I have a rock west 356 speedster with a Subaru engine and it is overheating. Anyone out there got and good solutions? The radiator is mounted in front of the engine behind the back bench. I tried cutting a hole in the back bench to see if that would increase air flow, which works at slow speed, but when you get some speed going the low pressure in the cabin works against the fan and it overheats.
Any ideas out there?
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Jim Kelly may have some insight.
Is it a new problem or has it always been an issue?
I battled overheating in my 2013 Subi turbo coupe from SAS for 3 years. It's 90% improved from stock, but I'm still tweaking. You need to be more specific in your description of overheating. Does it only occur in stop-n-go conditions? Highway speeds? Only when ambient air temps are over 80F, 85F, 90F, etc?
What engine, what rad, n/a or turbo? Is your rad ducted and shrouded?
I don't want to sound discouraging, but, in my case at least, I never found one source/shop/mechanic that solved the problem for me. I researched, fumbled around, had the car in a few shops, and ended up rebuilding the entire cooling system to my specs. My car is mid-engine, with the rad now sitting in the rear compartment (where the engine would sit in rear-engine application. Even with a dual grill, there was still too much back pressure on the fans, so I had to cut away almost all of the engine deck lid, leaving only a 4" exterior frame, and replace the lid itself with grill mesh. That one modification was a huge improvement in cooling.
Some generalities seem to apply to all overheating situations:
You need as big a rad as you can fit, with a 2-pass rad usually being sufficient;
Increasing core size of the rad, i.e., length x width, is more efficient than increasing thickness;
You need as much cool air to the inlet side of the rad as you can get;
You need coolant to move as fast as possible through the rad (up to 3 meters/second);
You need high pressure in front of the rad, and low pressure behind it. Proper ducting and shrouding is critical, since air wants to bypass the rad, and puller fans are generally more efficient than pushers;
As you move up in HP, such as with turbo/blower applications, excess engine heat becomes more difficult to shed.
As I have mentioned frequently in the past, whether we like it or not, and irregardless of our qualifications or lack thereof, we are the engineers who have to figure out the solution. Best of luck, and please keep the group informed of your progress.
Since car guys always seem to stretch the HP bounds of any engine we are exposed to, this is a problem that won't go away and will be solved eventually. However, since our cars have slightly different platforms for each maker (VW pan, tube frame, rear vs mid engine), one solution may not work for all models.
Post a picture. You need a couple electric fans thermostatically controlled. I think some kind of scoop to force air up to radiator and some way for it to exit out the normal rear engine grille. The low air pressure over the rear when running should pull air out that way.
Is it still under their warranty? Seems like a difficult place to get enough air flow. Maybe there is air trapped and you need bleeder valves like Ed used on his MGTD Subbie conversion (with radiator in the front). Water Wetter adds to coolant's capability to cool on a well engineered system.
the guys with front rads have a lot less issues....
IaM-Ray posted:the guys with front rads have a lot less issues....
Very true, but they give up about 75% of their usable trunk.
yes if you choose the trunk location.
Put the rad up front and duct it. It just works. If you have a 2.2 N/A you can use a pretty small rad. I use one from a Honda Civic/ Del Sol. It might work for a 2.5 as well. David Stroud's setup is from a Volvo & it's compact. Front mounting the rad sidesteps a lot of problems and mysteries about relative air pressures under the middle and rear end of the car.
"Front mounting the rad sidesteps a lot of problems and mysteries about relative air pressures under the middle and rear end of the car. "
No hokus pocus, Wisdom 
I have a Saab rad mounted almost horizontally up front and it works well. Stock stat and a Tom Shiels stat adapter. I use 1 1/2 inch aluminum tube fore and aft to the rad and that must help.
I lose no trunk space and have a narrow full size spare tire. I could post a cooling diagram tomorrow.
Elvis has left the building!
Not quite he is still talking to my wife....
All of the local water-cooled converted cars that I’ve seen locally, with rear mounted radiators have issues in one way or another.
I’ve seen 2 cars locally with a dual core civic/ del sol radiator running 250bhp and they’re cooling just fine. The radiator is up front though.
Please show some pictures of your set up. I’d be better be able to give more specific advice if I can see how it’s working.
I’ve looked and you can get a civic radiator in the nose with some work and also keep enough space for the spare. The battery would have to be moved to the back behind the back seat though. But you would retain almost all of the space in the nose though.
You can also do what I did. cut it all out and make it wider. But yeah....that's a bit of work.
Stan Galat, '05 IM, 2276, Nowhere, USA posted:IaM-Ray posted:the guys with front rads have a lot less issues....
Very true, but they give up about 75% of their usable trunk.
not 100% right. If you plan properly and move the battery to the back, then you can retain all your space in the nose.
Here's a simple coolant diagram that works. The front of the car is on the right.
Gary: I've copied you on an email with Peter Venuti. Pete has a Suby IM that he bought from IM as a roller with no engine and then he installed the Suby engine and cooling system (don't know how much, if any, of the cooling system was pre-installed, but we'll find out). I know of no cooling issues or maintenance issues with his car, so he might be another point of reference for you. Just saw him yesterday and he had traveled 2 hours on a highway in 88F heat with his AC on and didn't mention any issues.
Gordon
Ah--Saab, not Volvo. I got the country right. David, remind us what body-work (if any) you did to get that rad and duct and fan where it is. Also, that's like a Saab 93? The successor to the 900?
edsnova posted:Ah--Saab, not Volvo. I got the country right. David, remind us what body-work (if any) you did to get that rad and duct and fan where it is. Also, that's like a Saab 93? The successor to the 900?
Giday, Ed. My rad is out of a 91-98 Saab 900. The face of it measures 13" x 19" and it is mounted almost horizontal....like about 4" up at the front. My current scoop is 12" x 2 1/2" and I still think it is unnecessarily large. It used to be 18" wide and it cools just fine. The scoop does act as a "rock deflector " though which is comforting. It wouldn't surprise me if I could eliminate the scoop altogether and just install one of those honeycomb sheets that the dirt track racers put in front of the rads.
Having said that, the honeycomb sheet might disturb the flow on the bottom surface of the rad and bugger things up. Right now my rad has ram flow right up through it and a 12" fan to suck air up through it when stopped in traffic. It very rarely comes on.
It would not surprise me if someone could just utilize those small grilles beside the turn signals and get sufficient flow from them if some type of simple ducting was installed behind them. Everything is running so well right now that I'm not touching anything. I did take a cut out of the bottom of the bodywork just behind the bumper enough to allow the scoop to set up about 1/2" higher from road clearance. I have 5" clearance from front to back with the stock Soob oil pan. My rear motor mount now works very well and it seems to be a good combination with the heavy duty OEM front and rear tranny mounts. All seems good. The Frankenmotor seems to work well.
Here's a pic taken just before we didn't leave for Carlisle this year. Still needed a new rad and rear engine mount install, wiring clean up etc. plus testing. I did get the new aftermarket rad in and the bugger leaked. That's when we decided to stay home.
Just for the hell of it and because I've never heard that Peter Venuti has had any problems with his Suby cooling, I asked him what he was running and this is what I got back:
I'm running an ej22 normally aspirated from a 1994 Legacy. Using a 2002 VW Passat radiator and condenser(for the A/C). This is all in the front of the car, tilted back at a slight angle and inside the nose of the car just behind the front bumper.
Along with two 12" or maybe 14" inch electric fans. Steel tubing (I think its 1.25 inch, two of them to make the round trip) carries the antifreeze to the rear of the car under the passenger rocker but rises up on both ends inside the wheel wells. Connections to the radiator and engine are done using rubber hoses.
There's a small electronic module used to monitor the temperature and control the fans (I can get a model # if you need it). I have not done any of the reverse cooling mods to the engine manifold - it's just not necessary. There is a third hose as well that taps into the high point of one the steel tubes in the front passenger wheel well. This is maybe 1/4 inch and used to help get air out of the system. It runs to the back of the car to a burp tank (pressurized overflow). The second line on the burp tank comes from the hose going to the thermostat side of the engine. I did this in hopes of getting more air out of the system.
All in all I think it works pretty well the only place I had an issue filling the system was the heater core. Its lower than the engine and had air trapped in it when I filled it the first time. Easy fix I pulled the heater core line off the engine and filled that portion of the system with the garden hose.
So how does it work? It works well. I can drive the car on 100 plus degree days with high humidity and it keeps it cool @180 degrees. Now, if I'm driving hard, 80-85 plus mph on the highway running the a/c, the car will run warmer like 190-200. Its fine for the engine but I don’t like seeing it on the gauge - not that I slow down.
Only problem I have had with the system is wiring from the fans to the fuse box. Not sure the gauge wire but after driving hard as described just above for about 7hrs, up and down mountains, 85-80F degree day, the coating on the wires got hot near the fuses so I was not happy about that. My assumption is that because I'm running so long, so hard, with only a small opening under the bumper to feed air to the radiator that the fans are working extra hard drawing a lot of power for the duration. Just rolled 30k miles, this is my 7th season, so I'm pretty happy. Pete
