lets see,anything else? oh yeah,easier to work on.There is ample room under there and you`re better off with No intercooler then using a stock one,add some water injection if you can`t let go (of the h2o)

Quote:

Originally Posted by raceman (Post 3532433)

...and you`re better off with No intercooler then using a stock one,add some water injection if you can`t let go (of the h2o)

Yes, and let's not forget that the early 3.0L Turbo did not have an intercooler! Talk about a cleaned up engine compartment!

I have no practical advice for your project. But didn't Porsche's initial application of the turbo 911 use a water-to-air intercooler? IIRC, I read this in Paul Frere's Porsche 911 Story. The factory tried using a water-to-air intercooler, but when they actually showed up to race the car, whatever the governing body was ruled the water-to-air somehow illegal. Porsche went to the air-to-air intercooler, and that's the way it's been ever since. Will have to go home and see if I can find that reference.

Quote:

Originally Posted by Noah930 (Post 3533201)

It had to do with the space limitations of the air-to-air intercooler and the sanctioning body (FIA?) would not accept Porsche's "interpretation" of the rules for body modification to accept the IC.

OK. Went back and checked Frere's book. I have it backwards.

He discusses the 934 on pages 272-4:

Quote:

As there is no room for an air-cooled intercooler under the engine cover (which rules do not allow to be modified), the intercoolers are water-cooled. Circulation is by an engine-driven pump and the water must go all the way to the two front-mounted radiators, flanking the central oil cooler in the front air dam. Going through the intercoolers drops the temperature of the intake air from about 150 to 50 degrees C. The 934 is thus the first car in Porsche history in which water is used as a cooling medium. At the beginning of the racing season, the legality of the watercooled intercoolers was questioned, but the intercoolers, complete with their cooling system, are part of the intake system--which was eventually accepted. ... The engine bay lid used for the 934 comes from the standard Turbo fitted with air conditioning, featuring a large air inlet within the spoiler which, in the racing car, is used to duct cooling air to the turbocharger and to the transmission oil cooler.

Then, on pages 274-8, he discusses the 935:

Quote:

The fuel injection plant and the turbocharging installation were initially very similar to those on the 1974 Turbo-Carrera, but the intercooler had to be modified during the season, following a decision taken by the CSI. Originally, the air-cooled intercooler was located under the rear airfoil, within the engine compartment where it was housed inside a support bulging out from the engine bay lid to carry the load acting on the airfoil. The cooling air was ducted from the opening normally used, in the production car, to cool the air-conditioning condenser. Whereas it was clear that, in Group 4, the engine by cover could not be modified, Porsche had taken advantage of the greater freedom in the use of aerodynamic aids in Group 5 to use a much simpler and lighter air-cooled intercooler. But at the race in Imola, the scrutineers decided that the airfoil support could not be used to house any mechanical devices, and their judgement was upheld by the CSI who gave Porsche five weeks to make their car legal, according to their interpretation of the rules. The two existing cars (only two were built for the entire season) were modified to take water-cooled intercoolers, similar in their general layout to those used in the 934, but of a larger size. As in Group 5 the rear wings (fenders) are wider than in Group 4 and may incorporate air in- and outlets, advantage was taken of this to locate the radiators in the rear wings (fenders), just ahead of the wheels, which saved a lot of weight compared with the front radiator layout of the 934, but still added some 10 kg (22 lb) compared with the air-air intercooler. ... The new intercooling installation had no ill-effects on the engine's maximum power, but the drivers say that it made it less flexible, reducing its useful range.

Watercooled intercooler system on aircooled 911
WHY???
You can fit a huge intercooler under a ducktail and make a reliable 400-500 HP with CIS injection or 500+ if you decide to go with EFI, and when you combine that with the weight of an early car, what you get is mind boggling, scary fast performance that will accelerate as fast or faster than the latest from Porsche, Ferrari, or anything else on the road. What exactly are you looking to do? Sorry, but if it's not broke, don't fix it.
Bryan

Thank you for the responce, i will go on with the original aircooled intercooler. When using the original airfilter system, it looks like there is wery limited space to get the intercooler forward? Does anyone know what's used to de done here?

http://forums.pelicanparts.com/uploa...1192951718.jpg

There is advantages using watercooled system, but maybe not on an air cooled baced car. Disadvantage is that there will be more total weight. Remember that a smaller oil cooler also can be added to the same water loop.

But as long as i get the ducktail and a turbo engine in the car i'm pleased

Thanks

Kjell R

This eleminates the air breather issue:

http://forums.pelicanparts.com/uploa...1192978339.jpg

This is getting ready to go on my car:

http://forums.pelicanparts.com/uploa...1192978426.jpg

what is the air temperature increase from outdoor until it reach suction inlet? there must be a temperature increase since there is some kW that is removed from the intercooler.

It must be better to have a large suction pipe that goes around to the right side of the ductail air inlet to get cold air, then you will avoid some of the hot air from the intercooler.

The question is how many hp can you save if you get coold air (outdoor air) straight into the suction?

Kjell R

Here is a pic of the air cleaner I went with. It has a nice low profile and flows really well too.
http://forums.pelicanparts.com/uploa...1192991717.jpg

And a shot of how much intercooler you can get under a ducktail if you custom fabricate it for the application.

http://forums.pelicanparts.com/uploa...1192991907.jpg

where did you get that nice intercooler?

Kjell

My intercooler was custom fabbed to fit under a ducktail by Chris Carroll of TurboKraft in Tempe AZ. Chris is a great guy to work with and very fair with
his pricing as well.