Front Cooler w/o Cutting Tub

[North Coast Cab]

I currently run a 28 row factory cooler and need to add more cooling capacity. Will I get enough airflow upfront with a center mounted cooler without cutting and ducting the tub? I would change valence to the Rennspeed Ruf one with provisions for center cooler. Or am I better off upgrading to the full blown Carrera fender mounted cooler?

John

[MuffinMan]

"Enough" cooling is a relative term. I had an RX7 oil cooler in the front of my 911 with a 930S fiberglass spoiler with no tub modification. It cooled both my 2.7 and my 3.6 on the street without any problems, but at the track it just didn't quite get the job done. It was probably a combination of inferior airflow and cooler type/size, but a replacement with a fatty B&B cooler & tub notching solved track overheating problems.

If it's just a street car, I think you'll be fine without tub notching. Click on my "B&B" link in my signature to see pictures of the old cooler mounted without notching the tub. It will give you a good idea of how much room & what type of airflow you can expect.

[dean]

I installed a Mocal center oil cooler in my car without cutting the tub. I modifyed the stock SC valence. It was a lot of work and I don't really like how it looks but it works. In hind site I should have cut the tub. I think it would have been much easier and look better. There isn't much room behind the oil cooler but I think if the air gets in it will find a way out.



I don't know how much room is behind the Ruf valence but my advice is to just cut the tub. That is what I am going to do when I backdate some day

[North Coast Cab]

I track the car and that is where I've run into problems. It's not way too hot, but I'm very concious of the gauges and I want to bring the temp down. What if I added a small RX7 type inline with the 28 row? Not sure of the room with the Ruf valence, but I like the idea because it has nice inlets for brake cooling ducts as well.

John

[Chuck Moreland]

The amount of room behind the center-mounted cooler varies a lot with bumper type and cooler type. If you choose a combination that allows the cooler to be mounted close/flush with the bumper opening, you can create a decent air escape path behind the cooler wihtout cutting the tub.

But if you want to run the bigger coolers with many of the popular bumpers (RS, IROC, etc) you will need to move the cooler back against the tub.

Cutting the tub intimidates many, but it really isn't that big of a deal. Done properly it can look very clean - even factory. And it really isn't that hard to do if you reasonable skills.

[Bill Verburg]

Will I get enough airflow upfront with a center mounted cooler without cutting and ducting the tub?

Easily, especially if you leave the fender cooler in.

I run a B&B 20" cooler in a BW Ruf bumper, no other cooler at all and no tub mods. Temps are always well under 200&degF even w/ the 3.8RS


If the fender cooler is retained then an even smaller front mount which needs even less room would be needed.

[Chuck Moreland]

The RUF style that Bill has is one that provides quite a bit of space, this due to it being essentially flat across the front.

Contrast Bill's bumper with the IROC that tapers to the opening,



or the RS, even tighter



Don't be fooled by the size of the opening, you must have added width to accomodate the hoses and fittings that typically extend out the sides (width). These bumpers have surprisingly little space behind them.

These more limited bumpers require the fitment of a smaller cooler, or a large cooler pushed back against the tub to provide width to accomodate the hoses.

[BoxsterGT]

The Ruf front cooler package worked extremely well for me with a 550 hp turbo application on the track.

Its a proven design, it bolts on and fits without hassle.

Since the Ruf valence is mounted flush, it leaves more room for air flow.

I fitted mine with the Ruf in series with the stock front cooler and temps never got above 200 deg F even on the hottest track days.

I bought this same combination for my current project, but have since changed my plans...... again.

I am building a "Yellow Bird" clone for the street with about 450 hp. I have fitted two factory 87 911C type coolers instead, to allow room for a larger A/C condenser in the middle.

I can post some photos if anyone is interested.

Len

[BoxsterGT]

Sorry, I got carried away at the mention of Ruf.

I guess I should have read the question again before offering advice.

If you have a close to stock 911, add the Carrera front cooler.

It is reasonable in price and will perfom well for just about all street driving conditions and occasional track use.

Much less expensive than the Ruf package, although not as cool looking.

Len

[chrisp]

I had a Carrera fender cooler in my stock SC. It would run 220-230 on really hot (90+ deg) days at the track (the trombone ran 250!).

I bought a 44 row Mocal and positioned it behind an IROC style bumper (version w/integrated splitter). I have probably 1.5"-2" behind the cooler but because the tub isn't flat only about 1/2 of the cooler is that close to the tub. At the lower edge I probably have 2"-3".

I paid very special attention to keeping the air from spilling over once it's goes into the cut out. Air wants to find the path of least resistance. If there's a gap around the cooler (like in dean's pic) then you will get spillage around the sides. Enough opportunity for spillage and i suspect you could actually create a low pressure zone in front of the cooler as the air splits to go around a loosely fitting cooler (I've seen coolers with 3"-4" gaps on the sides..like a where a smaller cooler was installed in a previosuly owned bumper that had a large cooler in it). My opening overlaps the cooler by about 1/8-1/4" on all sides. When I put the bumper on it actually pushes against the cooler slightly.

I ran 10 days this year; 9 were above 75 degrees (3 were above 90 degrees) and one was 55 degrees. On the hottest days I ran 210 deg oil temps and on the cool day it would take 10-15 minutes at full song (w/engine already warm) to break 180 and then stabilized at 190.

Also keep in mind the smaller the opening (and by default the cooler behind it) the more aero efficient the overall car is. So the more efficient you can make the system the smaller the cooler/opening can be. The smaller opening also dumps less air under the car and that's a good thing. People are installing all sorts of splitters and deep front bumpers to keep air from going under the car. Chuck's built a ducting system that directs the air up and over the car so clearly it's a concern. Why would you then have gap around the cooler or a larger than necessary cooler dumping extra air under the car?

You can also add some vertical (frontward pointing) side plates on both sides of the opening if you need to increase the volume of air flow. Even with a tight cooler to bumper seal air still wants to spill to the sides, top and bottom of the cooler and pass around/over/under the car. The vertical plates will force some of the air from spilling over and send it through the opening.

[GeorgeM]

Cooler w/stock valance

I've since replaced this with a Ruf style f/g valence, but this one worked fine.

[dean]

The grille that I made for it covers those air gaps at the ends with solid stock. The above poster is right (Chuck)? about the lines adding width to the cooler. In my case they added about 4-5" if I remember correctly. So the cooler is hugh with the lines. I chose that cooler cause it was not so tall. But it is very wide. I am pretty sure my cooler wouldn't fit most valences without cutting the tub.

[si Banker]

I added a second oil cooler to my 1987. I removed the washer bottle from the left front fender and mounted the cooler using the existing hardware with some modifications. The hoses were run behind the front bumper.

Oil temps are 180 to a max of 190 on a Texas summer day in traffic.

[jtratza]

Bill, Where did you get or how did you fab the grills for the fog lights? Thanks

[Bill Verburg]

The amount of room behind the center-mounted cooler varies a lot with bumper type and cooler type. If you choose a combination that allows the cooler to be mounted close/flush with the bumper opening, you can create a decent air escape path behind the cooler wihtout cutting the tub.

That's very true. The Ruf on the late chassis has enough room, but the RS on my '72 had no room.

Bill, Where did you get or how did you fab the grills for the fog lights?

Both the center grill and fog grills were made from SC engine lid grills. You will need 2 of them.

[North Coast Cab]

Here's the valence I'm thinking about using. I can't go to a full fibergalss front bumper or I'll be assesed points in the Nasa TT group I run with.

Sounds like I need to find someone with this valence to determine how much room.

Jon

[87924gt]

Great thread, just what I'm looking for.
Steve E

[Miguel Antonett]

I installed a Mocal front cooler without modifying the tube. Used 1.5" spacers on top and 2" spacers for the bottom, then modified the existing valance at a local body shop keeping, pretty much, the original look and original rubber lip. Temps have not gone over 190 again, even during August in Alabama.

[David]

The PO of my car mounted a front cooler against the tub. It still runs cool but I'll space it out some.